400M heads on 351C

[Odmark]

Hey guys, quick question.

Before i start, i just want to say that i am aware that the 400M heads are worse then the 1972 2V heads that were on the car. But those heads are absolute junk and im just putting this together as cheaply as possible just to trade it for another car, and i found rebuilt 400M heads dirt cheap.

So the quick question is, do 400M heads fit the 351C with my current 2V intake and headers?

 

[Don C]

They should fit, they have the same size valves as a 2V with slightly larger chambers. They use the same intake and exhaust gaskets the 2Vs use. Depending on the year, they will likely have hardened valve seats.

 

[Ron Tanzi]

Do you know what year the 400M engine the heads came from? The casting numbers will tell you this. This would help be able to nail down combustion chamber volume. 400M engines from early on used dished pistons to lower their compression ratios to around 8:1 a 76 cc chamber on a stock Cleveland (with stock bore) with flat top pistons and the usual 2 valve reliefs will yield about 8:8:1. I have checked/confirmed the volume on stock open chamber 2V Cleveland heads and they run a volume between 75 and 78 ccs.