This is not on a mustang, its on my friends 1966 4-4-2. I figured the classic section would know the best.. THe engine will sometimes knock once or twice after the ignition is shut off. I tried backing off the timing to fix it, but when i back it off too much it gets really rough on idle. I was thinking another thing would be to use 91 octane, which is specified for his car. He is using 89. any other ideas?

 

the octane change should help. from most of the books i've read on engines they say knocking/pinging/detonation can occur if you use a lower octane gas. try putting some octane up stuff from like Autzone or Pepboys and see if that helps.

to other members, he says after the ignition is shut off, could it be dieseling(or however you spell it)?

 

yah i think thats what its doing, is its dieseling. If you just turn it on then off it wont happen, but once the engine is hot then it will happen. I guess it's just the fuel igniting from the compression and heat of the engine?

 

ya i would say the higher octane would help, sounds like its detonating because of the compression. Ya how do you spell diesil?

 

Rofl, Soaring, we need your help, we cant spel

 

I had a 454 suburban that was dieseling....It is from carbon deposits in the combustion chamber

I have found one carbon removing product that really works....It is a 3 step kit made by Berryman's Chemtool and I found it at Kragen behind the parts counter.

It says on the box that it isn't meant for retail sale???

1) Spray a can that says "Step #1" down the carb with the engine running...Use the entire can.

2) The kit comes with a clear hose. Put one end in the bottle that says "Step #2". Remove the PCV valve and connect the clear hose to the PCV valve's vacuum line. Start the engine and let it run until the bottle is empty (about 1 minute). Then reconnect PCV valve.

3) Pour "Step #3 in the fuel tank. Fill up the tank, get the engine up to temp (I ran up and down a hill a couple times).

About a week after I used this product, I pulled some of the spark plugs and they had loose carbon on them....They didn't before.

When spraying the chemical in the carb, the engine will try to die.....just raise the rpm's and it will be fine

This stuff worked for me so hopefully it will help your buddy too

 

Diesel

 

deecell

 

There is a product called SeaFoam that works somewhat the same. You get the engine hot, operating temp, run it up to around 3000 rpm and pour the stuff down the carb, slowly and in short intervals, it will break up the carbon that has formed on the piston tops. You can also use water, cold water works good.Its the steam that does the cleaning.

One thing to remember about it, if there is alot of carbon in the chambers, some could get stuck in the rings and cause problems. a 66 442 with the factory engine should have 10:1 compression, that is too much for cheap gas. if he wants it to live and be able to drive, he has to pony up for good gas, or change the heads. If its a 400ci engine, a set of J heads would work good. if its a nail head, he will end up getting good gas.

 

good thing someone passed english class.