Quote:
Originally Posted by RustyPile
Sorry if I confused you. Those Aluminum Edlebrock heads aren't really intended for a bone stock engine. The $400 heads I referred to are these cast iron heads, the Vortec being my first choice:
https://www.summitracing.com/parts/sum-151124
or these:
https://www.summitracing.com/parts/sum-152123
If you're "dead set" on aluminum heads, Edelbrock wouldn't be my first choice. Those AFRs are a bit cheaper and will probably work better than Edelbrock. AFR (Air Flow Research) has been in the head business a very long time. Much longer than copycat Edelbrock. For you, flow rates are more of a concern than metallurgy of the heads.
Let me see if I can do a better job explaining the mechanics of cylinder head selection.. Intake runner cc description is a way of measuring the size of the intake runner. The larger the number, the larger the runner. The larger the runner, the larger the flow rate. Large displacement engines turning a high RPM require a very large runner. Lesser displacement engines, such as your 327, have to turn higher RPM to benefit from the high flowing large runners. The air/fuel mixture at low RPMs in those large runners moves too slow. Large runners, coupled to small displacement and low (street level) RPMs lead to the fuel droplets separating from the air. This causes all sorts of run problems. For a stock engine on the street, runners in excess of 165 - 170 ccs don't add much benefit, because of the low RPM average.
I'm definitely not talking against the use of aluminum heads. They definitely have their place. Aluminum heads have their advantages. They dissipate heat much better. This means they handle detonation better at higher compression ratios. Timing settings can be more advanced or more aggressive without that dreaded "ping". |
Thanks for the explanation, that makes sense. So based on that information, maybe that specific AFR head wouldn't be the best choice then, as it has an intake runner of 195cc? I'll look at other AFR's, as they do seem pretty good and at $549 a head vs the iron ones at $393, the price is not that much more.
Thanks again, this really helps.