Carb help!
Thread Starter
Instructor
Joined: Feb 2010
Posts: 166
Likes: 0
From: Corvallis Oregon
Carb help!
So, my car was idling way too low, and sometimes it will almost die unless I put on the gas. I tweaked with the tuning on the carb, got some almost instant increase in performance. Then, on my break at work, I decided to fiddle with it a little. It sounded better, but when I was driving later, as soon as I let off the gas, it would die. Furthermore, the transmission was being very erratic and would not upshift very easily (still have this problem). So I did a little googling, found a basepoint (two turns from totally closed), and have gotten it to run somewhat normally.. It takes a hell of a lot longer to warm up though, not sure why. It sounds like a couple of the cylinders might be missing, too.
So here are my questions:
First of all, is it possible to tune a carb without an RPM meter? (I don't have one, and the RPM gauge doesn't work either)
Secondly, does it make sense that the carb tuning would screw up the transmission? Especially since I'm just adjusting the idler screws.
Here are my specs:
1975 L48
350/165hp
Edelbrock performer RPM intake, Edelbrock carb (not sure which one, can't find any numbers on it) with manual choke.
Auto transmission
So here are my questions:
First of all, is it possible to tune a carb without an RPM meter? (I don't have one, and the RPM gauge doesn't work either)
Secondly, does it make sense that the carb tuning would screw up the transmission? Especially since I'm just adjusting the idler screws.
Here are my specs:
1975 L48
350/165hp
Edelbrock performer RPM intake, Edelbrock carb (not sure which one, can't find any numbers on it) with manual choke.
Auto transmission
Racer
Joined: Nov 2009
Posts: 384
Likes: 2
From: Tulsa OK
be sure your ignition is optimally tuned before blaming the carb.
Replace points/condensor, set dwell and timing (read the timing "sticky").
Be sure this is all correct first.
As has been said many times, most suspected carb problems are actually ignition problems.
Replace points/condensor, set dwell and timing (read the timing "sticky").
Be sure this is all correct first.
As has been said many times, most suspected carb problems are actually ignition problems.
Thread Starter
Instructor
Joined: Feb 2010
Posts: 166
Likes: 0
From: Corvallis Oregon
I think both might be right, if i'm not wrong, the auto tranny uses the vaccum right?
And I was thinking the non-firing cylinders were some sort of igniton issue. Especially since it seems to be intermittent.
And I was thinking the non-firing cylinders were some sort of igniton issue. Especially since it seems to be intermittent.
Melting Slicks
Joined: Sep 2004
Posts: 2,412
Likes: 3
Move your idle mixture screws out evenly till you pull the highest vacuum. Rent a vacuum guage from autozone and hook it up.
If you still have 165hp you need to get a high flow cat. Should put you closer to 200hp, easily.
If you still have 165hp you need to get a high flow cat. Should put you closer to 200hp, easily.
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
Your symptoms are rough idle, late tranny upshift, engine wants to die... classic symptoms of a vacuum leak. Check the tranny vacuum line, the modulator itself, vacuum fittings on the carb, and other vacuum lines connected to manifold vacuum. You're sucking air somewhere.
Lars
Lars
