So it just hit me. I bought my wagon for $300 dollars with 197,000 on the clock. it now has 207,000 miles on it. It backfires like crazy, has since I drove it home. I checked out the timing with a light and its dead on, but could the timing belts be worn and still read correctly. Any insight would be helpful. Thanks

What model, year? is it turbo, carbed, fi?

carbed ones tend to backfire if the ASV valve or the EGR valve are gummed up/damaged - this is not unheard of - if it is a fuel-injected car, I would suspect timing belts.

Its an 86' gl wagon, d/r 5spd, Non-turbo, carbed. I did a tune-up when I first got it all fixed up, wires, cap rotor, plugs, air filter. Since then not too much that would affect the carb and that aspect of things. Let me know if you need more info. Thanks

I think backfiring can also be caused from leaks in your exhaust. I would also look at the timing advance on the distributer.

the ASV (air suction valve) is actually connected to your exhaust - it is one of those annoying environmental devices of questionable effictiveness

look up from under the car at where the Y-pipe connects into the cylinder heads - you should see a metal tube comming out of the head just above the Y-pipe connection - that is where the ASV connects - follow the tubes, and you will find two small metal boxes, with another tube comming out of each, and going into plastic silencers, and then into the air filter area. block the tubes off for the ASV in whatever fashion you like, and test to see if it backfires - if it still does, then I suspect the EGR system (independent of carb) or disty, usually T-belts do not strech (they snap), and if they do, it will do more than just backfiring.

 

you are setting your timing at 8-degrees before top dead center with the vacuum hose to the disty disconnected and plugged right??? and the car is warmed up??? - do you know if the advances on the disty are working right?? check the vacuum and centrifugal advances to make sure they are moving freely - before I converted my car to FI, I had an issue with the vacuum advance on the disty seizing

Thanks for the help. I thought that the backfiring was caused by leaks in the exhaust, but I got it all fixed up and blew out my new muffler. It was a cheapo one, but if the car didn't backfire it would have been fine. I will check out the ASV and see what that does. I had the car warmed up when I checked the timing. I didn't plug the vac hose to the disty though, and I'm not exactly sure about the advances on the disty. Again thanks for all the advice.

If you loosen the bolts holding the air pipes to the side of the exhaust port and slip a quarter under each one, it will effectively block off the ASV system, and you can reverse it if you decide to.

 

 

As for your original question, it's possible that the timing belt could be off by a tooth on either side and still have correct distributor timing. The distributor runs off the cam on the driver's side, but you adjust it indepently of the cam timing. You would have a rough idle and really low power if a belt is off by a tooth.

I am so stoked, I put the quarters in there to block the asv crap and now my car doesn't backfire. Thanks to everyone.

 

Josh