Thread: 350 running rich

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Originally Posted by 36 sedan

Jerry, I don't see where he raced or ran race fuel???
Am I missing it??

Post #19, 36 sedan, but it says specifically that a previous owner had run race gas in it (at some time in the past), not that it's running race gas now. Specifically,

Originally Posted by JD323

I should add that when he got the truck he said it ran great, but it started running poorly so he called me to work on it. He didn't drive it much, maybe 30 or 40 miles before it started acting up. He tried to get more information on the motor specs, but unfortunately had no luck. Since I've been working on it, it hasn't run good at all. When we took it for a ride, it would misfire horribly when getting on it at all. If you just put around with it, it seems to go alright, but as soon as you put anything into it it sputters and misfires something terrible. He said that one of the previous owners had raced it and ran race gas in it.

Thank you, totally missed it..

Originally Posted by JD323

I should add that when he got the truck he said it ran great, but it started running poorly so he called me to work on it. He didn't drive it much, maybe 30 or 40 miles before it started acting up. He tried to get more information on the motor specs, but unfortunately had no luck. Since I've been working on it, it hasn't run good at all. When we took it for a ride, it would misfire horribly when getting on it at all. If you just put around with it, it seems to go alright, but as soon as you put anything into it it sputters and misfires something terrible. He said that one of the previous owners had raced it and ran race gas in it.

For some reason I totally missed this and it changes everything!
So it ran good at this altitude?
Then it started running bad at this same altitude?
AND, it was raced on race fuel!!!

Not to sound mean, disrespectful or offensive but,
Have you performed a leak down test to know if there are any pistons and valves left in the motor?
Have you checked the rockers action to know if you have lobes left on the cam?

Sorry, but we need to take two maybe three steps back...

I apologize guys, I didn't see these posts until just now.

I did do a compression test on all but cylinders 6 and 8 because I couldn't get my compression tester in the hole with the headers on. I have the numbers written down at work, I'll post them when I get out there either later today or tomorrow. They weren't terrible, mid 120's if I remember correctly. I haven't checked the rockers at all yet because there's no valve train noise so I figured everything was fine there. I can definitely check them though the next time I go out there. It seemed like a carbeurator issue to me since it ran fine and then just started running rough out of the blue. I'm pretty sure he said he's only run premium fuel in it since he's gotten it but I'll ask to verify. We've run it out of gas a couple times now as the gas gauge doesn't work, so whatever old gas was in there should be all flushed out.

I'll pop the header off and do a complete compression test and check the valves.

No offense taken whatsoever!! Thank you for all the help so far, it's greatly appreciated!!

I was able to go work on the truck again today. Checked the valve adjustments and all seemed good to me, they were all just that the pushrod would spin, no slop in any of them. I also ran a complete compression test, the numbers are as follows:

1 - 130
3 - 120
5 - 130
7 - 125
2 - 125
4 - 130
6 - 130
8 - 125

The vacuum for the transmission was plugged into a t off of the brake booster, so I plugged the gauge in there. The numbers were definitely better! Still not making too much of a difference when turning the adjustment screws. The vacuum seemed to go down after an increase so I settled at 1/2 a turn out as that's where it seemed to be highest. I posted 2 videos, the first one is after about 7 or 8 minutes of running, the second is after maybe 15. It seemed to run pretty good in the beginning with clean plugs but the longer it ran the worse it got to the point of misfiring with any increase of the throttle as seen in video 2.

I didn't have time to mess with the jets or pv, so they're still the ones I put in last weekend.

Is there anywhere else that the carb could be leaking internally? The reason I ask is because the blue gaskets on the bowl and metering block almost seemed gummy/sticky like they're being dissolved by something?

https://youtu.be/P0DZCRpSkJ8

https://youtu.be/loKTfpLI-Xs

Originally Posted by DennyW

((I apologize guys, I didn't see these posts until just now.))
By the way, while you are u=on here for awhile, waiting on maybe a respnse, refresh the page before you leave to see if you have any replies...


((I haven't checked the rockers at all yet because there's no valve train noise so I figured everything was fine there.))
If the valves are adjusted to tight, you won't hear any noise...

Also, the main purpose of knowing the vacuum reading is to see if the right power valve is installed.

You must start at the basic checks, or you will just keep going in circles.

Thank you for the suggestions!!

Maybe now seeing a proper vacuum reading, the power valve isn't the proper one?

Sorry for the ignorance!! I haven't worked on a carbeurated engine in 20 years, and even then they were all Q-jets, I have zero experience with Holley carburetors.

Originally Posted by DennyW

Ok, Try this. With the vacuum gauge hooked up. Engine idling, Turn the distributor (advance timing) to get the highest steadiest reading. THEN, back down 2" vacuum.

I actually did slowly advance the distributor but there really wasn't much change on the gauge at all so I turned it back and left it. I will start there next weekend when I work on it again and report back.

Originally Posted by DennyW

Not a problem. I myself have worked on, and rebuilt all models all brands. Not bragging, but, just letting you know, I'm not to bad on carbs.\


Did you look at the link I posted on vacuum gauge readings?

I did, and the one I thought fit best was late valve timing, this is when I adjusted the distributor.

I do have a Facebook account that I use to shop the classifieds, I'll PM you my username.

The front seal is shot so the timing cover needs to come off anyway, I can definitely do that next weekend and check it out. I haven't looked at anything under the distributor cap other than to make sure the contacts were in good condition. I'll check that out too next time I'm there.

A quick check for timing chain:

Put a wrench on the harmonic balancer, while watching the dizzy button. If you can rock the crank back and forth and the button doesn't move, chain is slack.

Originally Posted by firebird77clone

A quick check for timing chain:

Put a wrench on the harmonic balancer, while watching the dizzy button. If you can rock the crank back and forth and the button doesn't move, chain is slack.

Thank you, I will try that!