exhaust gaskets

[madaca]

ok, so I finally got the vacuum leak from the carbs sealed tight. I bought a better gasket and it seemed to have worked. I am still having trouble getting the truck to run smooth. It sputters like crazy and backfires if I give it gas and every once in awhile it will smooth out. I am noticing air popping where the manifold meets the exhaust pipe. I believe I may need to change that gasket and might as well change the manifold gaskets as well. Does anyone think this will help the truck to run right? Could this be the cause of it sputtering? What about changing out the spark plugs. Maybe I should get new plugs and see if that solves the problem. Any help appreciated.

[Corts60]

It sounds like you have a timing problem if it is spitting out of the carb. What's your info on the engine, ie: small block? 350? mild cam? type carb?

That will help us better with troubleshooting...

[madaca]

It has a rebuilt 283 v8, rochestor 2 barrel carb. I have messed with the timing and it still doesnt run smooth. It has helped but still does not stay runninng. It will stay running for awhile if I close the top butterfly some but once I open it up it dies. It backfires sometimes if I give it gas. I just can't figure out what it is. Once in a blue moon it will run real smooth and then it goes bad again. I am wondering if I need to change the spark plugs.

[Corts60]

It's more than likely not the sparkplugs, although it couldn't hurt to change them. By describing how when you close the choke butterfly it runs better, you definitely have a vacuum leak. It may require you to pull the carb and double check that there are no cracks in the base of the carb or anywhere else on the main body. Also make sure that your air/fuel screw is adjusted correctly.

Try spraying carb cleaner around the carb base and see if it affects the way it runs. It should make it want to die. Also you could use starting fluid, and the opposite will occur, it'll want to rev up. I would spray all fittings on the intake too, just to be sure.

How long has this been happening?

[madaca]

Well it has been happening ever since I got the truck from my grandfather a few months ago. It sat in his backyard about a year without running. When I first got the truck I started it and it ran smooth and then it died about 15 minutes later. Since then I can start it but it runs poor, backfires and then dies after awhile. When I try to rev it up it will die. Every once in awhile it idles good and revs good but then goes bad again and dies. I am trying to get this thing running good so I can change out the brakes and tires and get it on the road and then slowly start the body work and paint. I have rebuilt the carbs and purchased a better base gasket and have checked for leaks and it seems to be good but I am still stumped.

[TimE]

It possibly could have jumped time.