73 stutter under part throttle
Thread Starter
2nd Gear
Joined: Mar 2015
Posts: 2
Likes: 0
73 stutter under part throttle
I've been working on a 73 corvette 350 4-speed the last few days. When i got it, full throttle did nothing but shake the crap out of you and It has a horrible miss under a load. I changed points, condenser, plugs, wires, cap, rotor, air filter, and fuel filter. I just rebuilt the carburetor and found that one of the tubes for the primaries had fallen out. I fixed that and finished the rebuild with no issues. However, after all of that, I drove the car and it has a miss under part throttle that kinda shakes the car a bit. It runs just about perfect at full throttle, but under light throttle it just doesn't feel right. Any suggestions from guys who have been doing this longer? Thanks!
Burning Brakes
Joined: Sep 2005
Posts: 1,050
Likes: 205
From: Lewes Delaware
Welcome to the forum and a few suggestions:
1) check your timing to make sure it is spec and is smooth from idle to 3500 (cruising) RPM
2) check for vacuum leaks on hoses, at carb and at distributor
3) check fuel pump pressure
4) check to make sure fuel filter is new and properly installed
5) check operation of accelerator cable at gas pedal and at carb. Make
sure it operates freely at idle thru WOT
6) check to make sure there is good spark at each plug at all RPM's
Others will chime in with more ideas. Let us know what you find. Also provide type of carb and any modifications from stock to help us with your problems.
Fran
1) check your timing to make sure it is spec and is smooth from idle to 3500 (cruising) RPM
2) check for vacuum leaks on hoses, at carb and at distributor
3) check fuel pump pressure
4) check to make sure fuel filter is new and properly installed
5) check operation of accelerator cable at gas pedal and at carb. Make
sure it operates freely at idle thru WOT
6) check to make sure there is good spark at each plug at all RPM's
Others will chime in with more ideas. Let us know what you find. Also provide type of carb and any modifications from stock to help us with your problems.
Fran
Thread Starter
2nd Gear
Joined: Mar 2015
Posts: 2
Likes: 0
Thanks! My timing is at 11* at idle with the vacuum line disconnected. The fuel filter is correct. I checked ever vacuum line in the engine bay and found nothing. The motor is a replacement from about 15 years ago. Was supposed to be a 370hp crate motor. But everything on the exterior of the motor looks stock. Doesn't seem to have a large cam but sound can be decieving. I will have to get back to you on the rest though.
Le Mans Master
Joined: Jul 2006
Posts: 8,117
Likes: 104
From: charlotte north carolina
This could be a "trailer hitching" problem that Lars has discussed recently. That is to say, there might be too much vacuum advance at light throttle cruise. Try disconnecting the vacuum advance to see if that solves the problem. If it does, have Lars send you one of his advance limiters that he posted about a few days ago.
