what does it take to get an 87 tpi intake manifold to fit onto 86 heads?

pics and directions appreciated.

 

lots and lots of work. By "lots" I mean "it bolts right up."

 

i was under the impression the angle of the bolts changed in 87

 

I only know of the bolts angle being changed for vortec style heads... I could be wrong, but I don't think so. Let me check before screwing you over.

 

You're wrong, he's right.

The center two bolt holes on each head are at 72 degrees instead of 90 starting in '87. Makes it easier to get a wrench on them. In order to get the '87-up manifold on '86-earlier heads, you have to elongate those four bolt holes in the base. It's not a bad idea to face them square, too.

Vortecs are completely different in bolt pattern and runner location (height).

 

I wish the smiley worked. I could have sworn...

 

With the right bit, it takes only a few minutes to elongate, with the wrong bit, it will take about 30 minutes to an hour.
We had the wrong bit and it took us almost an hour to elongate the 4 center holes.

 

rotozip?

 

what do you mean about face them square?

what type of bit do i use?

 

I don't know what the right bit is, but I was told if we used the right one it would be really quick.
We used a regular drill bit.

 

it takes 15 minutes with a grinder, just cut the rest of the bolt seat out toward the side of the mnaifold, and the angle nolong matters at all. Wiorks like a charm. thats how i'm getting my 86 TPI on my 88 heads so....

 

Where the bolt shoulder meets the base of these elongated holes, it will no longer be square. I've heard of angled spacers/washers to accomplish that, but never seen them. Most people don't bother, so the bolt only contacts the base on one side. The proper approach would be to mill/grind the mounting face so that it is square to the bolt.

 

oh ok i see what you mean now. i thought you meant make them square shaped instead of a circle or oval. man i totally missed that haha. on i will have it milled. thanks alot i appreciate all the help.