1960 Carb problem?
I think I'm looking at a carb problem here and need some advise.
Background:
1960 283/230. Rebuilt to factory specs. GM restoration parts "stock" replacement cam (as close to original specs as you can get). New valve springs. Original Carter carb.
Fresh rebuild, started last weekend. Ran for 20 min 2000 to 2500 rpm for 20 min to break in cam. Brought down to idle, set timing to 4 BTDC with vac disconnected. So far so good........
Some observations at idle:
Exhaust pressure on pass side seems to be less then on the drivers side using my hand at the exhaust outlet as a gauge. Heat riser is wired open.
Every now and then you will hear a pop in the pass exhaust.
Try to drive the car and there is no power and consistant popping in the pass exhaust, plus some coughing through the carb.
At 900 RPM, idle mixture screws have very little effect.
The car smells like it is running rich. After the cam break in I looked at the plugs and they all looked good except cyl 8 which was black and wet.
Things I have done:
Verified all valves are adjusted per cam specs. 0 lash plus 1/2 turn.
Measured vacuum - steady at 20 in/hg at idle.
Verified base timing at 4 deg BTDC. I moved it up to 6 and 8 with no real difference. I need to take some measurements on the advance both mechanical and vacuum. The original balancer is not on the car as the rubber is not in good shape. A GM replacement balancer is on the car. Prior to installation I verified the timing mark was in the same position as the original with respect to the keyway.
Ran a compression test. All 8 cylinders are 155 to 160. Note: when I pulled the plugs all 4 on the pass side were wet with gas. The four on the drivers side were dry.
I have no experience with Carter carbs, but do have a fair amount of background with Quadrajets and Holleys. The carb was freshened up (by me) prior to installation on the car. All I did was replace the usual carb kit parts and set the float level. I have found evidence, by way of some notes, that the original owner was tinkering with the jetting. He makes mention about changing the metering rods and jet sizes. I need to go back and confirm his notes vs what is in the carb.
Bottom line, I'm usually pretty good at figuring these things out, but this one has me looking for some advise.
Sorry if the email seems scattered. I tried to give as much info possible.
Tom
Background:
1960 283/230. Rebuilt to factory specs. GM restoration parts "stock" replacement cam (as close to original specs as you can get). New valve springs. Original Carter carb.
Fresh rebuild, started last weekend. Ran for 20 min 2000 to 2500 rpm for 20 min to break in cam. Brought down to idle, set timing to 4 BTDC with vac disconnected. So far so good........
Some observations at idle:
Exhaust pressure on pass side seems to be less then on the drivers side using my hand at the exhaust outlet as a gauge. Heat riser is wired open.
Every now and then you will hear a pop in the pass exhaust.
Try to drive the car and there is no power and consistant popping in the pass exhaust, plus some coughing through the carb.
At 900 RPM, idle mixture screws have very little effect.
The car smells like it is running rich. After the cam break in I looked at the plugs and they all looked good except cyl 8 which was black and wet.
Things I have done:
Verified all valves are adjusted per cam specs. 0 lash plus 1/2 turn.
Measured vacuum - steady at 20 in/hg at idle.
Verified base timing at 4 deg BTDC. I moved it up to 6 and 8 with no real difference. I need to take some measurements on the advance both mechanical and vacuum. The original balancer is not on the car as the rubber is not in good shape. A GM replacement balancer is on the car. Prior to installation I verified the timing mark was in the same position as the original with respect to the keyway.
Ran a compression test. All 8 cylinders are 155 to 160. Note: when I pulled the plugs all 4 on the pass side were wet with gas. The four on the drivers side were dry.
I have no experience with Carter carbs, but do have a fair amount of background with Quadrajets and Holleys. The carb was freshened up (by me) prior to installation on the car. All I did was replace the usual carb kit parts and set the float level. I have found evidence, by way of some notes, that the original owner was tinkering with the jetting. He makes mention about changing the metering rods and jet sizes. I need to go back and confirm his notes vs what is in the carb.
Bottom line, I'm usually pretty good at figuring these things out, but this one has me looking for some advise.
Sorry if the email seems scattered. I tried to give as much info possible.
Tom