problems with 302
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problems with 302
I have a 1988 f150 with a 302 converted to carb I just started having this problem with it it runs sluggish and backfires threw the carb only left side of carb thou and only spits out the gas no fire. It will only do this when I accelerate too much everything is good changed plugs wires and dist. cap and rotor what can cause this problem.
Posting Guru
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My first thought is a timing issue. Being it only backfires out the left side of the carb, makes me think something else is going on. Are you sure the wires are routed correctly? It really sounds like two are switched.
Posting Guru
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From: sunny fla sometimes windy
Pull the valve covers off and check your valves are all moving the same distance
with a gauge. Maybe a valve holddown is loose or someother stupid problem, but
it could be a bent valve and only when you get on IT does the pressures and temp
rise and force junk back into the intake. See carbs are not without their
problems and are not always the answer to fuel injection problems!!
with a gauge. Maybe a valve holddown is loose or someother stupid problem, but
it could be a bent valve and only when you get on IT does the pressures and temp
rise and force junk back into the intake. See carbs are not without their
problems and are not always the answer to fuel injection problems!!
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checked valves, lifters and cam all r good timing is good wires r not switched it was running fine but then started acting up. Its like my damn truck knows when Ill have some extra cash and then starts acting up. So what else can I check the timing belt did have some play and harmonic balancer looks like its going to give up would that cause it to backfire
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Even though I didn't mention it at first, I did have the same thought about a valvetrain problem and I'm kinda surprised you didn't find something there. My thought was you were going to find a spring that was broken very near the top or bottom, and still had enough spring to close the valves at low throttle. I think we're down to carb at this point, aren't we? Clogged tube from accelerator pump on one side of the carb? You can check that by looking at it holding the choke open with the truck not running, and see if the streams are equal.
Postmaster
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do a compression test..
is it a rebuild?
new cam?
what firing order are you using?
Balncer??? that has the timing marks on it, so if it's junk you could be way off on the timing
Timing belt??? Not a 302
if the "timing chain" is bad it could have skipped a tooth or two.....
How many miles on it?
sorry, you asked...lol we need info!!
is it a rebuild?
new cam?
what firing order are you using?
Balncer??? that has the timing marks on it, so if it's junk you could be way off on the timing
Timing belt??? Not a 302
if the "timing chain" is bad it could have skipped a tooth or two.....
How many miles on it?
sorry, you asked...lol we need info!!
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Posting Guru
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From: sunny fla sometimes windy
Of course I am the advocate for gas line dryer and my prescription is to double dose
with 2 of Iso HEET and 2 bottles of HEET and see how that does on whatever is in
the tank 3/4 1/2 and run it until 1/8 tank and refill with fresh fuel.
with 2 of Iso HEET and 2 bottles of HEET and see how that does on whatever is in
the tank 3/4 1/2 and run it until 1/8 tank and refill with fresh fuel.
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Postmaster
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I've seen many of your posts about using way more than the recommended amount of that iso dryer stuff I just never said anything but...
one must be careful of that dryer stuff, some of it is not good for injectors
one must be careful of that dryer stuff, some of it is not good for injectors
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fixed the problem did a compression test 2 cylinders had almost no compression blown head gasket between the cylinders runs good now but now when I gun it it backfires what can that be I changed carb to a 750 vac. sec. has 70 jets and .25 squirter is it too much gas for my little 302.
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Originally Posted by marioc956
runs good now but now when I gun it it backfires what can that be I changed carb to a 750 vac. sec. has 70 jets and .25 squirter is it too much gas for my little 302.
Postmaster
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check the rockers and make sure they are all moving the same... If you get a exhaust valve thats not opening all the way it will pop under a load. also check the firing order, you might have to use the 351W order or the 302 order, just try them both. if you run the wrong order it will skip at idle and pop when you step on it.
what were the readings from the compression test...?
what were the readings from the compression test...?
Posting Guru
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[QUOTE=HemiEater]check the rockers and make sure they are all moving the same... If you get a exhaust valve thats not opening all the way it will pop under a load. .
QUOTE] Just curious, HemiEater, have you ever broken an exhaust rocker?
QUOTE] Just curious, HemiEater, have you ever broken an exhaust rocker?
Postmaster
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not a rocker but I have broke a rocker stud... and I have had a wiped cam lobe on an exhaust valve...
A wiped cam lobe will leave the rocker tight but it will only open it (if at all) just a little. Thats why he should check them for even movment... These are thing I have had happen to me thats why I mentioned it, it's not to often I repeat what someone else as exprienced...
could be a lot of things wrong with it... could be a closed ex. valve is what took the head gasket??? you never know..
A wiped cam lobe will leave the rocker tight but it will only open it (if at all) just a little. Thats why he should check them for even movment... These are thing I have had happen to me thats why I mentioned it, it's not to often I repeat what someone else as exprienced...
could be a lot of things wrong with it... could be a closed ex. valve is what took the head gasket??? you never know..
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Had checked all rockers when tore it apart everything is fine put a 600 vac. sec with .73 jets works fine but now it hesitates when at idle then give it a rev it kind of stops then goes. Gas level is fine fuel filters clean runs smooth its just when I stop and then step on it it will hesitate. The compression test on those 2 cylinders were 30 and the others were 190 close to 200. Another thing the motor has 300k miles on it maybe more I think it was just time for the head gasket to go out. Everything looked good no cylinder was too scrathed up and pistons looked pretty good everything pretty clean Ive seen alot worse tearing apart chevy motors alot of gunk.