Ive been messing with the timing on my new motor. It seems to run best with a bit too much timing. Its about 10.7 to 1 and im running 91 oct. California... Right now the timing is set to 16 at Idle. It runs great. When I lower the timing I can feel a power loss. Does the cam Im running causing this? is 16 degrees advanced safe with this kind of compression and octane?

 

do you have any spark knock at 16? if not, you probably are ok.

 

On the street, it is not unusual for your engine to run better with timing too high for the fuel you are using, thus having better performance but having detonation issues. Generally the more timing you have, the better the engine will run, but there is a point where too much timing hurts the performance. The base timing is important, but the overall total amount of advance and when the timing curve finishes is more important in limiting detonation. You also have to consider mechanical and vacuum advance amounts if you are running a vacuum advance dizzy. What type of dizzy do you have? How much total timing do you have and when is the timing completely in?

I run a modest 12* at idle with a total of 36-37* by 3300rpm with just a tad of detonation in the very heat of the summer on my mechanical advance only MSD dizzy. I have a 10.2:1 aluminum head 383 running 93octane in Texas.

 

The cam is usually the cause. Don't be alarmed at 16. I'm running 20 intitial and my car runs great. As long as it doesn't ping you are good.

 

It's not too much if that's what it runs best with and doesn't ping on your fuel octane. Modified engines often need more initial timing to get them to idle correctly. I'm at around 16* idle as well. You usually need more idle timing to get higher and more consistent intake vacuum for a carburetor to idle correctly. It's just the nature of the beast.

 

The car is too damn loud to hear any pinging...at least i dont think there is any. at 18* it would deisel a lil when I shut the car off. so i put it back to 16*. no specs on the spark plugs to show detotnation. But on the other hand the plugs are white, same as new. too hot? total im at 38* at 3000

 

found great article on reading spark plugs
http://www.wallaceracing.com/plug-reading-lm.html

 

What does diesel when the car shuts off mean?

 

total timing is the biggest concern. If it's too much initial timing it will usually knock under 3k. Mainly just off idle under a load. I used to run 22-24 initial and 38 total with the N/A 302. With a nitrous retard you could activate it before you shut it off and have it pull 10 deg. My car was night and day difference with 18 deg compared to 22

 

isnt initial timing going to directly affect total? How can you change initial without affecting total. when I set it to 18* it was at 40* total...bad backfire after WOT...lol