Backfiring

Okay, now that I got the jeep on the road it decided yesterday to give up the ghost. I was cruising at about 45mph and it just started backfiring real bad, then shut down. Had to tow it home. What's the first thing to take apart? It was late and all I checked so far is whether or not the distributor was loose and it wasn't.
As added information, the distributor is one of those no name billet ones off ebay.........I've been hearing bad things about them. Also, the motor is the only thing I didn't go through during the rebuild.

 

I'm working through a similar problem, though on a 4-banger L-head . . . have you got your timing down pat, that was an issue I had to resolve.

 

What motor? 304? 258? 232?


Did you use the distributor gear that came with the new dist or the original gear that came from the old dist? I've got a cheap-o HEI also, I re-used the old gear from the factory dist and I havent had a problem in 2 or 3 years now.



On the last tioga run back in May we had a guy with a 360 and the HEI who ran into a similar problem. We checked by removing the dist cap and turning the motor with a breaker bar. At one point the distributor rotor stopped moving with the crank indicating that either the cam gear or dist gear had thrown a tooth. We didnt tear down the jeep to figure out which one though.

 

It does sound like something between the timing chain and distributor rotor broke or became disconnected
Is the rotor pointing to #1 with the timing mark lined up?

I'd also check to see if there is adaquate grounding of the distributor to the block and the block to the battery.
If you haven't already, clean those up,check the static timing, and start from there.

 

AMC 304 with aftermarket (chinese) HEI off ebay. Jeep has been running good for awhile(months). Was going to town to get some bolts for new seatbelts and on the way home out of nowhere it started backfiring (sounds like rifle shots). Towed it home and stuffed it into the garage. Distributor was tight with no movement and thats where I left it. I think it may be something broke in the timing system (could be a ground) or slipped a tooth. I'll let you know when I find the problem.

 

This just happned to me Sunday, Started just fine, drove about 6 blocks and when pulled from a stop light it backfired 1 time and died. Couldn't get it to start so towed it home, the distributor bug wasnt pointing to #1, re set it and wouldn't start, checked it again and at tdc compression wasn't pointing to #1. I assumed had jumped time so I tore it down. Turned out the distributor gear had 3 teeth knocked off and each rotation of the distributor it would get off about 1/8 of a rotation. I had a spare gear so I am going back together now. By the way 304 AMC and aftermarket HEI.

 

I am just going to throw something out there to check. I had a pickup brake down on the highway in front of my house last winter. the Ford p/u was backfiring and jumping like you discribe. he left it in my driveway and a month later he showed up with tuneup parts. I helped him and we could not get that truck to run worth a darn. and it ran fine up until a 1/4 mile from my house. I finally pulled the Dist out and there was no gear on the bottom. the roll pin had broke. so it had been running bad and out of time untill the roll pin completely gave and then it wouldn't fire.
I suggest pulling your dist and checking it out. It is a easy check!

And I have been running a billet dist on my 304 for a while and absolutely love it!. just double gasket them for the gear clearance.

 

Well, had a little time last night so I decided to dive into troubleshooting......pulled the cap off everything looked okay. started turning the motor over and the dist would make a revolution and then pause a little then kept going. It would turn 360 and pause and the pause would be a little off after each rotation. So, I started thinking dist gear might be bad. Pulled the dist and the gear was perfect.Crap. got a flashlight and looked down into the distributor hole and the cam gears look like they have been filed to razor sharp edges!!! I think thats where the problems is and that my timing has jumped at the gear. Time for a teardown and new cam,lifters,valve springs,timing chain.........the list can go on!!!!

Will take pictures after the teardown, which will be much later down the road. Time for the summer trip to the lake!!!

 

oofff. Sorry to hear that. When you but it back together, get a matched set of cam/dis gears and you will be fine. I thin www.bulltear.com sells them.

http://www.bulltear.com/catalog/product_info.php?cPath=21_35&products_id=33

 

Matched set of cam gears and distributor gears? I don't understand......... The distributor gear is ground onto the cam is it not?
Do you mean matched set that's on the crank and the cam? The gear I'm having trouble with is actually ground onto the cam that mates to the distributor. I haven't done much AMC work only chevy stuff.......

 

I just looked up that website...........does it mean I really don't have to pull the camshaft out?!?!?!?!?!?! woohoo!!!!!!

 

Unfortunately, I think so. The cam gear on the V8 is not integral to the cam as far as I know they are two separate pieces.

I've never had an AMC v8 open though, so I could be wrong. Timgr would probably have a better idea than me.

 

Is it possible to change the gear on the cam while it's still in the motor? I looks like it is keyed and may need a gear puller to get it off. Are there any special tricks?

 

I think you can change the cam gear with everythign still inthe jeep. No need to pull the motor apart. Just pull off the front timing cover, etc. While you are at it, replace the timing chain, rebuild the oil pump, etc.

Not nearly as bad a job as it might seem.........

 

Did some reading on the AMC 304 oiling problems between the cam-cam gear-distributor gear and the holes not lining up and causing the distributor drive gear to run dry and eat the teeth. Talks about the dist gear having 4 oil holes that can get plugged. Interesting.

 

Sooooo, been fighting the harmonic balancer for 2 days now! Any body have any good suggestions on removing a stuck balancer?!?!?!?!:?
I have rung the head off the puller tool twice now and the balancer isn't moving!!!! Soaked it with PB blaster as well! I'm ready to take the torches to it!!!!!! Any ideas?!?!?!?:?

 

I usualy tighten the puller to maksimum, and then give it a good wack with a hammer to shock it loose.
Sometimes it works, sometimes it dont.
Good luck with that good looking Jeep!!

 

The cam gear comes off pretty easy, I used an inexpensive puller, I have removed the harmonic balancer on both my 304 and a junkyard 360 recently, I used a no name harmonic balancer puller and an impact and both came right off. An impact makes a lot of difference in this type situation. I removed the bolt in the snout of the crankshaft removed the washer and put the bolt back in to protect the threads from the puller bolt and the balancer came off with use of the impact.

 

Well, thanks for all of the advice guys!!! The problem is definitely the cam gear! Will get pics soon. I had to take the torches to the balancer to get it off!!! Now its time to put everything back together!!!!

 

Fixed the timing........put a hole in the radiator........replaced radiator with new aluminum one........fouled two plugs....fixed plugs......melted spark plug wires......fixed spark plug wires.........broke clutch linkage.......fixed clutch linkage.......will it ever end????? I'm thinkin of leaving something broke!!!!!
Now on to installing poison spyder rocker knockers!!!