Manifold Intereference With Aluminum Heads
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Joined: Dec 2017
Posts: 73
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Manifold Intereference With Aluminum Heads
Has anyone that put aftermatket aluminum heads dealt with interference issues? With the stock ram exhaust on my '72 C3 it's looking like I may need to grind some metal off of square notches that are butting against the valve covers. The exhaust manfold won't completely mate to the head before hitting the very bottom of the valve covers at 4 areas. The valve covers are aluminum aftermarkets, so thicker than stock tin, but I had used them with the stock heads and never had any issues. Down at the engine block, by the flange, it's just about kissing the block too. I'm thinking these may have been areas where the cast was filled during manufacturing and probably OK to just grind the areas down?... but hoping for some feedback. I can post pics if this is confusing.
Pro
Joined: Apr 2010
Posts: 604
Likes: 249
From: Carson Valley
I had this issue last winter with the Flowtek heads when I installed a rebuilt engine in my car.
I clearanced a par of chromed stamped steel covers to fit the manifolds.
My eventual plan is to install headers, then my finned aluminum covers will go on.
I clearanced a par of chromed stamped steel covers to fit the manifolds.
My eventual plan is to install headers, then my finned aluminum covers will go on.
Pro
Joined: Aug 2010
Posts: 653
Likes: 454
From: Napa, CA
I had similar fitment issues if I’m translating your post correctly. The previous owner of my 73 had installed stock Chevy L98 aluminum heads that feature center bolt style valve covers. It had a fairly severe valve cover oil leak that I discovered was caused by the mating flange of the covers resting on top of rams horn manifolds instead of the cylinder heads. I resolved it by grinding some reliefs in the valve cover flanges that allowed the covers to drop down into place and seal against the heads. I think it might be caused by the exhaust ports being raised on these and other aftermarket heads. In hindsight, a cleaner solution should have been to grind the interference off the cast iron manifolds but I didn’t want to remove them for modification and risk creating any exhaust leaks by disturbing the sealing surface.
good luck with yours.
good luck with yours.
