[Steve C.]

Two additional considerations regarding the use of the 325cfm heads.

The choice of intake manifold and with it the discussion involved with port matching it to the intake port size. Example, a Butler 325 cfm heads uses a 1.180 x 2.35 tall gasket

Camshaft lift vs. Cylinder head flow limits....

Note at what lift is that 325 cfm head rated at. I will assure you it is well over 0.600" valve lift. Probably closer to 0.650" or higher.

.

[MerrittE]

Thanks for the feedback I misspoke the heads I originally planned to use were the 87cc version. If going with 72cc heads would 18cc dish heads be safe or should I go to 22cc dishes. I haven’t decided on a cam yet and that will definitely be something I would value input on too. I planned to go roller with butler scorpion rockers and cross wind or torker two intake. Originally I was looking at the butler 500 pump gas package.
This will be backed up by a 4l80e with probably the stock converter and an upgraded rear end but I haven’t landed on a ratio yet. Sorry for the jumbled post but I had to hit the road for a family deal that came up in the middle of this. Thanks for all the advice and I will check out the links above tonight.

[65 Lamnas]

Originally Posted by MerrittE

Thanks for the feedback I misspoke the heads I originally planned to use were the 87cc version. If going with 72cc heads would 18cc dish heads be safe or should I go to 22cc dishes. I haven’t decided on a cam yet and that will definitely be something I would value input on too. I planned to go roller with butler scorpion rockers and cross wind or torker two intake. Originally I was looking at the butler 500 pump gas package.
This will be backed up by a 4l80e with probably the stock converter and an upgraded rear end but I haven’t landed on a ratio yet. Sorry for the jumbled post but I had to hit the road for a family deal that came up in the middle of this. Thanks for all the advice and I will check out the links above tonight.

72cc heads > 16-18cc piston dish > 0 deck block for optimum squish, if at .030 and 4.25 for a 428 block, then that's about 10.6-10.8.....no problem on 92 octane with the "good" chambers. A ported HO intake would be nice with a stock converter if you need hood clearance, or else an RPM. I'm guessing it might be "soft" down low with the T-2 and a stock verter around town.

[hgerhardt]

My 428 with Ross flat tops and zero-decked block and 72cc E-heads is 11.4:1 and is happy with 91 octane. Cam is 248/254 @.050 and 114 LSA.

So much of this is dependent on cam timing. It's the dynamic CR that's important, not static. Dynamic CR is determined from when the intake closes on the compression stroke. The later the intake closes, the less dyn CR you'll have.

An example: this engine with the same cam originally had 87cc E-heads (9.7:1-ish) and I accidentally figured out that it ran better on 87 octane than 91. With the 72cc heads, throttle response is sharper, and I picked up around 1/2 sec in 1/4 mile. Much happier motor!

[torqjunki]

Originally Posted by hgerhardt

My 428 with Ross flat tops and zero-decked block and 72cc E-heads is 11.4:1 and is happy with 91 octane. Cam is 248/254 @.050 and 114 LSA.

So much of this is dependent on cam timing. It's the dynamic CR that's important, not static. Dynamic CR is determined from when the intake closes on the compression stroke. The later the intake closes, the less dyn CR you'll have.

An example: this engine with the same cam originally had 87cc E-heads (9.7:1-ish) and I accidentally figured out that it ran better on 87 octane than 91. With the 72cc heads, throttle response is sharper, and I picked up around 1/2 sec in 1/4 mile. Much happier motor!

Can you post up details on the 248/254 cam your running please sir? Working on similar combo.

[hgerhardt]

Originally Posted by torqjunki

Can you post up details on the 248/254 cam your running please sir? Working on similar combo.

Here you go. As you can see, it's ground 5 deg advanced, so I installed it straight up.

Also, all of my experience with this engine is with the older E-heads. Both my 87cc and 72cc heads are 27+ years old. In fact, other than replacing the valve springs a few years ago, It hasn't been apart in 25 years.

[torqjunki]

Thanks!! I like it. I don’t see LSA