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Discussion Starter · #1 ·
So I just picked up a Pontiac 400 to build. I've read a lot of people wanting 400-500hp on their builds. I decided to spend the extra money and got a 68 Pontiac 400 with #16 heads. Since I'm starting with a 350hp engine stock, could I just put in a mild cam, long tube headers with a little bit bigger diamter exhaust, and a 750cfm edelbrock, I should be in that mid 400hp range correct? The engine is all stripped down so really I could do whatever. I do need rods and pistons along with other parts as I only have a bare block, bare heads, crank, and intake, but I could probably keep the stock crank instead of using extra cash on a forged one since it should be a decent starting point correct? Not looking to build some untameable monster, just a very strong streetable car as it's going in my 78 Trans Am.
 

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Just put on a factory intake with a well preped QJ to start.4 tube headers will get you more but IM they are a PITA on the street.Get a set of larger outlet RA manifolds.A RA cam will get you more and you dont have to do much to your heads.If you go to a much bigger car you should change your valves and will need a diff spring kit.Whhile the heads are off you can have them clearanced for 1.65 rockers.This will give you some food for thought.Tom
 

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"...68 Pontiac 400 with #16 heads. Since I'm starting with a 350hp engine stock, could I just put in a mild cam, long tube headers with a little bit bigger diamter exhaust, and a 750cfm edelbrock, I should be in that mid 400hp range correct?..."

Don't think you can squeeze 450hp out of a 400 with a "mild cam, long tube headers with a little bit bigger diamter exhaust, and a 750cfm edelbrock," :no

For one thing, the #16 heads have too much compression for SAFE use with pump gas. Most Pontiac engine builders recommend 9.5:1 max--9.0 to 9.25:1 safer. OR, you can run a cam with lots of advertised duration, like a RA4 grind or larger, and make sure your total timing never gets high enuff to cause detonation.

You can run the #16 heads, with dish pistons, to reduce comp. But, when the comp is reduced, it's harder to make that 450hp you want. Yes, it can be done. And you can go with a stall converter and more rear end gear, to make your car "feel" like it has more power. I reckin you could call it more "seat of the pants" power.

BUT, as has been said many times, on this and other Pontiac forums, it is far easier to make 400+hp and 500ft lbs of torque, with a 455 or bigger, long stroke engine. The cheaper balanced cast crank stroker rotating assemblies are between about $1500 & $1800.

http://www.cnc-motorsports.com/eagle-b52400-pontiac-400-461-street-and-strip-balanced-rotating-assembly-10-1-1-mahle-flat-top-pistons.html

The best cheap iron heads for this stroker engine seem to be the 6x-8 heads. You can sell your #16 heads for plenty, to buy a good set of 6x cores, and pay for some of the machine work. There always seem to be plenty of 6x-8 heads for sale, in all stages and conditions, including ported and ready to bolt on.

"...it's going in my 78 Trans Am."

Keep in mind that the '68 block only has 2 motor mount bolt holes, which will require adapters to fit the 3-hole mounts in your '78 TA. Some have posted that the adapters don't work too well sometimes and require mods and fab work. :(

"... a 750cfm edelbrock..."

The only Edelrock carb I'd recommend is one of their Q-jets. But, I'd really rather have a PROPERLY REBUILT '76-'79 800 Q-jet, with the APT feature. Everyday & SMI have a good rep for these Q-jets. Everyday has one listed on their website, if you don't need the TH350 kickdown cable hook-up.

http://www.ebay.com/bhp/edelbrock-quadrajet

http://www.everyday-performance.com/quadrajet_carburetors.htm

http://www.everyday-performance.com/quadrajet_carburetors.htm#!/Pontiac-1976-Trans-Am-Firebird-400-Quadrajet-17056264/p/46561051/category=578011

http://www.smicarburetor.com/products/sfID1/28/sfID2/9/sfID3/100

FrankTinCA just bought one, with the TH350 kickdown cable type throttle lever, from Everyday.

http://www.firebirdnation.com/forums/topic/489889-frank-ts-68-coupe-restoration/?p=1311329
 

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Since the engine is apart and you need pistons anyway run the 16s and get dished pistons to keep you around 9.5 CR.Get a good set of forged rods and you should be good to go.With a 400 30 over you should be able to get a street friendy engine close to 400 but the Xtra 50 will start costing more and will be less street friendy.Tom
 

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Discussion Starter · #5 ·
I know a lot of people chase the 16 heads, but if no one can really use them on pump gas without detenation, what is eveyrone using them on, strip cars? The machine shop said they didn't want to take it over 9:5 CR but if I run a deeper dish set of pistons and throw a Ram Air camshaft setup with the 800cfm q-jet I should be running a pretty respectable engine you'd think?

Here's the ram air camshaft I was looking at

http://www.ebay.com/itm/Pontiac-400-4Bbl-1968-1979-Except-Ram-Air-Cam-Kit-camshaft-lifters-timing-set-/331510372061?hash=item4d2f8ed6dd:g:I08AAOSwiCRUbPAz&vxp=mtr
 

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16s are just another high compression head,like 48s62s12s and 13s.They will work fine with the proper dished piston.If you already had flat top pistons I would say sell the 16s and buy a head with larger chambers.Use as much as you have now.Dont just go on ebay and buy a cam you know nothing about.Contact someone like Dave at SD performance and tell him what your looking for and get a cam that will meet your needs.He is a pontiac builder and racer and head porter.Tom
 

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I know a lot of people chase the 16 heads, but if no one can really use them on pump gas without detenation, what is eveyrone using them on, strip cars? The machine shop said they didn't want to take it over 9:5 CR but if I run a deeper dish set of pistons and throw a Ram Air camshaft setup with the 800cfm q-jet I should be running a pretty respectable engine you'd think?

Here's the ram air camshaft I was looking at

http://www.ebay.com/itm/Pontiac-400-4Bbl-1968-1979-Except-Ram-Air-Cam-Kit-camshaft-lifters-timing-set-/331510372061?hash=item4d2f8ed6dd:g:I08AAOSwiCRUbPAz&vxp=mtr
A lot of guys are using the #16 heads for numbers matching rebuilds. Also, they can be used for street/strip heads on engines which are borderline. You can run the timing just a hair lower than optimum, at all times, on the street, with 93 octane pump gas, then up the timing and mix in maybe half & half race/pump gas, for the strip. And, some guys run E-85 all the time, so don't have to worry about compression.

But, the safest way to run the #16 heads(without racing gas or E-85) is as mentioned--use dish pistons to reduce static comp to 9.5 or lower. If you decide to go with dish pistons, I like the looks of the Icon IC891 pistons. The dish is 14cc, and they have a pin height of 1.720, which is .020 more than a factory 400 piston. This will require that less be milled off the block deck to achieve near zero deck height. Or, for about the same price, or slightly less, you can buy custom pistons from Auto-Tec with any dish size or pin height you want.

http://www.cnc-motorsports.com/icon-ic891-030-forged-dish-pistons-4-150-bore.html

https://rpmmachine.com/kbpistons-premiunforged-pontiac.shtml

I plugged some numbers into the Wallace CR calculator. Assuming the #16 heads have 72cc chambers, I came up with 9.62 static comp. But many have said that most Pontiac heads actually have lager than advertised chambers. I've read that most #16 heads have closer to 75cc chambers. So, if you plug 75cc heads into the calculator, it says 9.36 CR. So, this combo can be modified to produce no more than 9.5 CR.

400 + .030, 75cc heads, 14cc dish, .039 x 4.3 Fel-Pro #1016 head gaskets, .005 deck height CR = 9.36

The only ram air cam that will get you anywhere near 400hp, is the RA4(sometimes referred to as an 041 grind). There are several aftermarket versions of this cam. The cheapest is the Melling SPC-8. There are usually some of these for sale on Ebay for about $100. The Crower version is their #60919. Edlebrock even sells a version, which is only available as a cam/lifters kit.

If using this cam in a 400, I'd use only Rhoads lifters, and a 10" converter which will stall at least 3000rpm. If you use this cam/lifter combo in a 455+ you can get by with a stock 13" converter. That's what we raced.

http://www.ebay.com/itm/Engine-Camshaft-Stock-MELLING-SPC-8-fits-68-70-Pontiac-Firebird-6-6L-V8-/131527250214?hash=item1e9fa29126:g:~WEAAOSw-vlVjneN&vxp=mtr

http://www.summitracing.com/parts/cro-60919?seid=srese1&gclid=CjwKEAjw8NaxBRDhiafR-uvkpywSJAAxcl6fREsIc1HYNJ5X9lKkiBOKTuvjhRznK1_tk05e6U0T3xoCptHw_wcB

http://www.summitracing.com/parts/rhl-9518/overview/make/pontiac
 

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Discussion Starter · #8 ·
Is the RA4 cam going to be to much for the car if you drop the compression down? I'm sure I'd have to change my gearing to accomadate for the cam lift so I can get off the line. I wouldn't be totally against using lead additives to stay at the 10:5:1 compression ratio if that actually works.
 

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Is the RA4 cam going to be to much for the car if you drop the compression down? I'm sure I'd have to change my gearing to accomadate for the cam lift so I can get off the line. I wouldn't be totally against using lead additives to stay at the 10:5:1 compression ratio if that actually works.
No, if the compression is up near 9.5:1, the RA4 / Rhoads lifter combo will work. :yes

And, IF you run a converter with at least 3000 rpm flash stall, you'll be able to "get off the line".

There is only one lead additive that works. And it costs so much, that it is just as cheap to run a mix of race gas. BUT, if you really wanna run high comp, the cheapest solution is to run E-85, as mentioned.

High compression and low octane pump gas just don't jive together. You either need to lower the compression or increase the octane. It's just a simple fact of life we are forced to live with. :(

Now, having said all that, the RA4 cam may not be the best all around cam for a 400 engine. But it is just about the smallest one I can think of that will give you 400hp. There are smaller cams that will give you better mid range power and more low end torque.

Now, if you have an extra $1000 or so to spend on a cam set-up, the correct hyd roller will make more power than the RA4 and be more streetable at the same time. Roller cams have several advantages. But that's another discussion. :smile22:
 

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Just set the engine up to be able to pull into ANY gas station in your area.You will be much happier in the long run.If you cheat and get in bumper to bumper traffic on a very hot day you could start getting detionation.If you get on the edge you might have to retard the timing which can cause over heating.IMO its just not worth the Xtra few HP you will gain.You have to buy rods,you have to buy pistons so for a few hundred dollars more you can buy a 4.21 stroke 3in main aftermarket crank and have your 400 HP with no problem.Food for thought.Tom
 

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Discussion Starter · #11 ·
I've read a lot of mixed reviews on the RA4 cam. Can't really find any good videos of the idle/etc. I wouldnt mind a mildly choppy idle but I do want something that will get down the road decently fast. If I had the cash I'd just mimic the BRE Trans am and throw in an LS7 but I'm not that rich :ermm:
 

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"...You have to buy rods,you have to buy pistons so for a few hundred dollars more you can buy a 4.21 stroke 3in main aftermarket crank and have your 400 HP with no problem..."

I agree that this is the best path to the streetable power you want. Either a 4.21 or 4.25 stroke will make 400hp and 500ft lbs of torque, easy. :smile22:

http://lenwilliamsautomachine.com/455_Long_Block.html

http://lenwilliamsautomachine.com/455_Short_Block.html

http://www.sandovalperformance.com/#!product/prd12/2017678915/budget-series-shortblocks-starting-%40
 

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So even with a stroker kit, would you still run the RA4 cam?
Oh yeah, with a 455, I'd definitely run a RA4/Rhoads combo. It'll idle fairly smooth, has plenty of idle vac, lots of low end torque, and will pull strong to 5000rpm. perfect for street or mild bracket racing. An easy 400hp and 500ft lbs of torque, in the 3000-4000 rpm range. But there are bigger cams that will make more top end power, and smaller cams that will move the power lower in the rpm range. :smile22:
 

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Ever played wit the Hurricane/Tomahawk intake from Butler Performance? I like the idea it will still fit under the shaker but have also read people say to use the stock iron from the 68-72 engines as they don't choke out as easy.
 

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VERY hard to beat the factory intake.The dual plane intakes are a knock off of the RPM E intake and the single plane is a knock off of the Street Dominator.Tom
 

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Ever played wit the Hurricane/Tomahawk intake from Butler Performance? I like the idea it will still fit under the shaker but have also read people say to use the stock iron from the 68-72 engines as they don't choke out as easy.
I bought one of the single planes. It's a Pro Comp brand. They are all Chinese made, probably from the same origin. They sell very cheap on Ebay. Mine looks good. I bought it to put on a 455 bracket engine. Have not used it yet. The single plane is probably not as good on a 400. But they are OK on a 455. I bought a bracket car with a 455 in it. It has a Torker 2, which is a single plane. It has PLENTY of low end torque. Does not need a 2-plane to help with that.

2 advantages of the Chinese intakes, over a stock iron intake, are that they are much lighter, and do not have a heat crossover. Now, of course, if you drive a lot in cold weather, you may need the extra heat in your intake and carb. But, if not, the cooler intake and carb will produce a cooler air/fuel mixture, which is supposed to increase performance, some. And, the Chinese single planes will accept either a Q-jet or square bore carb. A Q-jet will not bolt up directly to a Torker 2. :smile22:

http://www.ebay.com/itm/Pontiac-326-350-389-400-421-428-455-Shootout-Intake-Manifold-Satin-/181603301013?fits=Make%3APontiac&hash=item2a48667695:g:Ni4AAOSwg3FUgQLF&vxp=mtr

There are lots of guys who say they hate the Chinese products and try to buy USA made stuff. If you're one of those guys, you'll have to forget about building a cheap Pontiac 400 block stroker, cause all the cheap stroker cranks and rods are made in China. Some are machined here. I suppose the only way to build a long stroke Pontiac, without Chinese parts, is to start with a 455 block and crank, then use factory cast rods, or high priced USA made rods. I think the cheapest USA rods are the Crower rods, for over $800. :shock:

http://www.summitracing.com/parts/cro-sp93419b-8?seid=srese1&gclid=Cj0KEQiA0-GxBRDWsePx0pPtp4sBEiQACuTLNhR90BlKS28v01ykvgsswTdYHuAop-oG3_r2VWbf6ZkaAiAX8P8HAQ
 

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Don,it is no problem building a long stroke USA pontiac engine.Its just numbers in a check book.There are many custom crank makers out there that will make you anything you want.Tom
 

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Discussion Starter · #19 ·
Might just stick with the stock intake then. Franks Pontiac has stock forged rods. Think that would be a solid investment?
 

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Don,it is no problem building a long stroke USA pontiac engine.Its just numbers in a check book.There are many custom crank makers out there that will make you anything you want.Tom
Yes, this is absolutely true. You can build a "Pontiac" engine today, without using a single Pontiac or GM part, or any part made in another country. In fact, all the parts can have been made AFTER there was no Pontiac brand cars even made any more.

And, as far as the "numbers in a checkbook" deal, I'm quite sure that many of us, including me, would buy the best of everything, IF we had plenty of money, so that price was no concern. :smile22:
 
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