I was wondering what they do when they machine your heads to fit bigger valave springs. I am about to run comp cams 943 springs and was told I need to get my heads machined. I was wondering what it is they do and would I be able to do it myself?

Thanks
Matt

 

The spring pockets are machined to a larger diameter. With the correct tool, you pilot off the valve guide. It could be done with an electric drill, although drill press, or better yet, a small specialty mill does a better/smoother job of it, providing the head is set up at the proper angle. For what is charged for the actual pocket machining, you'd end up paying more for the correct tool itself, plus the labor to do the job, providing it is done with the skill necessary.

 

It's pretty easy, IMHO. Not really a precision job. The cutters usually cost ~$80 with an arbor that fits in the valve guide to center the cutter. So, as Arnie said, it might be cheaper to have it done. Depends if you want the tools and feel confident trying it yourself. You can ruin the head.

There's a picture of the cutter and arbor at the bottom of this page http://www.compcams.com/catalog/313.jpg

Rich

 

how much does it usualy run?

Thanks
Matt

 

Just to cut the seats? Maybe $50 per head or a bit more. But the heads have to be disassembled (and reassembled) and that will add a lot to the cost if you are paying someone to do it.

Rich