[70KGOLD]

I am building a 400 stoker engine and was wondering if the 72 cc e-heads can be used on the street. My goal is to get into the 11s, drive to the track and some weekend car shows. Are they any proven combos like this out there?

[Steve C.]

Edelbrock heads would be a good choice but with the larger 87cc combustion chamber. The 72cc chamber would be a bit high for pump gas in my opinion unless you had dish pistons to lower the compression.
A friend ran cleaned up 87cc castings with no serious port work on his stroker combo for about 10.3 compression. With a mild 236 at .050 hyd flat tappet cam, Performer RPM intake and a Holly 750 carb it made 509-518 hp at 5200 rpm and plenty of low end torque at 570 ft.lbs. at 4200 rpm for a very nice street application.

[Hooter]

I run the 72cc on my street car with dished pistons for 10.3 compresson. Only 1 trip to the track with no tuning and ran a 11.57 through the mufflers on drag radials. Hoping for high 10's this year with some tuning, fuel system improvements, and switching from 3.55 to 3.73 gear.

[uneasyrider]

I think this would get you at or near there with the right gearing. It's what I'm doing and I would guess 500hp+. I'm sure there are a dozen other combos at minimum people are going to list and I'm sure there will be opinion about this combo too but here it is:

E-heads, 72cc (out of the box)

467cid (400 block 0.060 over)

10.2:1 compression

RPM manifold

Comp Cams 51-246-4

1.5:1 rockers

Eagle crank and H-beam rods

Pistons = SRP

Hooker Super Comp. headers (2" primary, 3.5" collector)

800cfm Q-jet

[77TA]

Go 72 cc on the heads... I have friend that runs 72 cc heads on his .060 over 455 and says it fine on pump gas.. THats what 11.5 to 12 to 1 compression... I always thought that was a bit much but he says it works for him.. With the 400 you would only be in the mid 10's so that should be great... Id also go with a solid lifter cam to turn up some RPM's ... I know a guy that used to post here and cp ( Hawkeye ) he ran a RA4 headed 400 o the mid 11's with flat solid cam fwiw.

[b-man]

I would buy the 72cc heads.

1) You can leave them as-is and try to run over 11:1 compression on your 400 stroker (461).

2) You can buy some dished pistons to achieve whatever compression ratio you're good with (I'd go for 10.25:1 max) and leave the 72cc chambers alone. The 72cc heads also give you the option of running them on a smaller 400 or 428, whereas the 87cc heads are really only good on a 455 or maybe a 428.

3) You can send the heads to Dave at SD Performance (or buy the heads from Dave) and have him open up the 72cc chambers to a better-shaped 85cc chamber with his CNC machine. This may be the best way to go.

The 72cc heads have a better port shape than the 87cc E-heads mostly by virtue of the shallower 72cc chamber. This allows for a better short-turn radius in the ports, and the max flow numbers (270 vs. 280) are a bit better even when looking at the ones provided by Edelbrock.

[flamedabone]

I love my 87 cc E heads on the street. I did have to run the Sealed Power .250 flat dome to get 10:1.

BUT, when I built my 455, the 87ccs got my 10:1 with a flatop.

PS. Who makes a forged dish piston for a 400?? I had to have a set made by BRC to get a forged dish...about 600 bills.

Good luck, -Abone.

[Karch]

Originally Posted by b-man

I would buy the 72cc heads.

1) You can leave them as-is and try to run over 11:1 compression on your 400 stroker (461).

2) You can buy some dished pistons to achieve whatever compression ratio you're good with (I'd go for 10.25:1 max) and leave the 72cc chambers alone. The 72cc heads also give you the option of running them on a smaller 400 or 428, whereas the 87cc heads are really only good on a 455 or maybe a 428.

3) You can send the heads to Dave at SD Performance (or buy the heads from Dave) and have him open up the 72cc chambers to a better-shaped 85cc chamber with his CNC machine. This may be the best way to go.

The 72cc heads have a better port shape than the 87cc E-heads mostly by virtue of the shallower 72cc chamber. This allows for a better short-turn radius in the ports, and the max flow numbers (270 vs. 280) are a bit better even when looking at the ones provided by Edelbrock.

What B-man said! Better short turn, for the same cost, and gives you more potential.

I have the 72's, and they were opened up a bit, and I have 11:1. I am unaware of any problems, I have not heard any audible knock, but I try to cut some racing gas with premium (usually 3 or 4 to 1 ratio).

[Steve C.]

This for conversation, just something to toss around...

For years we have read and heard many proffesional engine builders state to keep the compression at about max 9.5 to 1 on iron heads for pump gas. And yet we often hear about the hero super tuners out there touting they run 10 and even 10.5 with IRON heads and no apparant issues. Similar situation with aluminum heads, many proffessionals suggest no more than about 10.5 for pump gas, sometimes less. One such example, Dave Bisschop recommends a max of 10.25 with the 87cc Edelbrock chamber design. And for the 72cc chamber design about 10.5 max.

Now assuming for this conversation we did limit the compression ratio to no more than the often recommended 10.5 with the Edelbrock heads chamber design. And presumbing the heads are not ported, just out of the box. Now which would be the easiest and possibly better deal ... use the 72 cc chamber and presumably custom dished pistons, with the presumed extra piston cost, to bring down the compression ? Or just use regular flat top pistons with the 87cc chambers for the lower compression ? And bringing into the discussion, is it worth using the smaller 72cc chamber for ONLY 10 cfm extra flow at peak lift (and about 4 more cfm area under the curve) ?

[TheMonkey]

Originally Posted by Steve C.

.... is it worth using the smaller 72cc chamber for ONLY 10 cfm extra flow at peak lift (and about 4 more cfm area under the curve) ?

i wanted 10.25:1 on my 462. 2 options were to get 87cc heads with flat tops, or custom dished with 72cc heads. it was a couple extra hundred bucks for the custom dished pistons. i opted for the 72's & custom dished not for the extra air flow, but because dave indicated that the quench would be lower risk for detonation, and the extra $$ also gets lighter pistons. i was already under the 10.5 mark, but the idea of more safety net helped my decision. so my money was spent on lower risk, but as for the extra 10cfm & lighter pistons... i'll take it.

apparently, based on some other posts.... i'm being waaay overly cautious on compression.

[Karch]

Steve C.,

I do agree with you, that for a street motor, on a budget, the gains from the 72cc heads are not worth the worries of detonation.

I personally went with the smaller chambers as this was 7 years ago, and I got a very good deal on the heads ($900 bare for the pair), so I might some allowances, realized I wouldn't be driving the car that much, and like compression in general if I can avoid running race gas exclusively.

I also have room to increase my cam specs, but since my rods are not forged, I hesitate to do that.

But, again, I agree with you. In fact, if it were a daily driver, I would possibly look into seeing what would be lost in keeping the compression under 9.5 to run regular (gasp) fuel.

[b-man]

If you're starting from scratch on a new engine combo, buying a good quality Ross or SRP dished piston is not really much more expensive if at all than buying flat-top pistons. Even having a heavier but less expensive set of flat-top Sealed Power forgings dished is not a huge expense.

If you already have a good short block together with flat-top pistons, the 87cc heads would be the way to go or better yet the 85cc ones made from 72cc heads.

Of course the 72cc heads will not always be the way to go for all builders. But again if starting an engine build with a 'clean sheet of paper' the smaller chamber head with a dished piston would seem to be the way to go in my eyes, even if the port flow was exactly the same between the 72cc and 87cc heads.

[rohrt]

I know their are other Pontiackers that are running 11:1 with aluminum heads and running just fine. I guess its better to be safe then sorry.

[Bruce K]

10.77 here, and no problem with pump premium. Also, the engine keeps begging for more advance, seems to like 38+.

The amount of compression the engine can take depends alot on what cam you choose and how it is timed.

[Steve C.]

Ok between the two, and setting aside the minimal differance in air flow.

One set-up with a little deeper chamber and flat top piston, with no dish and only valve reliefs, for 10.5 compression. And the second with a little shallower chamber and a piston with a 20cc dish for the same 10.5 compression.

Is there any flame front and/or burn pattern issues with the deeper 20cc dished piston compared to the flat top piston ?

I was told by a friend about a discussion years ago with Jim Butler and at the time Jim favored a flat top. This came during a discussion about milling out a dish on a TRW piston to make them pump gas friendly with a small chamber iron head.

[Skip Fix]

My conversation with Dave Bisshop was for the little HP increase for 10.5-11.0 for E heads why take a chance if you get stuck having to get some low grade pump gas while really street driving it on an expensive motor? We went with 20cc dish with mine on a 455 to stay 10.25. I had the 72s in case we were to put them on a 400 they would interchange and not be too low.

On the dyno increasing octane over 93 did nothing for the motor.

[Hooter]

Originally Posted by Skip Fix

My conversation with Dave Bisshop was for the little HP increase for 10.5-11.0 for E heads why take a chance if you get stuck having to get some low grade pump gas while really street driving it on an expensive motor? We went with 20cc dish with mine on a 455 to stay 10.25. I had the 72s in case we were to put them on a 400 they would interchange and not be too low.

On the dyno increasing octane over 93 did nothing for the motor.

Ditto - Dave told me the same 3 years ago when building my combo.

[b-man]

Originally Posted by Steve C.

Ok between the two, and setting aside the minimal differance in air flow.

One set-up with a little deeper chamber and flat top piston, with no dish and only valve reliefs, for 10.5 compression. And the second with a little shallower chamber and a piston with a 20cc dish for the same 10.5 compression.

Is there any flame front and/or burn pattern issues with the deeper 20cc dished piston compared to the flat top piston ?

I was told by a friend about a discussion years ago with Jim Butler and at the time Jim favored a flat top. This came during a discussion about milling out a dish on a TRW piston to make them pump gas friendly with a small chamber iron head.

From what I've read, putting as much of the combustion chamber as you can in the piston itself is beneficial.

Aren't some of the best engine builders using heads with a tiny or even close to no combustion chamber along with a properly shaped dish in the piston these days?

I know this is the street forum, but wouldn't it be a good idea to mimic this type of build on a street engine if the additional cost for a properly dished piston is somewhat minimal in comparison to the rest of the build? That's all I'm getting at.

[Steve C.]

I don't disagree. I know little on the subject and putting forth conversation to get opinions. My 505 build is using a custom 27cc reverse dome piston with 72cc Edelbrock castings for about 10.2-10.3 compression. They are a JE piston very similar to the one Andy Mitchel used in his 505 Road Warrior build in the Dec 2005 Hot Rod on pg 128.

[Skip Fix]

Gosh no one has even brought up the old too big race head argument!

I want to think my Ross dish were around $550.