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.

[madaca]

If it did jump time, what all do I need to do to fix it? How can I really know if that is the problem?

[TimE]

The "backyard" way to check would be to pull the #1 plug, place your finger over the hole, have someone bump it over slowly until compression blows your finger. Then pull the dist. cap and see where the rotor is pointing. It should be pointing to the #1 cylinder (unless whoever dropped the distributor in just wired it up to wherever #1 was pointing-prior to pulling the cap, just make sure where the #1 plug is wired to on the cap and the rotor should be pointing there).

Hope this helps explain it and isn't too confusing. This may not be your problem but it's pretty simple to check and will eliminate this as being the problem.

Also, does it have fresh fuel and an inline fuel filter? There is the possibility of trash in the carb causing the erratic running. IDK, just trying to throw some suggestions out there.

I do agree with corts60 that a vacuum leak sounds like the culprit since it runs better with the choke partially closed(means when the choke is open, the engine is getting too much air) but the spitting through the carb sounds like a timing issue(hence I suggested checking your timing). Has the carb been tuned since it was rebuilt? It could possibly be "way" out of adjustment.

Hopefully someone else will chime in and offer up a little more than my "shadetree" knowledge.

[283 Man]

Tim thats the way Ive timed my 283,works fine!! nothing backyard about that just saves money Im all for that..

[Corts60]

I agree with checking the timing. And if you're by yourself, you can wad up a rag and pack it in the spark plug hole with a screw driver (not too far) and then bump the engine until it "pops" to find TDC of #1.

Also, a bad fuel pump could be contributing to this, it my be more than one thing.

[madaca]

ok, I have done the top dead center thing with my friend a few weeks ago and the rotor lined up good with the number 1 plug. I have drained the gas completely and I do have in inline fuel filter and the gas looks clean when I check. I have adjusted the two screws on the carb all the way in and then backed out 2 and a half turns. Is there anything else I can do to adjust the carbs. I will check some more for other vacuum leaks this weekend. I really think it is something small. Maybe I need new carbs though. Thanks for the help so far. I just really want to get this figured out so I can start driving it.

[skullboydeath]

Hi ill give you what I can from my experiances. When I bought my truck the po said it runs fine but he let it set for a couple of years and I had a hell of a time getting started I was going to rebuild it anyways so I really didnt care. Some one metion fuel pump check it that was one of my main problems if it has one of he old mechincal fuel pumps it could be your problem. They have a rubber diaphram that goes bad in them this will let fuel go into the engine. If it a small hole it could be enough to though off fuel pressure. Our in my case flood the whole engine. check your oil and see if there any fuel in it. Also it wouldnt hurt to rebuild the carb if its been setting a while these roch carbs are easy to rebuild and dont be scared.People think rebuilding a carb is like rocket science really all it is a few gaskets acc. pump and needels My kit only cost me about 12 dollars at advanced. I agree at first it sounds like a timing issue. Iam sure it is something small but usally the small things take the longest to find.

[TimE]

Well, if the timing is good then check the fuel flow from the pump as suggested. If you have a clear inline filter, watch it while somone is turning the engine over to see if it is getting plenty of fuel everytime the motor rotates and pushes the fuel pump lever. If you don't have a clear inline fuel filter, then just pull the fuel line off of the carb and run it into a bottle/can/jug/something and have someone spin the motor over to see if you are getting regular pulses of fuel.

My 65 LB was acting crazy at one point-would run fine and then act like it was running out of gas or either losing spark. This went on for about 2 weeks before the pump finally got bad enough to be apparent. It was an intermittent issue until finally, I was driving along about 2 miles from home and the truck shut off. It would crank right back up, run for about 3 seconds and shut off again. I thought I had a spark problem/something wrong with the old points dist. Turns out it was the fuel pump. It would pump just enough to get the engine to crank(after turning over a few times) but not enough to keep it running. Sorry for the novel.

[madaca]

I rebuilt the carb about two weeks ago or so just to be on the safe side. I can see fuel squirting into the carb when I give it gas but I have not checked for proper fuel flow while someone is cranking it. I will make sure I check that as soon as possible. It could be a fuel problem, because it cranks real good and once I pump it a bit, it will start but then dies shortly after. Maybe there isn't enough fuel going to the carb. Does make since. Thanks again for all the great tips. Hopefully I will have some progress this weekend.

[Corts60]

Originally Posted by madaca

I rebuilt the carb about two weeks ago or so just to be on the safe side. I can see fuel squirting into the carb when I give it gas but I have not checked for proper fuel flow while someone is cranking it. I will make sure I check that as soon as possible. It could be a fuel problem, because it cranks real good and once I pump it a bit, it will start but then dies shortly after. Maybe there isn't enough fuel going to the carb. Does make since. Thanks again for all the great tips. Hopefully I will have some progress this weekend.

OK, you've definitely got a fuel problem. Are you positive that you set your float to the reccommended settings when you rebuilt the carb? It sounds like the float might be set a little low and allowing enough fuel for start-up, but not continuous run.....

And the carb will "pop" and "spit" up when it is running in a lean condition and when you try and give it more gas like you described earlier. Hopefully it's something simple though....

[madaca]

I adjusted the float according to the info that came with the paperwork. I think I looked it up on line as well but can someone post what the specs should be so I can double check. I don't think I have that paper that came with the carb rebuild kit anymore. For now I will concentrate on fuel problems and see if that solves the problem this weekend. Thanks

[protrash64]

I had similar problems with an Edelbrock carb. After 3 days I put a new carb on and it ran with about 2 adjustments. My fuel was bad also....lots of black smoke!!!