Thread: Help with 390 heads

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If he's sticking with the stock exhaust manifolds have him take a look at the D2's in relation to the ex port location on the C6's. D2's have a raised exhaust port which might not match up very well on the C6's depending.Does he have headers? Or if not what exhaust manifolds doe he have to use? If that's all a non issue and the R heads have the right ex bolt pattern for his exhaust they can't hurt and are a good start. He can cc the head chambers (easy to do) and compare the two. And adjust the head gasket thickness to get the deisred CR. There are online calculators you/he can use to figure this out. Along with knowing piston height and dish size. This also leaves room to upgrade the intake, exhaust, carb etc.... later if he likes. He pretty much has everything he just needs to do some figuring to see where his CR will be at exactly. Google "engine math" and you should get some site sits to calculate everything. Email me if you can't and I'll send you a few. This way there are no surprises. You can get shim head gaskets that are .015 thick. Fel-Pro Vic Reinz are .042-045? and Cometic makes head gaskets up to .125 thickness. But Cometic gaskets are somewhat expensive (almost $200 a set) but reuseable. But he should be able to get the CR he's after doing a little homework.


Edit to add....if he had a 428CJ in there have him doublecheck the ex manifolds to the C6's if he's using the same ones. Port match will be good between the 2 just double check the bolt pattern. FE heads have 8, 14 and 16 bolt exhaust bolt patterns. The vertical 8 pattern is common to early lowriser heads and all pickups. 14 bolt was the GT and CJ pattern. 16 bolt heads can use both exhaust patterns thus the 16 bolt holes. Those normally are later service heads.