Hi. I run a 632 engine with Old 14-degree heads (CFE). I hurt the motor quite often and it seems to detonate a lot. What could I be doing wrong? The 2,800-lb car runs 6.88 e.t.'s. I run 2 stages of nitrous: 34 nitrous jet, 30 fuel jet; 32 nitrous jet, 30 fuel jet. I run 5.5 lbs. fuel pressure.

Sal

Hi back at ya, Sal.

Yours is a very common problem with the racers who use the Olds style heads. The problem is that with the valve angle and the small combustion area in the head, they are way too efficient! The Olds head makes a ton of power on a nitrous engine and that is why they are commonly used. There are a few guidelines to follow, such as timing retard and plug depth into the head.

An Olds headed engine wants less timing than a Chevy of Pontiac headed engine, so change your timing program first thing. You did not say in your letter how much you are retarding, but I am sure you use the typical program with a nitrous engine of 27 or 28 degrees at idle, then 10 or so degrees out when the car leaves the starting line, then the balance out when the second stage comes on, down to 14 or 16 degrees total.

You will need to look at your program and get more timing out on the leave, say 14 degrees, and then the balance out when the second stage comes on, down to probably 10 or 12 total degrees. Work with this a bit to see what makes your engine happy.

The second thing to look at is indexing your spark plugs into the cylinder heads so they don't go too deeply into the combustion chamber and, if possible, all ground strap electrodes should stand the same height vertically. This can be done with plug washers and it seems to make a big difference in stopping detonation.

Sal, with a little patience and careful tuning, you will solve your problem. Let me know if I can help more.