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It's my first build and I would like input. Shooting for safe operation on 89/91 octane. I live at 5,150' elevation so the cam would need sufficient vacuum for the brakes. It had 14" with the stock cam. At that elevation I could go a lot higher on the compression, but the problem is it will most likely be driven to sea level at some point and I'd prefer it to not need race gas at that elevation. It may end up a dog at my elevation if it needs to be built to survive at sea level on 91. Hoping for at least 350hp at my elevation. It also needs to work with the stock converter and 2.73 rear end. I have about $3,500 budget. The block work will be about $700 of that.
So far on the list is:
Pro Comp heads
Electric fuel pump (Summit says 50gph is good enough for 600hp)
Voodoo 262/268
1.6 roller rockers
7111 intake with electric choke
HEI recurve kit (How's this one from summit?)
Is this gasket/ring/bearing kit a good deal?
Fel Pro .043 head gasket, so I'll need the pistons to sit about .005 out of the hole.
Has anyone used BBF pistons and milled the tops to get the desired flat top compression height?
3191HC says a top land of .296 and comp height 1.752
S3157HC says top land .408 and comp height 1.770
I don't know if the .408 is a typo or true(seems like a big difference from .296), if true you could have a compression height of any where from 1.77-1.562 going with a .200 top land that I've read is the safe minimum for NA.
Can the stock 403 intake manifold be port matched to the Pro Comp heads, or will I have to go with a 7111? I'd think it can if 2711/3711 can be and they're supposed to be a copy.Why do people get oil restrictors in the block and a 7-8qt pan? I would think I don't need that with my mild build. I've also read not to use vacuum advance. Why not?
Can the stock rod and main bolts be reused? I know the head bolts can't.
Thanks for any help.
Last edited by Vengeance; July 23rd, 2020 at 04:14 AM.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,721
Keep in mind 350 HP @ 5100 feet is 470 sea level HP roughly. The 3500.00 budget and vacuum will be your problem. My car ran 11.60 @ 5800 feet elevation 8000 DA (Bandimere) with 370 observed dyno HP @ 3650 pounds, 350 HP might be a lofty goal.
Last edited by VORTECPRO; July 23rd, 2020 at 05:03 AM.
I don't know how accurate it is, but the Wallace racing elevation calculator says 430hp at sea level will be 363hp at 5,150'. I was going to do a similar build to one that made 430hp.
Shoot for 9.5:1 static. Keith Black has a piston that’ll get you there with the Procomp heads. You’ll make your 450 at sea level number if you do it with all the right pieces.
However in my experience expecting to get all this done for $3500 is pipe dream but.........
ONLY the SBO Performer RPM can be port matched to BBO heads (without welding on additional material).
My build was 450hp and only pulled 12" vacuum at sea level, using the next step voodoo cam (old number 60803).
The KB pistons are pretty good, but a little pricey.
Unfortunately I think the budget will get busted really quick, especially if you need to buy the heads. Re-working OE heads tends to be nearly as expensive. The cheapest effective way to get there is find some SBO heads that are already in good shape, do the basic stuff to them, use that cam and a performer rpm intake, with the stock bottom end. You'll be in the neighborhood, but you're at the point where adding a halo girdle is an awfully good idea. But that involves quite a bit more machine work as the mains have to be honed, you have to use main studs, and the caps modified. There's a good chance it'll live a happy life without it though in your setup without a girdle.
All Olds bolts can be reused - they didn't use torque-to-yield back then.
The Performer series (2711/3711) and Performer RPM are quite different. The RPM not only raises the carb, but raises all of the runners, giving much better potential. And the Performer series doesn't have enough material to match to BBO heads.
The main block restrictors are a bad bit of nonsense that became popular. They're not worthwhile, they restrict oil at the wrong place.
Running a big pan isn't about running a whole lot of oil. It's about getting the oil to sit lower - further away from the crank. So yeah, that requires modifying the dipstick as well.
I've also read not to use vacuum advance. Why not?
I thought it was race-only cars that ditched the vacuum advance. On a street driven car, vacuum advance will help with idle quality (and vacuum), part throttle driveability, and cooling.
My experience with an HEI distributor (mine's off a 78-79 403) was to retain the factory center bar and weights and use one light/one medium spring. The factory center bar / weights gave 18º mechanical advance so I was able to set the initial to 18º for 36º total. The higher initial made the engine idle smoother with higher vacuum signal. I originally used a Moroso HEI Advance Curve Kit with a center bar and weights that gave 24º mechanical advance, so the initial was set to 12º for 36º total. The engine idled with a noticeable lope, the vacuum was bouncy 14-15, and the power brakes didn't work so well (hard pedal). After going back to the factory center bar / weights with 18º initial and connecting the vacuum advance to full manifold vacuum the idle smoothed out a lot, the vacuum increased to a steady 16", and the brakes worked normally.
Shoot for 9.5:1 static. Keith Black has a piston that’ll get you there with the Procomp heads.
Even with aluminum heads? I was going to go for 10:1, but I'll keep it 9.5:1. I can get there with the stock pistons and milling the heads to 66cc and the block to .005 out of the hole with the .043 FelPros. How much can the block be safely milled? I also won't need to rebalance with stock. Could I leave the crank alone or does it have to be ground 10/10? I read someone say "Grind the crank 10/10, even if it doesn't need it, so that each main and rod journal can be radiused more fully at each end. Clevite 77 bearings for an Olds already have extra chamfer on the edges to accommodate extra journal radius." in reference to fixing the oiling problem.
Originally Posted by oddball
My build was 450hp and only pulled 12" vacuum at sea level, using the next step voodoo cam (old number 60803).
The 430hp build pulled 22" at 800' with the cam in my list. He was running 10.2:1 but using 93 octane.
The KB pistons are pretty good, but a little pricey.
That's why I asked about the Ford pistons. The Oldsmobile pistons are always around $400 and the Ford's are $115. You could get the exact compression height you want and still only spend half the Oldsmobile price after milling. You could do your own fly cutting(sanding) for very cheap; just time consuming.
All Olds bolts can be reused - they didn't use torque-to-yield back then.
Thanks. That'll help with the budget.
The main block restrictors are a bad bit of nonsense that became popular. They're not worthwhile, they restrict oil at the wrong place.
Running a big pan isn't about running a whole lot of oil. It's about getting the oil to sit lower - further away from the crank. So yeah, that requires modifying the dipstick as well.
Would I be fine with the stock oil pan and just opening up/chamfering the oil drain backs? I've seen people run a roll pin in the pushrod instead of buying more expensive oil restricting pushrods, and those are boats that run full throttle for extended periods.
Originally Posted by Fun71
I thought it was race-only cars that ditched the vacuum advance. On a street driven car, vacuum advance will help with idle quality (and vacuum), part throttle driveability, and cooling.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,721
Originally Posted by Vengeance
I don't know how accurate it is, but the Wallace racing elevation calculator says 430hp at sea level will be 363hp at 5,150'. I was going to do a similar build to one that made 430hp.
Te question is: at 5150 feet elevation in Wyoming.................when is the DA ever 5150? Example Pueblo Colorado around 4900 feet altitude.
For Bakersfield, CA density altitude = 3442.92 ft
So it averages out to about the same difference as the physical altitude. Lower altitudes are usually hotter.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,721
Originally Posted by Vengeance
For Bakersfield, CA density altitude = 3442.92 ft
So it averages out to about the same difference as the physical altitude. Lower altitudes are usually hotter.
I can tell you this, my shop sits @ 6400 feet, last week a 586 corrected HP engine made 414 HP observed HP on my dyno. Thats close to 30 % @ 6400 feet in the summer.
If there's money left (doubt there will be) I would get a 3.08 rear. I don't know how much of a performance difference there is from 2.73 to 3.08. Highway rpm is a concern.
Or maybe even a 3.23 if this is a 3 speed trans. With overdrive, 3.73 works nicely. I did the rear end first just because it was easiest. It did make a dramatic difference.
I understand about the money. This should be an excellent build.
I am here in Lakewood, Colorado and also live in the terrible performance world of 8000' + Density Altitude.
I hate to be the bearer of bad news, but, you will have to modify at least one of the following: horsepower goal, budget,engine type.
At an 8,000 foot D.A., you will lose ~30%+ of your power (observed Dynomometer at altitude) vs. a sea level (corrected dynomometer reading)
-You can build a 500hp+ (500hp at sea level = 350hp at elevation) 403, but, not for less than about $8K, also, no guarantee on longevity with just a simple ladder-type main support
-You can build a 400hp (400hp at sea level = 280hp at elevation) 403 for about $5K
-I honestly don't think you can reach your "vacuum requirements" at this elevation with the higher HP build 403, but you "might" be able to with the 400hp combo, depending on the heads and cam size
With Vortecpro's help and guidance, we built an Olds 468 (455 overbored .060) that pushed 605hp at sea level corrected with some ignition issues, and ~420hp observed at the Colorado Springs high elevation where Vortecpro's dyno is located. This level of engine wouldn't be likely duplicated for less than $12K-$14K if we had to do it over again. In our situation, we lucked into a good deal on a bunch of good builder parts and an extremely talented and kind engine developer/machinist/builder, so it was closer to $7K for our cost.
Another choice to match your power goals to your budget is to look at an engine swap to a different family of engine:
- well built Chevy 454 Big Block is best bang for the buck in a GM car- very easy to hit 500hp+ with a good budget combo
- 6.0L LS with good cam and good intake (lots of combos of 6.0L's get over 500hp with a decent size cam, valvesprings, tune, and intake)
-Turbo LS engine, can be a stock 4.8, 5.3, or 6.0L, and will easily make 500+ hp on a low boost number
Without a better gear ratio to match the new power curve, and at least some additional torque converter stall speed, you may be disappointed in the overall performance of any combo (unless you go turbocharged where gear ratio won't be as important as naturally aspirated combos)
What size fuel pumps are people running that use aluminum heads? Summit says 50gph should be enough.
Are you talking a mechanical fuel pump? There's only a handful of options. I'm not sure which, if any, fit on a small block with aluminum heads. You can grind the head - A LITTLE - for clearance, but you run into water pretty fast. Dig around, some folks have posted about it and some of the books have references to this.
It's best to convert to an electric pump if at all possible.
Hood clearance on the formula/trans am will be a MAJOR issue. We did Holley Dominator Intake on our olds small block 421/424 stroker or whatever it came to be and HOOD BARELY cleared. I don't care how many ways you slice it - the low profile hoods on these cars will be your limiting factor. We wacked off .375 (3/8) off the dominator and then used a Pontiac 400 air cleaner base - MAJOR $$ and a Pontiac 400 shaker hood - which we offset the bottom a bit. Just to find that 400 base was not easy and we paid $500 for it. Those 77-79 Pontiac 400 bases are very expensive used and will need to drop down to get the hood to close with anything but a stock height intake. You may be able to get some more clearance on the formula hood, but be careful. Its very tight fit on our Trans am and we don't have any room for the shaker seal.
90% of the people here may have NO clue the major issue you will have with anything but a stock 403 intake / 3711 performer and small block heads on Firebird.
You may want to talk with Dave at Pro-Touring Fbody and see if he has or will make any more 403 drop bases for the Firebird. I bought two from him last year before he sold them at PRI. That is about the only saving grace you may have other than stock. Unless you are shooting for the moon here for HP - I would suggest you stick with small block heads and the performer. Port the hell out of them both. That is of course if you don't care about the hood.
I read the grinding to fit a mechanical will only work on the BB and you must use an electrical for SB. So I'm looking at this one which is 50gph. Everyone else seems to be using 130gph, which I would think is over kill.
Originally Posted by olds403
Hood clearance on the formula/trans am will be a MAJOR issue.
Yeah, I've read about that. I have the link to this saved (1 3/4" drop base) just in case. I don't know if that will work though. I think as long as it's 14" it should. It's the biggest drop I could find.
Someone on transamcountry said "i know i definatley wont have a clearance problem...i have a 78 formula. right now i have the performer(not the rpm) with a 1 in. carb. spacer and a 3 in. spacer between the carb. and air cleaner and i still have at least 2 more in. to go before i hit the hood."
I ordered the aluminum heads today so I'll definitely be using those. I'll do slight port work based on the guide on this site and the "ProComp Teaser" thread.
Last edited by Vengeance; July 29th, 2020 at 12:34 AM.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,721
Originally Posted by olds403
Hood clearance on the formula/trans am will be a MAJOR issue. We did Holley Dominator Intake on our olds small block 421/424 stroker or whatever it came to be and HOOD BARELY cleared. I don't care how many ways you slice it - the low profile hoods on these cars will be your limiting factor. We wacked off .375 (3/8) off the dominator and then used a Pontiac 400 air cleaner base - MAJOR $$ and a Pontiac 400 shaker hood - which we offset the bottom a bit. Just to find that 400 base was not easy and we paid $500 for it. Those 77-79 Pontiac 400 bases are very expensive used and will need to drop down to get the hood to close with anything but a stock height intake. You may be able to get some more clearance on the formula hood, but be careful. Its very tight fit on our Trans am and we don't have any room for the shaker seal.
90% of the people here may have NO clue the major issue you will have with anything but a stock 403 intake / 3711 performer and small block heads on Firebird.
You may want to talk with Dave at Pro-Touring Fbody and see if he has or will make any more 403 drop bases for the Firebird. I bought two from him last year before he sold them at PRI. That is about the only saving grace you may have other than stock. Unless you are shooting for the moon here for HP - I would suggest you stick with small block heads and the performer. Port the hell out of them both. That is of course if you don't care about the hood.
I always lowered the engine in he car when I had clearance problems which in my case helped drive line alignment, but this can also open up a bunch of new problems as well.
Like I said, 90% of the people here have no clue on how difficult this will be to make work all of this work in a Firebird/Trans Am. There has been a couple of us make it work with a non stock intake and I am one of them, but yet to do the RPM. RPM will bring a new host of issues with the carb/throttle body -you use. The total height will all have to calculated into your plan along with knowing ahead of time if the drop base you plan will HIT anything else. Like the firewall/distributor. and any of the linkage/fittings on your setup.
I suggest you start to mock this up and measure. There is like zero hood clearance on the 403 air cleaner used on the Firebird/Trans am and it ONLY fits the 77-79 Firebirds.
Bill Webb at Southern Classic Trans Ams did a 403 with BB heads and RPM. Bill took a stock aircleaner and not only dropped it, but also cut the upper parts off and cut out a middle section and then rewelded everything. Only solved part of your problem with the Allstar base. You still have to find out how much you can go up from there with your air cleaner element and lid. You can see the AllStar base in the backdrop - Not like its a drop in. Absolute nightmare.
The picture below is a 77-79 Pontiac base that has been cut out and dropped to the right height. Unfortunately, you will have a nightmare ahead of you.
What would really be helpful is for a complete performance package solution for the 403 77-79 Firebird Olds powered cars. Being that we did a full frame off restoration here recently on one of these we know how much of PITA all the parts are to get and time/effort to make anything, but stock package work. We were very close to doing a LS swap, but the car was a numbered PaceCar. 403 blocks are scare and nearly everything has to be custom made/ordered. Would I do it again.....No.
Last edited by olds403; July 29th, 2020 at 11:10 AM.
Is the valve placement and angle the same for the original SBO heads and the Pro Comps? I'd prefer to use the old heads for fly cutting valve reliefs if needed, to not mess up the guide hone in the new heads before they're ran.
Is the valve placement and angle the same for the original SBO heads and the Pro Comps? I'd prefer to use the old heads for fly cutting valve reliefs if needed, to not mess up the guide hone in the new heads before they're ran.
Unless you are going with huge lift and less than a .040" head gasket you won't need any cuts.
I might be going with Chevy 454 flat top pistons and .035-.037 quench. It depends how much boring the machinist tells me the cylinders need. The Chevy pistons are a better match than the Fords. It's already the perfect compression height and the pin is only .009 bigger.
Does the BBO and SBO use the same timing set? Summit/Jegs/eBay keep telling me they can't use the same set.
I found a 9 keyway adjustable for BBO that I'd rather use than the 3 keyway adjustable I found for the SBO.
There are only a few quality sets on the market, and yes, they're the same across all the "modern" olds gas V8's. I'd recommend one of the Cloyes billet sets, or going to an Olds vendor.
Bernard Mondello
BTR Bill Trovato Racing
Rocket Racing and Performance
the best timing chains I have seen are the Bernard Mondello and BTR ones......not the standard run of the mill Cloyes..... But the true roller sets with extra machining and marked alignment dowel holes for easier/extra advance and retard To get the cam dialed in where you want it.
This one is the premium version
I’m all about supporting your local shop but being from Ohio, I always dealt with Jegs or Summit as they were in my back yard so to speak.
"Reasonably priced"?😂
That's way too much for me.
The most I'd go is this one.
This is the 9 keyway I was looking at(Pro Comp), but will go with the Comp Cams.
July 23rd, 2020, 04:09 AM
