versized carb, or badly tuned?
 

I bought this 85 GS yesterday for a GREAT deal. I was told the only thing wrong was a snapped throttle cable. Check it out, and when I get there, I noticed it already had a holley carb, RB manifold, and full true dual RB exhaust. SWEET... And some other choice upgrades I keep finding...The guy didn't have a battery so i never even tried to start it. I figure, at this price, I'm taking it no matter what...

So today I fix the throttle cable and change the plugs, then do a few other precautionary things to make sure I don't ruin it on the first start up. Including spraying a bit of carb cleaner into the carb before start up. I have no idea how long it's been since it's been cranked over... Turn the key, it starts right up runs for a few seconds then dies. Try to restart, no go. Spray some more carb cleaner, boom... cranks up just fine. I continue to spray a bit of carb cleaner before each time I start it or it will not start up. So I turn the idle screw so the carb is a bit more open for start up, it cranks up and holds idle clean at 2500 for a little while then starts to die out as I am turning the idle screw down. I do this a few times and every now and again, I try to throttle it (all of this done standing over the engine, not with the gas pedal) it I throttle it really soft, it will rev up smoothly. But i have to do it very slow. if I just try and throttle it, it just bogs and wants to die.

It never stayed running on it's on more than one minute. And it will only start if I spray some carb clean before hand.

I do not know if it's a 600cfm or another size, The guy didn't even know what the racing beat manifold was called... So any guesses, to large of a carb, or badly tuned and need to be rebuilt? (by rebuilt, i mean the carb, not the motor)O

i am having the same problem and i am running a 600 so it might just be that your running to big of a carb. and is it a 12a or a 13b

its a 12a. I know a 465 is ideal, but i bought the car like this. One thing i noticed is It has a holley fuel pump and regulator also. I think it is flooding it badly...

The fuel pressure was close 7 psi. And I'm pretty sure a stock or street ported 12a with a holley will only need about 3-4 psi of fuel pressure.

yea lower it down to 3-4 psi and a 600 is a big carb for a 12a. Try ebay looking for a 465 and then sell the 600.

The psi is really a function of the carburator involved, not the engine its on.
Holleys normally run fine from 4 to 9 psi. If you look on the holley there are
probably some numbers that can let us ID the carb. Right now it sounds like
a lot of guessing.

So lets figure out the carb first and then determine what changes to make.
Take some pics and throw em up for us to see. I'm no Holley expert but I'm
sure someone will be able to help id the carb.

If its a 600, it can work on a stock port 12a but it will require some finesse
to get it usable.

Sounds like you got good deal on the car. Good luck with it.

numbers on the choke horn are 1850-4 and below that is 0266. So it is a 600cfm carb.

I'm going to get a rebuild kit for it today. Anything wrong with the Holley rebuild kits you can get at autozone (or similar store)?

Have you replaced the fuel filter? Could be dying after start due to starvation.




.

Ya to me that sounds like a fuel starvation issue. Check your fuel filter, and your actuall fuel flow through the carb. Might have a stuck needle valve or something. Rebuilding the carb isn't a bad idea either. A 600 holley is plenty big for a 12A that isn't heavily ported, but it should still start and run. If it was too rich, spraying the carb cleaner to get it started would make it worse rather than better.

I rebuilt the carb, but left the bowls as is. Gave everything a REALLY good cleaning. Then turned the pressure down to 6, as it was closer to 8 psi than anything. It runs pretty good now. Not perfect, but good for a large 600cfm on a stock 12a. I think there might be a small street port on the motor, but I am unsure... Kinda sucks when the previous owner knows nothing about there car.

I think I'll be switching to my webers anyway. I'll just mess around with the holley a bit more for the learning experience.

Messed with it a bit more. It has trouble starting when the engine is cold. but as soon as it warms up, it runs great and hold a clean idle. But while it's still cold, I have to hold the throttle above 1500 rpm for it to stay running or it will stumble and shut off.

I'm going to pick up a set of #56 jets tomorrow and see if that helps the cold starting problem. I have 64's in there right now...

Hmm, seems like if it were running rich then it would perform better when cold, and worse when warm. Isn't that basically what a choke does? Are you sure you're not moving the wrong direction by putting smaller jets in? Just a thought...

bump