Lack of carb/tuning exp talking
 

I dont know that this is a problem as such, but another thread prompted me to ask:
On my car, when cranked, the car idles at about 1500, and then drops to 900-1k when dropped into gear (sometimes causing stalling if the car isnt warmed up enough).
I know this shouldnt be normal, and I know the carb is probibly in need of a rebuild, just from looking at it. Are there any simple things a carb novice can do to smooth things out? (I am already planning of ordering a petronix ignitor and coil once the money situations better, but any other tips would be appreciated, ie changing timing/ playing with the current setup etc)
BTW, what should the car be idling at given its current state? I wanna say 900, but I might be wrong. Also, would that be for P/N, or in gear(its never specified,so I decided to ask):rolleyes:
Thanks,

J

800-600
 

Mine idles at 800 in neutral and drops to 600 in gear when tuned correctly. That's with a CC 268 HE cam and 9.5/1 TFTW heads, Performer intake and 625 Road Demon. That's after it's warmed up though.

Rev

Anyone have a guesstimate as to where mine should be idling given the noted mods?
I think it needs a tune up anyway, but it seems like its been stumbling/hesitating a lot more recently, (Tune up coming this weekend, and a Petronix and coil on order, hopefully next week), I'm hoping the previously mentioned will help, but I'm thinking that the carb may need a rebuild/tuning.
Can anyone recommend a good primer/manuel for tuning carbs? I know the principals, but have little hands on expierence. I know Holleys got a "big carb book" and am thinking about getting it, but if theres anything else out there I should read, I'd love to hear about it.

Thanks,
J

Holley red book
 

Holley also has a little red book, not very expensive , I think.

Rev

You're idle is dropping when in gear because of the load of the engine. If it stalls , let it warm up fully, if it still stalls you'll have to bump up the idle some. Without knowing what kind of cam you're running it's hard to reccomend timing numbers. If it's stock or close to it somewhere around 6* BTDC should be ok.
That little red Holley book is a must read. But it does only cover 4150 and 4160 models. So if you have a different model it will be know good. If so try "Holley carburetors,manifolds&fuel injection" It covers alot more carbs and has more tips. It sounds like your carb just needs to be "dialed-in" and not rebuilt. Good luck

Thanks for the info folks, I'll be checking out those holly books. I believe mines a 4160, but I'd have to double check to be sure.

J

you might also check for vacum leaks and timing.. a 500-600RPM drop isnt normal..

too high
 

At 1500 in park, the torque convertor is engaged too much. That may be why it drops 600 when put in gear. The idle is too high anyway. Will the car not idle any lower? Seems to me there's a vacuum leak or the idle mixture is too lean for some reason. With the butter flies open that much. the engine is into the "intermediate portion of the idle slot" and may even be drawing from the main jets.

Rev

I'll answer waht I know so far:
Dark Knight: I do need to check the timing, but I have to get a decent t-gun first (most likely next paycheck, the one I have is for crap)
As far as vacume leak, for all intents and purposes, the car doesent have a vac tube system. The dist. is capped, and there are no other vac tubes on the engine.

Rev: As far as turning the idle down, I havent tried screwing with it without some info to refer to, like I said, I'm kinda paranoid about playing with it at this point due to lack of exp. (I know how to, but the only carbs I've played with were quadrajunks, years ago, and I'm just not feelin' that frisky without more info)
The car seems lean on several cylinders according to the plugs, but seems rich when I get on the gas (lots of smoke at warmup and WOT,unless I'm reading it wrong*quite possible*)
As for the carb, its a Holley 4160 (aka model 7154) that looks about older than dirt, hence my rebuild question. BTW, can someone define the difference between various Holley part numbers vs. carb numbers? Same general design but different years?
Is there any way to look up the specifics of my model?

Can anyone tell me more about this particular model, and would I maybe be better off shopping for a newer/more advanced one?

Thanks again,

J

*edit to previous post: The car does have a vacum lead off the back of the manifold, but its tied to the brake booster.

I'm starting to wonder if the problem really lies with the carb or maybe something else. I added a while new spark system over the last week or so, new ignitor, coil, cap/rotor, plugs, and wires. The car ran great for about a day and a half, and is now back to stumbling, stuttering and new to the mix, slight backfiring.

With the car in P, the idle will be at about 1500, with "twitches"upward of about 100 rpm according to the tach, several to a second. These are accompanied by a popping in the exaust up near the engine, almost like a baby backfire.

As you try to accelerate, the car is stumbling badly until the rpm get up to about 2k-3k, then it seems to smooth out. Same with slowing down, once the RPM gets low, the car starts to bog and stumble again.Also, up to about 3k, there seems to be a reedy quality to the way its running, with surges and weak spots.
When I pulled the plugs this weekend, there was oil on the threads of 1 or 2 plugs. I'm starting to wonder if I should dig out the gauge and check the compression.
I dont know if this could be maybe a combination of things or what, but any help is appreciated.

J

*addendum* The g/f just informed me that while driving the car (10 minutes ago), the car got up to about 50-55, and she heard a small pop, and the car blew a large black cloud out of the tailpipe. Running rich? Like I said previously, there was a bit of carbon on the plugs, but it wasnt a heavy crust. At this point I dont know which way to jump with this... :confused: