Carb question

W

Wageslave

G-Body Guru
Jan 25, 2017
731
482
63
#1
I have a 4.3 V6 with an ebay Rochester 2GC carb on top. For the most part it runs quite well. It has good idle characteristics and has decent power at full throttle.

The problem that it seems to have is when I am at moderately low RPM in high gear (using engines torque more than HP), and am slowly accelerating, the engine will occasionally pop through the carb and then immediately start pulling again like nothing happened. If I give it a little more gas after this happens the power starts to drop off until the RPM comes up a little, then it accelerates like normal.

It almost acts like it is going lean during this time, but this carb should have came jetted too rich if anything (supposedly calibrated for 350). I have also wondered if there may be too much vacuum advance, but I would have thought I would have seen signs of knock if that was the case. The underhood temperatures are fairly cool and I don't have any hot restart issues, so I don't think vapor lock is an issue.

What do you guys think?
 
olds307 and 403

olds307 and 403

Comic Book Super Hero
Oct 14, 2008
3,396
784
113
Melville,Saskatchewan
#2
What are you running for timing? It does sound lean, but could be retarded timing.
 
W

Wageslave

G-Body Guru
Jan 25, 2017
731
482
63
#3
Somewhere around 8 degrees BTDC or so. This engine did not have a degreed timing tab, just a zero pointer, since it was meant to be set at 0 with the computer, so it was a bit of a guess.

It starts pinging if I advance it too much farther, but part of that may be too much total timing from that ebay distributor.
 
olds307 and 403

olds307 and 403

Comic Book Super Hero
Oct 14, 2008
3,396
784
113
Melville,Saskatchewan
#4
That sounds like it might be close, a dial back timing light should work with that pointer.
 
fleming442

fleming442

Comic Book Super Hero
Dec 26, 2013
3,627
1,654
113
#5
that ebay distributor.
I'd start here. My neighbor's Astro van had something screwy happen with the dist. once, and I can't remember what it was. I do know that we couldn't fix it, and had to seek professional help. It sounds like the timing is all over the place if it's backfiring then pinging. Maybe the pickup is bad?
 
W

Wageslave

G-Body Guru
Jan 25, 2017
731
482
63
#6
I think I may have found the problem. I was plugging the port for the air choke and when I pushed on the carb, the whole thing shifted on the base plate and idled down.

Chinesium for the win. I guess I will be taking that thing apart and loctiting everything.
 

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