Hey guys, just picked up my new DD. Its an 88 RS, L03 (originally 305 TBI) car. Its got a Holley 4 BBL, when i pickerd it up last week it ran fine, no problems at all. Drove it 15 miles home and it was fine for the next couple of days. The morning i left to get back to SC (from Florida) the trouble started. After about and hour or so of trying to get it started she finally fired. Eversince sunday its been acting werid. Anytime i go to put it in reverse or driver she just dies right out. This happened a couple of times on I-95 too, and that sh*ts scared me! Its like when she isn't getting enough throttle the car just shuts off. I mean i know this things been jerry-rigged as far a the TV cable and all but the first 2 or 3 days driving it was perfect. Now i did the one and only thing i could think of first hand, changed the fuel filter. But same manorisms when put in gear. A supervisor of mine told me to let the car idle and take off the vacuum advance on the pass/side. He said when i pulled it off i shouldn't feel any vacuum, but when i throttle it up i should feel (with finger/thumb) some vacuum. Well i did that just now. I slowly pulled off the vauum advance off the carb and she just died right there. So I guess(ands PLEASE correct me if im wrong) thats telling me that in park/neutral the vacuum advance is working, when it should only be working when shes in gear. So can you guys tell me what my next step would be? Im very interested in carbs (kinda why i snatched this one up as opposed to any ole 2.8/3.1 MFI f-car) but really don't know whole lot if anything about'em. Any help/tips/advice is VERY VERY much appreciated! Thanks!!

 

Well I hope to give you some thoughts...as little as i may know... as silly as it sounds one of the first things i would look into is how the fuel mix is... make sure it is not to lean or rich. You would be able to tell using a good clean set off spark plugs and running it with them... refer to a manual that has the spark plug reading guides.. if you dont have one then just google it it will come up in the images. Second make sure that the idle circut is operating correctly. If you happen to know any old school mechanics they would be able to help you out. The carbe me be due for a rebuild. The best suggestion i can make is to buy a book on holley carbs... That should be able help you understand it better... There not that bad once you get to understand them.

Hope this helps

 

Thanks man. Yeah my dad (not mechaniclly inclined at ALL) mentioned that it just may need a rebuild. I got a buddy in shop whose got some extra Edelbrock 650s he's willing to let me use and stuff. I dunno i always heard Holleys and Q-jets when tunned properly can be BADASS carbs. I really wanna get my feet wet with carbs, they intrigue the hell outta me..

 

Not completely positive... but a few things to check are the TCC solenoid ( maybe on this car ) or something with the converter clutch wiring. It could be locking up in gear and killing the car.. but some other things since its jerry rigged is little things like the distributor/ timing.. maybe not tightened down.. might want to do a compression/ leakdown test on the cylinders since it might lead to some internal problems like worn out parts and possible leakage from a head gasket.. and of course check and make sure fuel filter is new/clean and that there is some fuel pressure not just volume.
Just start with obvious items first and yes buy books.. and magazines those can help you with tuning more than anything.

 

I'm no carb expert by far, but I have been learning and heavily researching ever since I bought an edelbrock setup in December, and since, recently swapped it for a 750 holley because...well...that's a discussion for another thread. From what I have found and worked with myself, I suggest the following:

I would start simple. You'd be surprised how many people jump the gun and buy an entirely new ignition system, or something of the like just to find out they have a bad ground, or a $5.00 plug wire that has burnt through against a header. Take baby steps and get a baseline of all your figures here...there is no telling what the previous owner did to this car and you want to make sure all your simple, yet crucial elements are all working in conjunction with one another.

-Timing (get a timing light, and make sure you pull off the vacuum advance to the distributor and cap off the port on the carb). This will tell you your initial idle. What setup do you have? You may need to raise or lower your timing depending on this. (I'm assuming you know how to check for this...if not, just ask)

-Vacuum - Get a vacuum gauge from autozone for like $20. Hook it up to the manifold vacuum port on the carb, and see what number you are pulling at idle. You are looking at high teens for a stock/mild cam, mid-low teens for a semi/decently aggressive cam, and low teens to single digits for a huge/race cam. Vacuum leaks can give you all sorts of problems. If you find you have low vacuum, bust out the can of carb cleaner and while the car is idling in park, spray it on vacuum hoses, fittings, manifold where it meets the carb/heads/block. If you hear the idle raise, you found your leak. Seal it off as needed. Just dont spray it INTO the carburetor as this defeats the purpose...but I think that goes without saying.

-Approximation on rich/lean according to camarokracker's advice. You may be in need of richening or leaning out your carb, although I think the main focus here would be on setting the idle screws, as the main and secondary jetting wouldn't affect idle as much as the idle mixture would. (at least this is what i found on my old edelbrock, correct me if I am wrong with holley's.) But fresh plugs will give you an indication of your air/fuel ratio at idle, so get a new set, idle for some time as you do your other checks for timing and vacuum, and then check them. You should be able to get a reading then. (besides, you probably could use a new set anyhow, haha)

Now, I have yet to do this myself, but I've been reading up on it, and members have been telling me to get this done to address an off idle bog of mine. With your vacuum gauge hooked to the manifold port, you want to adjust both of your idle mixture screws for maximum vacuum. This is commonly maladjusted with people who don't know much about carbs and thinking they are richening their mixture for performance (when in reality the idle mixture means squat for performance, and only has to do with smoothness in transition from the idle circuit to the cruise circuit, and the rich/lean condition at idle.)

Refer this article to see how it's done http://www.chevyhiperformance.com/howto/45638/

And also, I am surprised noone has inquired yet, but what is the rpm the car idles at now? If it is too low, it could be juuuuust on the edge of stalling in park, and when you get that rpm drop when shifting into R or D, it goes under that stall point and stalls. You may only simply have to raise the idle screw a turn or two. But if it is already idling at a healthy RPM, then this wouldn't help much. Not sure that this is your case, as you said you had that hard starting issue, indicating a fuel problem. But it is easy to diagnose nonetheless and should not be overlooked. Oh do this too, at idle, see if there is any play in the throttle lever at idle. What I mean is jiggle it enough to where you can see if theres play, and not so much that you actually open the throttle blades. Initially on my holley, I would let off the gas and the car would idle higher. I checked and found that the throttle cable was just barely too tight, only letting the throttle lever to go fully back to rest half of the time. Again, simple check, couldn't hurt. Make sure all is well in the throttle cable/travel department.


Get some of those figures, and get back to us. Also, make sure you tell us what setup it is that you are running. Changes in heads and cam can shed new light into the subject.

 

Thanks guys for all the advice! 2 good buddies of mine and myself worked on her for about 3.5 hours tonight. We "set" the timing and put all new mechanical weights in. She still dies out under a load unless we set the idle at like 1800 RPM! And even then sometimes dies out. But i got her on base in the shop parking lot. Tomorrow we're gunna go during lunch and bring one of the shop supervisors and have him take alook at it, the guys a REAL bow-tie freat and knows everything SBC, GEN II and GEN IIIs so I know with 4 of us out there we'll solve the prob. i hope

 

Wow, 1800rpm is pretty high. I'm thinking since it is in shoddy shape, maybe the carb is in need of a good cleaning? Might have some dirt and whatnot stuck in the jets or nozzles. I have seen people on this forum with problems that were alleviated thanks to some carb cleaner.

You guys will get it, especially with the supervisor taking a look.

 

Finally got her figured out. So basically the problkem was that with 2 PCVs fitted to a y-connector running to the carb was robbing the engine of vacuum. Put a new cap, rotor, plugs wires, and new mechanical advance spring kit in there too. base timing is set at like 10* advance. I were able to turn the idle down too. when shes in gear her RPM is kinda low but in park it goes back up some to about 1k. So i gotta friend of mine who's gunna sell me one of his edelbrock 650 cfm carms and an edelbrock intake for it. Shes only stalled out on me once since yesterday when we got her all good and timmed and i believe its more on the fuel/carb side of things. Who knows when that holley thats on it now was rebuilt so i'll prolly just buy a rebuild kit of this edelbrock and rebuild and slap that intake on and change out the stock located TBI fuel filter and do my oil change and call her good. The only other thing i need to do is take the oil pressure sending unit around back of the intake and tape up the threads.(when my friend was setting the timmin yesterday i think he may have bumped the sending unit loose) I tried to swing it back to tighten it down but it hitsan intake stud so i'll address that issue tomorrow(should do the WP on it too) Gotta admit she impressed me yesterday and even layed alittle rubber down (ole' one wheel peel) too, even with 2.73s!! Rockin out the L03 DD like whoa! Thanks for all the advice and tips guys!

 

Again guys Thanx for all the help and suggestions!! This week I put on a edelbrock performer intake, 600 cfm carb and one of those 360* edelbrock air cleaners. A good buddy of mine had some leftover parts from his Formula that didn't go on his forged 355 '92 Z28 so he hooked me up. Anywho just for sh*ts and giggles im gunna buy a rebuild kit for the holley that was on it and rebuild it (kinda use it as a training aid if you will). All i gotta do now is spend some time making the battery/ignition wire to the distributor more stable on the underside of the cap and she'll be good, then its on the my gauge cluster and little interior things. After all that comes exterior cosmetics...