[jayzinn]

Beginning the process of building a stroked 400 for my '70 LeMans. I have been looking at different options as far as cylinder heads. I am planning on doing a stroked Eagle 4.25 crank/6.8 h beam rods. My goal is to make 500 hp. I am on a blue collar guy budget. What heads would you recommend? I have had people tell me all sorts of different things. This is my first venture Into Pontiac performance. I have been told the heads need to make around 280 cfm to achieve the 500 hp mark. I have been told a set of 6x ported heads would get me there as well as all of the aftermarket aluminum heads. Also, have any of you ran Speedmaster heads? I am worried about quality issues with them. Please help!!!

[PunchT37]

I think a rough guesstimate is 2 times head flow at 28 inches. So, with the right cam, intake, exhaust, etc, 250 to 260 should get you damn close.

[JLBIII]

Here's a formula from one of Rocky Rotella's books:

Peak air flow= (target hp ÷number of cylinders) ÷ Cpower. Use 0.260 as the Cpower value

[Gach]

Here’s a proven combo for you, there’s also a video of him at Norwalk to kind of back it up. In a 1967 GTO which weighs 3600#’s its a 400 block with 4.25 stroke crank think it works out to 461-462 ci. All on pump gas. Out of box E-heads 72 cc heads. Cliffs Q’jet believe its a RPM Edelbrock intake Crower 60919 hyd cam. Ran 11.60’s at Norwalk has gone faster but he doesn’t want to put a roll bar in it, so he has a block of wood under gas pedal…LOL which works out to 500 hp. Perfectly Streetable

[jayzinn]

That equals out to 240.38 cfm.

[Gach]

Here’s a proven combo for you, there’s also a video at Norwalk to kind of back it up. In a 1967 GTO which weighs 3600#’s its a 400 block with 4.25 stroke crank think it works put to 461-462 ci. All on pump gas. Out of box E-heads Cliffs Q’jet believe its a RPM Edelbrock intake Crower

[jayzinn]

Originally Posted by Gach

Here’s a proven combo for you, there’s also a video of him at Norwalk to kind of back it up. In a 1967 GTO which weighs 3600#’s its a 400 block with 4.25 stroke crank think it works out to 461-462 ci. All on pump gas. Out of box E-heads 72 cc heads. Cliffs Q’jet believe its a RPM Edelbrock intake Crower 60919 hyd cam. Ran 11.60’s at Norwalk has gone faster but he doesn’t want to put a roll bar in it, so he has a block of wood under gas pedal…LOL which works out to 500 hp. Perfectly Streetable

Any other specs on the car? What trans/convertor and what rear end/gearing?

[Gach]

Its turbo 400 trans, 3500 stall convertor 3:73 rear gear. Shifts at 6200 rpms. Steel rods. I think there Molnar rods, and Ross pistons. I sold him the crank its a cast crank, with mains turn down to 3”. From crankshaft specials.. I couldn’t talk him into going with a steel crank. LOL. I’m not sure on the rod length.

[Gach]

Q’jet with Edelbrock dual plane intake. Think thats the rpm intake.

[Gach]

Timing locked out distributor timing all in by 1500 rpms. Runs 36 degrees total timing.

[Gach]

He did run 11.40 with it but his track cut him off no roll bar, him and I were laughing when he came up with idea of block of wood under gas pedal. His new neck name is Woody. Although wife didn’t like that…LOL

[Gach]

It’s a nice easy Peezy combo, credit goes out to Cliff R jetting on Q’jet work out perfectly. But I definitely would go with Steel Crank. The heads flowed 280 cfm out of the box he did have them checked out. By Gabby.

[Dragncar]

Originally Posted by jayzinn

Beginning the process of building a stroked 400 for my '70 LeMans. I have been looking at different options as far as cylinder heads. I am planning on doing a stroked Eagle 4.25 crank/6.8 h beam rods. My goal is to make 500 hp. I am on a blue collar guy budget. What heads would you recommend? I have had people tell me all sorts of different things. This is my first venture Into Pontiac performance. I have been told the heads need to make around 280 cfm to achieve the 500 hp mark. I have been told a set of 6x ported heads would get me there as well as all of the aftermarket aluminum heads. Also, have any of you ran Speedmaster heads? I am worried about quality issues with them. Please help!!!

You can make a lot more than 500 HP with 280cfm iron heads. Not sure how streetable it might be though. You can make just about any Pontiac head get you 500 HP. The more they flow the less cam you will need and that will tame down its street manners.
What heads do you have right now ?
You are better off with a Scat or Molnar crank. Less of a chance of having to have it re ground even though it is new. Well, zero chance if its a Molnar. Eagles are known to have occasional machining problems, Ohio's too.
Molnar rods, you are not going to have to worry about re sizing., spot on size and not that expensive. You just need a angle gauge to tighten the rod bolts vs just a torque wrench.

[jayzinn]

Originally Posted by Dragncar

You can make a lot more than 500 HP with 280cfm iron heads. Not sure how streetable it might be though. You can make just about any Pontiac head get you 500 HP. The more they flow the less cam you will need and that will tame down its street manners.
What heads do you have right now ?
You are better off with a Scat or Molnar crank. Less of a chance of having to have it re ground even though it is new. Well, zero chance if its a Molnar. Eagles are known to have occasional machining problems, Ohio's too.
Molnar rods, you are not going to have to worry about re sizing., spot on size and not that expensive. You just need a angle gauge to tighten the rod bolts vs just a torque wrench.

The car has it’s original 350 in it now. My plan is to build the 400 while still being able to drive and enjoy the car while doing so. I have a ‘72 400 lower rotating assy that I am building. I have went down the ported factory iron head road and came to mostly dead ends. Nobody wants to mess with porting a set of iron heads and the ones that do want to charge the same amount I can buy a brand new set of aluminum ones.


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[Gach]

Originally Posted by jayzinn

The car has it’s original 350 in it now. My plan is to build the 400 while still being able to drive and enjoy the car while doing so. I have a ‘72 400 lower rotating assy that I am building. I have went down the ported factory iron head road and came to mostly dead ends. Nobody wants to mess with porting a set of iron heads and the ones that do want to charge the same amount I can buy a brand new set of aluminum ones.


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Exactly!!

[Gach]

You can definitely make more then 500 hp with out of box E-head, that’s a no-brainer. Of course it depends on what your really looking for. Nice street cruiser that has the capability of running mid 11’s. But if your shutting for 10’s high 10’s low to mid 10’s then your talking more cam. Roller.

Butler has some real nice rotating assemblies. Scatt cranks and rods, all balanced and clearances checked. I know they’re pricey, but by time your done shopping around, crank.. rods..pistons, from this guy that guy then having get it all balanced this is wrong that wrong it can be a nightmare. Theres tons of YouTube videos of guys who have bought Butlers rotating assembly. I’ve been very impressed with. I’ve done a few for Friends helping them out. The thing is once you have your mind set on what you want, you’ve already priced things out and know whats affordable to fit your pocketbook.