Edelbrock 60929 Cylinder Heads tech help

[Wedgeamacallit]

Hello everyone. I have a tech question that I am trying to figure out what to do. Currently have a 440 bored 030 over with TRW L2266F30 pistons which are 089 in the hole. I have cast iron 906 heads that are cut 080. I am running a .039 compressed head gasket. Compression is right about 10.1. Running a torker 2 intake with a 750 holley dp. Cam is hydraulic 232/242 at .050 with 504/528 lift on 114 lobe. I have a set of 60929 edelbrock heads which are 84cc. If I cut them .60 and run a .027 compressed head gasket that will be me at about 10.2 compression. I feel I need the compression to be higher with the aluminum head. I was hoping to get a 50-60 horsepower gain with a head swap. I was also thinking of using the performer rpm intake with it also. The car makes 338 horsepower at the wheels with the 906 heads. I really do not want to tear it down to deck the block or change pistons. Any thoughts/opinions are appreciated!

 

[RustyRatRod]

No way do you have 10:1 compression. About .0067" equals one cc. Divide your .080" cut by .0067. That's like 11 with somethin left over. So, 906 heads usually spec out at 90ccs give or take. So 11 minus 90 is 79. Plug all that into the United Engine compression calculator and I get 9.439:1. Gettin a piston capable of zero deck height such as the six pack pistons will really help. Then you COULD get 10:1 without cutting your aluminum heads. I think even WITH aluminum heads and your "supposed" 10.2 you're not gonna be pump gas friendly with no quench.....and you'll have no quench at .080" in the hole. Just food for thought.

Oh and what in the world are you trying to do with that wide *** lobed cam? No wonder it makes only 338 RWHP.

 

[Wedgeamacallit]

Hi Rusty. Thanks for the input. Guess I was given the wrong info about the 80 cut and my CC.
I should have used the L2355F six pack piston and I wouldn't have an issue. So if I cut the aluminum heads you think I'll have pump gas issues? What compression would I be at with the Edelbrock cut .60? Is it the same formula? I'm happy with the cam. Runs better with it than a 509 purple shaft. Thanks again for the help

 

[Flys-Lo]

338hp at the wheels? What's that translate to at the flywheel?

 

[RustyRatRod]

I'm not sure you would need to mill the aluminum heads with the six pack pistons. You'll need all the info on the pistons first. Where they sit at TDC, the piston head cc volume and all that there kinda good stuff.

Hi Rusty. Thanks for the input. Guess I was given the wrong info about the 80 cut and my CC.
I should have used the L2355F six pack piston and I wouldn't have an issue. So if I cut the aluminum heads you think I'll have pump gas issues? What compression would I be at with the Edelbrock cut .60? Is it the same formula? I'm happy with the cam. Runs better with it than a 509 purple shaft. Thanks again for the help

- - - Updated - - -

338hp at the wheels? What's that translate to at the flywheel?

I would guesstimate around 400 at the flywheel.

 

[IQ52]

Let's get some things sorted out here.

#1, you don't have to raise the compression with aluminum heads, thats poo-poo.

#2, tell us about the 906 heads, have they been ported, bigger valves? Better yet, what do they flow at .500" lift? A typical stock 906 will flow 230 or so cfm at .500". The RPM will flow 270 or so. In THEORY that could be 80 HP at the flywheel.

#3, if the 906 heads are stock, just bolting the RPM heads on will give you a horsepower jump. 50-60 at the wheels? Hhmmmm

 

[RustyRatRod]

I was under the assumption that he wanted to raise compression, not necessarily that he thought he had to with aluminum heads. I couldda read it wrong. You know me. lol

 

[Wedgeamacallit]

Hello. The 906 heads are not ported. I only installed stock size Milodon street valves and had the heads cut 80. I also gave the wrong cam spec. Cam is on a 112, not 114. I never flowed the heads. I was trying to get the compression at least about the same, if not more but I didn't want to change pistons or deck the block. Sounds like out of the box, the edelbrock heads will make some nice power over the 906 combination I currently have. Thanks a ton for the information

 

[IQ52]

Recalculating, recalculating.

Using the intake valve closing figures from the Crane H-302-2, I have you right now as about 9.7:1 compression and 8.1:1 dynamic (as I calculate it) and I don't hear you complaining about detonation.

Therefore, if you bolt on the RPM heads as is with the .027 gasket, I get, 9.1 and 7.6.

If you mill the RPM .050" and use the .027" gasket, I think you will be back to 9.7 and 8.1. Except you will have all the extra flow you get from the OOTB RPM vs the unported 906, which is considerable.

Even if I've guessed a little off here and you have 10.0:1 and 8.4:1 dynamic, with the hydraulic cam closing at 43 degrees @ .050", I believe you are still pump gas compatible.

You always have the option of using the .039" or thicker gasket later if you experience detonation.

 

[RustyRatRod]

Thanks for settin me straight, Jim. I can always depend on you to square it up.

 

[Wedgeamacallit]

Do you feel it would be worth doing the 50 cut on the Edelbrock? Pump gas is not a problem. We run 92-93 octane, 36 total timing. Any benefit to mild port work? Thanks again

 

[IQ52]

Do you feel it would be worth doing the 50 cut on the Edelbrock? Pump gas is not a problem. We run 92-93 octane, 36 total timing. Any benefit to mild port work? Thanks again

I figure if you mill the Edelbrock heads you MIGHT gain 8-12 HP. You decide if that's worth it to you. If you have milled the 906 heads .080", it is unlikely the pushrods will be the correct length for the RPM head. If you mill the RPM head, they STILL may not be correct.

If one knows what they are doing, there is always a benefit to doing a valve job and port work. A little benefit, doing it mild, and a lot doing it wild. DONE CORRECTLY, using a standard port window, you cannot get the ports too big in an Edelbrock RPM head to hurt a MILD 440 engine, let alone one that is already putting down 338 RWHP.

 

[GrabberOrange69]

I always run as much compression as I can stand. The rule of thumb is 30 hp per compression point for a 350ci engine. That doesn't take into account the seat of the pants torque and quicker, crisper throttle response you get upping the compression. The more compression you run (to a point), the more cam overlap and duration you can stand and still idle at a decent rpm. Rusty is right about the lode separation; get a cam with 108-110, ESPECIALLY if you are looking to get the compression ratio over 10:1. That wide separation will increase effective cranking pressure - a no no if you are also raising the compression as you want. Don't know if you built the engine, but I suspect the wide sep was chosen to compensate for the lower compression ratio your engine has at present.

Good luck, and above all - have fun!

 

[IQ52]

I always run as much compression as I can stand. The rule of thumb is 30 hp per compression point for a 350ci engine. That doesn't take into account the seat of the pants torque and quicker, crisper throttle response you get upping the compression. The more compression you run (to a point), the more cam overlap and duration you can stand and still idle at a decent rpm. Rusty is right about the lode separation; get a cam with 108-110, ESPECIALLY if you are looking to get the compression ratio over 10:1. That wide separation will increase effective cranking pressure - a no no if you are also raising the compression as you want. Don't know if you built the engine, but I suspect the wide sep was chosen to compensate for the lower compression ratio your engine has at present.

Good luck, and above all - have fun!

Somebody slept through cam school class. Narrowing the lobe separation will increase the cranking compression because it closes the intake valve sooner (i.e. the Thumper and Whiplash cams). A wider lobe separation is an effective tool if you have too much compression.

His cam has a long advertised duration 302/312. Crane spred the lobe separation to reduce the overlap so the engine would idle better.

 

[Wedgeamacallit]

You are correct. The cam makes some noise but it does idle better than previous 509 cam. We are using the small block converter which is border line for the combo. May step up the converter in the future to the 3000-3500 range.

 

[GrabberOrange69]

Somebody slept through cam school class. Narrowing the lobe separation will increase the cranking compression because it closes the intake valve sooner (i.e. the Thumper and Whiplash cams). A wider lobe separation is an effective tool if you have too much compression.

His cam has a long advertised duration 302/312. Crane spred the lobe separation to reduce the overlap so the engine would idle better.

Well, now I'll admit to sleeping through English class, but not through cam school. So I'll assume I didn't get the advanced class.

However, I'm here to learn.