I do know that the only real perfect technique of doing this is to remove the cylinder head from the engine and manually remove the carbon from the head surface. I would like to know if anyone has had any good results from using any of the liquid chemical ways of blowing out carbon buildup in the cylinder head surface. You know the poring of or spraying of "gunk" down the carb at high engine RPM and watching those nasty carbon bits get blown out the tail pipe. I would greatly appreciate any "real" advise of the matter. As far as actual chemicals and actual workable techniques. Failing that, i am prepared to pull the head myself and clean off the carbon myself. The reason for all this, is that i am getting "pre ignition" and the pinging i am getting is caused by heavy carbon build up. I have done "EVERY THING ELSE" in this regard and carbon build up is the last possible bugaboo. Thank you for any and all help folks, it is very much appreciated. Cheers. George.
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1957 Pontiac Pathfinder Deluxe sedan restored 261 six
1974 Chevrolet Caprice Estate wagon low mileage original 400 V-8
Pinging is caused at point of combustion, by way of weak spark, not enough combustion, timing is usually the issue, either retarded too much or advanced too far. If I remember correctly she should be 4 degrees before top dead center, that's two marks on timing plate, each mark is two degrees. Carbon build up will cause pinging too. I've had 6 bangers with beautiful combustion tests 130s perfect, but what a dog, no power, I took head off and 23,000 original miles she was half inch thick of carbon on top of piston heads. Head went to shop for cleaning and flexing, then straight blade razor blade and vacuum, clean carbon off pistons without scratching them. I don't use chemicals in my motors.
You could try gaping your spark plugs slightly tighter. Instead of say .044 gap them at .042 or .040 but not smaller. You just want slight. It creates a bigger bang in combustion chamber burning fuel hotter, more efficient and cleaner, a couple hp more too, no more black tailpipes which means no more carbon build up on heads. I run all my vehicles .002 smaller than recommended. I'd gap yours .004 smaller and take it for hwy cruise, but don't leave plugs gapped that way for long, maybe a week or so of good driving, if left, you'll "burn" your valves and seats. The extra combustion will burn off most if not all carbon buildup on your piston heads. its same concept as MSD, multiple spark distribution, except way cheaper, easier, outta sight and does the same job
-- Edited by Indian on Saturday 16th of May 2015 12:03:46 AM
Thanks for all the advise Ron and Pete. I have done everything possible to my ignition system and i do mean EVERYTHING. My ignition system could not be any better. I will try blowing it out with chemical cleaner and failing that, i will be pulling the head and doing it the old fashion way. Cheers. George.
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1957 Pontiac Pathfinder Deluxe sedan restored 261 six
1974 Chevrolet Caprice Estate wagon low mileage original 400 V-8
If you're running a electronic module in your distributor; i would make sure that timing is perfect when you ""snap"" the throtle . Had the same problem on my 68 camaro from a elecronic conversion kit from Crane-Cams . Base timing was perfect but was getting lots of pre-detonation at idle and around 3000rpm in load . Bought a MSD distributor and the poblem was fixed !
If the engine is cold and you can hear it "pingning"" ..... it's probably not carbon.
-- Edited by MickyG on Saturday 16th of May 2015 03:36:34 PM
If you're running a electronic module in your distributor; i would make sure that timing is perfect when you ""snap"" the throtle . Had the same problem on my 68 camaro from a elecronic conversion kit from Crane-Cams . Base timing was perfect but was getting lots of pre-detonation at idle and around 3000rpm in load . Bought a MSD distributor and the poblem was fixed !
If the engine is cold and you can hear it "pingning"" ..... it's probably not carbon.
-- Edited by MickyG on Saturday 16th of May 2015 03:36:34 PM
The pinging is only during hard "hammer down" operation and yes folks i have done everything there is to do and yes i actually know what i am doing. I know at this point that i have to pull the head and get rid of all that nasty carbon build up. These "old " 261 inline six banger's did not have the most ideal combustion chambers and they were prone to more carbon build up than average. Thanks for all the advise folks. Cheers. George.
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1957 Pontiac Pathfinder Deluxe sedan restored 261 six
1974 Chevrolet Caprice Estate wagon low mileage original 400 V-8
I have used water for de carbonizing, pour it down the carb of a hot engine running at least 2000 rpm and it steam cleans the carbon away. It takes about a quart in most cases, pouring slow enough that the engine keeps running. Olds engines were the most common victims of this treatment in my younger days.
George, I'd go with the SEAFOAM this stuff is amazing, been around since the 40's but I just started using it 2 winters ago in cars & snow blower in gas, but can be used in OIL & they have other products too. Worked great in blower stopped the no start & removed the water in fuel [have switched to non ethanol] but thought the engine was going to blow up when it started to get the water thru it, cleared up in less than 4 minutes but a lot of backfires then smooth as a kitten!!!
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Some times I wake up GRUMPY, but today I let her sleep in !!!!!!!!BLACKSTOCK Ont.
GM "Cleens" worked for me on my 396 I bought in the 80's. I guess it had years and years of city driving on regular leaded fuel and was full of carbon. About a week after I had it I laid a licking on it one evening and it developed a knock, which had me worried but my mechanic brother laughed at and assured me it was a carbon knock (loose carbon chunk). His diagnosis was bang on. I poured a can of liquid (not spray) Cleens slowly down the carb stalling it with the last bit of liquid. Let it sit about 10 minutes, took it for a run, knock cured.
A week or two later, same thing, repeat as necessary. For about a year I always kept a full can of Cleens in the console and ended up having to do the treatment away from home a number of times, ( 10-12 times total ) until it finally was cleaned up and never gave trouble again.
I'm a firm believer in GM Cleens for this type of situation George.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars
I've only used tap water a little bit but that Cleens always cured the carbon knock with one application. I've seen older mechanics use tap water with great success though, as you say.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars
I went through eight liters of water and it made no change. Carl, this GM Cleens, is it sold at GM dealers? I might be trying that next or here comes the head off. Thanks everyone. George.
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1957 Pontiac Pathfinder Deluxe sedan restored 261 six
1974 Chevrolet Caprice Estate wagon low mileage original 400 V-8
It used to be part #992872 if my old parts brain is still working. (I can double check that tomorrow at work). I don't think we have it at work any more, but that is not saying GM doesn't have it any more. By all means, just call a dealer and ask, but many of them who say "yeah, we have it" will be talking about 993026 which is an aerosol Cleens and I was taught by a veteran mechanic that the spray method is not near as effective as the liquid which you pour in.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars
Here is an update on my cylinder head situation. The head is in a really good shop in Toronto, having "everything" done to it. I should have it back in a few days from them. I have cleaned up the engine block deck to get it ready for the head. I just got all my required gaskets to do everything required. I cleaned all the head bolts and chased all the threads in the block. By the way i am replacing all the valves and all the springs as well because i never want to do this again. Cheers. George.