De-carboning engine

[Mike McKown]

Honest Charley Speed Shop sold water injection

kits as did J. C. Whitney and others in the middle '50's as an aid to stop detonation and spark knock. I believe the water reservoir was a quart size jar and the water flow to the engine was intiated when the engine vacuum dropped (acceleration) Don't know if it helped or not but my recollection is the gasoline back then (1955) was of very low octane. Lot's of stock 6 banger Chevies would spark knock on regular gasoline.

In 1962 when I was hanging out at the Chevy dealers garage, I saw a mechanic revving a 250 or 300 horse 327 while he slowly poured water down the intake. Lot's of steam. He said that the then new 327's were having a problem with carbon build-up on top of the pistons. The carbon would get compressed between the piston top and the cylinder head and cause the piston skirt to slap the cylinder wall making a noise. He further advised that this advice came from a zone service rep as the recommended fix for this problem. In theory, the steam would blow the carbon off the piston and in this particular case, then engine quieted right down. At one time, I thought there was a TSB or other service document published to state this but I can't find it in my files.

I have tried this on several engines that I owned that I suspected had carbon stuck on the valve seats and it seemed to make them smooth out and run better.

[John G.]

Re: De-carboning engine

Yea Chuck, if memory serves I seem to remember once pulling off the SB heads and having an impeccably clean combustion chamber and piston top in one cylinder due to a blown head gasket. Seems a little coolant got in there and did the deal.

Those old Ford flatheads were something in their day, alright. Guys considered them a dime a dozen as well as good boat anchors .. . . But, like a lot of things old and now hard to come by I bet those old flatheads are worth their weight in gold now .. ! ..

John

[Roy B.]

Re: Speed Shop sold water injection "help me out"

These responses are interesting to read about oil and carbon. Ever thought about a steam engine having carbon or lack of piston oil? Where talking ONE minute of treatment here. Any one remember the WW2 spit fire Mustangs that used WATER to gain altitude to reach German bombers. Dint' they have gasoline piston engines?? How did they do that???? WHY????

[Duke W.]

Re: DDT

Yes, the streamlines will tend to be of minimum curvature and migrate toward the port walls to make their way past the valve, particularly at low lift. They won't come down the valve stem and then flair out rapidly with the shape of the valve head, so the air in this region is "dead" and not sufficiently fast to erode away deposits, but I don't this deposit buildup hurts flow and may even improve it by providing better direction to the flow.

The same phenomenom causes most the flow to go along the top side of the port, unable to make the sharp bend of the "short side" radius. Like anything else, the incoming air/mixture will take the path of least resistance. This is also the reason why good porting instructions usually say to leave the short side radius mostly alone.

A better valve shape would be to have a more gradual radius from the bottom of the stem to the edge of the valve to somewhat eliminate this dead zone of turbulence, but the weight of the valve would be greater unless it was hollow, which would increase cost.

Such a valve shape is easier to implement on small valves (such as on a four-valve design) and the shape is sometimes referred to as a "tulip valve".

I think the best way to recognize carbon buildup is an increase in detonation tendency, which is typical as the carbon buildup reduces chamber volume (increasing the CR) and also gives rise to more "hot spots" than can cause preigntion, which can lead to detonation if the timing is already fairly aggressive for the fuel octane quality.

Most engines develop an "octane appetite" with age. On an engine without excessive oil consumption the deposit buildup will usually reach a steady state at about 20K miles of normal driving. At that point the octane requirement is a little higher, but the rate of deposit formation is about the same as the rate of deposit elimination. If oil consumption is high, or the mixture too rich, the steady state deposit volume will likely be greater than with modest oil consumption and a proper mixture.

Duke

[John H.]

Re: Speed Shop sold water injection "help me out"

Roy -

The 2-stage supercharged Rolls Merlins in Mustangs and Spitfires had an auxiliary water injection system, but it was for emergency use only, not for any "normal" flight conditions. A twisted safety wire held the throttle lever out of the WEP (War Emergency Power) detent; when needed, the lever was jammed forward, breaking the safety wire, and 30 seconds was the maximum duration allowed at that power setting. Crew Chiefs were not happy when a pilot brought one home with that wire broken, as it mandated an immediate engine change

[Duke W.]

Re: Speed Shop sold water injection "help me out"

The big aircraft recips or yore used water alcohol injection along with overboost for both takeoff on heavy multiengine aircraft and "war emergency power" on fighters. For takeoff the duration was typically no more than two minutes. At war emergency power the engine would usually be in the overheated range and possibly damaged after about five minutes, but if it got you away in an emergency it was a plane and pilot saver. On fighter aircraft, war emergency power was engaged by the pilot pushing the throttle through a wire stop. That told the ground crew to change the engine if the pilot forgot to mention in debriefing that he had engaged war emergency power.

BTW, the the turbocharged Olds "Jetfire" 215 CID/215 HP aluminum V-8 from the mid-sixties used "Jetfire Fluid" under boost, and I think Olds sold the stuff over the counter in gallon jugs. It was just a mixture of water and denatured alcohol, but I don't know if they ever published the exact formula.

Water/alcohol injection will keep an engine out of detonation when overboosted and provide more fuel for the overboost condition, all of which adds up to extra power for a short duration. The Germans accomplished the same goal with nitrous oxide (N2O) injection, which is popular today with street racers.

The important point is that the water alcohol injection in these examples include reasonable metering systems to flow the correct quantity to accomplish the design objective.

When you pour water down the carb with a pitcher or hose, you are not metering it very precisely, and one unfortunate consequence might be pooring in enough to cause hydraulic lockup and a bent connecting rod!

Duke

[Mike McKown]

Re: Speed Shop sold water injection "help me out"

John:

Would it not be a true statement to also say the reason for the engine change was because the WEP lever caused the supercharger boost to go off the guage and the water injection system helped prevent engine damage? In other words, the boost on the engine is what mandated the engine rebuild, not the water injection. Without the water injection, you may not have made it back to the garage?

[Mike McKown]

Re: De-carboning engine

John:

I think this thread more or less atarted as a "decarbonizing" thread. Your analogy is correct and right on target.

A lot of people either don't know (if they are not old enough) or forgot (if they are old enough) that in 1965 if you tore an engine down after ten years of service, it was plugged up with all kinds of sludge and carbon. Sludge would be so bad, it would obscure the rocker arms and the lifter valley to the point you would have to use a putty knife to scrape the stuff away to service it. Fast forward about twenty years. Now you can take one apart with twice as many miles and there is almost no sludge or carbon (relatively) present in the used engines.

Used to be common to hear the term, "I'm gonna' take her down the road and blow her out"! I haven't heard that term since leaded gas came in. When I was a "clean-up boy" at a Pontiac dealership in the middle '60's, that was one of my jobs was to take an old lady's new Pontiac down the road to blow it out and make it run better. Only regret, the sales manager had a 421 Super Duty Catalina and I never did get to "blow his out"!

But, yes. Carbon in the engine was a problem back then and if you didn't know it, you either forgot or you are too young to remember.

[Dick W.]

Re: De-carboning engine

Very popular service station additive in the '60's was Wynn' "Carbon Blaster". Dose of this, go down the road wide open for a mile or so and watch the sparks come out of the exhaust.

[Roy B.]

Re: DDT "Duke say that again" *NM*

[Roy B.]

Re: Duke "again wha?"water injection "help me out" *NM*

[Mike McKown]

Dick, I'll second that

and another similar product I had success with on a 193? Austin Bantam was a can of "Casite". It was smoking pretty bad and didn't run all that good. I put a can of the stuff in the crankcase and the black stuff just rolled out the exhaust! It did not overhaul the engine but it sure ran better and smoked a lot less. Put that stuff in a modern car and you probably wouldn't get a puff of smoke.

[Dick W.]

Re: Dick, I'll second that

Better luck than I had with Casite. Put it in crankcase of '56? Dodge with samll hemi. Ended up replacing all the hydraulic lifters. Remember the sludge of old? 100,000 miles was almost unheard of for engine life. Lubricants have sure improved

[Mike McKown]

Maybe I got off clean

because the Bantam was a flathead engine with solid tappets.

Be my thinking that the PCV valve cleaned up the engine about as much as the oil improvements.

[Chuck S.]

In Those Days...

The antidote for crankcase sludge was Texaco Havoline motor oil changed on a regular basis.

Once upon a time (1960-1961), when I was just a little tyke, I worked as parts gofer at the largest dealership in my little town. (Don't tell anybody I worked at a blue oval dealership...tell them I played piano in a ho' house. )

Anyway, the shop got a Texaco company car (57 black Chev 4 dr sedan) in for an engine overhaul. I don't know the mileage, but I expect a company car saw a lot of action. When the mechanics had torn down the engine, they were raving about how clean everything was inside...no sludge, no nothing but an amber stain on iron. What was the secret, I asked...They replied that it was the Texaco Havoline motor oil that was used to maintain the vehicles.

I used Havoline in my personal cars (Chevrolets) for years with the same result. When the valve covers were removed, there was no sludge...only an amber stain on the metal. But, when the oil was drained, the bottom of the drain pan would have a couple tablespoons of thick black/white pasty stuff which I presumed to be lead from premium gasoline.