Any of you folks drive your car in the winter? It seems that the air affects the way the car runs. Cold and dry, cold and damp, warm and dry ect.ect.
I have a 350 with an rpm airgap, edelbrock 600, mild cam that's a little lopey. It also has an accel super coil.I was told that the motor was built to L-82 specs,(if that means anything) and best I can tell the timing is set to about 14 on the tab. I generally try to keep the timing just below the point where the starter drags when engaged.
I've adjusted timing, air fuel mixture and still it stumbles and spits when at low rpms or when I get on the gas after deceleration.
Any Idea's?
Thanks Mark

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72ss (clone)
Mark's Website (http://home.triad.rr.com/steelewebsite/chevelle.htm)

"If con is the opposite of pro, is Congress the opposite of progress?"

[This message has been edited by ss_72man (edited 11-18-2002).]

HiYa

I suspect a very lean condition all the way around. Increase your pump throw, change the rod's (richen) or next jet size (up) and go from that point. You can also look at the rod springs, orange is straight from the shop. One thing about the airgap is it takes a long time to get up to a decent temp range to properly mix the fuel. Good luck


Jim

Make sure the timing is advancing as engine speed increases. How cold are we talking about? Carb icing may be a problem if this is happening after the car has been driven a short time. Other than that, do as Jim says and try and enrichen it a bit.

Thanks Jim and Randy but.........
You guys are over my head with the metering rods and springs and carb icing and what not.
Not your fault of course , I'm not a motor head by any means.
I'd love to learn it though.
Jim made a point that I can relate to.
It takes this motor 10 minutes at 95 degrees (outside temp) to warm to 180.
And Randy, I have kept the timing light on it while bringing the rpm's up and it's working.(vacuum advance)If that's what you meant.
I have a limited knowledge of how an engine works but the small technical things are as foreign as chinese to me.
I've been thinking it may be the carb.
I could probably tackle a carb rebuild but I really don't know what I need (to make it richer or leaner) and don't know the "tricks" to taking them apart and putting them back together.(without messing up some small part or something)
Anyway, you've possibly confirmed my suspicion. I was thinking about getting on Edelbrocks web site and reading up on carb tuning.(but hell, I still don't know what the pump is, or metering rods, or any of the other parts are by just looking at them)
Anyway I'll keep you posted. I may try this soon if I can buy a kit or something to try.
Thanks guys, Mark

I just got off the phone with Edelbrock.
They are sending an owners manual with diagram.
Guess I'll try to tackle the rebuild/tuning when it gets here.
Thanks,
Mark

<BLOCKQUOTE>quote:</font><HR>Originally posted by ss_72man:
I just got off the phone with Edelbrock.
They are sending an owners manual with diagram.
Guess I'll try to tackle the rebuild/tuning when it gets here.
Thanks,
Mark<HR></BLOCKQUOTE>


You dont have to order one, the exact same manual is right on Edelbrocks website. Im surprised they didnt tell you that.

Hold off before tearing into that carb because it may not be a carb problem. Does it only do this when the engine is warm, or all the time? I couldn't tell from your initial post.

The distributor should have both vacuum and mechanical advance. It sounds like the mechanical advance is working properly from your description. But a pop back problem after deceleration could be the result of a bad vacuum advance chamber. You can check it by pulling the cap and attaching a hose to the can on the side of the distributor, and then applying vacuum to it. The base plate of the distributor should move. A hand held pump works best. You can pick those up at just about any parts store that sells tools.

Next, check for vacuum leaks. Do a good visual inspection of all the vacuum hoses on the engine. Make sure none are cracked or broken off their connections.

Only after you're positive the ignition system is functioning 100% should you go into the carb. It may something as simple as a bad accelerator pump.

But the icing issue needs to be addressed, especially in colder climates. The Airgap manifold would be especially susceptible to icing, judging from it's design. As air flows through the venturis of a carb, the pressure drops which causes a corresponding drop in the temperature of the air. That's just a property of physics. In cold climates, the air is colder to begin with. As the temperature of the incoming air drops, it reaches its dew point and even small mounts of moisture in the air can be deposited on the throttle blades of the carb and freeze. This has always been a problem with recip engine aircraft, and they have air ducts which duct warm air from a shroud around the exhaust manifold into the carb. What you need to do next time this problem occurs is pull over and stop the car, shut off the engine, open the hood and feel the carb body. If it feels especially cold, there may be ice forming on the blades of the throttle. With the engine off, pop the air cleaner lid and look down into the carb and see if there is ice on the throttle blades. (ENGINE OFF!!!!) Icing causes all sorts of weird problems, sputtering, popping back, loss of power, etc, and you want to eliminate it a possible cause. If this is a problem, you may need to call Edlebrock and see if there's a warm air kit you can install to prevent it.

But be sure and let us know exactly if this problem shows itself all the time, only when the engine is cold, or after the engine is warm.

[This message has been edited by Randy Mosier (edited 11-19-2002).]

Thanks for your responses.
Kinda funny but I got to looking really close at my "new" fuel lines that I installed
about 6 months ago. Cracked beyond belief.
I went and bought some fuel injection line(seems its a lot stronger)and replaced them.
I also noticed today that my fuel filter had a big bubble in it.(yeah it's one of those glass ones, but it was there when I bought the car)
Now it's full and it's running quite a bit better.
I re-adjusted the timing to about 14%(that's with the vac advance off and the hole in the carb plugged, right?) and adjusted a little on the air fuel mix.(I went 1/4 turns until it started to run good and stopped, right?)

The manager at one of the auto chains here said that with a carb spacer it might ice up.
I also installed a new cowl induction hood last summer. I've got the door up (until I buy the vac can to make it work)and I can see that the air cleaner sits right up in the hole.(May explain the cold air).
Again, thanks for the post and Randy I'll have to read yours a few times (to make it sink in).Oh and by the way, it was spitting and sputtering all the time. Only after it got warm it was a little better(but still a pain in the......)
Thanks ,
Mark

To set the idle mixture, turn the screws in untio the engine starts to stumble or idle rough, than back them out until you acheive the best idle.

Just make sure to check all the vacuum lines. Also, it wouldn't hurt to give it a once over with some Berryman's B-12 (an aerosol carb spray cleaner available at any parts store). With the engine idling and the tranny in park, spray the B-12 in short bursts around the hoses, the vacuum fittings, the intake to head mating surfaces, and the base of the carb. If you should notice a sudden increase in idle speed while doing this procedure, you probably have a vacuum leak in that area. Just take care not to let any of the overspray get sucked into the carb while doing this, because it can give you a false indication of a vacuum leak. (That's why I say spray in short bursts.)

Ummmm Randy. How important is the choke as to how the car runs once warm?
Today, just fooling around, I twisted the choke until it closed the front door on the carb just a little and the car started running really good.(as in when I gave it gas) I didn't think the choke worked at all, but I noticed that it would turn further than I previously thought.
The arm inside wasn't even touching the spring.
How do I adjust it to the proper setting?
Mark

Thanks folks for all your time and effort
Looks like all this stuff is on hold.
In the course of the day today, I have lost my brakes and the heater core has sprung a leak. Yes! In the last two hrs!(kinda funny, I just had the thing out about a month ago and I could still see the new stickers on it from when it was purchased about five years ago.)I pressure checked it then out of the car and thought it was still good. I am totally disgusted with the whole thing. Think I'll park it for a week or so and see how I feel.
I don't see how you folks do it.
It may be a cheap paint job and Ebay for this POS!
Thanks again ,Mark

The choke should be wide open when the engine is warm and should not be a factor in engine performance. As you closed the choke butterfly, the engine smoothed out? Is that correct? If so, it sounds like it's running lean. That's usually a quick way to check for vacuum leaks or a lean condition.

Look at all the hoses in the engine compartment. If you don't have a bad vacuum leak, then you will need to go in and see if there's a problem in the carb, or maybe richen it up some. At that point, you may need to locate someone in your area who is familiar with performance carbs and can set it up for you.

After all else that went wrong today I did check for leaks and found none.
It does run better with the front door about half closed so there is something goofy, I suppose.
I'm gonna park it for a while, kinda thinkin about getting rid of it.
I've got some other things to fix before then.
Thanks for your time.
mark