69 GMC C-15

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TravisB

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Mine had the stone filter in the carb (Q-jet), and metal filter between fuel pump and carb on front of block next to water pump. About the random miss, assuming this is stock distributor, have you checked the dwell on the points? Can also be caused by weak condenser. Alot of my old running issues like random lean/rich went away with a new set of points/condenser.
Still on the stock dizzy and I have not checked the dwell. I replaced the points and condensor in 2011 maybe. That could be my issue but it's not had 3k miles put on it in that time. After the carb rebuild and it was still doing it I started to think it might be in the spark side of things too.
 

DoubleDingo

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Have you thought about converting to HEI? It's easy.
 

TravisB

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Well I still haven't found the problem but it does have a real hesitation if you whack the throttle open real fast. Revs good if you roll into it though. Probably need to check my plugs after the super rich conditions from the flooding before. Also found my new filter gasket leaks but the old one is still good. So much for new things...

Dwell angle:
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Upside down Rpm: 850
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Vacuum:
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TravisB

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Maybe these links will work.

Timing is around 5-6 degree advanced at idle. Interestingly with the vacuum advanced connected or not it didn't really change.

https://photos.app.goo.gl/FY3kbniygnB5zkmQ7

This what happens when you whack it open fast.

https://photos.app.goo.gl/A1BH2ePaHdgueczy6

Listened to the second one this morning... wow I had the dog upset. Sorry about that yipping in the video. He's got this urge to bark at me every time I try to drive away so I guess he was just using this as ample opportunity.
 
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75Monza

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TravisB

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Maybe these links will work.

Timing is around 5-6 degree advanced at idle. Interestingly with the vacuum advanced connected or not it didn't really change.

https://photos.app.goo.gl/FY3kbniygnB5zkmQ7

This what happens when you whack it open fast.

https://photos.app.goo.gl/A1BH2ePaHdgueczy6

Listened to the second one this morning... wow I had the dog upset. Sorry about that yipping in the video. He's got this urge to bark at me every time I try to drive away so I guess he was just using this as ample opportunity.
Alright guys watch that second video and tell me what I've done here. I think it's worse than before. It starts great cold. But after the choke turns off it starts flooding like the float has stuck. So bad it can die. You can hear the bowl drain into the intake. Give it a few and it'll start right up and run like what it does in the video. Drives and stuff but if you hit the throttle too quick it chokes and spits.
 

TravisB

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I've got a feeling my new accelerator pump is bad and it's going to have to come back off in favor of the old one.

I have a weird cold start flooding problem too I need to figure out. Once it's warm it does alright if you can live without that pump shot on punching it.
 

TravisB

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Alright after dreaming about this one all night I decided to climb under the hood this morning and see if the pump would trigger a stream of fuel and it doesn't. So that is my issue, or the float bowl got empty overnight and there was nothing to squirt. Either way, I took it back off and will see if we can find another problem.
 

TravisB

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Well the problem is revealed. Not sure if I did that or my new part was garbage. Looks we'll be trying the 50 year old accelerator pump this weekend. Now to find out why the float is sticking occasionally...
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75Monza

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I would probably take it of and tear it down again, checking every little thing. When I strip a carb down to nothing, after cleaning I check every port using my small rubber cone nozzle air gun and seeing how much air comes out the other side. Sometimes I've had build-up down a port that just will not come out very well, I bought an assortment of longer sewing needles a long time ago and use them to scrape out anything that soaking for a day didn't get. That site where you found the videos, Mike's carburetor parts, has got a ton of info in there. Assuming yours is the brass float, shake it and make sure you don't hear sloshing. I've had to repair a pin hole on a float before because a seam started to come apart after cleaning. Another thing that can mess you up is check balls and the springs behind them. I like to check the ball diameter with a mic and compare before I drop one in, you can do the same with the accelerator pump if you have and inside bore gauge. Most carb kits nowdays are not the greatest at sticking to spec since they are trying to make a universal kit most of the time.
 

TravisB

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Been quite a while since I made an update to this one. I have been driving this truck pretty regularly since I got the carb mostly lined out. I still have a little part throttle miss that I haven't been able to sort out but we went on a 350 mile trip in October with the local cruise group to see a bunch of covered bridges in KY.


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TravisB

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Truck Model
C10
Engine Size
350
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