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Odd Ping - Power Loss -


James_Douglas
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Hi all,

 

Anyone ever had a problem with pinging leading to fuel starvation at FULL throttle going up a very long hill?

 

In the last couple of weeks I have had pinging on long uphill grades.  The odd thing is it does not happen until I have been going up the hill for a while and the engine gets good and hot (like all these old flatheads when pulling up a long hill).

 

If the ping was due to timing it should start at the beginning of the high load high speed run up a hill. Yesterday I got it not only to ping but also to burble, loose power, and almost stall near the top of a long grade.

 

It has been unseasonably warm around here the last few weeks.

 

A casual look at the dizzy and the carb looks ok.

 

I am wondering about an odd/rare issue and sent this to a friend at Chevron and asked that he forward it to the gas guys...

 

************

 

I am one of the few people that drives daily a automobile from the 1940's around San Francisco Bay.  In the spring this year I am having an issue that seem to be a combination of pre-detonation and vapor lock all at once.  It is subtle and only happens at freeway speed going up long hills at full throttle. (5000 pounds and 100 HP!)

 

These little one barrel carburetors never vapor lock at anything other than idle in stop and go traffic.  I have never seen one do it highway speed.  However, I am getting a ping after a long up hill climb and the engine bay and carburetor heats up real good.

 

We are hypothesizing that I am getting bit by the Winter gas with a very high Reid Vapor Pressure (RVP) being run in a carburetor during a more hotter than normal April.

 

The Winter Gas comes out of the pressurized fuel line into the carburetor bowl at atmospheric and starts to vaporize thus leaning the mixture which causes a ping.  Once it gets hotter on a long pull up a hill it then goes into full vaporization and it losses power, sputters, and I have to pull off the road.  Full Vapor Lock at full throttle. If the engine cools down at all the whole thing goes away.

 

So, what is the winter RVP on regular gas in the Winter time in Northern California?

 

********************

 

I am waiting on an answer, but I am wondering if anyone else has had an issues on the late spring or fall with odd pinging that goes away once the air-temp/fuel types are all "lined up".

 

Thanks, James

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I guess it might be the higher volatility of winter fuel. Can't remember when the switch is but I think we are still on winter stuff.

 

But have you checked for proper flow and pressure at the output of the fuel pump? Might be a weak pump or restriction in the line from the tank is reducing fuel flow a bit. Not enough to notice on the flats but enough to have insufficient capacity for when you are pulling a hill.

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James, any possibility of carburetor icing??? This would lean the mix and might cause the stumble and pre ignition of a too lean fuel charge. Especially at WOT you might be getting evaporative cooling enough to ice the main jets and or maybe a loss of vacuum signal to the intermediates. Pull over and check the base of the carb for any sign of frost next time it happens. Your winter mix gas is probably adding to the evap cooling side of the equation.

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But that what they had the heat risor on the car to stop the ice effect at the base of the carb. I had this happen when my Heat riser when on my 39 desoto in the winter. So when coming to a stop light I would just pull the throttle cable out to runthe car at a higher rev's.

 

 

So since you are IN SF did you disconnect the Heater risor?

 

JAmes:  In 1976 i rode a bicyle across the USA and then came into Oaklyn Allemdia NAval Station and stayed with a friend of mine. Took me 60 days to cross the us. Left from Williamsburg VA. We came down from Sacarento inthe morning and then spent a week riding inthe SF area before heading back to Philadelphia.  SF is a real neat town to visit.  Are you on the SF side of the Oaklyn side of the Bay?

 

Rich HArtung

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I guess it might be the higher volatility of winter fuel. Can't remember when the switch is but I think we are still on winter stuff.

 

But have you checked for proper flow and pressure at the output of the fuel pump? Might be a weak pump or restriction in the line from the tank is reducing fuel flow a bit. Not enough to notice on the flats but enough to have insufficient capacity for when you are pulling a hill.

Todd,

 

Back up electric fuel pump makes no difference.

 

James

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James, any possibility of carburetor icing??? This would lean the mix and might cause the stumble and pre ignition of a too lean fuel charge. Especially at WOT you might be getting evaporative cooling enough to ice the main jets and or maybe a loss of vacuum signal to the intermediates. Pull over and check the base of the carb for any sign of frost next time it happens. Your winter mix gas is probably adding to the evap cooling side of the equation.

 

Greg, A very interesting thought?  I will check that the next time I get it to happen. As a flyer, I should have thought of that!  Getting old!

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If the engine begins to ping, don't let it continue. It will cause some serious damage. Like punching holes in the tops of the pistons, minor things like that. Hopefully I've misunderstood, but it sounds like you kept driving/going up the hill with the engine pinging? Tell me I'm wrong!!! :)

 

Might not hurt to turn the timing back a bit, but I understand that it's not the primary reason...you just don't want to let it keep pinging, slow down, shift down, go slow, whatever it takes so the engine does not continue to ping.

 

Is the carb possibly running too lean to begin with, and the other things aggrivate the problem? Fuel lines not too close to the head, block, exhaust manifold, etc?

 

Just some thoughts.

 

ken

Edited by Lumpy
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James;

Run a pint or so of water down the throat of the carburetor when the engine is running at 1500 RPM's or so. You may have carbon build up in the combustion chambers that creates hot spots and dieseling (AKA pinging). By running the water through the carburetor you are in essence steam cleaning the combustion chambers.

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Hi all,

 

Anyone ever had a problem with pinging leading to fuel starvation at FULL throttle going up a very long hill?

 

Yes, hillclimbing on the Wasatch range in my '67 scout.

 

I think I was low on gas & it got so steep the pickup in the tank started coming uncovered. Or maybe the fuel pump was weak, because the engine pinged a few times and died.

 

(BTW, short wheelbase vehicles do not steer well in reverse at speed, even with reverse engine braking, Also, Scout brakes are not self energizing in reverse. It was a wild ride down.)

 

As for your friend's car, does it have vacuum advance or just mechanical?

 

I might go drive it around with a temporary vacuum gauge on the wiper hose & watch what the needle does on a hill.

Edited by Ulu
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That is true, may be time to de-carbon the head. On motorcycles of the same era as our cars, it was common practice, and factory advise to pull and de-carbon the heads at pretty short mileage intervals, like 3000-5000 miles.

 

k.

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If the engine begins to ping, don't let it continue. It will cause some serious damage. Like punching holes in the tops of the pistons, minor things like that. Hopefully I've misunderstood, but it sounds like you kept driving/going up the hill with the engine pinging? Tell me I'm wrong!!! :)

 

Might not hurt to turn the timing back a bit, but I understand that it's not the primary reason...you just don't want to let it keep pinging, slow down, shift down, go slow, whatever it takes so the engine does not continue to ping.

 

Is the carb possibly running too lean to begin with, and the other things aggrivate the problem? Fuel lines not too close to the head, block, exhaust manifold, etc?

 

Just some thoughts.

 

ken

The timing was turned back a lot and made no difference. This car is run daily for the last 13 years.  It has also climbed out of Yosemite valley on the north road in July with 100DF heat and never had this problem.  Something odd is going on.  I will dig deeper into it later in the week. 

 

James

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Yes, hillclimbing on the Wasatch range in my '67 scout.

 

I think I was low on gas & it got so steep the pickup in the tank started coming uncovered. Or maybe the fuel pump was weak, because the engine pinged a few times and died.

 

(BTW, short wheelbase vehicles do not steer well in reverse at speed, even with reverse engine braking, Also, Scout brakes are not self energizing in reverse. It was a wild ride down.)

 

As for your friend's car, does it have vacuum advance or just mechanical?

 

I might go drive it around with a temporary vacuum gauge on the wiper hose & watch what the needle does on a hill.

 

Back up in line boost pump made no difference.  Standard Auto-lite dizzy.  Full tank. 

 

Keep posting ideas folks, I will check each one.

 

James

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James;

Run a pint or so of water down the throat of the carburetor when the engine is running at 1500 RPM's or so. You may have carbon build up in the combustion chambers that creates hot spots and dieseling (AKA pinging). By running the water through the carburetor you are in essence steam cleaning the combustion chambers.

 

 

Hi Don,

 

I will do that. 

 

James

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Havent heard this one yet.  What condition is the rubber hose just before the mechanical pump if you still have one???  They rot from inside out and restrict fuel,,,dont ask me how I know.  outside looked good,,,inside collapsed...or like others have said,A restriction elsewhere like tank exit.

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If the car ran like a champ before, i would first assume that it was an environmental issue instead of a engine issue. The winter fuel mix is a good observation, i know here in Kansas the switch takes place in March and then back again in September. Also something worthy of noting is that e15 has an uncanny ability to absorb moisture, so depending on how long your tank set full or the fuel quality at your last pit stop, your tank could have a fair amount of water in it. If the fuel got cold enough anywhere along the line you'd get some nice slushy ice crystals.

Edited by JDaniel64
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James;

For what it is worth I think it may have more to do with the winter blend fuel than some here may think. I noticed something was up with it this fall and I am just guessing but I think this year the blend is different than it has been in the past. Combine this with the warmest and driest winter on record.........and I think this may just be the culprit.

 

Jeff

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James;

For what it is worth I think it may have more to do with the winter blend fuel than some here may think. I noticed something was up with it this fall and I am just guessing but I think this year the blend is different than it has been in the past. Combine this with the warmest and driest winter on record.........and I think this may just be the culprit.

 

Jeff

San Francisco climate being controlled by the Pacific Ocean is one place in the USA that has less temperature fluctuation than anywhere else in this country. I am surprised that they do a summer/winter blend change in there gasoline.

 

http://www.weatherpages.com/variety/least.html

 

The city with the least variety of weather is San Francisco, CA. San Francisco is located in a unique location on the end of a narrow peninsula surrounded on three sides by water. San Francisco averages only 2 days per year above 90 degrees, and less than one morning per year below 32 degrees. Temperature-wise, it is hard to tell the difference between summer and winter. Both are cool and there is also little difference between morning and afternoon temperatures.

 

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The fact that you have been driving it for 13 years up and down and around and around, kind of reinforces the idea that you have reached your carbon-up limit. Now Don's idea is not bad, but I think a better idea would be to pull your head off (the one on the engine) and really properly de-carbon it. It's extremely easy to do on a flathead six, no excuse not to. Too much carbon is not so odd. Again, a flathead motorcycle will have the heads off to do that once a year, or so many miles, which ever comes first. A flathead six is not that different.

 

ken.

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The timing was turned back a lot and made no difference. This car is run daily for the last 13 years.  It has also climbed out of Yosemite valley on the north road in July with 100DF heat and never had this problem.  Something odd is going on.  I will dig deeper into it later in the week. 

 

James

How's the cooling system? Maybe the coolant distribution tube is getting clogged.

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Well, the plot thickens...

 

Retarding the timing did nothing. Checked the dizzy on the bench, nothing...except...the flair on the vacuum advance was leaking a bit, but just a bit.  Fixed it and not effect.  Checked the card, everything looks good.  Checked the fuel flow, nothing there. Ran some water through it at high idle, as Don suggested, got some carbon out the back.

 

Took the car out for a ride this morning.  Bad.  Very Bad.

 

Headed over the GG Bridge. It did not make it up the hill to the tunnels going north.  In 3rd under a load it would start coughing and want to die. That odd high frequency ping and then burble and then power loss.

 

Had to down shifted into 2nd to keep going at 35 PMH and went through the tunnels and pulled off about a 1/4 mile after and shut it down.

 

The temperature went from 185 to 210 very quick when I shut it down.  Lots of vapor out the oil filler screen.

 

In 10 minutes it was cool to 180.  Double checked the water, just fine.

 

Limped the car south bound and across the bridge and home.

 

On flat ground or slight hill ran just fine.  No engine heat up going down hill or slight up grade.  Fill throttle on slight up grade ran fine.

 

Once home we pulled the plugs and did a compression check.  All the holes are down to about 100PSI from the original rebuild number of about 145PSI 40K miles and 10 years ago.

 

BUT.  Hole number 5 was 75PSI.  We went and took a good look at the plug from #5 and the electrode was completely gone down to the insulator.

 

I suspect that either I had a fuel problem as discussed that caused a lean condition that caused that plug to fail or for some reason that plug failed and hurt the valves or piston or cylinder walls.

 

In the AM, the head will have to come off.

 

James

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Have the valves been adjusted during that last 40k? Had a 223 Ford that only had 28k from the factory and ran like garbage and progressively got worse at operating temp, turns out the valve clearance was way WAY off. No gap whatsoever on the exhaust side and very little to none in the intake, maybe 0.001-0.004. Compression would be reduced with wearing seats and out-of-spec valve clearances. Something to maybe check before dismembering the engine. 

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