hopefully you guys can help with my mates 440

[benno440]

my mates got a 69 charger with a 440 (unsure if it has been stroked or whatever)
it has indy heads
hyd cam
roller rockers double springs
eddie torker intake
demon carb(unsure of size as is no part no. on it but it is pretty big)
hooker headers
big cam (as vacuum we couldnt get over 10)
msd electronic ignition 6AL & blaster 2
727 torqueflite
holly pump a reg set at 6psi

now my questions:
everytime he turned the engine off it overran, so we did the timing or at least what i thought it should of been, it fixed the overrun.
but has a massive flat spot when you hit the throttle and when you get to about 3500-4500 rpm it pings its tits off, and we couldnt get vacuum over 10" so i am guessing its got a big cam in it.

what could this be? timing or carb etc.

 

[samedaze]

my mates got a 69 charger with a 440 (unsure if it has been stroked or whatever)
it has indy heads
hyd cam
roller rockers double springs
eddie torker intake
demon carb(unsure of size as is no part no. on it but it is pretty big)
hooker headers
big cam (as vacuum we couldnt get over 10)
msd electronic ignition 6AL & blaster 2
727 torqueflite
holly pump a reg set at 6psi

now my questions:
everytime he turned the engine off it overran, so we did the timing or at least what i thought it should of been, it fixed the overrun.
but has a massive flat spot when you hit the throttle and when you get to about 3500-4500 rpm it pings its tits off, and we couldnt get vacuum over 10" so i am guessing its got a big cam in it.

what could this be? timing or carb etc.

The running on sounds like it could be not enough octane in your gas whats the compression in the motor? You might have overcorrected the timing to compensate for the running on, hold the throttle about 2800rpm adv. the dist till it starts to ping and back off slightly should be in the ballpark of where you need to be.

 

[benno440]

we have no idea what the compression is or what is really in the engine as he bought it like this but he runs 98 octane i am not sure what the comparison is to us fuel though

 

[samedaze]

You should also ck the springs in the distributor if he was racing the car before you got they might be stiffer than you need not letting it advance at lower rpms.

 

[IQ52]

Do a cranking compression test.

 

[coloradodave]

You should also ck the springs in the distributor if he was racing the car before you got they might be stiffer than you need not letting it advance at lower rpms.

Sorry, but this doesn't make sense. Jeez, I'm turning into Rusty...lol

 

[benno440]

You should also ck the springs in the distributor if he was racing the car before you got they might be stiffer than you need not letting it advance at lower rpms.

thats what another mechanic thought to check too

- - - Updated - - -

Do a cranking compression test.

sorry but how do we do that?

 

[scotts74birds]

I know for a fact that Aussie fuel is different. My Harley is tuned for U.S. 92 octane. When I took my bike there and used their 94 octane, the motor rattled like a garbage-disposal full of drywall screws! I had to use generous amounts of octane-boost to to keep the detonation away. Reason being is the different computational methods used to establish the octane ratings. So if the motor is built for U.S. premium (say 92-3), your 94 will be unsuitable. 98 may even be borderline. Without knowing the CR, it's hard to guess at fuel requirements. From the "run-on", or "dieseling" issue, it appears that something is causing a "hot-spot", or other source of ignition in the combustion chamber. http://en.wikipedia.org/wiki/Dieseling This is a great description of some of the causes. Cheers mate!

 

[benno440]

god damn fuel companies, you would think they would be the same, especialy if they say it is 98 octane

 

[ws27]

Couple of basics I can think of to check. Idle speed too high? That can cause run on. Also carbon build up. You can reduce the carbon by spraying water in to the carb while the engine is running at a high idle. use a spray bottle, don't just dump water in.

 

[benno440]

i fixed the overrun with the timing now it just has a bad flat spot and pinging at high rpm,

 

[ws27]

i fixed the overrun with the timing now it just has a bad flat spot and pinging at high rpm,

Yes, my concern is that when you fix the timing back, the run on might revist you.

 

[benno440]

is there a way to check the compression or engine size (CI) without stripping it?
also whats the best way to time it? i started at 15 initial then 38 total at idle it got massive flat spot after that but did get rid of the overrun, like i sai i think it is a performance 440, so if it is should my intial be higher or lower and total be higher or lower. also with the vacuum gauge on the demon carb i could not gte it any higher than 10 and it was fluctuating a bit and thats with the mixture screws at about 1 1/2 turns out.

i am not really sure on what i am doing here but i spent neally a whole day researching and the more i read the more difficult i found it, is there an easy way to do this?

 

[68GTX440]

In the old day's I never used a timing light to adjust timing. When I test drove a car I would adjust the timing a little at a time then when it started pinging you back it off just a tad till ping quit and everything worked great. Keep in mind the more you advance the timing the higher your idle will be so adjust the idle down as needed to allow the engine to stay running in gear. Try this method and see if your detonation/dieseling quits. Hope this helps without knowing all the details of the build on your friends engine.

is there a way to check the compression or engine size (CI) without stripping it?
also whats the best way to time it? i started at 15 initial then 38 total at idle it got massive flat spot after that but did get rid of the overrun, like i sai i think it is a performance 440, so if it is should my intial be higher or lower and total be higher or lower. also with the vacuum gauge on the demon carb i could not gte it any higher than 10 and it was fluctuating a bit and thats with the mixture screws at about 1 1/2 turns out.

i am not really sure on what i am doing here but i spent neally a whole day researching and the more i read the more difficult i found it, is there an easy way to do this?

 

[IQ52]

Cranking compression..........Go to any auto parts store and get a compression tester. They will come as a kit and should come with instructions. In case not..............Remove all the spark plugs and the coil wire. Open the throttle fully. Screw the tester hose into one spark plug hole at a time, attach the gauge and crank the engine over 4 or 5 times. Record the pressure on the gauge and check all the cylinders. If you don't know the actual static compression, you must find the cranking compression. Then some educated answers can be applied to your conundrum.

 

[Dennis H]

In the meantime, don't let it run on. Shut it off in gear. It was timing when mine ran on.