3500 head hole conundrum..

[Guest]

In the end of a 3400 head there are 3 bolt holes on one end, and 4 on the other.

On the 3500 head there are the 4 bolt holes on the same end (as the 3400), but on the other end there are only 2 bolt holes.

What I am wondering is if anyone has drilled the third hole in a 3500 head, and if so, is there enough material in the head to not break into the water jacket?

[Guest]

I took a close look at one of my spare 3500 heads and it looks like this area is just solid aluminium. In comparing it to a 3400 head I have kicking around, it looks as though the 3400 head has some extra material in the water port to allow for a thick material area around the bolt.

I'm comfortable drilling this third bolt hole, I just won't make it as deep as it is in the 3400 head.

[1988GTU]

Wondering why those holes were limited from factory? They musta known these motors would find there way in a rwd application and wanted to boss block us LoL

[Guest]

I doubt GM ever thought about RWD swaps where the gen2/3 660 were concerned, they like to push V8s for that.

I don't think I've seen this particular hole used in an OEM application, which is likely why GM eliminated it on the 3500. This hole wouldn't be a RWD specific thing anyway, it's just a bracket that I'm recycling from my Franken60 swap has that 3rd hole and would feel better in having it there, even though it really isn't needed.

[ForcedFirebird]

Even if it broke in the water jacket, you would just need thread sealer like the iron head water pumps did. if you like, I can link you to my photobucket albums that shows how I did my f-body iron head brackets.

[Guest]

Oh I know I could just use sealant, I would just prefer to not need it.