Porting small block 915 j-heads
A question: Would it be stupid to shorten the guide at least .200”
Normally, I don't, cause I'm using a lot of spring pressure compared to stock and geometry is compromised.
In your case, however, you could probably get away with it. (mild cam, low spring pressures)
Keep in mind, shortening the guide reduces stability. You could run a tighter clearance, but that is limited. (stick the valve)
There is airflow to be gained though.
I'm sure someone will chime in here. I would be interested in their take too. (I hope all of this translates into Swedish correctly..) :)