454 valve cover ?

ericcarr2000

Ensign
Joined
Mar 19, 2010
Messages
903
Ok as some of you probably know by now, I will be repowering my sundancer with a mildly built 454/b3 power plant. One question I have is can I sufficiently install 'tall' valve covers instead of the 'short' ones?
I didn't know if I installed the tall ones if they would hit the riser or not. Does anyone have s set of tall covers on theirs?
 

Fun Times

Moderator
Staff member
Joined
May 16, 2009
Messages
8,776
Pretty sure the valve covers are going to hit the center flow stock exhaust system. Aftermarket performance exhaust or 496 exhaust do give you more play room.

http://forums.iboats.com/forum/engin...r-fit-on-a-454
http://www.offshoreonly.com/forums/d...bbc-print.html

Question
Mercruiser 454 ci exhaust manifold - spacer of some kind needed
I’m using Comp Cams roller rocker arms with tall valve covers. When bolted up, I have no clearance between exhaust and valve cover. What can I do to solve this problem? Is there some kind of exhaust gasket spacer available?

Answer
You may need to fabricate your own brackets for that or check with someone specializing in performance marine products.
 
Last edited:

ericcarr2000

Ensign
Joined
Mar 19, 2010
Messages
903
Is there some sort of a spacer I could put on the exhaust riser to move it out just a tad bit?
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,581
Is there some sort of a spacer I could put on the exhaust riser to move it out just a tad bit?

The heads sit at an angle toward the exhaust, the exhaust is vertical. Putting a spacer on the exhaust riser just makes it higher, it doesn't make it further away. You might be able to find an exhaust spacer to move the exhaust manifolds further away from the head, but then you need special bolts and double the gaskets.

Question: Why do you want to put taller valve covers anyway?

Edit: maybe the better question is why are you certain the rockers will hit the current valve cover?
 
Last edited:

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,581
Guess I should dig into it a bit more, but I don't see an issue even with roller rockers. Is Crane Cams or someone else saying you need a taller cover.

My 502 went from standard to a very high lift cam and rollers pushing 530HP and I still have the standard valve cover
 

ericcarr2000

Ensign
Joined
Mar 19, 2010
Messages
903
I don't know, I'm having a mildly built 454 being built as we speak and was thinking if my stock height valve covers were going to clear the roller rockers is all.
Didn't know if I was going to need to install s taller pair,
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,581
I don't think you will have any issue, there should be plenty of room.

Example: My stock 502 had a high lift cam and full roller rockers installed and I'm still using the factory valve covers. Went from 415 to 530HP
 
Top