Posted: 11/16/13 06:37 PM
pro comp 8-stack injection 347 stroker afr renegade heads f cam holley dominator ecu fast dual sync distributor. Holley tech helped me set up computer, When started exhaust pops thru #8 stack. Can't keep running long enough to check timing. Was told that if timing is way off, it would cause this condition. I think I may have screwed up installing head gasket. Any ideas? read fast forum and they said timing issue but offered no fix HELP
Posted: 11/16/13 11:03 PM
disable the igntion system completely..
disable the fuel injection system.. so it cannot spray.
either crank the engine and listen to the speed of the cranking as each cylinder comes up on the compression stroke. if you have a low or leaking compression you will get a faster cranking speed for that one cylinder.. and you should be able to hear it..
you can also do a compression or cylinder leak down test.. seeing if an intake valve is leaking back into the intake.. or an exhaust valve is failing to open.
are your spark plug wires properly separated??? so there is no inductive cross firing.. what.. yep.. the high voltage going down the spark plug wires creates a magnetic field around the wire.. and can induce a ghost spark in a near by wire..
this happens usually on the last two cylinder on the drivers side of small block chevys and small block fords. you did not mention if you have the 4/7 swap in the cam.. or the second small block firing order that might screw this up..
pull the spark plug wire off at the spark plug of the cylinder thats backfiring thru the intake and stick a spark plug into the end.. wrap some wire around the shell and ground it.. so the spark does go thru this external spark plug but cannot ignite the air fuel mixture in the combustion chamber..
does it still backfire...
i have not had my hands on one of those distributors.. i looked online.. and it looked like the duel sync distributor uses a magnetic trigger wheel like a pertronix with cavities with tiny magnets and green tape holding them in...
i like to dead stick my magnetic pick up distributors..
i set the damper to the base timing i want.. 6 or 8 before.. i then turn the distributor housing to align the pole piece on the pick up coil with the tips of the reluctor pole piece.. when the magnetic pole pieces align.. this is where the ignition system is going to fire the coil during start up .. before the electric spark timing takes over..
so.. i don't know if you can see the pole piece or magnets in the reluctor on the distributor shaft.. or the pick up coil center...
you can.. rotate the distributor with the crank set at base timing.. turning the housing in the opposite direction from the shafts rotation.. do this with the ignition on.. and either a timing light over the coil wire.. or the end of the coil wire rigged into a grounded spark plug or spark tester.. when the ignition flashes gets you really close to base timing.
this give you the ability to set the distributor in place before you are ready to crank the engine, and when you reach thru the window.. the engine starts on the first try..
there is a bunch more stuff to check after you have done these.
please also check the ground connections...
between the negative battery post and the engine block
between the Negative battery post and the BODY...
between the engine block and the body..
and... between the engine block and the computer grounds.. not the body .
and the ignition system grounds and the engine block..
why do i mention all this.. i work all the time on OEM fuel injection systems on cars and trucks.. and this is the steps that i take when i get a backfire thru the intake or throttle body..
post results to some of these tests and settings.. i do look thru this forum for new posts 3 or 4 times a day or night..
you can also.. take pictures and upload them to photobucket.. and paste the links here so we or I can see whats up in pictures...
Posted: 11/18/13 04:52 PM
thanks for the info. I am leaning towards timing and possible crossfire issues. I work a lot and may not work on the car for a couple of weeks or even months, but I will get back to you and let you know the outcome.