Timing - Carbon
Thread Starter
Safety Car
Joined: Feb 2006
Posts: 3,557
Likes: 0
From: Ridgeway VA
Timing - Carbon
I have a '70 SB 300 hp that's been souped to about 400 (or so a
mechanic told me). I've had it for about 8 years and recently had
a complete tune-up including new distributor done - worked great
for about six months then ping/pong in the engine - retimed and
works great now. The shop said there is a possibility of "distributor
walk". Or, I might need a GM liquid product into the carb that
cleans the carbon off the piston heads and thus lots of black smoke
thru muffler. Question - is the GM product the solution? or can you
suggest other things to do.
Thanks in advance. Peter
mechanic told me). I've had it for about 8 years and recently had
a complete tune-up including new distributor done - worked great
for about six months then ping/pong in the engine - retimed and
works great now. The shop said there is a possibility of "distributor
walk". Or, I might need a GM liquid product into the carb that
cleans the carbon off the piston heads and thus lots of black smoke
thru muffler. Question - is the GM product the solution? or can you
suggest other things to do.
Thanks in advance. Peter
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
Originally Posted by PETKAH
I have a '70 SB 300 hp that's been souped to about 400 (or so a
mechanic told me). I've had it for about 8 years and recently had
a complete tune-up including new distributor done - worked great
for about six months then ping/pong in the engine - retimed and
works great now. The shop said there is a possibility of "distributor
walk". Or, I might need a GM liquid product into the carb that
cleans the carbon off the piston heads and thus lots of black smoke
thru muffler. Question - is the GM product the solution? or can you
suggest other things to do.
Thanks in advance. Peter
mechanic told me). I've had it for about 8 years and recently had
a complete tune-up including new distributor done - worked great
for about six months then ping/pong in the engine - retimed and
works great now. The shop said there is a possibility of "distributor
walk". Or, I might need a GM liquid product into the carb that
cleans the carbon off the piston heads and thus lots of black smoke
thru muffler. Question - is the GM product the solution? or can you
suggest other things to do.
Thanks in advance. Peter
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
Originally Posted by Jud Chapin
Running at higher RPM's will generally clean it out. When engines are carboned up, they will usually generate a lot of pinging at just normal timing advance. If you take it out on the highway and get the RPM's up for a pretty good for a stretch and see a lot of nasty looking smoke exiting your exhaust, that is a sign of carbon build up. Out of curiosity, do you run your car at highway speeds often, or just run it at a slower pace. With today's cleaner fuels, though, I didn't think this was that much of a problem as back in the days of leaded gas. I'm sure others will help us out with this.
Thread Starter
Safety Car
Joined: Feb 2006
Posts: 3,557
Likes: 0
From: Ridgeway VA
I usually run no more than 80 every once in a while with city
only about 10% of driving. (It has side pipes and it is not cool
to sit in traffic and smell exhaust - so I mostly drive in the country.)
I have not had overheating problems at all as it's at just over 180.
More information - I am a superb detailer inside/out/engine compartment -
but still learning about engine, drive train, suspension, etc.
Therefore I rely on some good "NC country boy" mechanics. That said,
the differential has dragster or clutch car gears - what this means is that
I idle at about 1100 (because the engine is souped) and must put in
neutral at stop signs or else it will cut off. Because of those rear gears
I can spin the tires but - I do it rarely because I don't want a new
project. By the way it is an automatic with AC setup. Perhaps why I can't
punch it at 80 or above is that the differential drives the engine ( I have
been told) and it sounds like it's going to blow the engine.
only about 10% of driving. (It has side pipes and it is not cool
to sit in traffic and smell exhaust - so I mostly drive in the country.)
I have not had overheating problems at all as it's at just over 180.
More information - I am a superb detailer inside/out/engine compartment -
but still learning about engine, drive train, suspension, etc.
Therefore I rely on some good "NC country boy" mechanics. That said,
the differential has dragster or clutch car gears - what this means is that
I idle at about 1100 (because the engine is souped) and must put in
neutral at stop signs or else it will cut off. Because of those rear gears
I can spin the tires but - I do it rarely because I don't want a new
project. By the way it is an automatic with AC setup. Perhaps why I can't
punch it at 80 or above is that the differential drives the engine ( I have
been told) and it sounds like it's going to blow the engine.
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
Originally Posted by PETKAH
I usually run no more than 80 every once in a while with city
only about 10% of driving. (It has side pipes and it is not cool
to sit in traffic and smell exhaust - so I mostly drive in the country.)
I have not had overheating problems at all as it's at just over 180.
More information - I am a superb detailer inside/out/engine compartment -
but still learning about engine, drive train, suspension, etc.
Therefore I rely on some good "NC country boy" mechanics. That said,
the differential has dragster or clutch car gears - what this means is that
I idle at about 1100 (because the engine is souped) and must put in
neutral at stop signs or else it will cut off. Because of those rear gears
I can spin the tires but - I do it rarely because I don't want a new
project. By the way it is an automatic with AC setup. Perhaps why I can't
punch it at 80 or above is that the differential drives the engine ( I have
been told) and it sounds like it's going to blow the engine.
only about 10% of driving. (It has side pipes and it is not cool
to sit in traffic and smell exhaust - so I mostly drive in the country.)
I have not had overheating problems at all as it's at just over 180.
More information - I am a superb detailer inside/out/engine compartment -
but still learning about engine, drive train, suspension, etc.
Therefore I rely on some good "NC country boy" mechanics. That said,
the differential has dragster or clutch car gears - what this means is that
I idle at about 1100 (because the engine is souped) and must put in
neutral at stop signs or else it will cut off. Because of those rear gears
I can spin the tires but - I do it rarely because I don't want a new
project. By the way it is an automatic with AC setup. Perhaps why I can't
punch it at 80 or above is that the differential drives the engine ( I have
been told) and it sounds like it's going to blow the engine.
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
Originally Posted by PETKAH
Yes, running hi test pump gas - Exxon or Shell.
Can the "distributor walk?" Or what else could cause
the timing to change?
Tnx
Can the "distributor walk?" Or what else could cause
the timing to change?
Tnx
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Melting Slicks
Joined: May 2001
Posts: 2,131
Likes: 4
From: May help you? You can sure as hell try!
A worn timing chain can cause the timing to be erratic making it hard to set the timing properly. That may be what the mechanic is referring to by "distributor walk".
As others have mentioned, chamber deposits can cause the engine to ping even if the timing is set correctly. It is possible to clean combustion chamber deposits by misting water into the carb and revving the engine slightly. Just be careful not to add too fast or you run the risk of hydrolocking the engine. There are also commercially available chamber deposit cleaners.
As others have mentioned, chamber deposits can cause the engine to ping even if the timing is set correctly. It is possible to clean combustion chamber deposits by misting water into the carb and revving the engine slightly. Just be careful not to add too fast or you run the risk of hydrolocking the engine. There are also commercially available chamber deposit cleaners.
Racer
Joined: Sep 2005
Posts: 453
Likes: 1
From: Austin TX
A lot of people use a product called seafoam that you can administer through a vacuum port on the carb or I guess you could directly pour it in slowly from up top. It's supposed to clean out carbon buildup and makes your vehicle smoke quite a bit while doing so. If you use it you might want to check your plugs afterwards though, could foul them up.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Originally Posted by blctalon
A lot of people use a product called seafoam that you can administer through a vacuum port on the carb or I guess you could directly pour it in slowly from up top. It's supposed to clean out carbon buildup and makes your vehicle smoke quite a bit while doing so. If you use it you might want to check your plugs afterwards though, could foul them up.
Also GM Top Engine Cleaner- works good.