pinging issue

[nqkjw]

a lean condition with the outer carbs butterflys opened by way of there idle screws(direct connection 6 pack carbs have idle screws on all 3)  causing a lean condition because the motor is not pulling only thru the ctr carb down the freeway.sucking air thru partially open butterflys.i currently have the outboards involved in the idle settings!!!

Sounds very possible to me.
Those outboard carbs have no mixture screws in the metering blocks(well,mine don't)so possibly there is no idle circuit in the outboard carbs.
With the butterflies cracked open you would experience vacuum leak symptoms I would guess.
I'd still set the butterflies at only just cracked open to avoid binding.

[nqkjw]

yes they r 4782-4783 direct connection mech race 6 pack setup..acc pumps on all 3 carbs    they have been great..
do a thread search here on the 472 4783 carbs..thanks.

Found your thread and a few others too.
Great reading

[high perf mopar]

Sounds very possible to me.
Those outboard carbs have no mixture screws in the metering blocks(well,mine don't)so possibly there is no idle circuit in the outboard carbs.
With the butterflies cracked open you would experience vacuum leak symptoms I would guess.
I'd still set the butterflies at only just cracked open to avoid binding.

thats what i was thinking..vacuum leak.at each end of the intake.my thinking was to open them so that going down the road they would add gas from the main circuit..i guess that did not work.right now they mostly set to idle off the outboards with very little ctr blades open.faster the engine runs the worst the leak..goes lean..no adj idle circuits on the end carbs..but they have idle screws!so i used them..im going to close them back to just barely sitting on the screws to prevent binding and retune the ctr to idle off of,,it'll probable eliminate the off idle hesitation also..and get better mileage..those 77 jets in the ctr now should cure any lean issues..

[cudabob496]

thats what i was thinking..vacuum leak.at each end of the intake.my thinking was to open them so that going down the road they would add gas from the main circuit..i guess that did not work.right now they mostly set to idle off the outboards with very little ctr blades open.faster the engine runs the worst the leak..goes lean..no adj idle circuits on the end carbs..but they have idle screws!so i used them..im going to close them back to just barely sitting on the screws to prevent binding and retune the ctr to idle off of,,it'll probable eliminate the off idle hesitation also..and get better mileage..those 77 jets in the ctr now should cure any lean issues..

I've read that lean or rich does not cause pinging. Pinging is most probable when the A/F ratio is at the perfect 14.7.
Also, a different fuel source can cause it, regardless of the octane rating. Did your area change the gasoline content
for the summer?

[Chryco Psycho]

less heat helps , blocked heat crossover , cooler thermostat , colder air to the air cleaner , is the cooling system clean for max efficiency in heat tranfer ?

[high perf mopar]

I've read that lean or rich does not cause pinging. Pinging is most probable when the A/F ratio is at the perfect 14.7.
Also, a different fuel source can cause it, regardless of the octane rating. Did your area change the gasoline content
for the summer?

probably,,the oil companies do what they want,,they have so much money that they dont even need the 10 commandmants.

[high perf mopar]

less heat helps , blocked heat crossover , cooler thermostat , colder air to the air cleaner , is the cooling system clean for max efficiency in heat tranfer ?

there eddy heads,no heat crossover,160 high flow thermostat,hole in the hood for air,everything is clean and new,less than 1500 miles on the drivetrain..was running at 160 degrees yesterday cruising down the freeway at 65 mph .pinging intermintant..

did not have time today to test the carb theory..fuel is supposed to cool the combustion chamber and i have xtra air going into intake at both ends..without xtra gas... 

[cudabob496]

probably,,the oil companies do what they want,,they have so much money that they dont even need the 10 commandmants.

Other articles say lean can cause pinging, but I remember taking the primary jets lower and lower on my 850DP, until
the engine would just run out of gas before I could get into 2nd gear (down to 66 jets), but I never heard pinging.

[Chryco Psycho]

The flame works the same as an oxy act torch , more Oxygen more heat , more fuel less heat .
 I cannot remember if the end carbs have mix screws , I thought they did ?
 If not try closing  down the idle on the end carbs so you have better fuel distribution . or if they do try opening the end carbs & increasing the mix there & reducing the idle on the middle carb & reduce fuel at idle , the 4 end cylinders could be running lean if the center carb is supplying most of the idle circuit fuel

[high perf mopar]

The flame works the same as an oxy act torch , more Oxygen more heat , more fuel less heat .
 I cannot remember if the end carbs have mix screws , I thought they did ?
 If not try closing  down the idle on the end carbs so you have better fuel distribution . or if they do try opening the end carbs & increasing the mix there & reducing the idle on the middle carb & reduce fuel at idle , the 4 end cylinders could be running lean if the center carb is supplying most of the idle circuit fuel

the end carbs do not have idle mix screws,,only an idle speed screw,,the end carb butterflys r opened up much more than the ctr to provide the idle speed,ctr carb is barely open at idle compared to the outboards.,in theory at highway speeds i think they r acting as a big vacuum leak without adding more gas..end cylinders go lean??we will find  out soon..easy to adj,,work keeps getting in the way though..

i dont remember it pinging when we 1st took it out on the road but the tune was diff,,,carbs..

[Chryco Psycho]

no idle screws in the carb base either ? I thought they had idle adjustment somewhere on them .

[high perf mopar]

no idle screws in the carb base either ? I thought they had idle adjustment somewhere on them .

no,not on the mech carbs,just the ctr,just tested it by closeing the out board idle screws,speeding up the ctr,,if its better its just barely,,so much for that theory.

as soon as u get it up to freeway speeds,60+, a very lite not all the time ping starts,,want to make it louder more noticeable,push the throttle a little..total dist timing is around 32.

the dynamic compression ratio chart shows it at 8.7....im thinking i might have suped it up just a little too much for calif pump gas..timing is now retarded from optimal,that crisp throttle response i had is now flat..and im sure the retarded timing is holding more heat into the motor..as long as i stay off the freeway it does not seem to be a problem i have to worry about..but 2500+ rpm freeway speeds it starts to ping...

[cudabob496]

no,not on the mech carbs,just the ctr,just tested it by closeing the out board idle screws,speeding up the ctr,,if its better its just barely,,so much for that theory.

as soon as u get it up to freeway speeds,60+, a very lite not all the time ping starts,,want to make it louder more noticeable,push the throttle a little..total dist timing is around 32.

the dynamic compression ratio chart shows it at 8.7....im thinking i might have suped it up just a little too much for calif pump gas..timing is now retarded from optimal,that crisp throttle response i had is now flat..and im sure the retarded timing is holding more heat into the motor..as long as i stay off the freeway it does not seem to be a problem i have to worry about..but 2500+ rpm freeway speeds it starts to ping...

above 2500 rpm starts to ping? smells like a messed up distributor, or valve train issue.

[high perf mopar]

above 2500 rpm starts to ping? smells like a messed up distributor, or valve train issue.

maybe,,when testing it today after closing the outer butterflys i left the vacuum advance hooked up..this system worked great b-4 the cam/heads change but now im wondering how much manifild vacuum is dropping off when the throttle blades open.this cam produces more vacuum than b-4..great idle and throttle response but,,tomorrow will be another testing day without it hooked up.8 degree's vacuum timing added at 8"vac.

[cudabob496]

maybe,,when testing it today after closing the outer butterflys i left the vacuum advance hooked up..this system worked great b-4 the cam/heads change but now im wondering how much manifild vacuum is dropping off when the throttle blades open.this cam produces more vacuum than b-4..great idle and throttle response but,,tomorrow will be another testing day without it hooked up.8 degree's vacuum timing added at 8"vac.

I'd be inclined to get rid of the vac advance. Makes there a potential
for problems with a race type engine.

In fact, vac advance adds about 50 degrees advance to an engines timing when cruising.  If you floor it, and the vac advance does
not retard timing fast enough, you will definitely ping with all that advance still in there. I think vacuum advance can be adjusted to
go away faster.