Alan454

I have a stock Gen IV Merc 7.4L Bravo I with stock cast iron exhaust manifolds. My old cast iron heads are shot and I would like to replace them with Edelbrock Aluminum Performer RPM heads. However, I have found out that the four external head bolts on the Edelbrock heads nearest the exhaust ports are raised quite a bit. As I recall, clearances between the head bolts and the exhaust manifold were very tight on my engine - unfortunately I no longer have my stock heads for any measurements.

I know that this is a pitifully low performance engine for this forum, but does anybody know whether those Edelbrock heads and my stock manifolds will mesh OK?

Thanks for any help!

Noise Pollution

THe stock manifolds should bolt up. If the exhaust ports are raised .300 you'll need 1 inch longer bots. I would buy a set of ARP bolts for the new heads.They'll come with washers so the bolts don't gaul the alumium.

big jing 2

put these heads on my boat 2 years ago, everything will fit. Eldebrock supplies the longer bolts with the heads...ken

Alan454

Thanks for the fit info! I already have ARP's for the stock heads hopefully they will fit except for the longer holes.

I have flat top pistons yielding a 8:1 comp ratio if I believe the manual - I am estimating that the new heads will bring it up somewhere between 8.2 and 8.4:1 as I'm not totally sure of the stock head volume. Do I really have a (plug?) clearance problem with these pistons?

Thanks for the responses

offthefront

I have M IV's with the RPM heads and the bolts did touch the Manifolds ... Gill Exhaust .... Dremel solved the problem ...m