engine pops thru carb

gzminiz · Mar 27, 2006

I wouldn't say it was lean rather fuel not combusting. Check plugs and wires. I had a friend this weekend with a 89 cavalier that was having the same issue. Pulled the plugs and the terminals were corroded and the plugs where horrible. Replace those and the plugs and no more problems. Check the current gap, over time it will get farther away and could cause the spark not to jump.

Hack · Mar 27, 2006

gzminiz said:
I wouldn't say it was lean rather fuel not combusting. Check plugs and wires. I had a friend this weekend with a 89 cavalier that was having the same issue. Pulled the plugs and the terminals were corroded and the plugs where horrible. Replace those and the plugs and no more problems. Check the current gap, over time it will get farther away and could cause the spark not to jump.

Thank you for the info. The plugs, cap, rotor and wires are new on this one, though.

YesDear · Mar 27, 2006

This may be a stupid question, but did you remove the vacume line from the distributor when you timed it? If not, your timing could be retarded enough to pop.

Hack · Mar 28, 2006

Yes said:
This may be a stupid question, but did you remove the vacume line from the distributor when you timed it? If not, your timing could be retarded enough to pop.

Yes we did.

One thing my buddy noticed yesterday is that the Holley carb instructions say to connect the vac advance to ported vacuuum. Right now it's connected to manifold vacuum. We're hoping that might do it.

D.Hearne · Mar 28, 2006

I always connect the distributor advance to ported vacuum.

Hack · Mar 30, 2006

Update:
Well my friend moved the vacuum line over to the ported connection. The engine still pops and bogs. He wants to make the adjustment to the accelerator pump, but he isn't sure how. I lent him my books on it, but everything says, "adjust it" but not how.

I haven't been back to his house to see if I could figure it out. Odds are if he can't I won't be sure either. I'm sure if either of us had seen it done, we could do it. There are things we could try, but we'd prefer to do it correctly the first time rather than mess up the carb worse than it already is.

Any hints? Pictures would sure help! Do you bend the arm that rides on the plastic cam? Do you bend something else? Is there a way to adjust the location of the cam?

Thanks!

badazz68stang · Mar 30, 2006

it very well could be a lean pop, but i would check the firing order because i had the same problem, pop thru the carb under a quick accelerator romp and i had the 7 and 8 wires crossed. 289/302 15426378 i think

ttoney · Mar 30, 2006

Mine was doing the really bad when the Gas tank was full of rust and other nasty crud. As soon as I put in a new tank and ensured good flow, it was all better. Check out fuel flow all the way through the carb.

Hack · Apr 1, 2006

Both of the last two posts are good thoughts. We aren't sure about the gas in the car. He put in a new filter, but there could still be some crummy gas in there.

My friend wired it to the modern HO firing order 13726548 (same as the Cleveland firing order) - we are assuming that it is the original engine.

He went to a local auto parts store and had them pull another Holley. He told me that the Holleys on the shelf had no slop in the accelerator pump linkage, and his does. So his wasn't adjusted from the factory. We both think that this is at least the next thing he should do, but we still aren't sure how it should be done.

If anyone could give details on how to adjust an accelerator pump, that would be great!

sixtynine Mach · Apr 1, 2006

This might seem lame (embarrassing because it happened to me) but the first time I installed a carb (Holley) I didn't put the spacer that goes between the carb and the manifold. Thought I didn't need it. Anyways, car started fine and idled fine but when I gave it gas to actually get the car moving it sputtered and backfired until the car picked up speed. Turns out that I had a vacuum leak. Even though the carb bolted on fine to the int. manifold, it had a slight overhang. Just enough to make my life miserable for a few weeks until we tracked it down. Anyways, just a thought. Good luck.

palerider94 · Apr 2, 2006

I just put a new holley and am having a similiar problem - everything I read so far leads me to believe it is running lean and need to change cam/shooter. Here is a couple links I found that seem to give some idea of what's going on -I'll probably call Holley on Monday and talk to thier tech guys - I'll let you what I find ou thanks

http://www.holley.com/data/Products/Technical/199R10321.pdf
http://www.fordmuscle.com/archives/1999/12/holley/index2.shtml

palerider94 · Apr 2, 2006

One more post on cam/shooters

http://home.hiwaay.net/~brewer69/stangholleytech.html

D.Hearne · Apr 2, 2006

Hack, check the vacuum advance on the distributor to see if it's functioning. I just played with my 68 Merc the other day and it had developed a popping too. Turned out the diaphram on the dist advance was busted. It would advance only as far as the centrifugal would go and no more, when you reached a certain rpm, the popping would start. Replaced the vacuum module and that cured it.

Hack · Apr 2, 2006

D.Hearne said:
Hack, check the vacuum advance on the distributor to see if it's functioning. I just played with my 68 Merc the other day and it had developed a popping too. Turned out the diaphram on the dist advance was busted. It would advance only as far as the centrifugal would go and no more, when you reached a certain rpm, the popping would start. Replaced the vacuum module and that cured it.

I think that the vacuum advance is working, because when you hook the vacuum advance up, timing goes to somewhere in the neighborhood of 30 degrees BTDC at idle.

Thanks for the information, everyone. The web sites really show the parts and the reasons why you might have to change them.

It's wierd, because none of the articles explain how to adjust the slack out of the linkage. Or is it just me?

Edit: I've been thinking that the engine idles too well to have a vacuum leak. About how many inches of vacuum should the engine have at idle? There's just a little shake to the engine at idle, which I attribute to weak compression in one of the cylinders.

palerider94 · Apr 2, 2006

Another post - this one is a tuning guide by Holley - pretty good. I'm learning more about carbs than I ever cared to.

http://www.holley.com/data/TechService/Technical/Carburetor Tech Info.pdf

Hack · Apr 2, 2006

palerider94 said:
Another post - this one is a tuning guide by Holley - pretty good. I'm learning more about carbs than I ever cared to.

http://www.holley.com/data/TechService/Technical/Carburetor Tech Info.pdf

Sweeet! That's perfect. Thanks!

engine pops thru carb

gzminiz

New Member

Hack

YesDear

New Member

Hack

D.Hearne

New Member

Hack

badazz68stang

New Member

ttoney

Member

Hack

sixtynine Mach

Member

palerider94

Member

palerider94

Member

D.Hearne

New Member

Hack

palerider94

Member

Hack

Similar threads

engine pops thru carb

New Member

New Member

New Member

New Member

Member

Member

Member

Member

New Member

Member

Similar threads

Privacy & Transparency

Privacy & Transparency