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Not too shabby, with pushrod tubes that you just about can't get away from on the Olds Decent seats and bowls Exhaust looks decent - too bad there is a head bolt that exists between the two ports, but wonder what raising the roof on the ports may show on a flow bench? Looks like there is still a pretty good amount of casting thickness there to still work with. Good sized valves 2.125 Intakes, 1.710 Exhausts But why leave the chambers with such a coarse seemingly partial finish? It's just a matter of programming, so why not have it make a few more finish passes to smooth the chambers out to help eliminate any possible hot spots?
I don't recognize their work - suppose these are being done in house? Or does anybody recognize them? It's like a fingerprint, you can always tell if you have seen it before elsewhere.
I recently had a set of Speedmasters CNC ported for the Twin TorqStorm build, though they ended up falling short on the exhaust side, so will use them on my 488 instead - they will run very well on that engine. So just digging around looking at other head options for getting the most exhaust out of the cylinders as possible. Intake is no problem, as it's going to be shoved in at 15 +/- pounds of boost - getting it out the exhaust side is the challenge. The heads I had done ended up only managing 180 CFM at .600", while these Edelbrocks are at least coming in at 209 CFM at .600" - almost 30 CFM better. If I can't get the exhaust out, I can throw all the boost I want at it, but it will be directly limited to what it can exhale.
Yeah, just me thinking out loud. Anybody know of a conventional Olds head that can do better on the exhaust side? That's where I need to focus my attention, so let me know who's been able to accomplish the best work on the exhaust side that you may be aware of. I did see that Chadmans exhaust hit 240 CFM on his highly worked Wensler / RR heads with very high lift. Thanks!
I've seen their stuff before but haven't heard of anyone running their stuff, Olds or otherwise. They're just about 15 or 20 minutes from me. The address on their site points to a residential house just outside of town. Hmm.
Chamber finish might be a matter of having the right tool to make a nicer finish on that surface. It's not particularly easy because you're mostly cutting on the end of the tool but also hitting the sides due to the contours.
Intake flow seems pretty high to me. Not impossible, but definitely impressive. There's not enough exhaust roof room to do much of anything worthwhile. The entire port needs to be moved like in a Batten. I got nearly identical exhaust numbers with just Dumbass Home Porting..
"Conventional", meaning OEM cast iron head doing better? No. Battens would do better, but then you're in the world of Batten stuff. Or for those that are real serious, custom billet heads like what the Hunts are teasing everyone with.
Hi Mark.
Care to elaborate?
Enhancements would lead one to think a step forward in performance, do you have the data to back up that statement?
Still finalizing it but I’m not using the stock 2.150 intake or 1.68 exhaust valves for a variety of reasons.
And the only ones doing the runners AND the chambers are me and Peyton.
If two or three people bake an Apple pie.....one tastes better than the other two. It would seem that one person used something to enhance the flavor. They all used apples and pie crust. One could also assume there could be differences in CNC programs.
As a point of information here from a retired machinist, I can see differences between the heads in this thread and the ones Mark Remmel does. I haven't seen a close up off Travato's CNC work,
I can tell you the heads shown in this thread he was using a Ball End, End Mill. The spacing between machining passes shows its a wider pass than Mark's heads. I also wonder if he is using a 2 Flute End mill or he is pushing the feed rate and thats giving the coarse texture in the combustion chamber. And also notice the cutting tool "Chatter" in the radius between combustion chamber roof and the sides.
.....Just my two cents worth.
Last edited by OLDSter Ralph; Sep 9, 2023 at 08:13 PM.
If two or three people bake an Apple pie.....one tastes better than the other two. It would seem that one person used something to enhance the flavor. They all used apples and pie crust. One could also assume there could be differences in CNC programs.
As a point of information here from a retired machinist, I can see differences between the heads in this thread and the ones Mark Remmel does. I haven't seen a close up off Travato's CNC work,
I can tell you the heads shown in this thread he was using a Ball End, End Mill. The spacing between machining passes shows its a wider pass than Mark's heads. I also wonder if he is using a 2 Flute End mill or he is pushing the feed rate and thats giving the coarse texture in the combustion chamber. And also notice the cutting tool "Chatter" in the radius between combustion chamber roof and the sides.
.....Just my two cents worth.
You should check out the PDD CNC Edelbrock heads on face book. He is also working on a set of max effort billet heads.
The spacing between machining passes shows its wider pass than Mark's heads.
That's what I meant when I said it was a matter of programming, as you can change the amount, direction, and depth of the passes when plotting what the chamber is going to machine like. Of course the cutter being used is a factor, but you program around that based upon its actual cut patterns. Touch down with the cutter, rough in, then make a series of finer passes even in multiple directions to achieve a finer end result.
I know I could make those Competiton Components heads "happier" with an afternoon spent with the air motors, but having to take the heads completely apart and put them back together asks the question of why not nail in the first place in the CNC machining process? Yes, it may end up taking up to twice as long per head, and I get it, trying to keep costs down as time is money... A heavier coolant flow, faster feed rates, different cutters. I have put my hand and nose prints all over the booth glass at Grant Racing watching a Brodix monster BBC Chevy going through the motions - very cool to watch right there in front of you. Reed Grant has an awesome programming that initially rough cuts quickly, chips flying out of the ports with everything dancing around rather quickly, then the same cutter comes back and finely finishes the ports - you can hear the major difference when it finishes with the rough cut than doubles back for the finer cut. The RPM's increase dramatically for the finish passes, leaving an almost polished surface. I should have shot some video. I have tried to coax him into some Olds head work, but he is soooooo heavily buried that he can't keep up as it is. Fun to walk around his shop watching how much automation he uses in so many various processes. He says that's how he can be in three to four places at the same time
By way of comparison, here are the chambers of the work Mark (cutlassefi) did for me:
VERY IMPORTANT: Please note that I requested that the chambers be opened up to help unshroud the valves. These ended up at 85cc for use on a 4.350" bore size. My target compression ratio was 9:1 when these heads were done, as I am supercharging the 535. If I instead choose to use these heads on the 488, I will have to have them milled further to bring the chamber volumes back down smaller to better facilitate the 488 (that run the Mahle 22cc dish pistons in the Eagle stroker package). Good thing these Speedmasters have a reasonably thick deck - not sure how much they're going to have to be milled to get the chambers back down to 75cc to get back up into a 10:1 area - don't feel like switching pistons in the 488 as they are perfect, already fully broken into their respective bores.
Uh oh, I just realized that I may have painted myself into a corner though. While I had the heads out for photography, it occurred to me to grab a 455 head gasket and compare it against the chambers. Requesting to have the combustion chambers opened up means they are a bit wider now, so it looks like I would have to obtain some head gaskets that can provide a 4.250" to 4.275" combustion chamber fire ring, as the standard 455 Cometic 4.200" gaskets I have on hand now checked against the heads have a small amount of the fire ring overhanging into the chambers = won't seal properly. I will have to study this further, as running a 4.250" - 4.275" ID fire ring on a 4.155" bore may not yield optimum results. It will seal to the block properly, but the chambers being just a twinch wider than the bore on each side (left and right or fore and aft depending upon how you want to look at it) may present a problem. Running a standard 455 4.200" ID Cometic on a 4.155" bore yields a .075" area divided by two = an area of .0375" between the cylinder and the head. Running a custom 4.275" ID head gasket changes that to .120" difference divided by two = and area of .060" circumferentially between the head and the block, with the chambers possibly being .020" +/- wider on each side in relation to the bore. Oh how I drive myself nuts with this stuff!
Or? Hmmm... maybe I run these initially on the 535, not getting hung up on the 30 CFM exhaust difference for now. Looks like I have got some further thinking to do. I'd rather overbuild the 535 now with some really good flowing exhaust ports and detune for use in the G body (knowing the exhaust port flow will accommodate enough flow for any possible future uptuning) (possibly in a different chassis). At the current 180 CFM at .600" lift, I have a wall / limit requiring a future cylinder head change to uptune the engine. Things that make you go hmmmm....
I'm not on Fakebook either. Being the apparent dinosaur that I am, I want nothing to do with social media.
Laughing at myself now - you may as well go ahead and pile it on!
If you want to get them down to 75cc then you’ll need to take about .055-.060 off.
But you’ll need to measure along the way because the side walls of the chambers don’t go straight up and down, they’re flared a bit just like they are at the squish pads. In order to make them straight, that would’ve required a third CNC revision.
Just an fyi.
That's what I meant when I said it was a matter of programming, as you can change the amount, direction, and depth of the passes when plotting what the chamber is going to machine like. Of course the cutter being used is a factor, but you program around that based upon its actual cut patterns. Touch down with the cutter, rough in, then make a series of finer passes even in multiple directions to achieve a finer end result.
I know I could make those Competiton Components heads "happier" with an afternoon spent with the air motors, but having to take the heads completely apart and put them back together asks the question of why not nail in the first place in the CNC machining process? Yes, it may end up taking up to twice as long per head, and I get it, trying to keep costs down as time is money... A heavier coolant flow, faster feed rates, different cutters. I have put my hand and nose prints all over the booth glass at Grant Racing watching a Brodix monster BBC Chevy going through the motions - very cool to watch right there in front of you. Reed Grant has an awesome programming that initially rough cuts quickly, chips flying out of the ports with everything dancing around rather quickly, then the same cutter comes back and finely finishes the ports - you can hear the major difference when it finishes with the rough cut than doubles back for the finer cut. The RPM's increase dramatically for the finish passes, leaving an almost polished surface. I should have shot some video. I have tried to coax him into some Olds head work, but he is soooooo heavily buried that he can't keep up as it is. Fun to walk around his shop watching how much automation he uses in so many various processes. He says that's how he can be in three to four places at the same time
By way of comparison, here are the chambers of the work Mark (cutlassefi) did for me:
.......I'm not on Fakebook either. Being the apparent dinosaur that I am, I want nothing to do with social media.
Laughing at myself now - you may as well go ahead and pile it on! Paul
"Of course the cutter being used is a factor, but you program around that based upon its actual cut patterns. Touch down with the cutter, rough in, then make a series of finer passes even in multiple directions to achieve a finer end result." You DON'T "touch down with the cutter, rough in, then make a series of finer passes. You set a "Z" as your reference point on the head gasket surface. This is called "Z zero" and establishes the depths for all combustion chambers......otherwise you could have different CC's in each of the combustion chambers.
"Rough machining followed by a lighter "Finish cut" is basic "Machining 101" taught to machinists for 70 years or more. You just "discovered" a basic machining principle.
"I know I could make those Competiton Components heads "happier" with an afternoon spent with the air motors," It would be a "very long afternoon" because you have EIGHT combustion chambers to do. But hey, you can clean the heads one more time before you reassemble them.
In the end, I would not buy the first set of heads you showed pictures of, based simply on the workmanship (tool chatter marks, ridges). The idea behind CNC machining was to make identical combustion chambers and ports.
.....Just my two cents work.
Yeeeowwww - I almost lost it when I saw those max effort PDD billet heads - holy catfish!
The work on their Edelbrock heads looks nice - the bevel around their combustion chamber perimeters is a touch I also believe to be helpful. I wonder what their flow rates are coming in at on their Edelbrock heads. The max effort heads are what I feel I really need to let the 535 breathe - I'm sure their flow rates must be downright awesome. LARGE price point aside, I want to stay with a conventional intake / exhaust interface to keep it all under the low-profile G body hood line. I have envisioned hand making a sheet metal custom intake manifold, but I have to draw the line somewhere. The Offenhauser low rise dual quad intake will have to be worked as it is, though helps to equalize cylinder to cylinder runner lengths.
Mark, yes - thank you for your input, was thinking .065" - .075" cut on the head decks, which may also bring the combustion chamber perimeters back into the 4.200" Cometic head gasket ID, then working well on the 488. Curious - what about a "round two" on my Speedmasters? Do you feel you could put a larger exhaust valve in and open the exhaust ports up any to gain some further CFM ? Can the existing seats handle being opened up to accommodate a larger exhaust valve? Set the CNC program on the exhaust ports to remove 15% more material in key areas of the exhaust ports, essentially hogging them open larger where needed? For what I have into them, maybe I just need to have you go at them one more time to squeeze 30 more CFM out of them? Your thoughts please. The intakes are fine, the chambers are great, just need more exhaust flow.
Ralph - you are the machinist... I didn't discover anything, only documented what I observed in process... of course you have to tell the machine where your reference points are. I'm talking about once that is done, the machine in process of getting busy, and how Reed's final passes in the ports come out almost polished. An afternoon's time is all it would take me to very carefully smooth out those rough combustion chambers equally in the Competiton Components heads - I'm really really good with air motors. I have ported many heads before in my life, though don't easily have access to a flow bench these days, so flying blind without is not what I want to do (driving across town to flow a port at Reed's shop every time I make some moves). You can always take more off, but it's a little bit harder to put it back on (doh!), never mind hitting water (where the *fun* really starts).
Ok - let's keep it going! Talk to me guys - I just want to make the 535 breathe (obviously easier said than done on an Olds). The reading on the boost gauge will be irrelevant if the exhaust can't get it out. For everything that I am putting into this twin supercharged 535 build, I want to hit a mark in my mind where I have done everything realistically needed / possible to prevent the classic case of hindsight - should've / could've / would've - we've all been there.
7 PSI ??? Where did you get that notion? The TorqStorm twin supercharger package that I have is easily going to build WAY more boost than that - remember, we're talking 2 superchargers, not one. I'm looking at starting off in the 15 PSI +/- range as a general target. I'm currently working with a friend of mine from RideTech just down the street from me on his SEMA Mustang build that also has the TorqStorm twin supercharger package. We just got that running and oddly ran into a scenario where that rascal is already starting to build boost at 1200 RPM's (!) = definitely need to slow the superchargers down, as the BOV's are already starting to blow off at 1500 RPM making it hard to get it to idle back down. Boost at idle - never saw that one coming lol. This is on a World Products 427 Ford small block stroker engine. My 535 inch build is going to be moving a LOT more air than Andrew's "little" 427 Mustang is, with calculations showing my build will likely start building boost at about 2500-2800 RPM. With 535 base cubes to start with, I may even change pulleys to delay boost coming in until higher up in the RPM range depending upon how it behaves. I want this build to run with a high level of civility when just rolling down the road but go Dr. Jeckel / Mr. Hyde when I head deeper into the throttle. Probably 8 MPG when staying out of it, maybe 5 MPG when I am on it while running E85, maybe 10 MPG when on gasoline (!)
If I had the cubic dollars to do the Payton Hunt PDD Max effort Oldsmobile billet heads, I know I could get near the HP and Torque levels that beast in the video makes. BUT, reality check says um, no... So, I just want to get the exhaust numbers up high enough in the heads to work well with the ARH 2" primary tube headers and the ARH 3" exhaust.
Again, your friendly Ukrainian mad scientist scheming away on another wicked build. No way I'm going to let Andrew's Mustang take me out. After he's done with the show circuit, we have a grudge match in the making. He has lots more rear tire, but I have programmable traction control that he does not. Olds versus Ford - gotta gap his ***! 100 more cubes, vastly more experience building and driving - it's over before it even starts LOL.
Paul
Last edited by Clark455; Sep 11, 2023 at 03:40 AM.
Mark, so you believe you can coax some more flow out of these exhaust ports with some revisions? Stuffing a slightly bigger exhaust valve in? I believe there is plenty enough seat left, BUT I'm currently measuring in at .059" between the intake and exhaust valves as they sit. I know the very outer edge of the valves can be machined to bring their OD's down - been there / done that before when I used to have the equipment eons ago. If you feel comfortable that we can do it, that would be highly optimum, also helping further your evolving development on the Speedmaster heads in process for all future work. As mentioned, the intakes and the chambers are spot on target for me. After I got the heads back from you, I kept staring at them, tempted to whip out the air motors on the exhausts. But again, flying blind without direct access to a flow bench could get me looking good to my eyes, but potentially backwards / sideways on flow. If we can stuff a larger valve in, wittle some more shavings out of the right places in the ports, I'm willing to go "ROUND TWO" with the Speedmaster head development program with you. The short block isn't near built yet, looking at maybe January providing all goes to plan, so the heads are just sitting here - may as well have you take another run at them on the exhaust if you say the word.
One rabbit sitting in a hat - now the magician has to just pull the rabbit out of the hat (without getting bitten). Those super cool tricks don't always come easy.
If anybody can do it, I know you can do it. C'mon, let's take another run at them!
Thoughts?
Ya just gotta love it when you find the right side of your brain arguing with left side of your brain about stuffing more money into it, right?
That's what I meant when I said it was a matter of programming, as you can change the amount, direction, and depth of the passes when plotting what the chamber is going to machine like. Of course the cutter being used is a factor, but you program around that based upon its actual cut patterns. Touch down with the cutter, rough in, then make a series of finer passes even in multiple directions to achieve a finer end result.
I know I could make those Competiton Components heads "happier" with an afternoon spent with the air motors, but having to take the heads completely apart and put them back together asks the question of why not nail in the first place in the CNC machining process? Yes, it may end up taking up to twice as long per head, and I get it, trying to keep costs down as time is money... A heavier coolant flow, faster feed rates, different cutters. I have put my hand and nose prints all over the booth glass at Grant Racing watching a Brodix monster BBC Chevy going through the motions - very cool to watch right there in front of you. Reed Grant has an awesome programming that initially rough cuts quickly, chips flying out of the ports with everything dancing around rather quickly, then the same cutter comes back and finely finishes the ports - you can hear the major difference when it finishes with the rough cut than doubles back for the finer cut. The RPM's increase dramatically for the finish passes, leaving an almost polished surface. I should have shot some video. I have tried to coax him into some Olds head work, but he is soooooo heavily buried that he can't keep up as it is. Fun to walk around his shop watching how much automation he uses in so many various processes. He says that's how he can be in three to four places at the same time
By way of comparison, here are the chambers of the work Mark (cutlassefi) did for me:
VERY IMPORTANT: Please note that I requested that the chambers be opened up to help unshroud the valves. These ended up at 85cc for use on a 4.350" bore size. My target compression ratio was 9:1 when these heads were done, as I am supercharging the 535. If I instead choose to use these heads on the 488, I will have to have them milled further to bring the chamber volumes back down smaller to better facilitate the 488 (that run the Mahle 22cc dish pistons in the Eagle stroker package). Good thing these Speedmasters have a reasonably thick deck - not sure how much they're going to have to be milled to get the chambers back down to 75cc to get back up into a 10:1 area - don't feel like switching pistons in the 488 as they are perfect, already fully broken into their respective bores.
Uh oh, I just realized that I may have painted myself into a corner though. While I had the heads out for photography, it occurred to me to grab a 455 head gasket and compare it against the chambers. Requesting to have the combustion chambers opened up means they are a bit wider now, so it looks like I would have to obtain some head gaskets that can provide a 4.250" to 4.275" combustion chamber fire ring, as the standard 455 Cometic 4.200" gaskets I have on hand now checked against the heads have a small amount of the fire ring overhanging into the chambers = won't seal properly. I will have to study this further, as running a 4.250" - 4.275" ID fire ring on a 4.155" bore may not yield optimum results. It will seal to the block properly, but the chambers being just a twinch wider than the bore on each side (left and right or fore and aft depending upon how you want to look at it) may present a problem. Running a standard 455 4.200" ID Cometic on a 4.155" bore yields a .075" area divided by two = an area of .0375" between the cylinder and the head. Running a custom 4.275" ID head gasket changes that to .120" difference divided by two = and area of .060" circumferentially between the head and the block, with the chambers possibly being .020" +/- wider on each side in relation to the bore. Oh how I drive myself nuts with this stuff!
Or? Hmmm... maybe I run these initially on the 535, not getting hung up on the 30 CFM exhaust difference for now. Looks like I have got some further thinking to do. I'd rather overbuild the 535 now with some really good flowing exhaust ports and detune for use in the G body (knowing the exhaust port flow will accommodate enough flow for any possible future uptuning) (possibly in a different chassis). At the current 180 CFM at .600" lift, I have a wall / limit requiring a future cylinder head change to uptune the engine. Things that make you go hmmmm....
I'm not on Fakebook either. Being the apparent dinosaur that I am, I want nothing to do with social media.
Laughing at myself now - you may as well go ahead and pile it on!
Paul
I think you’re confused on where the fire ring is on the cometics. Aren’t they all 4.400”?
the bore diameter is whatever you ordered but the fire ring is the same on all Cometics
something isn’t right with 180 for a ported head like that. my iron ports with a 1.625” go 193+ at .700” and do not stall all the way through .800”
I can see at least 5 to 10 cfm just by looking at the valve face
I can see at least 5 to 10 cfm just by looking at the valve face
Right. That, and widening the chambers to unshroud the valves further, along with running in a larger 4.350" cylinder bore also helps flow immensely as compared to a stock shaped / sized chamber and the constraints of the small bore 4.155 +/- usual big block with cylinder walls right close to the valves that impeded port flow. Just taking the same head off a standard big block 4.155" bore and putting on a 403 with a 4.350" bore increases port flow considerably because the cylinder walls are further away from the valves / combustion chambers.
I will grab the camera later tonight and take some pics of the Cometic 4.200 bore head gasket against the cylinder heads to illustrate and may even have time to spank the valves out of one cylinder to provide views of the ports.
Heck, maybe the flow bench results were just skewed? There are a LOT of variations when running a flow bench - you can cheat to artificially swell the flow rates, or not have it set up just right and the readings come up short.
Here are the flow reports - not sure what bore size they were flowed against (likely 455):
Int.#1
Flow
.100 2 28.00 69.60 .0 65.7 Int #1
.150 3 28.00 50.80 .0 97.6 Int #1
.200 3 28.00 63.00 .0 121.0 Int #1
.250 3 28.00 79.80 .0 153.3 Int #1
.300 4 28.00 47.40 .0 179.9 Int #1
.350 4 28.00 55.70 .0 211.4 Int #1
.400 4 28.00 64.00 .0 242.9 Int #1
.450 4 28.00 71.60 .0 271.7 Int #1
.500 4 28.00 76.10 .0 288.8 Int #1
.550 4 28.00 78.80 .0 299.0 Int #1
.600 4 28.00 77.40 .0 293.7 Int #1
.650 4 28.00 78.90 .0 299.4 Int #1
.700 4 28.00 80.20 .0 304.4
Valves are SI Stainless SEV Series
Valve Sizes are Intake 2.125 / Exhaust 1.68
Spring Rates are 140# on the seat and 400# at .600” lift
Valve Seat Angles are 45* with a 30* top cut and 60* bottom cut
Combustion Chamber Volume 85cc
I'm looking at running .600" lift, as I want to minimize how hard I'm pounding the valve train as I want to retain durability for cross country trips such as the HotRod Power Tour and such. Pounding the valve train harder with higher lifts isn't worth the 5-9 CFM to me.
Right. That, and widening the chambers to unshroud the valves further, along with running in a larger 4.350" cylinder bore also helps flow immensely as compared to a stock shaped / sized chamber and the constraints of the small bore 4.155 +/- usual big block with cylinder walls right close to the valves that impeded port flow. Just taking the same head off a standard big block 4.155" bore and putting on a 403 with a 4.350" bore increases port flow considerably because the cylinder walls are further away from the valves / combustion chambers.
I will grab the camera later tonight and take some pics of the Cometic 4.200 bore head gasket against the cylinder heads to illustrate and may even have time to spank the valves out of one cylinder to provide views of the ports.
Heck, maybe the flow bench results were just skewed? There are a LOT of variations when running a flow bench - you can cheat to artificially swell the flow rates, or not have it set up just right and the readings come up short.
Here are the flow reports - not sure what bore size they were flowed against (likely 455):
Int.#1
Flow
.100 2 28.00 69.60 .0 65.7 Int #1
.150 3 28.00 50.80 .0 97.6 Int #1
.200 3 28.00 63.00 .0 121.0 Int #1
.250 3 28.00 79.80 .0 153.3 Int #1
.300 4 28.00 47.40 .0 179.9 Int #1
.350 4 28.00 55.70 .0 211.4 Int #1
.400 4 28.00 64.00 .0 242.9 Int #1
.450 4 28.00 71.60 .0 271.7 Int #1
.500 4 28.00 76.10 .0 288.8 Int #1
.550 4 28.00 78.80 .0 299.0 Int #1
.600 4 28.00 77.40 .0 293.7 Int #1
.650 4 28.00 78.90 .0 299.4 Int #1
.700 4 28.00 80.20 .0 304.4
Valves are SI Stainless SEV Series
Valve Sizes are Intake 2.125 / Exhaust 1.68
Spring Rates are 140# on the seat and 400# at .600” lift
Valve Seat Angles are 45* with a 30* top cut and 60* bottom cut
Combustion Chamber Volume 85cc
I'm looking at running .600" lift, as I want to minimize how hard I'm pounding the valve train as I want to retain durability for cross country trips such as the HotRod Power Tour and such. Pounding the valve train harder with higher lifts isn't worth the 5-9 CFM to me.
More pics coming later - stay tuned.
Paul
the 5 to 10 cfm im talking about is from adding a good radius to the ex valve face at the margin. Nothing to do with pounding anything..yours don’t have that. It’ll add some cfm from lifts just off the seat to mid range ,then diminishes.
I am not the world's greatest photographer, so here is an overabundance from a whole bunch of different angles and lighting, each seemingly highlighting at least something different than the prior so as to get the "full picture"
I think you’re confused on where the fire ring is on the cometics. Aren’t they all 4.400”?
the bore diameter is whatever you ordered but the fire ring is the same on all Cometics
And more, illustrating the head gaskets, dowel pinned into place for accuracy:
4.200" MLS 4.200" ID MLS head gasket overhanging into the right and left side of the enlarged combustion chambers 4.200" MLS 4.200" ID MLS head gasket for 4.125" bore Screwdriver indicating the fire ring / combustion chamber seal 4.200" ID MLS head gasket for 4.125" bore Screwdriver indicating the fire ring / combustion chamber seal
Above are the 455 head gaskets - below are the 403 head gaskets
4.400" ID MLS head gasket for 4.350" Bore Screwdriver indicating the fire ring / combustion chamber seal 4.400" ID MLS 4.400" ID MLS
So see the fire rings? aka combustion chamber seals? They are indeed sized accordingly - they are not all 4.400" unless you've been using the wrong part numbers for the 455's with the smaller bores (!?) The 4.400" are for the 403's, and the 4.200" are for the 455's
Study away and give me your thoughts. I'm thinking hog the exhaust bowl open for a larger exhaust valve, mow some more material out of some key places in the exhaust ports = should be able to get some more CFM out of these exhaust ports. I am not sure how much more the exhaust seats can be opened up before they could become a possible liability. Under boost, there are going to be some pretty high exhaust temps (EGT) - HOT / FIRE !!!
I welcome all thoughts and suggestions! What would you do to feed a twin supercharged 535 Olds build?
(yes, of course the exotic PDD billet super heads would unleash the full potential, but again, costs aside, would require different exhaust and induction which I prefer to stay away from as per the very low hood lines of a G body where my goal is to hide all of this under the stock hood)
Paul...
Last edited by Clark455; Sep 12, 2023 at 07:46 PM.
And more, illustrating the head gaskets, dowel pinned into place for accuracy:
4.200" MLS 4.200" ID MLS head gasket overhanging into the right and left side of the enlarged combustion chambers 4.200" MLS 4.200" ID MLS head gasket for 4.125" bore Screwdriver indicating the fire ring / combustion chamber seal 4.200" ID MLS head gasket for 4.125" bore Screwdriver indicating the fire ring / combustion chamber seal
Above are the 455 head gaskets - below are the 403 head gaskets
4.400" ID MLS head gasket for 4.350" Bore Screwdriver indicating the fire ring / combustion chamber seal 4.400" ID MLS 4.400" ID MLS
So see the fire rings? aka combustion chamber seals? They are indeed sized accordingly - they are not all 4.400" unless you've been using the wrong part numbers for the 455's with the smaller bores (!?) The 4.400" are for the 403's, and the 4.200" are for the 455's
Study away and give me your thoughts. I'm thinking hog the exhaust bowl open for a larger exhaust valve, mow some more material out of some key places in the exhaust ports = should be able to get some more CFM out of these exhaust ports. I am not sure how much more the exhaust seats can be opened up before they could become a possible liability. Under boost, there are going to be some pretty high exhaust temps (EGT) - HOT / FIRE !!!
I welcome all thoughts and suggestions! What would you do to feed a twin supercharged 535 Olds build?
(yes, of course the exotic PDD billet super heads would unleash the full potential, but again, costs aside, would require different exhaust and induction which I prefer to stay away from as per the very low hood lines of a G body where my goal is to hide all of this under the stock hood)
The 4.200" bore MLS head gasket shown is the Cometic MLS Head Gaskets C5809-027
The 4.400" bore MLS gasket shown is the Mr. Gasket MLS Head Gasket 3247G
Note: HOLLEY IS STILL GIVING AWAY THESE MR GASKET 403 MLS HEAD GASKETS AT A STUNNING $18.90 EACH AS OF THIS WRITING. I bought 10 of these just stocking up due to the price point. 10 at $18.95 = $189.95 - STILL cheaper than just buying 2 Cometics (!)
These head gaskets BELOW are the ones I intend to run on the 535 to handle any and all boost I may throw at it without worry - not much more than the Cometics at $139.92 apiece:
SCE ICS Titan S793843 Olds 4.380 ID - NOT the proper size for a 455.
NOTE: These have a very solid built in combustion chamber stainless o-ring and will Brinell the engine block and cylinder heads. This means it will leave a pronounced circular indention into the softer aluminum of the cylinder head and also somewhat into the deck surface of the engine block. Great for sealing very high cylinder pressure, and "happy" when replaced with the same exact gasket, but these are permanent indentions that would take milling of the head and block decks to remove. For the sake of clarity, once you go to these and they leave their pronounced witness marks into the heads and block, you should not risk switching to a different head gasket design without milling the heads and block to ensure a proper seal with a different design head gasket. You don't run these and then just swap them out for any other head gasket. Once you go to these, you stay with these, which is not a bad thing, but some need to know that there is no turning back without milling the heads and block.
Last edited by Clark455; Sep 12, 2023 at 11:29 PM.
The date on yours seem to indicate a production of 07/11 - old designs?
3.920" bore isn't correct for the 455 with the 4.125" stock bore size either...
The H2187SPL045S number doesn't come up on the Cometic website or an internet search. The "SPL" suffix may be an indicator of "special" one offs, or these are in indeed an older discontinued design. I did have to rub my eyes there for a minute when I first saw them, as they struck me as rather odd. The silver rivets holding the sections together are also something I haven't seen before in a Cometic, as compared to the one you have lower down for the 4.400" bore that I am used to seeing.
I get a kick out of seeing "Olds 455 BB/SB 4.400" as that can cause some serious customer confusion. Your 4.400" bore versions show a date of 05/05 - not sure what gives.
Definitely "trippy like a Mississippi hippie"
Last edited by Clark455; Sep 13, 2023 at 11:08 AM.
The date on yours seem to indicate a production of 07/11 - old designs?
3.920" bore isn't correct for the 455 with the 4.125" stock bore size either...
The H2187SPL045S number doesn't come up on the Cometic website or an internet search. The "SPL" suffix may be an indicator of "special" one offs, or these are in indeed an older discontinued design. I did have to rub my eyes there for a minute when I first saw them, as they struck me as rather odd. The silver rivets holding the sections together are also something I haven't seen before in a Cometic, as compared to the one you have lower down for the 4.400" bore that I am used to seeing.
I get a kick out of seeing "Olds 455 BB/SB 4.400" as that can cause some serious customer confusion. Your 4.400" bore versions show a date of 05/05 - not sure what gives.
Definitely "trippy like a Mississippi hippie"
i never said the 3.920” was for a 455, I said it’s for the late 400, which is why it’s 3.920”. It is special order.
the silver rivets aren’t rivets..they are machine screw and nuts so I can can take them apart for easy cleaning when reusing them or to change the middle shim to a different thickness
you don’t think you’ll need O rings? How much boost?
I reused mine. Drilled the rivets, cleaned each layer, then sprayed each layer with copper RTV. Worked fine, but I did just buy a new set, probably won't do it again.
the silver rivets aren’t rivets..they are machine screw and nuts so I can can take them apart for easy cleaning when reusing them or to change the middle shim to a different thickness
You know, as your eyes get older... I thought those may have looked like screw heads, but couldn't tell for certain in the pics.. Are you Loctiting the little screws and nuts to make sure the ones inside of the engine valley won't come apart? Or removing them counting on the dowel pins in the block decks to maintain proper placement? I'd sure hate to have those little screws come apart inside of the engine.
i never said the 3.920” was for a 455, I said it’s for the late 400, which is why it’s 3.920”. It is special order.
Aha, so these ARE indeed a special order, which explains the fire rings being so far away from the actual cylinder. That had me really scratching my head. Well, actually still has me scratching my head as to having the fire rings so far away from the cylinder...
I think you’re confused on where the fire ring is on the cometics. Aren’t they all 4.400”?
The way you were speaking about them ALL having the fire rings at 4.400" is what ran me off in the notion that you may have also been speaking of 455 head gaskets. At least that's what I got out of reading your statement...
you don’t think you’ll need O rings? How much boost?
I am not sure how much boost the Twin TorqStorm package is going to tolerate with methanol injection and E85 air charge cooling (non intercooled). My off the cuff target is 15 PSI, but I don't want to risk tossing a head gasket if it ends up being able to take more. During the first 100 miles, I won't even have the supercharger belt on. After that, I'll put the belt on, setting the BOV's (blow off valves aka waste gates) at 3-5 PSI until about the 500 mile mark. Once the 500 mile mark has been achieved, I should have the majority of the tuning ball parked in. That's when I intend to slowly start creeping up on the boost a couple of PSI at a time adjusting the tune as I go towards the 1000 mile mark. Once at that point, it will be a graduation of 2-3 PSI at a time until I hit the point where the engine starts complaining OR the chassis is complaining constantly up against the traction control. If it will take 20 - 22 pounds of boost on E85 (while fire hosing methanol down the throats of the superchargers) without rattling under boost setting off the knock sensors (doubt it), well then by golly I will certainly not want to be worried about tossing a head gasket (!) These SCE Titans are o-ringing the package without the absolute permanence of actually machining for o-rings.
Can the cometics be reused? or are they done after there compressed?
Depends upon who you ask... Dale seems to imply that he is re-using them. I know some split the rivets, clean them up, spray them down with Permatex copper spray-a-gasket or Hylomar, stuff them back in and have no problems. BUT, you couldn't pay me to do that as it becomes a choice of a "coupla hundred bux" versus possible head gasket problems = no thank you, I will replace the head gaskets instead of rolling the dice. If you are in a scenario where you are constantly yanking the heads, such as dyno testing or drag strip class specified tear downs, then it starts adding up quickly, definitely looking at re-using them. If you are in a build where you want to build it once, build it right, and not look over your shoulder concerned about popping a head gasket, then do not re-use. Absolutely no no to use on one engine then attempt use on a different engine in my opinion. If you are re-using on the same engine, the same basic crush points / patterns will be there as per the machining and how the decks on the heads and block have settled. Guys that re-use make sure that the block side stays to the block side, head side stays to the head side, and do not mix up passenger to driver's side during re-assembly. The middle is a thicker flat steel shim without embossments, so its not particularly subject to losing any of its properties if / when re-used.
Paul (aka BigBlock Pauly and / or Maxboogie from my days of Unlimited Racing back in Detroit)
Last edited by Clark455; Sep 13, 2023 at 04:45 PM.
CNC Ported Edelbrock Heads
Costs
Machining
15 + PSI of Boost
