Cylinder Heads: Marine or Auto

[roemere]

I thought that you could use automotive heads and that the only difference was to make sure to use a marine head gasket.

In tracking down replacement heads, I was told the following by a vendor: "all the ford marine small blocks come with the guide and posi-lock style rockers. You would have to get the right rocker arms for these but they would work"

Can someone expand on this for me? If I purchase these heads, can I use the rocker arms from my existing heads? Does this person know what they are talking about? Googling "posi-lock style rockers" doesn't get me anything....

 

[PlayDate]

Posi lock refers to rocker arm nuts which are locked in place with a set screw after adjustment. Most marine engines use stock lock nut style nuts to hold the rocker in place.

This is an example of a perma-loc
http://www.summitracing.com/search/product-line/arp-perma-loc-rocker-arm-adjusters.

Hot rod or performance engines use perma-locs so that the rocker arms don't loosen under high rpms.

Now to your question.... you didn't mention the type of Ford engine you are working on. That said, there is no issue in using automotive heads on a marine engine if the valves and guides are of the same material you already have on the engine (A 302 is a 302 and a 351 is a 351 either windsor or cleveland). That means that if they are stainless steel on your existing engine....I would make sure that is what you put into the automotive heads. Bronze guides are also a good thing since steel on steel can rust during winter months. A marine head gasket is a must.

I have seen double stacked rocker arm nuts on some Ford engines but not very often.

Hope that helps,

John

 

[roemere]

Thanks!

 

[roemere]

Ok, I am lining up parts to replace those damaged by the freezing (heads and exhaust manifolds). One of my sources also has a 302 4bbl intake and carb (marine) and he wants to know if I want those as well (good price if I buy the whole "bundle").....since I have it apart, is it worth swapping the intake for a 4bbl? What will I gain?