!!!!HELP!!!! haunting missfire wont leave!!!!

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72451scamp

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ok so i have a 73 duster that had a stock 318, it ran on all 8 when i got the car, then probley 2 months after it started to miss but it was weird because it was like it would clear out sometimes and come back again, then about a month later it turned into a dead miss. so i got 68 318 heads that were rebuilt because i was told it was a burnt valve, it was still doing it after the new heads so i put a 4bbl holley carb and intake, still didnt help,and somebody on bigblockdart said it was a cam lobe that went flat so i got a cam from a guy and its the 340hp cam that had 500 miles on it and brand new lifters, and i got my dads 70 318 out of his dart swinger and put that cam in it and put it in my duster, the miss is still there so i put 3 different distributors on it and new cap wires rotor plugs and a new control box, i also fixed a wiring mess that the guy did before me, THE MISS IS STILL THERE! we cant figure out whats wrong with car!!! anybody have the same problems?
huh.gif
or a solution, we also ran a compression test and holes 2,4,6,8,5 where around 120psi, and holes 1,3 where 140-148 and hole 7 was around 110-115 THANKS GUYS!!!:-(
 
It appears you've covered most of the basics. Those compressions are pretty wide. Perhaps an intermittent ignition short, timing chain/gear issue, loose electrical connection, fuel delivery or contaminated fuel supply, balancing issue.Vacumn problem. Is engine grounded to body? I'm just throwing out possibilities. Mike
 
the timing chain has maybe 30 miles on it fuel contaminations is a possibilty but the thing that baffels me is that its done the same things with two different motors thats why we figures is has to be the car weve gone thre different distributors control boxes cabs wires plugs went threw the wiring back to the harness that goes to the main harness and cleaned up all the bad spots i mean i dont know what else it could be...:-(
 
Fuseable link problem? Do you have ampmeter? Sometimes they create connection problems that are intermittent because all the electrical power runs through a connector on the rear of gauge. Theres an article on those showiing a switch to voltmeter. I'm including the link to on bottom. You're just going to have to start again with the basics, and weed out everything. Check that fuel tank, pickup, strainer sock in tank, fuel pump, etc.. Have fresh fuel. Could very well be water in fuel. Mike
http://www.madelectrical.com/electricaltech/amp-gauges.shtml
 
thanks for the help mike, ya we really are leaning towards electrical becuase the odds of twodiffent motors doing the exact same things to many sounds pretty rare especailly when we know that this motor ran perfect before we threw it in the car but i will keep you updated on what it was thanks alot
 
Did you use the same intake on both motors?Could be a warped intake and therefore have a vaccum leak? Does it miss at an idle? If so have you shorted out each cylinder while it is running to detemine which cylinder is not making power. Have you disconnected all the vaccum lines going to the brake booster, to other accessories to determine if a leak is creating a too lean condition? You need to find out which cylinder is not making power to start narrowing things down. M2C
 
find a mechanic with a temperature gun. he can find the dead cylinder by the lower temp. what color are plugs. plugs should leave a clue. possible flooding or lean carb, weak coil
 
well i feel kind of dumb but problem is solved we went to fire the car today and for some reason we thought to pull the vacuum off the brake booster and..... is stopped missing, the break booster went and thats what was causing the miss but thanks for all the help:thebirdm::love7:
 
72451scamp said:
well i feel kind of dumb but problem is solved we went to fire the car today and for some reason we thought to pull the vacuum off the brake booster and..... is stopped missing, the break booster went and thats what was causing the miss but thanks for all the help:thebirdm::love7:
Click to expand...

Sometimes we complicate things by over looking the simple things, glad to hear you found the problem.
 
dont feel so bad ,i pulled my 360 down to the shortblock because of a starter one time. starter spun motor but was shorting insideand screwing with electronic ignition.
 
I know how to solve that problem. Get rid of the power booster.
Go manual. I have front disk and manual on all my cars. I converted them.
Manual stops just fine.
Simple is better IMO. For lots of reasons.
 
adriver said:
I know how to solve that problem. Get rid of the power booster.
Go manual. I have front disk and manual on all my cars. I converted them.
Manual stops just fine.
Simple is better IMO. For lots of reasons.
Click to expand...

yaa i plan on doin that just havnt got around to it....

but once again thanks everybody for all the help!!!
 
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