sbc ,idle rpm what you guys running?

[RITTER]

When you change into gear it idles fine, but sometimes it will drop lower than 700 rpm and will stall out if it is cold.

If its doing it when its cold, the engine just needs to warm up a little more or you need to adjust your choke :idea:

 

[Kwik_Cutty88]

When you change into gear it idles fine, but sometimes it will drop lower than 700 rpm and will stall out if it is cold.

If its doing it when its cold, the engine just needs to warm up a little more or you need to adjust your choke :idea:

Yeah. It's just me getting used to having a carb'd car and letting it warm up. That's really only when it does it now, after a month of tuning.

 

[RITTER]

A carbureted engine likes to start to build a little temperature before they go into gear

 

[DoubleV]

A carbureted engine likes to start to build a little temperature before they go into gear

Not if it's tuned properly. :wink:

I can't speak too much for giant race cams that can barely idle in the best of conditions, but in a 'normal' cammed engine a properly tuned carb should be able to be put into gear immediately after a cold start and idle perfect ( albeit at a sleightly higher rpm than normal because the choke is on ).

Kwik, sounds like to me you have one or more of the following; a crappy carb, an incorrectly calibrated carb, an incorrectly tuned carb, and last but not least the mechanical advance on your distributor may be coming in too soon ( aka at idle speed ) as well. Also it sound like maybe your cam is bigger ( you said .513 intake .498 exh ) than what you may think. Big cams will always need more rpm to idle, but regardless you seem to have some issues that need to be addressed.

P.S. Why did your builder say you have to run 14* base timing? What is your TOTAL timing at and what rpm is it all in by?

 

[Kwik_Cutty88]

A carbureted engine likes to start to build a little temperature before they go into gear

Not if it's tuned properly. :wink:

I can't speak too much for giant race cams that can barely idle in the best of conditions, but in a 'normal' cammed engine a properly tuned carb should be able to be put into gear immediately after a cold start and idle perfect ( albeit at a sleightly higher rpm than normal because the choke is on ).

Kwik, sounds like to me you have one or more of the following; a crappy carb, an incorrectly calibrated carb, an incorrectly tuned carb, and last but not least the mechanical advance on your distributor may be coming in too soon ( aka at idle speed ) as well. Also it sound like maybe your cam is bigger ( you said .513 intake .498 exh ) than what you may think. Big cams will always need more rpm to idle, but regardless you seem to have some issues that need to be addressed.

P.S. Why did your builder say you have to run 14* base timing? What is your TOTAL timing at and what rpm is it all in by?

I think its a crappy carb. Or just needs to be tuned. I want to take it all apart clean it and do a jet kit. As far as the cam here is a link to the specs. http://www.compcams.com/Company/CC/cam- ... d=216&sb=0. And I am my engine builder, well along with my dad. He did the timing on it a few times to get it right, but I cant remeber what it is so I'll have to ask him.

*BTW Grandprixpaul, sorry for the thread highjjack! :|
AND BTW

 

[Doober]

That's not too much to be able to idle at 700-800 easily. I have a 350 that moves less air with almost as much cam (hint: look more at duration than lift to get an idea), and it's a pretty mild idle. It doesn't have a choke so I have to play with the gas until it's warm enough, but after that it will idle down almost to 500 before it starts to load up at all. I have a 600cfm manual choke Edelbrock that I got from the junkyard 12 years ago, and I've never opened it up... it could use a rebuild/tune for sure.

 

[LSCustoms]

The only thing a stall is going to affect at idle is keeping the car from lerching forward (if it has a large cam) Your car not idling at a "normal" idle speed is a different issue. Turning the idle up to keep the thing running is just masking the problem :|

Yes but like I said the stall converter isnt big enough so that when i am stationary the car will idle too low and stall. It usually only happens when I change from park into gear, hence me two-footing it (a little bit of brake and gas). Once I get like say a..2500 stall converter I can turn the idle down to a regular speed and I wont have to two-foot it.

r u sure your stock converter isnt broken, anyway i agree with some of what others have already said, so i will only add, that i think you should take the car down and have it dyno tuned to get the best results

 

[Kwik_Cutty88]

The only thing a stall is going to affect at idle is keeping the car from lerching forward (if it has a large cam) Your car not idling at a "normal" idle speed is a different issue. Turning the idle up to keep the thing running is just masking the problem :|

Yes but like I said the stall converter isnt big enough so that when i am stationary the car will idle too low and stall. It usually only happens when I change from park into gear, hence me two-footing it (a little bit of brake and gas). Once I get like say a..2500 stall converter I can turn the idle down to a regular speed and I wont have to two-foot it.

r u sure your stock converter isnt broken, anyway i agree with some of what others have already said, so i will only add, that i think you should take the car down and have it dyno tuned to get the best results

Nope the transmission is all good. We pulled the pan and converter and checked it before we dropped it in. And yeah I have been thinking about getting it dyno tuned, and my dad has some thing...it like an air fuel monitor. So I think I'm going to try and tune with that to see if it gets any better. But as of now it's running fine.

 

[gbondo57]

check for vac port leaks, like that big one on the back of the carb for pwr brakes.

 

[crotchss]

Also when you guys are setting your timing, are you unhooking the vacuum advance? and is it hooked to the timed port? I had a guy once that I built a engine for and it ran great on my break-in/test stand. Then he picked it up and put it in his car and said it had no power. I went to his house and pin pointed the problem right when I arrived, vacuum advance was hooked to the full-time port and he was setting it with the vacuum hooked up. So when he stepped on the throttle all the vacuum goes away as does the timing. After that simple fix the car ran and performed great. Sometimes you just have to check those little things.