While having my engine rebuilt,i bought some used aluminum 91
vette heads from the guy who was doing the rebuild.My engine is a 5.7L TPI for a 87 Z28. The base wouldn't line up perfectly with the heads, he drilled the holes to make it fit.thus having to use some larger bolts with large washers to cover the drilling. this looks kinda ugly to me, but he said it wouldn't be a problem. Now i want to buy a "big mouth" base. do you think the drilled holes will be a problem? Also, there are holes in the side of the heads.On the driver's side,the hole is plugged with a screw-in type plug, but on the passenger side there is no plug. What are these holes for? and should i just plug the right side?
all opinions are welcomed.

thanks, Big John

 

The enlargement of the holes in the base doesn't matter. The Vette heads use the 55-86 bolt arrangement, where all 6 intake bolts on each side are paralle; but your 87 base uses the 87-up pattern, where the center 2 intake bolt holes on each side are at a different angle. What he did, was to allow the earlier style bolt angle to work in your head.

The plugs in the heads are for the fan switch on the pass side, and the temp gauge sender on the driver's side. You'll need the plus out of both of them so you can put the parts in there that belong.

 

Hey thanks alot RB83L69! i really appreciate your response. I guess the 91 vette didn't use the temp guage. I don't think my old heads had the hole for a fan switch,(i'll have to take a look at them tomorrow)
I have read some of your responses to other ?'s and man you sure know your stuff!! It is really nice to have someone out there who knows what they're talking about and don't mind answering questions.
by the way, does the letters in your signature stand for:RE BUILT?

 

Actually, the Vette probably didn't use the fan switch in the head, it was mounted somewhere else (water outlet or something; I don't recall offhand); and you have the heads on the other sides from where they used to be on that car. The heads themselves are the same, so it doesn't matter which side they go on, as far as that goes.

RB is my initials. I have a 83 Z28, I'll bet you can figure out which motor it came with!!

Glad to be of help.