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Old 03-18-2013, 09:13 PM
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Best way to get over 400hp out of a Pontiac 400

I am currently in the middle of a full restoration of a 67 GTO and I have the original 400 with 335hp. I'm currently running Hooker headers and 2 1/4 exhaust with glasspacks. From this point what would be the best way to get over 400hp.

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Old 03-18-2013, 09:28 PM
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Have the heads ported and get a good cam matched to your combo. After proper tuning you should be a little past your goal. Your heads will need to be done by a good head guy though, it's not super hard but I've seen some horribly butchered.
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Old 03-18-2013, 09:36 PM
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What would you suggest as far as carb and intake setup i have a Q-jet and cast intake? Also would a MSD ignition be worth getting?
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Old 03-19-2013, 01:17 AM
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Keep in mind that the Ram Air III & IV engines were pushing close to that in stock trim, they were just grossly under-rated at 366HP & 370HP respectively. So you really will need to do very little to reach your goal of 400 HP, headers and a Ram Air III or IV cam should do it.
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Old 03-19-2013, 05:30 AM
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Add a Isky cams 280H Mega cam
ISKY Racing Cams - Do It Right. Race with the Legend. Camshafts, Connecting Rods, Valve Springs, Lifters
Be sure to get and install the correct valve springs etc.

Edelbrock Performer RPM intake. Holley 750 Double pump carb
Auto trans: get a 10" 3000 stall 3.90-4.11 gears
4 speed 3.90-4.10 gears.

Get rid of the restrictive glass pac mufflers.
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Old 03-19-2013, 06:44 AM
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Quote:
Originally Posted by ap72 View Post
Have the heads ported and get a good cam matched to your combo. After proper tuning you should be a little past your goal. Your heads will need to be done by a good head guy though, it's not super hard but I've seen some horribly butchered.
Not all pontiac heads will make 400 hp with the ease you say. In a 67 gto i think it was still the smal valve head. The later heads flow better than the 67. But I think you could slip a set of ram air III heads on the car without effecting the numbers matching aspect. But unlike a chevy it will be clear to anyone that knows pontiacs these are later heads.

400 is possible and easy to do but dont think its a port job and cam away. You will also need to replace the intake and carb with something alot better than stock. along with new pistons and distributer.

Aluminu heads and large cam will hit the mark very easy, but not going to look factory.

FYI a 455 crank can be put into that block. That is the easy way to make 400 hp. a 600 lift solid roller cam would help lot as well. 400 tq no problem 400 hp well its got to be right. My 455 with good heads and ok cam made less than 400 hp. After about 6G's she made well over 500 and would luanch the heavy car like it was a feather.

As with all the pontiac guys on here I always recommend a call to Butler performance. He will get you setup with the right parts to meet your goals. His prices look high but when you get done with machine work and parts you will be spending more to do it yourself. Butler has the poncho figured out and has everything you need to make it scream. I would recommend a full motor from him and a stock rebuild for the oem motor as to protect the cars value.
Butler Performance - Specializing in Pontiac Engines Heads and Performance Parts
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Old 03-19-2013, 06:45 AM
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Originally Posted by 67goatfan View Post
What would you suggest as far as carb and intake setup i have a Q-jet and cast intake? Also would a MSD ignition be worth getting?
Your going to get a lot of different ways to go with this and this is mine..


The stock Quadrajet intake is one of the best. Check out Cliffs Quadrajets for a Quadrajet carb...

If your staying at 6000 rpm, I'd clean up the stock single points distributor. Use a set of Accel 23 oz points (#8101). Use the Accel 32 oz #110128 if reving above 6000 and epoxy the vaccum advance plate....

Modify the vacuum advance for 10 degrees, mechanical for 20 and have it start to come in at 900-1000 and all in by 3000.. I like manifold vaccum..

Snip the resister line and run a new piece of #12 from the ignition switch "run" terminal to a 1.5 ohm resister on the firewall like the Super Duty cars had and feed the coil with that..

Adjust the voltage regulator for 13.5 to 14 volts..

You'll love that stock points system..

Last edited by Bonneville462; 03-19-2013 at 06:54 AM.
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Old 03-19-2013, 06:56 AM
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Quote:
Originally Posted by 67goatfan View Post
What would you suggest as far as carb and intake setup i have a Q-jet and cast intake? Also would a MSD ignition be worth getting?
getting a better ignition is DEFINITELY worth while, but MSD isn't the only source, check out Performance Distributors.

For 400hp you can probably get by reusing your stock intake and carb but upgrading to a better intake will surely help- I'd still keep your stock carb if it's in good shape.

A good cam and head work will make a huge difference in itself, and is probably enough to get you over your goal on the combo you already have.

Head work is NOT cheap though.
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Old 03-19-2013, 07:06 AM
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If you want to use a hydraulic flat tappet cam, install a stock replacement camshaft. That is because today's low ZDDP motor oil will ruin a high performance camshaft if it is used with the high spring loads that is required for such a camshaft. If you choose not to use high rate valve springs so you can use no lead pump gas, keep in mind that a camshaft with more than .460" valve lift will lose control of the valves, meaning, loft the lifters over the nose of the cam lobes and float the valves. That will occur at a lower RPM than it would with a stock camshaft.

A stock Q-jet and a stock manifold is hard to beat. Get a good three angle valve job on a pair of 1967-1970 GTO/Firebird 400 heads with 10.5:1 compression ratio and install a free flowing exhaust system. Use a good high performance hydraulic roller camshaft with a 3000 stall converter and/or 3.90 :1 rear end gears. Be certain your cooling system is up to the task because low gears and a high stall converter will cause the engine to overheat.

Camshafts are as varied as women's shoes. A good street/strip camshaft is a Comp Cams 51-433-9 hydraulic roller used with Comp Cams 857-16 hydraulic roller lifters and Comp Cams 994 valve springs. There is no need for a MSD ignition system. Use a stock HEI conversion or a Pertronix breakerless system if you don't like to adjust the point dwell and replace the points every 1,000 miles.

Be prepared to use a 50-50 mix of 93 octane pump gas and 108 octane racing fuel or 100% 100 octane racing fuel. The 108 octane racing fuel is high lead but the 93 octane pump gas will lower the lead content......Have a tank of 93 octane no lead when State inspection time rolls around.

Last edited by MouseFink; 03-19-2013 at 07:15 AM.
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Old 03-19-2013, 07:20 AM
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Quote:
Originally Posted by MouseFink View Post
If you want to use a hydraulic flat tappet cam, install a stock replacement camshaft. That is because today's low ZDDP motor oil will ruin a high performance camshaft if it is used with the high spring loads that is required for such a camshaft. If you choose not to use high rate valve springs so you can use no lead pump gas, keep in mind that a camshaft with more than .460" valve lift will lose control of the valves, meaning, loft the lifters over the nose of the cam lobes and float the valves. That will occur at a lower RPM than it would with a stock camshaft.

A stock Q-jet and a stock manifold is hard to beat. Get a good three angle valve job on a pair of 1967-1970 GTO/Firebird 400 heads with 10.5:1 compression ratio and install a free flowing exhaust system. Use a good high performance hydraulic roller camshaft with a 3000 stall converter and/or 3.90 :1 rear end gears. Be certain your cooling system is up to the task because low gears and a high stall converter will cause the engine to overheat.

Camshafts are as varied as women's shoes. A good street/strip camshaft is a Comp Cams 51-433-9 hydraulic roller used with Comp Cams 857-16 hydraulic roller lifters and Comp Cams 994 valve springs. There is no need for a MSD ignition system. Use a stock HEI conversion or a Pertronix breakerless system if you don't like to adjust the point dwell and replace the points every 1,000 miles.

Be prepared to use a 50-50 mix of 93 octane pump gas and 108 octane racing fuel or 100% 100 octane racing fuel. The 108 octane racing fuel is high lead but the 93 octane pump gas will lower the lead content......Have a tank of 93 octane no lead when State inspection time rolls around.
There is a WIDE gap between a stock replacement cam and a racing cam... Some cams don't wear long, and some will last for almost forever- such a blanket statement on cams seems pretty ignorant.

That being said it would be prudent to run a cam that does NOT require overly high spring loads.

There's also no reason he couldn't run 9.5:1 compression and get 400hp from 87 octane gas, his goals do NOT require race fuel at all.

Everyone on this board is in such a hurry to spend someone else's money and to call something impossible that is done pretty damn regularly- like a mild cam swap.
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Old 03-19-2013, 07:29 AM
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There is a WIDE gap between a stock replacement cam and a racing cam... Some cams don't wear long, and some will last for almost forever- such a blanket statement on cams seems pretty ignorant.

That being said it would be prudent to run a cam that does NOT require overly high spring loads.

There's also no reason he couldn't run 9.5:1 compression and get 400hp from 87 octane gas, his goals do NOT require race fuel at all.

Everyone on this board is in such a hurry to spend someone else's money and to call something impossible that is done pretty damn regularly- like a mild cam swap.

I think what mouse was saying is that the stock cams from pontiac are bigger than you think for one and that with 2.11 valves it will need a 600 to 700 lift cam to make big power. SO yeah you will need a to go big cam with all the trimmings or use one of the long duration cams from poncho. they made a nice slection.

Its not an sbc a 450 lift cam will not make 400 hp with those big valves. it will choke it out. Stock is probably more than that anyway.
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Old 03-19-2013, 07:45 AM
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Guys....

'67 GTOs came with 670 heads (cast into the center exhaust ports). These are among the BEST of the iron d-ports. The chamber is "closed" around the spark plug. This makes for more emmissions (the reason they changed them to "open chamber" in '68), but horsepower does NOT "suffer". In fact, these are the castings on Gene Kinch's "Gallopin' Goat", a 9-second, 3,100 lb. GTO with no adders. This one sports a BUNCH of port work, though. Not very many 9-second ("on motor") d-port cars "out there". A few...

It wasn't specified whether or not "pump gas" is a requirement. If so, a "dished" piston with 16 CCs in the "dish" will put your right above 9:1, where "you want to be". And while there's a lot of hub-bub about "quench", unless you're pressing "the edge", it's not that important here. Keep static compression around 9.3:1 and everything is "happy".

In lower compression engines (under 9.5:1), we use Comp XE grinds, almost exclusively. None better we've found for a combination of drivability and power production. The hydraulic flat-tappet versions are pretty much all that shows in their catelog, but ALL the grinds are available. Our most popular are the XS274S (236/242 @ .050) solid flat tappet, and XR282R (242/248 @ .050) solid rollers. Particularly with 400, they "like" solid cams. The rev potential is really good when the heads are done correctly, and 400 has the short stroke to back it up. Many happy customers with 406s that "peak" around 6,600-6,800. (Yes, you CAN rev a Pontiac, IF everything is "right") the stock rods GOTTA go. For the higher revs, use 6.8" BBC rods (we use Eagle). The nodular crank is up to the task.

The factory Q-Jet intake is a good one. Better than Performer on the high-end, better than RPM on the low-end. With extensive porting, can rival RPM "up high". Cliff's Q-Jets are among the better ones available. If you can't handle the "waiting period", get one of their kits and have a local "guru" install it. Q-Jets are very good carbs. The mid-'73 and later are 800 CFM, if that sound like "you"... The earlier are 730 CFM. This is "enough" to feed a mild 400, but not a "hot" one.

Many ways to "skin this cat", so be careful. There are many self-proclaimed "experts" regarding the Pontiac, and some actually ARE. Some are not. I agree, Butler Performance is an excellent shop. It's not the ONLY good one, though... And beware the "builder" that doesn't HAVE a shop... There are few of those out there, too. Contrary to popular belief, the guy that shoves the pistons in the holes is not necessarily "the builder". Engine building is a "trade" not an operation. The "operation" often confused is "assembly". The "builder" is the one that measures everything, makes determinations for what's needed, and decides what modifications are called for for a given application.

For a more complete recommendation, please state specific goals and an approximate budget. '67s are too cool, and NEED to be running like a GTO is supposed to... (:-

Jim
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Old 03-19-2013, 07:52 AM
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Some cam discussion went on while I was typing...

ALL the factory grinds EXCEPT 041 (Ram Air IV) had .407 or .408" lift (@ the valve) with 1.5:1 rockers. It wasn't until the mid-to-late 60s, the concept of "mean lift" was integrated into factory "thinking".

Comp XE grinds and Lunati VooDoo grinds are specifically designed for lower spring rates for "street" use. They also work very well in the low-compression environement, as previously stated. Flat hydraulics should have around 120 lbs. at the seat, solid flat and hydraulic roller, 140-145 and solid rollers, 175-180. No need for MONSTER springs until revs exceed 7,000.

FWIW

Jim
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Old 03-19-2013, 08:07 AM
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The best running Pontiac I had was a 1969 Firebird 400 with a 4-speed. No air. I bought it in 1970 with 4,000 miles on the odometer. I blew the 10 bolt, 3.36 open rear end with a pair of Goodyear 11" wrinkle-wall slicks a month after I bought it. The Pontiac 50,000 mile drive line warranty installed a 4.33 4-pinion Safe-T-Track and replaced the drive shaft. I never had any more problems with the rear end even after I started racing it. The Dallas TX Pontiac Zone Office knew I was racing the car and did not say a word.

Here is the 400 CI, 450 HP engine after I put the magic touch to it:

1969 #48 heads, stock ports and valves. .
Crane Z-300 solid flat tappet camshaft, .485" valve lift, 300* duration @ .006"
Chevrolet GM-5231585 edge-orifice solid flat tappet lifters.
BB Chevy L88 valve springs, 140 lb. seat pressure/ 350 lb. open
Sharp 1.5:1 roller rocker arms
Stock rods with ARP rod bolts.
TRW forged flat top pistons.
Stock flywheel
Schieffer 10.5" bonded and riveted clutch disc.
Schieffer 10.5" Rev-Loc diaphragm pressure plate.
1969 Firebird 400 H-O exhaust manifolds with a chambered exhaust system.
Engine balanced with 1/2 gram.
Kim Barr Racing Engines.
High 11 second ET.

This was when 105 octane leaded premium was still available at the pump and no State emissions checks.

The only problem I had and was never solved was the cooling problems with the stock three core radiator (non-A.C.) with 4.33:1 rear gears.
If I had to drive on the highway, I had to keep it below 50 MPH with the trucks and buses. The engine temperature was OK around town.
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Old 03-19-2013, 08:57 AM
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I raced my friend's 1967 L88 427 Corvette convertible., no radio, 4-speed with 4.56:1 gears at least a dozen times. I could never beat him, no matter how hard I tried. With 11" slicks, I could pull him two car lengths out of the hole but he was beside me within about 200 feet and ahead of me by two car length through the eyes. His '67 Corvette was rated by the factory at 430 HP and my 1969 Firebird 400 coupe had 450 HP at 6,500 RPM.

How could that be?

Reason:
The 1967 L88 Corvette was rated 430 HP at 5,600 RPM (for government purposes)
The 1967 L88 Corvette had 560 HP at 6,600 RPM.
His L88 Corvette could clock 11.5 ET consistently with street tires and side pipes
(Only 2 of the 20 1967 L88 Corvettes made with side pipes)
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