Chris 84TA

i need one rebuilt... and upgraded...

the stock lg4 carb just cant keep up with my new engine...

it is using tons of gas... about 4-6 mpg

the guys at the shop said it needed a rebuild...

any suggestions...


btw... my engine is:
355 cuin.
Vortec heads
9.7:1 compression
ZZ9 cam /w 1.6 RR
Performer Vortec Intake
1 5/8 headers

thanks,
Chris

laiky

good stock rebuild with richer secondary rods, remove all plugs and tune it on a gas analyzer

laiky

forgot my sig

84TAProject

Laiky is that under a CCC? Wow if it is. How does it run at cruise and part throttle? What do you have done in terms of metering rods/hangars? I may be getting a small roots blower soon, and will see how that runs under the CCC. Probably have the same or less air/fuel demands of your motor with that little blower up top. Did you open up the AV flap to allow more air in?

laiky

It runs OK, i just retuned it on an inspection machine ( 4 gas analyzer) and a snap-on scanner. It has some problems, but far less than i ever thought i would have. The most annoying problem i have is dieseling, it happens occasionally but i can't seem to nail it down. Every time i make an adjustment it goes away for a week or so then comes back. Now i just let the clutch out in gear as i'm shutting it down. The second problem is an occasional tendency to not Idle, this happens mostly when its very moist or raining out, i remember having this problem long before i put the 383 in. It doesn't "cut out" it just idles down to nothing, i restart it once or twice and then its gone, runs fine again. Other than that it seems to run really great, the idle needs to be a tad higher than stock, arounf 900 rpm. I havent tried to really richen up the idle yet. Last week i got fed up with the surging idle, and i was getting acheck engine light so i went over to the shop i used to work at, put it on the scanner and inspection machine. i found it was very rich at cruise ( rich exhaust error code ) and way lean at idle. So i readjusted it, and its much better now. In my case i believe my carb is suspect, i have had drivability problems with the stock 305 , so i am reluctant to blame the new motor.

What you should do IMHO:

complete by the book stock rebuild
knock out ALL of the adjustment plugs.
Base line the adjustments according to the book
get a selection of richer secondary metering rods

You must read the factory manual section on tuning the ccc until it makes real sense to you. Its confusing but once you get some experience doing it the right way its not so hard.

You will need a way of reading some outputs from the computer, this can be done with a voltmeter and a dwell meter, a piece of software called winaldl (free) another piece of software i forget the name of ( expensive), Or a diagnostic scanner.

Adjust the carb as prescribed by the factory manual until you get the reccomended readings. Your cam is designed to be computer friendly, it had a wide lobe center and reasonable intake duration so it shouldn't give you a lot of computer related problems.

On the secondary side:

file the stop for the airvalve to get the full 90 deg opening. start with a richer secondary rod ( my car won't accellerate with the stock secondary rods) and go from there. Resist the temptation to loosen the airvalve until everything else is right. It will just confuse the tuning process.

If there is any more help i can give you just PM me