[Formulajones]

Originally Posted by rohrt

Well ya done opened the box now. What is this method about to which you speak of?

LOL

What Paul does with his builds is advance the camshaft until the intake lobe lift is about .035-.040" higher than the exhaust lobe at TDC overlap stroke.

His theory, that I've tried on a few engines now and found it works, is that at TDC overlap when the piston starts down the bore it pulls more on the intake valve this way, which isn't pulling in the super hot gasses "as much" from the exhaust valve and creates a cooler combustion process as the piston comes back up on the compression stroke.

The only issue with this method is that it's tough to get there on really wide lobe separation camshafts. So if you use a cam with 112 or 114 LSA, you likely won't reach those numbers. You can get part of the way there, but not all the way without going to a ridiculous amount of advance.

On the 114 LSA cams I've done for instance, I've gone as far as about 107 ICL install position and found about .025" higher on the intake lobe on TDC overlap stroke. So not quite .035-.040" that Paul shoots for, but better than not at all. I didn't bother to push the ICL any tighter on those camshafts.

In fact as an experiment I did this on my 400 RAIII with iron 12 heads and the 068 cam running 10.13:1 compression and it's been running great on 91 octane for several years on the street and with a lot of track abuse.

This method is a lot easier to obtain on camshafts with 110 LSA or tighter.