Piston choice for Edelbrock Heads?

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Speedotann

Speedotann

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Good Morning,

I have been researching a lot lately on heads. Looking at Iron and Alum. Can't find a straight answer on what piston CC works best with Alum. I hear you should calculate 1 compression point higher than Iron, some say it doesn't matter. Anyone have any experience suggestions? If KB745's are used with 63cc iron head, what would it do putting on a 63cc Alum head? It will be a 408-410 with Comp High lift 564/564 (Same cam as Car Craft Build, IMM). This car will NOT be driven all of the time, so any suggestions on a different cam would be a consideration. I want to also use Forged pistons and stuck between 1.55 and 1.6 rockers. Thanks

Brian
 
Compression ration won't change if you're going from one 63cc head to another keeping everything else static.

Usually with aluminum heads you can bump compression a bit because of aluminums heat dissapation qualities.

If Brian is doing the machine work, speak with him about what to run and a good engine combo for our pump urine, errrr gas, we get around here.
 
I myself like to build flat top and zero deck set up's with that head and a .040 (approx. ) head gasket for good quench.
 
I run the KB745s in my car, Edelbrock heads, with a 4" stroke and a .039" head gasket and I have a static ratio of 10.3:1. Keep in mind the 63 CC heads typically measure out around 64-65 CCs. Since my heads were ported by Shady Dell I had him mill the heads down to 62 CCs. I run 93 pump gas but I would bet lower octane fuel would run fine. If I were you being in CA and you want to run pump gas I'd just run the 745s with the heads uncut, .039" gasket, and you will be able to run on low octane fuel no problem.

I would have a good shop like Indio Motor Machine check those heads over before you run them too. Have the valve job cleaned up, surface trued, valve guide clearance checked/corrected, and a littlle bowl blending would go a long way. And make sure the valve springs are correctly matched to the cam you run.
 
With a 4" stroke and closed chamber aluminum and a street car, I run a dish. SRP makes a good one for reasonable money that will still yield decent compression with good quench. Depending on the package, I'd run either 65, 63, or 60ccs with them.
 
moper said:
With a 4" stroke and closed chamber aluminum and a street car, I run a dish. SRP makes a good one for reasonable money that will still yield decent compression with good quench. Depending on the package, I'd run either 65, 63, or 60ccs with them.
Click to expand...

I was looking at the SRP 16.9cc dish. It says they use 6.125 rods. What is the deal w/ that. Will they work with 6.123? I was thinking 63cc to have the comp like 10.4, 10.5. That too much?
 
As recommended here, aim for zero deck for quench effect and you'll need dished pistons for 10.5 max compression w/aluminum heads.
 
I did miss the stroker mention in the reply. I'm with these guys. Sorry, I was thinking stock stroke 360, in which I'd use a flat top/zero deck slug.

The dish in the stroker set up will keep this streetable/pump gas freindly.
 
Thanks guys.... Rumble, it's cool.... I figured thats what you meant when compression came out to 11.5. LoL

SRP's with 6.123 rods? why does it say they require 6.125 rods? I think those would be the most cost affective with keeping compression good.
 
no. I don't now why they say "Must use...." Do the math. A .002 is nothing for piston operation. Clearance is near nothing. If you want to be exacting, this you should know. But when the engine block goes to the machinest, measuring up the block, rods, pistons, etc.... should be part of the deal.

I don't see .002 being a problematic factor.
 
nah, it's just a mistake. The rods are 6.123. Kind of like 440Source's "short" 6.76 rod which is .008" shorter than factory RB rods. The production variances in the stroke length and indexing will be more than that .002". As far as compression, the higher the better, and use the cam choice to balance it out for pump gas use. I've seen as high as 125:1 static with pump fuel, but you need to understand it's the dynamic compression ration that really matters. With aluminum heads, closed chambers, a tight quench, and dished pistons, you should have no issues running a static ratio of 10.75:1 with a cam in the 235°@.050 range... Which is very small for this package.
 
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