I've got 291 casting heads, no accessory bolt holes in the fronts. I need those holes. I talked to a machine shop about it and they said to tap the holes myself, it can be done. I can do this very easily at home, I have all the tools. I just want to know does anybody have or know where I can find a diagram that gives the measurements for the bolt holes on the fronts of the heads. I've got $1400 in these heads so far and really don't want to buy new heads, yet. I'll be going to the wrecker tomorrow to see if I can make some sorta template or maybe even score a set of 64cc heads ( yeah right ). I just thought I'd ask.

Thanks
Dustin

 

Wow, a machine shop told you to tap your own heads. They must be pretty busy to be turning away customers.

I don't have the diagrams you're looking for, but I'd suggest looking for another shop to do the tapping. Unless you're good at it, I've heard that it's easy for the home mechanic to tap the holes at an angle accidentally. I was looking into tapping my heads for screw in rocker studs and the consensus was that it was money well spent to get the pros to do it.

If you're adventurous maybe give it a shot. I don't think I would for the money necessary to get a shop to do it.
My $0.02.

 

It's a small shop only 3 staff. And he didn't outright tell me to do it myself. He wants me to bring in the whole engine, with the brackets for the serp. belt system all mocked up on it and then the shop would do the procedure. But if the shop did the tapping and something happened I'm still S.O.L anyways. I think I'm gonna try to find a set at the wreckers or on E-Bay, gotta do something soon.