Originally Posted by kringold
The heads are installed and on a daily driver. I don't want to tear the engine apart just to get the port dimensions.
I did, that's how this started. The ones I bought don't fit, like I was told they would. They hit the motor mounts.
Ah, I see. Is there a motor mount problem or just the wrong headers?
Try for a refund on those headers if they cannot be reasonably modified.
I suggest you use the gasket idea. Gaskets will always be bigger than the ports but will give you a dimension to work with.