Quote:
Originally Posted by swamp rat
I had the same problem with my K20, i bought an HEI and Edelbrock tall valve covers and couldn't use them, come to find out the K20 uses the rear bolt holes for the engine mounts, the C10's and probably the C20's use the front bolt holes.. Go figure. Thats why i ended up with the Mallory unilite.
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From what I've been able to determine, Mike, rear mounts were used for all six cylinders and small blocks with manual transmissions (on C10s at least). Front mounts were used for all big blocks regardless of transmission type and small blocks with automatics. Not sure if this is 100% accurate, but a good rule of thumb.
I made the decision to use the rear mounting holes because I like the look of the engine set back and the improved handling. I modified the firewall / floor to accommodate my automatic transmission. I did the same to my silver '68 and had no issues with the HEI or the valve covers, so I assumed a repeat performance would be okay. I neglected to take into account the added height of the finned covers, plus the added thickness of the adapters that convert the center bolt Vortec heads to a perimeter bolt pattern. Then I added a chrome spark plug wire cover to the top of the HEI which I didn't have on the '68.
So effectively, I could fix the problems by removing the spark plug cover and going to a lower profile set of center bolt valve covers ...or just beat the crap out of the firewall. Well, maybe not that, exactly. But I can put some smooth pockets into the affected areas that will provide the clearance I need without looking too out of place. In for a penny, in for a pound as they say.