cutlassefi

Simple, I base my recommendations based on my own experience.
Case in point, I did a 380 stroker, RPM intake, 9.0:1, 216/221 Hyd roller cam, 7a heads with 2.00/1.625 valves. During wot dyno pulls it started pulling almost 2" of vacuum above 4500rpm or so, and that was with a 750 Quick Fuel carb. That means there is a restriction somewhere in the intake tract.
Your carb is too small.

HWYSTR455

My experience is the same, on a 355, ended up with a Crane HR 809621, which is a 222/230 @.050, .542/.563 lift, on a 112 LSA, think it's perfect for a daily driver with some punch. Above 4800 or so it starts pulling vacuum with a 670 Holley & RPM intake, and choking on the top. I had a 770 on it for a while, but the idle circuit was crappy, think there was a casting issue with the aluminum ones when they first came out, so went back to the 670. Noticeable drop off at the top.

With 3.42s, 3000 stall, TH400, headers, 2.5 full exhaust, street tires (275/40/17), full street trim, A/C running in staging lanes on a 100+ degree day, 210 water temp, did a traction limited uncorrected 13.66 . Fairly confident I can get it into the 12s. Iron heads.

.

cdrod

Yesterday, I dropped off my block to the engine builder. It was a momentous occasion as months have passed since I last spoke with him about my build. He's unfamiliar with the Scat rods that so many here have endorsed, and he didn't like the idea of using the Chevy pistons with un-needed valve reliefs either. So he wants to plan out my build using parts he knows, which probably means eagle rods and somebody's custom pistons - $$$?? He's built a few Olds motors and seems to understand that they are different than Chevy motors, but I still plan to double check him before starting to cut anything. He is also concerned that the ProComp heads do not fit my goals of low-end torque, snappy throttle response and reasonable mileage. My rear gear is 3.42:1 and the final drive ratio with the 0.67 OD trans will be 2.29:1. I appreciate his caution against building an aggressive motor for a daily driver (with AC, PS, PB, etc) but many here have said the PC heads will work just fine.

So here's my idea and my questions:
1. Can he build the motor with 10:1 CR using the AL heads and have the option to switch to the #7 irons if the throttle response is doggy?
2. Is 10:1 CR too high to run the #7 iron heads?
3. The AL heads have a 70cc combustion chamber, the #7s is probably 68-69cc.
4. Can I reduce the CR to 9.7 by increasing the head gasket thickness when changing from AL to iron heads? Maybe use .020" gasket with the AL and use an .043" gasket with the iron heads.
5. Is there an optimal quench distance (piston to head) that works best with the small block Olds?
6. Will lowering the CR from 10:1 to 9.7:1 (to switch from AL to iron heads) make the cam too big?

I look forward to your comments.

HWYSTR455

You either build the engine to accommodate alum heads or the iron heads, that's pretty much your choices (in a nutshell). So no sense worrying about the CR when switching.

With your final drive ratio, the moment you put any kind of load on it, it will downshift, so pointless to not change the rear gears as well. Any hill or grade, and that thing will 'hunt' for a gear, and not only will it drive you crazy, it also puts a strain on the trans. More gear will help any concerns of 'bottom end' too.

Theoretically, alum heads 'require' a higher static CR over iron, because of thermal heat loss, and as a rule of thumb, that's 1 point. So an engine with iron heads, if you target 10:1 SCR, with alum heads, you would target 11:1.

Generally, higher static CRs offer better low-RPM performance, all else being equal. That's why some cams are designed to provide more pressure, or dynamic CR at lower RPMs, and are used/work well in low-SCR engines.

There will always be compromises, can't have a 3000HP engine and get 50MPG. But if you select stuff for compromises within reason, you can acceptable performance and economy.

You want examples of drive ratios that work? Look at the spread in new cars, that will give you an idea. Have to keep in mind gear splits too, which is why many OEs are going to 6, 7, and 8 speed or variable transmissions.

.

wr1970

Seems to be a lot of waffle going on in this thread wants torq at low rpm up to about 4500 and yet says wants gas milage.Says this isn't a race motor but is setting it up to perform like a race engine!! The whole deal about keeping it a resto mod with 350 just sounds like a waffle to me. You are not building a correct restore.Excuses, excuses performance requires dollars and gas milage is secondary.Yes you can make a performance engine but you may have to give up some miles per gallon to get it. The real answer is what you are willing to accept.Good luck with the build it will be interesting to see how it comes out and if it meets your expectations. Some good advice has been given in this thread. Carry on guys.

olds 307 and 403

CP makes a 4.125" bore, 1.3cc dish stroker pistons that work with a 6" rod and come set up with the sbc .927" pin. BTR Performance brought them to market and they cost $680 with rings from him. Bill Travato is an Olds guy, wrote the High Performance Olds book and was a National record holder with Olds power.

captjim

I have given this advice a bunch of times. Instead of trying to re-invent the wheel, just copy an existing build that meets your goals and fits your budget. Mark and other Olds builders have dyno and track proven builds/parts combinations, choose one and go with it. You are making this more complicated that required, IMHO.

olds 307 and 403

I would measure the Procomp heads combustion chamber, most say they are 80+ CC out of box. I wouldn't go too small on the cam with 9.7 to 1and iron heads. Get the pistons from BTR, mill the Procomp heads and add a cam to match, Mark or Bill can help you with that.

cutlassefi

Some inaccurate or at the very least incomplete info.
Raising the compression ratio helps power and efficiency everywhere, not just at low rpm. It's one of the only things you can do that'll make that type of difference.
And if you're going for mileage as well and the most power possible, take a lesson from the current stuff. Thin ring packs and short piston skirts for less drag, light internals, and the most efficient cylinder heads possible. And that ain't the stock irons. Add to that roller cams that have less friction while allowing higher, faster lifts without added duration. You can make the better part of 400hp with reasonably good efficiency, just got a work at it a little harder than the Chevy guys. I know, I did it.

Of course fuel injection would be in the works as well, but only partially for the fuel side. Being able to control spark for maximum efficiency from cold start startup to hot running can have a huge effect on overall fuel consumption.

Do what you want to do and whatever your budget can afford. Just sayin.

cdrod

Bernard Mondello has already milled my ProComps down to 70cc. I didn't think to ask him how much was removed to make this happen. Is it a big cut to drop 10cc?

Mark:
I've decided to stay the course with the ProComp heads and use a .027" head gasket and shoot for 10.5:1 compression ratio. If the throttle response is poor (because of the intake port velocity of the larger port) I'll have the machine shop go through my #7 iron heads and use a .051" head gasket to bring the compression ratio down to 10:1. I can sell the aluminum heads to help pay for the machine work on the iron heads. I really think I'm gonna be alright with the aluminum heads. Like you said in your earlier post, it just makes sense with all the other "upgrades" I have planned for this motor (narrow ring pistons, small journal stroker crank, roller cam and full roller rocker arms).

Do you see any problems with my "back-up" plan approach? I think it's good to have options as long as I don't have to make compromises to keep those options.

cutlassefi

You won't need a backup plan, the Procomps will work just fine for you.

olds 307 and 403

It will probably be a .070" or so cut, more than likely your intake will need cut a similar amount. Especially with Ultraseal or other composite gaskets. I wish we were a big enough market to have heads with two chamber sizes, 67 and 77cc chambers from Edelbrock would mean bolt on and go for us SBO guys. Procomps need gone through anyways but adds to the cost.

cutlassefi

Christian, I have to disagree a bit.
Thankfully we can mill the heads enough to make a difference. And secondly the Procomps are half decent right out of the box, certainly no worse than a set Edelbrocks.

80 Rocket

Despite what BTR says about the Edelbrocks in his book, they will probably need work out of the box. And when it comes to Pro-Comps, they most definitely need work out of the box.

Now if your out of the box Pro-Comps come from Bernard Mondello, well, those have been worked over by him and are right. So, let's not confuse a set of Bernard Mondello Pro-Comps as out of the box compared to the joe shmoes selling Pro-Comps straight off the ship from China, because chances are, they are ****.

From what I see on ebay, you can buy Pro Comps a bit cheaper than what Bernard Mondello sells them for, but you will most likely need a competent head guy to go through them, and they would be cheaper if you actually got them done right through Mondello (Bernard Mondello, not Mondello Performance Products, stay FAR away from them).

And if you are serious about horsepower, the Rocket Racing heads are where it is at for gains. When I decide irons have been maxed out for what I am doing, my next logical step is a set of Rocket Racing offerings.

cutlassefi

Don I'm guessing by your words "because chances are" that you're speculating here and that you've never actually had a set of Olds Procomps in your hands?

If so then my experience is vastly different from your opinion. 1 complete set from Bernard, just fine. 2 sets purchased elsewhere bare but otherwise ready to go. Champion race heads in Florida checked them and commented the valve job was "pretty good" right out of the box. And they're thicker in the needed areas than an Edelbrock is.
If you don't know first hand then please don't post. How would you like it if someone posted the same way about Rocket Heads?

For the last time, my first hand experience with 3 sets of Procomps is that they're just fine.

80 Rocket

Your experience differs from someone else in the industry with their first hand experience.........someone who has had a lot more then 3 sets of Olds Pro Comps in their hand. Look, my opinion is not formed on some bias towards China. I know first hand they can manufacture decent products as I have imported from their before. I have also imported from Korea and Indonesia.

My opinion is also not formed on the basis of one person, but of many. One of the others is in the guide making business and told me he sells a ton of replacement guides for Pro-Comp heads because they are junk out of the box. It just so happens they require a special guide because of the OD.

I would almost say Pro Comp is paying you to defend them because you are really looking silly. I'm sorry, but I would trust the opinion over someone who deals Pro Comp stuff all the time over your three sets you had in your hands.

Tell me, what was the guide clearance out of the box?

cutlassefi

I don't work for or am a dealer for Procomp, period. I pay what everybody else pays.
And guide clearance was .0012-.0014 on the intake and a bit looser on the exhaust iirc.
And bottom line it sounds like you're still taking someone else's word for it. Buy a set and evaluate them for yourself, not thru someone else. I'm pretty sure you'd want others to do the same with a set of RR heads right?

Thank you.

Boldsmobile

Don, you can also substitue champion for first hand.

captjim

Just curious, Don, what is the cost of the RR heads and dedicated intake, just to compare costs? Thanks.

80 Rocket

$2800-$3000......not sure but it is in that window.

80 Rocket

I wonder if they hand hone the guide clearance at the factory specifically to every valve then, because I know first hand that the Pro Comp valves are all over the place and it takes about three sets to make one consistent set as far as stem diameter goes.

If you dispute the fact that Chinese valves are known to be all over the place for consistency, well, now I know for a fact you are full of it.

I'm sure John @ Rocket Racing would definitely appreciate it if EVERYONE bought a set of Rocket heads so they can have an opinion on them. I'm sure Chevrolet would like everyone to buy a Chevy truck to form an opinion on them. I'm sure the shady auto repair facility in town would love for everyone to bring their cars to them to see if they do good work on cars as well.

cutlassefi

Thank you Don I appreciate the kind words. You're right I don't know a thing. However I try not to assume like you apparently do. I didn't use Procomp valves, I used SI, which as I mentioned before are made in Brazil not China. So who looks the fool now? Done here, sorry for mucking up this thread.

Thank you.

80 Rocket

Are you hard of understanding the English language? My whole premise, to which you rebutted, was that an out of the box head from Pro Comp is junk. Now you are telling me you used different components and had the heads custom tailored by your head guy?

Here's my quote:
"So, let's not confuse a set of Bernard Mondello Pro-Comps as out of the box compared to the joe shmoes selling Pro-Comps straight off the ship from China, because chances are, they are ****."

So, you have had one set by Bernard (which is gone over by him), and at least one set done by your head guy, or both......so tell me, how the hell can you give an educated opinion about a fresh off the boat Pro Comp "ready to bolt on" when you yourself apparently have no experience.

Is this a joke?

cutlassefi

You have your opinion and I have mine. As mentioned, done here.

80 Rocket

No you're not.

olds 307 and 403

Mark compared bare heads awhile back, Procomp's were better than the Edelbrock's in some respect. I know you guys are looking at selling ported iron heads, are the aluminum heads really that bad?

67 Cutlass Freak

I personally spoke with the one person who has sold more Pro Comp heads than all others put together, just last week. He likes the extra material in places for porting. He also told me the overall machined surfaces and alloy strength is very good, for the price. He purchases the heads ten sets at a time. He has seen a lot of problems and rejected a significant amount. He rejects any that have been welded on. He saw some big problems with guide to valve clearance, mostly on the exhaust guide. He told me he measures every one. He has seen them @ .006" clearance. He told me if the first one was out of spec, than all the rest were as well. He told me he has had quite a few guys that purchased them from no name vendors on Ebay, and they were total garbage, that he had to fix. I do not have an axe to grind here. I am glad that Pro Comp is offering a stock replacement aluminum head, that is considerably more affordable than the E-brocks. They are much easier to port than the cast iron junk. From what I have seen, the out of the box flow numbers are pretty lack luster. This same expert told me that Ebrocks are even worse when it comes to guide clearance. He said every one is too tight out of the box, and not just Oldsmobiles. My best advice to anyone interested in purchasing Pro Comp heads would be to buy them bare, and bring them to an expert. Now I hope that I didn't just get myself in trouble by passing on that info.
Have another beer guys... Dave - The Freak

Boldsmobile

Dave, your input - as is Dons - is always appreciated. Even if you didn't have Champion check them out.

80 Rocket

This has nothing to do with iron heads. This has everything to do with a misleading statement by cutlassefi:

"And secondly the Procomps are half decent right out of the box"

That's why I clarified by saying getting your Pro Comps from a trusted source, like Bernard Mondello, is the way to go because you can at least know that they have been checked out by an experienced engine guy. That was my whole premise, and kind of an endorsement for Pro Comps, wouldn't you say? How this can be misconstrued as me trying to sell an iron head is beyond me. Or how cutlassefi would jump on me after that statement is beyond me as well.

Moreover, Mark has zero experience with an out of the box assembled Pro Comp from some fly-by-night ebay vendor. That is what I am trying to warn people of, not to go down that route with these heads, because chances are you will have wasted a bunch of money.

I don't know if anyone here is familiar with speedtalk.com, but that site is pretty much the pinnacle of hardcore engine/machinist talk. Let's see what the big time players in the industry have to say about Pro Comp stuff:

http://speedtalk.com/forum/viewtopic...o+comp#p498253

http://speedtalk.com/forum/viewtopic...hilit=pro+comp

Here's a very good read about iron vs. pro-comp:
http://speedtalk.com/forum/viewtopic...hilit=pro+comp

Here is an older thread detailing the issues Pro-Comps had, or may still have (the timeline of this was the same time cutlassefi did the Edelbrock vs. Pro Comp thread here on CO):
http://speedtalk.com/forum/viewtopic...hilit=pro+comp

All in all, I believe in bare form, you can probably get a usable product......and in the right hands, the Pro Comps can be made to work. Hopefully without too much correction, but the consensus is that they have room to port and they are a good casting for the dollar spent (the newer ones, not the older stuff).

Maybe something got lost in translation with Mark and myself. Maybe he would agree with the premise I laid out. Or, maybe he disagrees with my opinion formed by using a simple internet search to see what the top engine/head guys in the country have to say about Pro Comp stuff, as well as other avenues of forming an opinion.

I think there is nothing more to say in this thread about Pro Comps. Stay tuned for a new thread........should be fun gents!

cdrod

Hey guys:
I have an opportunity to buy 2 standard-bore 403 blocks for $100. The motors are disassembled, but the guy has the heads, intakes, and all the rotating assemblies. Wouldn't the 403 be better than a 375cid stroker for a high-torque, low rpm, street engine? Assuming the same goals and internals, i.e. 400HP, 400TQ, better rods and pistons, etc. Should I be worried about the windowed mains at this power level? Everybody keeps telling me there's no replacement for displacement, but I don't want a big block.

olds 307 and 403

There are actually decent pistons available for the 403, either Arias forged or KB hyper pistons. You need either #8, 4A or big block heads with the above pistons. Both pistons are lighter than stock and the 403 rods are the strongest small block rods. Put in ARP fasteners and a girdle if you are worried. The 403 can run very hard, just keep your rpm's reasonable.

captjim

IMO, the windowed webs are not the problem, the Siamesed, thin cylinder wallas are. Difficult to properly hone, ring seal is an issue, as is overheating. Fine for a mild/hot street build. But, if I were you, I would do the budget both ways and see where you come out. With the stoker you will get less cubes but a rock-solid bottom end, better rods, better bore/stroke ratio, for a few $ more. Just my opinion.

olds 307 and 403

I would get the KB pistons in .024" oversize and either SBC rods or your 403 rods resized with ARP bolts. That will put you at 10.5 to 1 with Felpro gaskets. J&S has a no machine girdle or mill your cap girdles plus many others offer the same. The 403 does run warmer, just make sure your cooling system is up to par. The 403 will go together cheaper than the stroker will.

cdrod

Remember the A-team from 70's TV (I'm showing my age here). Well the boss character's signature line was, "I love it when a plan comes together!" Well I feel exactly the same way! After a a lot of reflection, contemplation, questions, etc. I've decided to move forward with my 375cid SBO stroker plans. I looked up a machinist I had used 20+ years ago, who is now semi-retired but still has his shop and tools. He & I came to an agreement on the machining costs, I will provide all the parts and he's going to let me help with the blueprinting. I plan to assemble the engine myself to save on labor costs. I've crunched the numbers pretty hard and have a clear budget for this build now - which is what I wanted from the previous engine builder. I am posting my budget looking for input from those that have done this before me and for the benefit of others who may be considering a similar build. I still need to get with Mark (CutlassEFI) on the cam specs, but most of the other details are decided. Here's my budget/plan:



There is a pdf version in the attachments of this thread if you can't read the embedded image above.

cutlassefi

A few things.
First of all I applaud your decision. I think you will be very happy with the results. Man I wish I could get someone to do a 3.875" SBO crank. I'd bet they'd sell like hotcakes.

That's a great list but I have some concerns.

1)$120.00 to open up the drainback holes? Takes 30 min.
2) .015 square deck? How does he know how much it will take to clean and truly make it square? Hmmmmm...
3) Don't widen the rod journal anymore than necessary, cut the rods to achieve the clearance you need, and cut the big side, they're offset.
4) $250.00 General labor? I'd get a better explanation there.
5) Why are you spending $190.00 on Cometics? If your guy decks the block correctly and the crank stroke is accurate you can be within a couple thousandths of where you need to be. Then use a std .040 head gasket and you're there.
6) Use the 7/16 cap screw rod, much better piece. Use one of the new Mahle pistons as well, better ring pack and cheaper than the CP's.

These are just a few tips. Again overall I think this is a great plan. Keep us posted!!!!

cdrod

Mark see my answers above in bold type. I have attached my clearances worksheet below if you want to check my calculations.

Thanks for your input on this, it is very much appreciated.

captjim

Couple of other things; Mark knows much more than I do about this, but I am not a huge fan of the HV oil pumps on street cars with snug bearing clearances. Also, can you get a quality balancer for $80?

cdrod

Jim:
This is a Professional Products balancer. Didn't think I needed an SFI type balancer for a daily driver. Is this not the best part for my application? See pdf below.

captjim

I have no idea, but i would ask Mark or anyone else who has used one.

cdrod

I've started the ball rolling on the small block stroker engine. It's been like Christmas around my house as the big brown truck has been delivering the engine parts to my front porch. I dropped off the parts to the machine shop on Thursday to check the block and crank; then off to the crank grinder to stroke the crank. After planning for this build for over a year, I'm so excited, I'm almost walking on air right now!

Here's a pic of the parts: