ping under load

[orange-c10]

i bought a 70 c-10 with a stock 350 and a q-jet 4 barrel. its been pinging when i put it under a load. thinking that it is probably timing. just wondering what it shoud be timed at so i can check it. thanks

[Longhorn Man]

Try running mid grade fuel instead of the 86/87 octain.

[jhow66]

If it is the stock engine the book says TDC with a straight shift and 4* BTDC with a automatic. (Vacuum hose off advance can and plugged). If engine has never been opened you can give it a drink of water and it will help your pinging. (carbon buildup on top of pistons has raised the compression ratio) Just get you a 2 liter drink bottle (or smaller) and fill it with water. Remove breather and start engine. With one hand operate throttle at a higher speed then idle and with other hand with your finger over bottle, dribble water through carb opening. Experiment with rate of water and speed of engine until you find the combo. This will steam clean the carbon off you pistons and lower the compression ratio. The above info carries no warrenty.

[MrC1]

Don't pour too fast though. Hydro lock would be a thing.

[bryanw1968]

I wouldn't buy mid grade fuel. From what I've been hearing people either buy regular or super. The mid grade sits there for weeks or months and the octane rating degrades. The last time I bought mid grade to save a few bucks the truck ran worse than on reg. My .02 cents......

This could also be a timing issue as mentioned above. Deposits or just being out of time.

Good luck!
B-dub

[Billla]

Originally Posted by bryanw1968

I wouldn't buy mid grade fuel. From what I've been hearing people either buy regular or super. The mid grade sits there for weeks or months and the octane rating degrades. The last time I bought mid grade to save a few bucks the truck ran worse than on reg. My .02 cents......

Ultimately fuel quality - either octane rating or age degradation - comes down to timing too. A lower quality fuel will tolerate less total timing.

[Billla]

Originally Posted by jhow66

If it is the stock engine the book says TDC with a straight shift and 4* BTDC with a automatic. (Vacuum hose off advance can and plugged). If engine has never been opened you can give it a drink of water and it will help your pinging. (carbon buildup on top of pistons has raised the compression ratio) Just get you a 2 liter drink bottle (or smaller) and fill it with water. Remove breather and start engine. With one hand operate throttle at a higher speed then idle and with other hand with your finger over bottle, dribble water through carb opening. Experiment with rate of water and speed of engine until you find the combo. This will steam clean the carbon off you pistons and lower the compression ratio. The above info carries no warrenty.

Not to be disrespectful, but I've never heard of this before and IMHO it would be a cold day in Phoenix before I would do this. Yes, it's possible to get a carbon deposit that causes pre-ignition, but I would look to something like Sea Foam before I would pour water into the carb.

Can I ask where this tip came from?

[jhow66]

Originally Posted by Billla

Not to be disrespectful, but I've never heard of this before and IMHO it would be a cold day in Phoenix before I would do this. Yes, it's possible to get a carbon deposit that causes pre-ignition, but I would look to something like Sea Foam before I would pour water into the carb.

Can I ask where this tip came from?

It came from me (71 years young) and the old time mechanics that told me about it. Wonder what % of Sea Foam is water? I have cured many carbon knocks this way. Hope it does not turn cold on you The only differance between water and sea foam is the solvent. Water steam cleans-foam steams cleans with a solvent-one is free-one cost $s-take your pick. The next time you go to rebuild a engine try it and see how easy the carbon that is left comes off. It is called experience young fellow.

[70rs/ss]

I learned it from and old timer too, and it does work! I've even heard seen adding diesel fuel in through the plug hole, turn over a couple of times (with plug out) let sit over night or two, put plugs back in run (watch smofe for awhile) then carbon free!! The water is faster and will not bring the fire department to your house!!

[Billla]

Originally Posted by jhow66

It is called experience young fellow.

I've got a bit myself after 25 years of working on these things too I'm reasonably careful regarding processes I've never seen in a factory service manual. I'm glad it's worked for you; we'll have to respectfully agree to disagree

I have used some of the cleaner products carefully drawn in via a vacuum line into the carb, but never poured anything in directly. I have to admit that I've also never run into surface detonation, but my work has been primarily with non-stock engines.

Anyone else had good results with this method?

[jhow66]

Originally Posted by Billla

I've got a bit myself after 25 years of working on these things too I'm reasonably careful regarding processes I've never seen in a factory service manual. I'm glad it's worked for you; we'll have to respectfully agree to disagree

I have used some of the cleaner products carefully drawn in via a vacuum line into the carb, but never poured anything in directly. I have to admit that I've also never run into surface detonation, but my work has been primarily with non-stock engines.

Anyone else had good results with this method?

Billla-didn't mean any animosity-just having a little fun. I have used your way also. I also build non-stock engines-here is one in my '56:

[67ChevyRedneck]

Originally Posted by jhow66

If it is the stock engine the book says TDC with a straight shift and 4* BTDC with a automatic. (Vacuum hose off advance can and plugged). If engine has never been opened you can give it a drink of water and it will help your pinging. (carbon buildup on top of pistons has raised the compression ratio) Just get you a 2 liter drink bottle (or smaller) and fill it with water. Remove breather and start engine. With one hand operate throttle at a higher speed then idle and with other hand with your finger over bottle, dribble water through carb opening. Experiment with rate of water and speed of engine until you find the combo. This will steam clean the carbon off you pistons and lower the compression ratio. The above info carries no warrenty.

I've read that too, and that's how I set up my truck. Ran good, but didn't feel like it had any power. I read a few other posts about this on the board and the overall consensus I got was that 6-8 dbtdc worked best in non-computer 350 engines. I did it to mine (I think I set it at 8) and it ran much better.

My 2 cents

[Billla]

Originally Posted by orange-c10

i bought a 70 c-10 with a stock 350 and a q-jet 4 barrel. its been pinging when i put it under a load. thinking that it is probably timing. just wondering what it shoud be timed at so i can check it. thanks

It's almost certainly a timing issue caused by either static timing or the advance curve. Given that it's under load, I would first suspect the vacuum advance.

I would disconnect the vac advance and check centrifugal advance first. Advance should be all-in before 3000 RPM and should not exceed 34-36 degrees. Set static timing ensure no more than 36 degrees total advance. It's not uncommon to need 12-14 degrees initial advance on a modified engine to see 34-36 degrees total, but a stocker should be closer to 8-10. Anything really wacky here in terms of the RPM that it's all-in at, total advance or required static advance means someone's been monkeying with the centrifugal weights or springs or they're sticking. They should rotate very loosely on the pins and have a bit of moly lube on the dimple underneath that they bear on.

Next, ensure the vacuum advance is connected to a ported vac source on the carb and hasn't been moved somewhere else - too strong of a signal means too much advance under load. Ported vac is taken from directly above the throttle blades. Then take the engine to that all-in RPM slowly and see how the advance changes - vac advance should add another 12-14 degrees of advance at part throttle. If you're seeing WAY more than that then consider replacing the can - it's an easy swap, and an adjustable item is your best bet.

[Longhorn Man]

Water in the carb works great, and ppl in smog states still do it. ATF is another popular fluid to dump in the carb.

As for mid grade, that's what I run on my cad motor. I have yet to get a 'bad tank' of it, however, I DO carry a bottle of booster just in case as I have heard of the 'bad gas' storys.

[orange-c10]

thanks guys. im going to try timing first because this is an all stock motor so it should run on regular. it shouldnt have that much carbon in the motor because its fairly new. if the timing checks out i will definetly take the carbon build up and better gas into consideration. ive used seafoam before in my newer chevy so i know it works great. i would be a little scared to put water in the carb but i have heard of it before and i know people that have done it.

[Longhorn Man]

that is a LOT better than the quickie lube places that advertise the solvent flush deal... at least the Diesel has some lubricating properties to it.
I would recomend an oil and filter chainge 1500 miles after the diesel bath though.

[junkyardjohn]

Yep.. I Should Have Mentioned That I Changed It Again After About 100 Miles. (& It Was Filthy) John

[Billla]

Originally Posted by junkyardjohn

Yep.. I Should Have Mentioned That I Changed It Again After About 100 Miles. (& It Was Filthy) John

I guess I would worry about the reduced lubricity. I have no doubt it cleans out crud, but I'd worry about washing the bores with it. I've always stayed away from the engine flush concept but then again I use synthetic in everything and change oil every 3K.

[Jim_PA]

Originally Posted by Billla

I've always stayed away from the engine flush concept but then again I use synthetic in everything and change oil every 3K.

Dang, i bet the oil companies love people like you. And back to the water subject, what's the big deal? Haven't you ever heard of water injection systems?

[nevada70chev]

thanks john, how is kentucky? sure will missing having you close.

[Billla]

Originally Posted by Jim_PA

Dang, i bet the oil companies love people like you. And back to the water subject, what's the big deal? Haven't you ever heard of water injection systems?

Well, sitting on a 186K mile 1995 LT1 and a few other high-milage engines, I guess I'm not too worried. I see it as pretty cheap insurance.

Yes, I have heard of water injection - we use it in racing engines at Reno in the Sport Class. It cuts the life of the engine by over 50% and the bores look like hell when we tear them down. The Merlin aircraft engine (P-51D) had water injection, and if it was used to exhaustion (about 8 minutes I think, but I'd have to look) the service manual called for immediate replacement.

Hey, it's a difference of opinion I'm not going to change my mind based on my experience, and you're not going to change yours based on your experience. It's all good

[Huck]

Old guys, old tricks---tried and true but carefully administered. Talk to a toyota mechanic and they ill tell you of a carbon build up problem on toyo's that got solved the old fashion way too. Carefully running water thru the carb is a well know method of removing carbon buildup---goes WAY back. Running higher octaine is more of a factor of engine design--. I ran a 97 corvette on regular for years with no ping as it was electronically controlled. Got 31mpg over the road too!! I tried that on a Porsche 928s4 and it didn't like anything other then premium.
High mileage engines often have multiple issues with rarely a simple solution to all but clean is never bad!! Huck (:>)

[Billla]

Originally Posted by Huck

Old guys, old tricks---tried and true but carefully administered. Talk to a toyota mechanic and they ill tell you of a carbon build up problem on toyo's that got solved the old fashion way too. Carefully running water thru the carb is a well know method of removing carbon buildup---goes WAY back. Running higher octaine is more of a factor of engine design--. I ran a 97 corvette on regular for years with no ping as it was electronically controlled. Got 31mpg over the road too!! I tried that on a Porsche 928s4 and it didn't like anything other then premium.
High mileage engines often have multiple issues with rarely a simple solution to all but clean is never bad!! Huck (:>)

The R22 Toyota engine had a real problem with this, but the service manual fix was to suck up some engine flush gunk with a vac hose.

Engine design is a factor - specifically static compression ratio and cam overlap - but timing must almost always be adjusted to match the fuel. Many PCM tunes on late-model engines just advance the timing and add more total timing to add HP, but then require premium fuel.

[Huck]

Lessons learned--had a 91 Chev pickup with 4.3 which I bought new. Drove it 140,000 miles. From 40,000 to 90,000 it would ping under load. I tried higher octain gas, different heat range plugs, etc. Timing was electronically controlled. Finally brought into a shop who hooked up a computer which said """"anti knock sensor""' which was faulty. $23. later with a new sensor, it was like new!!! dumb, dumb, dumb!!hehehehehehehehe

My guess on yours would be the intital timing (i usually go 4-8degree adv) and depending on your ignition (stock or HEI), you need the correct vac advance hookup. Most times this fixes the problem without changing the fuel grade.

[nevada70chev]

so adding water down the carb, very slowly will help clean out the carbon? what will the exhaust look like when you are doing this, can you tell if you are adding too much water? thanks, i'm getting the ping too, stocker with 1406 jetted & rodded for altitude with hei.