Chasing high RPM pinging
Thread Starter
Melting Slicks
Joined: Jul 2001
Posts: 2,664
Likes: 1
From: Boston MA
Chasing high RPM pinging
OK, a distributor rebuild has solved the timing problems, and I've set 37 degrees total mechanical advance (12 initial + 25 certifugal). Yet at high RPMs, I still have pinging. Any suggestions? This is a high mileage L82 (93K). A friend suggested that there may be carbon build up in the cylinders, and to blow out the carbon by dripping water into the carb. Whaddya think?
Thanks
Thanks
Pro
Joined: Sep 2002
Posts: 690
Likes: 1
From: near Memphis TN
Re: Chasing high RPM pinging (Swamp Thang)
L82's varied in compression ration based on the year I think. What is the compression ratio?
You don't mention the vacuum advance, that could be your problem if you have too much vacuum advance but that would most likely bring a problem in mid RPM cruising as well.
I heard carbon build up can be a problem and careful use of water will burn it off.
If it's just a compression ratio problem than you can a.) retard timing even further, you may very well get better perfomance with 32-36 total regardless of pinging or not; b.) take the heads off and get a thicker gasket to raise the compression; c) find a gas station selling race gas or start purchasing toluene.
You don't mention the vacuum advance, that could be your problem if you have too much vacuum advance but that would most likely bring a problem in mid RPM cruising as well.
I heard carbon build up can be a problem and careful use of water will burn it off.
If it's just a compression ratio problem than you can a.) retard timing even further, you may very well get better perfomance with 32-36 total regardless of pinging or not; b.) take the heads off and get a thicker gasket to raise the compression; c) find a gas station selling race gas or start purchasing toluene.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: Chasing high RPM pinging (Swamp Thang)
Is it off of the throttle? Vacuum advance might be adding to many degrees. I bought a Crane adjustable vacuum advance.
Le Mans Master
Joined: Jun 2002
Posts: 8,339
Likes: 24
From: I can walk to MA
Re: Chasing high RPM pinging (gkull)
I'll stop on my way home this afternoon and take it for a test drive.
When you get it back on Tuesday, all will be well.
ps - Don't beat on my 266k mile Buick while I'm gone !!!
:D :lolg: :lol: :lolg: :D
Seriously, a small cup of water down the hatch while running WOT - can
blow out all the carbon, but you risk trouble - such as a chunk getting caught
in the valve seat, etc.
There is a fine line between setting timing for top performance and pinging.
I usually do NOT use a timing light - get it close (like you do) and tweek it in
by driving. If it pings slightly, just back it off a degree.
:seeya
When you get it back on Tuesday, all will be well.
ps - Don't beat on my 266k mile Buick while I'm gone !!!
:D :lolg: :lol: :lolg: :D
Seriously, a small cup of water down the hatch while running WOT - can
blow out all the carbon, but you risk trouble - such as a chunk getting caught
in the valve seat, etc.
There is a fine line between setting timing for top performance and pinging.
I usually do NOT use a timing light - get it close (like you do) and tweek it in
by driving. If it pings slightly, just back it off a degree.
:seeya
Melting Slicks
Joined: Sep 2003
Posts: 3,050
Likes: 2
From: Orange Ct
Re: Chasing high RPM pinging (Swamp Thang)
Back in the 70's when the best gas you could get was 91 0ctane, Eldelbrock
sold a water injection system. When the vacume droped and a rpm level was reached it would spray water down the carb (old idea from WW2 fighter planes) I bought one and it did stop the pinging on my 11-1 engine.
sold a water injection system. When the vacume droped and a rpm level was reached it would spray water down the carb (old idea from WW2 fighter planes) I bought one and it did stop the pinging on my 11-1 engine.
Team Owner
Joined: Sep 2003
Posts: 88,393
Likes: 2
From: eville in
Re: Chasing high RPM pinging (w1ctc)
ARE you sure it's pinging??? and not another noise :skep: up your octane in
about 1/4 tank of gas and see if it goes away.. also if possible do a high
RPM shut off and read the plugs.... it could be a lean out at high RPM :thumbs:
about 1/4 tank of gas and see if it goes away.. also if possible do a high
RPM shut off and read the plugs.... it could be a lean out at high RPM :thumbs:
