[NeighborsComplaint]

Shop owner decides his fresh out of the paint shop Grandville convertible runs a little rough and decides to de-carbon it. Formula 1 motor rpms ensue. A buddy who works at the shop sent this to me. Don't know if he broke it yet but it doesn't run at all now.


https://youtu.be/CazDrTpvsY8.

[72projectbird]

Rev it until the valves float, then back it down 100rpm.

lol

[NeighborsComplaint]

Originally Posted by 72projectbird

Rev it until the valves float, then back it down 100rpm.

lol

Yeah. It was forward thinking of Pontiac to design in a rev limiter. I had a Lemans with a 326 like that. You always knew when to shift as it started to break up just before it fell flat on it's face.


Update: He finally got it to restart. Carbon bridged a couple plus. Now having my buddy do a proper tune-up and carb rebuild.

[Sirrotica]

FWIW, drizzling water down the throat of the carb at about 2000 RPM is a lot more effective for removing carbon from the top end of the engine, than revving the crap out of the engine, and possibly spinning a rod bearing..........

[mgarblik]

Originally Posted by NeighborsComplaint

Yeah. It was forward thinking of Pontiac to design in a rev limiter. I had a Lemans with a 326 like that. You always knew when to shift as it started to break up just before it fell flat on it's face.


Update: He finally got it to restart. Carbon bridged a couple plus. Now having my buddy do a proper tune-up and carb rebuild.

I am glad he didn't ruin the engine. The car looked to be in good condition. Reminds me of my first month on the job at the Pontiac dealer. Customer brings in a 1968 Bonneville, 428 HO that was running rough. Tune-up expert at the dealer says get in we will take this one to lunch. He floored it out of the dealership and it fell flat and would barely accelerate, black smoke pouring out the back. He drove it to the grocery and we went in and bought a box of minute rice. After we ate a fast food lunch, we went back to the dealer. He mixed up a gallon can of top GM top engine cleaner and water, about a 50-50 mix. Told me to hold the engine at 2-3000 RPM's no matter what. He took off the small vacuum line from the air cleaner to the intake and attached a long vacuum hose to the can of cleaner/water mix. Proceeded to suck about half the mixture through the engine. Looked like the dealership was on fire, huge black plume of smoke. Then he stopped and slowly poured the box of rice through the Q-jet carburetor and through the engine. It sounded terrible and you could see and hear little bits of rice shooting out the dual exhausts. He followed this with the rest of cleaner and water. Put the air cleaner back on and we took the car out and ran the crap out of it for about a half hour. Took it back to the dealer, no smoke, purring like a kitten and running like a tiger under full throttle. All I can say is it worked and I DO NOT recommend it. But it was big fun for a 20 year old new Pontiac mechanic. BTW, I remember the car very well. It was a beautiful aqua marine metallic blue with a matching vinyl interior and it was a 4-door. I remember the long branch exhaust manifolds and how really fast the car was when we were finished with it. I remember thinking that 4-door beast would have given my 70 TA a decent run at the time. I remember the car breaking the tires loose from a 10-15 MPH roll and staying loose well into 2nd gear.

[68GTO82]

Owned a 69 GTO second owner low mileage daily driver. My wife drove it for our daily. I would come home from work on occasion and she would say the GTO needs tuning up and supper in a half hour. She drove it like a good mother with a cookie cruncher passenger.
The first wot nothing but black smoke with a lot of bucking like a wild horse. After several applications of this scientific application no more black smoke, pulled like the horse it was and purred like a kitten.
Returned home, dear GTO is tuned up let's eat.
Such fun!
My current 68 GTO does not suffer from that malady.
83 years and still going strong (sorter).

[Heybuck]

My sister-in-law had a Nissan Bluebird wagon. 4 cylinder 2000cc manual nothing sort of car. But it was all she could afford.

It started to run badly and ran on after switching off something terrible. Local mechanic quoted more than the car was worth to "de-coke" it. Asked me if I could do it? Sure. Leave it with me for a week.

I pulled the windscreen washer line off, redirected it into the carburettor with a regular garden spray misting nozzle at the end, I simply drove it to and from work for a few days on the freeway, just regularly touching the windscreen pump switch. Each trip of about 20 miles, I topped up the bottle and repeated the performance. After 2 days, no more run-on. But I did it for a week and that old Nissan idled smooth as silk. And NO money changed hands..

[Baron Von Zeppelin]

I bet a lot you guys remember in middish to late 70's when about half of peoples cars wouldn't shut off when they turned off the key ?
The new pisswater unleaded fuels

Those were wild times
Sounded like a Briggs & Stratton that was within a second of throwing a rod.
Most everyone in my family got used to turning off switch while still in Drive.

Would see people (mostly women) get out of their car and leave it dieseling , and go on into the store and let it do its thing until it stopped on its own.
Common site back then.
Wildest sounding and most pitiful thing i can remember, mechanized self-destruction.
Most sounded like they just died a horrible death when they finally shut off.
Made me cringe

Something in this thread make me think about that , though not related.
I wasn't driving yet during that time period, but was heavily into cars.

[flyingn]

yup remember those times well. It was very odd

Originally Posted by Baron Von Zeppelin

I bet a lot you guys remember in middish to late 70's when about half of peoples cars wouldn't shut off when they turned off the key ?
The new pisswater unleaded fuels

Those were wild times
Sounded like a Briggs & Stratton that was within a second of throwing a rod.
Most everyone in my family got used to turning off switch while still in Drive.

Would see people (mostly women) get out of their car and leave it dieseling , and go on into the store and let it do its thing until it stopped on its own.
Common site back then.
Wildest sounding and most pitiful thing i can remember, mechanized self-destruction.
Most sounded like they just died a horrible death when they finally shut off.
Made me cringe

Something in this thread make me think about that , though not related.
I wasn't driving yet during that time period, but was heavily into cars.

[Greg Reid]

I had a 69 Buick in the 1990s that what run on for as long as you wanted to leave it there but only when I used regular unleaded. It would actually blow smoke rings from the dual exhaust. Even leaving it in gear would not shut it down. One day I had to actually cover the carburetor with both hands. No problems at all when I used mid-grade or premium fuel.

[Sirrotica]

Had a customer with a 70 T bird in the late 70s that would ping and detonate, not shut off, with pre ignition. His wife was on him to get it fixed because she was embarrassed when it would run on for 15-30 seconds, pounding and pinging. I ran about a half gallon of water through it as he watched me, he thought I was crazy, but he knew very little about cars.

Years later, he told me after I was all done de-carboning it it ran soooo much better, and shut off when he turned the key off. He confessed that at the time he thought I was going to ruin his car by dumping water down the carb.............LOL

Whenever I did a tune up, and I just couldn't get the idle silky smooth, I'd do the same thing. 99 out of 100 times after running about half a gallon through the carb, the engine would run like a Swiss watch, smooth as silk. I had one guy told me the idle was so smooth he thought the car had stalled, and tried to restart it while it was running...................

Getting the carbon off the valve faces, and behind the valve, out of the combustion chambers, and off the top of the pistons can make a huge difference in how a engine idles, and runs, and water is virtually no cost.

[Region Warrior]

Yep, used to do the water trick back in the 70's. Learned it from my father, who learned it from local shop in the early 60's.
Other thing was take "the 9 mile stretch" down I65 and back at 100-130 mph
A lot of people think i'm nuts when I tell them gas(except lower octane) is way better then was back then.
When's the last time you had to de-carbon or even change a fuel filter on your daily driver?
Modern vehicles don't even have one except a sock in tank.
Couldn't leave fuel sit for 6 months.
Have 1 yr old fuel(mid-grade) in generator and snow blower. Both started right up and ran smooth 2 weekends ago.

[Mr Anonymous]

I did the ice water trick on an 85 S-10 blazer with a carbed 2.8v6. I whacked the throttle open and proceeded to nearly drown the poor bastard. I'd blocked the radiator with a piece of cardboard, and get it a little "extra warm" beforehand. It belched a tremendously nasty cloud of **** out of it, wafted thru the garage and an screen door, set off the smoke alarm in the house. Also left a oddly shaped discoloration in the gravel driveway that I obscured with a rake before the wife got home. For a 180,000mi untouched 2.8, it ran like the proverbial watch. Sailed thru the IM240 emissions test after some carb work too. I had nothing to lose!

[dhcarguy]

I remember my Dad doing the water treatment many times. I do not remember where he poured the water,. Is it right to pour into the throttle body or into the fuel bowl??

[red1975pacer]

On my 2012 Camaro SS its showing a lot of carbon black from the back exhaust. Now its not blowing black smoke , but the tailpipe exhaust is a dry looking carbonated mess. Im running 93 octane gas, and the car has 14k miles. Is this a problem?

[Greg Reid]

Originally Posted by dhcarguy

I remember my Dad doing the water treatment many times. I do not remember where he poured the water,. Is it right to pour into the throttle body or into the fuel bowl??

Everybody (always 'old' guys) that I ever saw do it back when I was a teenager dribbled it right down the primary while holding the throttle open to maybe 2000 rpm. For some reason they always insisted that it should be a 'little' Coca Cola bottle full of water. Lots of black soot always poured out while they were doing this trick.

[ANDYA]

Never tried the water trick, was always nervous putting water in an engine. When I was a kid an old timer told me to pour Marvel Mystery Oil slowly down the carb. Figured MMO is petroleum based just like gas and oil so it would be safer than water. Rev the engine and slowly pour in a bottle until a large amount of smoke comes out of the exhaust. At that point I pour it at a faster rate until the engine stalls. Leave it to soak in the engine for about an hour and then start the engine. It will smoke up like crazy for a while until it clears itself out. Over the years I have cured several engines that had a rough idle with MMO.

[Will]

Never did the water trick myself...

I remember when my dad first let me drive his Formula. He babied that car, don't think he ever just stomped the gas to the floor. Well, I'd driven my crazy brother's '70 SS 350 Camaro a lot and wanted to see how the Formula compared. Imagine my disappointment when I stomped the gas and not much happened because the secondaries were sticking. Took a few times of me driving it to get the carbon blown out and the carb linkage all freed up, LOL.