525 heads
 

I know the bolt pattern on ex side is different ,I want to use cmis that I have,anybody drill and tap t hem out ??? How deep did u go ??? TIA

Why not drill the CMI's to match the bolt pattern?

Ive done what Bill 3 is saying, but that stainless flange is tough stuff

Heads
 

Aluminum is alot easier I only have one set of heads most I have are iron

I have done it and it worked but getting the bolts in kinda sucked. Wasn’t a quick way of clamping to my mill so I used a mag drill. Worked really good.
https://cimg1.ibsrv.net/gimg/www.off...da93bab832.png
https://cimg3.ibsrv.net/gimg/www.off...e6260939e1.png

These started as 525's that I drilled a standard pattern in so they can be used on either head on the dyno. Either way, yes it can be done and not a tough job.

F2,

Pro tips...

A cobalt split point drill makes it much easier. They are only minimally more expensive than a standard HSS drill. A good cutting oil also helps a lot. Run the spindle considerably slower than you'd think you should.

Thanks. Brad.

Heads
 

Thanks guys mag drill good idea

those headers look so familar, good job buddie!