Just wondering if it's possible to use bronze guides in a cast iron head. I'm sure there is a difference in heat expansion rates where I think the bronze will try to expand first.

 

Common practice although I have never used 'em.

 

If done correctly, with the proper clearance, it's a forever repair.
New guides are coated with Loctite before being pressed-in, and I've never heard of one moving.
Don't sweat the small stuff!

 

There are also thin-wall sleeves, and threaded inserts like a heli-coil made of bronze.

 

BMC engines used pressed in bronze alloy guides as did many other manufacturers, I guess the metals they were alloyed with gave them similar heat expansion qualities.

Roger.

 

I bought a guide made for a Brodix head because the dimensions were what I needed and did a test fit and of course it fit loosely in some of the guide holes so they might not work. The guides I removed were .565 OD. Had the problem off one guide coming loose. Haven't had much luck finding guides a little bigger.

http://www.summitracing.com/parts/bro-sh5651132p

 

Honed bronze guides are the best way to do the job.

 

If the replacement guides are sliding thru the head that is not good.

 

I would think any competent machine shop can hone the head and provide oversize guides...

 

Looking at the old guides it looks like whoever put them in had drilled the holes just a little too big cause they use a punch to make indentations on the guides to make them fit tighter. Sooner or later more would have come loose.