(2) Two Degrees BTDC to Avoid Pinging
Thread Starter
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
(2) Two Degrees BTDC to Avoid Pinging
I finally took my C3 in to have the timing and carb properly calibrated. I just called and the shop mgr told me the initial timing was set at (2) TWO degrees BTDC. And to think initial should be around 10-12 BTDC. I wonder how much 'go power' I was giving up. He said he was just starting on the carb.
I had retarded the timing to avoid pinging but had no idea that it was that far 'back'.
How much do you think I was giving up in torque/hp? I hope he can set it up with proper initial mech and vacuum advance while avoiding pinging. The distributor is the Accel HEI type with adjustable vacuum canister. No wonder I was only making max 160rwhp! Good grief!
I had retarded the timing to avoid pinging but had no idea that it was that far 'back'.
How much do you think I was giving up in torque/hp? I hope he can set it up with proper initial mech and vacuum advance while avoiding pinging. The distributor is the Accel HEI type with adjustable vacuum canister. No wonder I was only making max 160rwhp! Good grief!
Racer
Joined: Oct 2001
Posts: 271
Likes: 0
From: St Louis MO
Re: (2) Two Degrees BTDC to Avoid Pinging (TedH)
You are going to be REALLY happy when you get that car back. I feel a significant difference in acceleration with 4 degrees. I once told my mechanic that he cstrated my car by setting the advance back that far. Just make sure your fuel system/carb is working good. That alone could be the source of your pinging.
Gary
Gary
Le Mans Master
Joined: Sep 2000
Posts: 5,635
Likes: 4
From: Orlando Floriduh
Re: (2) Two Degrees BTDC to Avoid Pinging (Garys '68)
Ted... you need to have some one re-curve the distributor. Rather the reterding the initial you need to limit the total degrees. That way you get bottom end power and get rid of pinging. Check out Lars distributor kits. :cheers:
Thread Starter
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
Re: (2) Two Degrees BTDC to Avoid Pinging (silvervetteman)
The shop just completed the distrib re-curve on the car when I called (that's how I found out about my poor 2 degree BTDC initial advance). In addition to the re-curve he is recalibrating the carb (mixture and 2ndary metering rods). Using engine dyno in his shop to test the results. I hope to get a healthy, happy C3 back on Monday!
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Re: (2) Two Degrees BTDC to Avoid Pinging (TedH)
There you go, anyone with a dyno and knows what in hell he's doing is worth is weight in gold,....unfortunately that's what we have to pay.... :D :D :eek: :cool:
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
Re: (2) Two Degrees BTDC to Avoid Pinging (TedH)
Ted -
It really sounds like you have something not set up right in your distributor. The dyno tuning will certainly determine the point where peak power is being developed for your total max timing, but if your initial timing is ending up at 2 degrees BTDC, then your centrifigal advance curve is too long, and it needs to be shortened. There is not a Chevy engine ever built that will achieve peak off-idle throttle response at 2 BTDC. I'm sure your dyno guys have correctly determined that the total timing cannot be advanced any further without detonation and a decrease in performance, but you need to get your initial timing up into a usable range by shortening the advance curve and maintaining the timing point they have established for peak power. This will give you a massive, noticable increase in off-idle torque and throttle response. Tag me back if yuo need any info on this.
It really sounds like you have something not set up right in your distributor. The dyno tuning will certainly determine the point where peak power is being developed for your total max timing, but if your initial timing is ending up at 2 degrees BTDC, then your centrifigal advance curve is too long, and it needs to be shortened. There is not a Chevy engine ever built that will achieve peak off-idle throttle response at 2 BTDC. I'm sure your dyno guys have correctly determined that the total timing cannot be advanced any further without detonation and a decrease in performance, but you need to get your initial timing up into a usable range by shortening the advance curve and maintaining the timing point they have established for peak power. This will give you a massive, noticable increase in off-idle torque and throttle response. Tag me back if yuo need any info on this.
