i bought a B&M blower and its made for the early style heads. im running late style heads and do not want to change them because i have them fully tricked and it would be a big loss. ive heard of people elongating the 4 center bolt holes to make early style manifolds fit on late style heads. has anyone done this? is it hard? i dont want to go screwing it up on a blower manifold, that would be even a bigger waste. is there anyone who could do this for me that has the experience?

 

I did it to a ZZ4 intake manifold. It's not hard, the hardest part is elongating them ENOUGH. A large bastard file worked well (any hardware store should have one, you're looking for one around 5/16" diameter). You elongate them OUT at the top. I.E. the old bolts looked like this (from the front of the engine):

/ \
Angled in quite a bit.

The new ones look more like this:
| |
Not quite, but ALMOST straight up and down.

On the ZZ4 manifold this did NOT leave a lot of metal around the bolt hole... so I test-fit it repeatedly rather than over-filing.

I then filed the top of the bolt hole flatter so the bolt shoulder would rest on it a little better, but I didn't use a wedge-shaped spacer or anything... not sure if you can even get them.

Be careful not to use too long a bolt after doing this! The bolt may now go further in the hole because of all your filing, and I had a bolt contact a pushrod. Luckily all it did was bend the pushrod slightly... (I noticed this when I later removed the rocker arms and valve covers for some reason).

 

yea, just walk in there and say you're looking for a large bastard.


lol, seriously though, its not too hard, you just make the holes more oval shaped.

on this page, you can see some adapter bushings....
http://www.professional-products.com/Power_Plus.html

pro-products stuff is usually pretty cheap, so if you can find someone that carries them, they should be able to order the spacers.. the part number (and pic) is on that page.