korax123

I did a search on backfiring but came up with nothing.

Ok my friend bought a 87 Trans-Am GTA for $200 for his son. There were 3 different brands of wires on the car, part of the cap was broke off and the rotor was severly burned. Here is the kicker the car ran pretty descent.

So we go and change the wires, plugs, cap, and rotor with new ones. Go to fire it up and the car backfires out the exhaust on us. We put piston 1 to TDC checked the wires like 9 million times. We get spark to cyl #1 heck we even put the dizzy on both ways to see if it did anything.

It's like with more spark the car wont run. Any suggestions on what to check???

I know mostly about Honda's and I own a Saturn Ion Redline 2.0 Supercharged and never really worked on these kind of cars.

spills

iTrader: (9)

biggest thing Ive seen people do is put the dizzy in 180 degrees wrong. Distributors are very touchy too, just slightly turning it causes a noticable difference on how the motor runs. First thing I would do is bring the #1 back up to TDC, take the cap off and make sure that the rotor is pointing towards the #1 cylinder. When I first changed my dizzy on the 305, I actually spun the oil pump shaft when I was pulling it out, and when I reinstalled it I could not figure out what the damn problem was!! A long screw driver and a few choise words later, I lined the pump back up and all was well.

korax123

We tried it both ways pointing the rotor toward where the #1 spark plug wire points and towards the cylinder. It just acts the same but thanks for the reply. BTW it has a 350 in it.

AlkyIROC

#1 plug can start anywhere on the cap. Is #1 cylinder on TDC or is #6 on TDC? You put the distributor on both ways?? Unless you pulled the distributor out, the rotor will only go on one way and will point to where the #1 plug should be when the timing marks on the balancer are lined up. #1 plug wire is normally around the 5 o'clock position when looking at the distributor from the front.

Other than that, the simplest mistake is mixing up #5 and #7 plug wires since they are right beside each other on the cap and in the head. Distributor rotation is clockwise and the firing order is 1-8-4-3-6-5-7-2

When in doubt about finding #1 TDC you have 2 choices. First is to remove the rocker cover and watch the valves while bumping the engine over. When the timing marks reach TDC on the balancer, the intake valve should have just closed before that. The other way is to pull the #1 spark plug out and put your thumb over the hole or just use the butt of a screwdriver. When you bump the engine over, as the piston comes to TDC on the compression stroke, air will be forced out. Partially plugging the hole will make hearing it easier. Once you know #1 is at TDC on the compression stroke, look to see where the rotor is pointing. It should be close to where #1 plug wire should be. If it's pointing at #6 or anywhere else, pull the distributor and rotate the shaft 180*.

korax123

The thing that is wierd is the car ran and we just changed the cap rotor and wires the way we pulled the wires off is the way we put them back on. THe car was running before. We go to fire it up and it backfires. Thats what doesn't make sense. Today we messed with the dizzy taking it completely out and turning it around and then putting it back the other way.

I will check our firing order but we are putting the wires the way it says to in the chiltons.

MaxxMitchell

iTrader: (4)

Another trick if your close with the timing, is to go ahead and hook up a timing light, crank the motor while using the gun. If the marks are no where close, adjust until they are close. I have done this on serveral cars, and now if there is a problem, like 180 out, this showes it pretty quickly to save time.

Double check your fireing order first, then try the timing trick. If the timing is right on, pull a plug and see if you have flooded the motor, if so, sit and crank it with the pedal tot he floor for 10-15seconds, or until it starts to try to fire.