Sudden rough running, out of ideas

[alexiskai]

I've decided I'm just not going to try to repair a carburetor, the time/tool investment and risk of mistakes is just too high for me. I'm just gonna treat 'em like a single component to be repaired by someone else or swapped out.

I've installed the Bert's carb and made no changes other than checking where they had the idle screw set. Like I said I haven't started the car since then, but I'll report back when I do.

[Tom Endy]

Inspect the modern lower plate you installed. You are likely to find a burn arc where the contactor was rubbing the flat plate. The arc is caused every time you move the spark handle though its paces. The burn will eventually become severe enough to cause the car to run poorly.


Tom Endy

[30 Closed Cab PU]

Originally Posted by Jacksonlll

If the plugs are black and fuzzy, clean the, don't just look at them. I must assume that you did clean them.

Was looking for your U-tube videos - can't seem to find them can you post a link to them, please?


Thanks

[Ernie Vitucci]

Question for Tom Endy. Do you recommend the original distributor configuration or the modern upper and lower plate...Thanks, Ernie in Arizona

[Jw]

Plugged up muffler? Restricted muffler, engine cant breathe

[alexiskai]

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Originally Posted by Tom Endy

Inspect the modern lower plate you installed. You are likely to find a burn arc where the contactor was rubbing the flat plate. The arc is caused every time you move the spark handle though its paces. The burn will eventually become severe enough to cause the car to run poorly.

That's a good point. I don't think that'll happen with me because I installed the Nu-Rex modified distributor shaft that advances the spark, so I'm not moving the spark handle hardly at all. I can see how it might happen to others, though.

I wonder if you could mitigate that issue through the use of a conductive grease.

Originally Posted by Jw

Plugged up muffler?

Checked and eliminated that somewhere earlier in this topic.

[Tom Wesenberg]

Wireless top plates are a problem, and I'd never use one. They have poor contact, even if you have an advance and don't move the plate.

[30 Closed Cab PU]

Had Nurex wireless modern plates, worked ok for awhile. Then chased odd issues for a month. Went back to original plates (with pigtail and short proof original style condenser) with Brattons modified point block so points line up, all the odd issues went away.


Some of the issues - poor idle. Come to a stop and go up a hill (motor lugging some) motor missing - once over hill within a few hundred yards would clear up. Other things too.

[alexiskai]

The "wireless" aspect of the "modern" plates was not really a big attraction for me when I was choosing them. I wonder why that's such a common part of the design from different vendors if it's the source of so many problems. You'd think someone would try to occupy the market niche of "modern plates that are more reliable."

[30 Closed Cab PU]

The weakness with the original design is the "Pig Tail" wire connecting the upper and lower plates can break and open and also short to the plates and to the body. The constant movement of the upper plate when adjusting tteh Spark advance stresses the wire causing it to break.


The other weakness is the placement of the condenser so close to the exhaust manifold. Heat is the enemy of a condenser. This has been rectified somewhat for the original design by introduction of the short proof condenser and over all better quality of condensers these days .


Due to these two issues the after market came up with a "better idea" - move the condenser to to the upper plate where it is cooler, and get rid of the pigtail wire.


And after a while the A community has found that the wireless plates introduce their own issues, which are difficult to troubleshoot if you are not aware that the wireless plates suck. Intermittent connection, poor connections, and wear from the wireless contacts rubbing on the plate every time the spark advance is moved.


Since people still order/buy them so the vendors sell them.


I prefer the original design with the short proof condenser, original design points, and the Brattons modified point block. The modified point block is needed because the manufacturer of the points does not make them correctly anymore, and the contacts do not mate properly. The modified point block lines up teh contacts. This issue is only present if you go to the original design. I make it a yearly maintenance check to inspect the pigtail wire.

[alexiskai]

Sounds like if someone's already installed a modern upper plate and wireless lower plate, "retrofitting" the upper plate with a modified-pigtail lower plate such as Bratton's part #17270 might take care of the connection issue without requiring replacement of both plates and a return to the original condenser setup.

[30 Closed Cab PU]

Originally Posted by alexiskai

Sounds like if someone's already installed a modern upper plate and wireless lower plate, "retrofitting" the upper plate with a modified-pigtail lower plate such as Bratton's part #17270 might take care of the connection issue without requiring replacement of both plates and a return to the original condenser setup.

Hopefully you will get info from others, I cannot comment since I have no experience with that configuration of parts. The setup that I had problems with were the Nurex modern upper and lower plates and went back to the orginal design/setup.

[Stew]

My 31 was running rough. It began to really run badly after about five minutes. I initially swapped the distributer and carb with no change. I changed out the coil and it ran perfectly. Coils can be finicky as they heat up. Just a thought.

[jquinlan]

Originally Posted by Patrick L.

Spray the intake area to check for a leak

Patrick, what do you spray around the intake area and how does it display as bad? Just curious. Thanks

[alexiskai]

Finally got a chance to run the car with the Bert's carb for about ten minutes in the driveway, no road testing yet. It still stalls if you give it no throttle at all, but if you put the throttle lever on just a click or two it runs fine. Very smooth. Ran it up and down the driveway up to 2nd gear, seemed fine. I was able to close the GAV all the way once the engine was warm. I'll continue to noodle with the settings to see if I can get that idle speed down.

So to conclude, here are the repairs I ended up doing over the course of this investigation:

• Cleaned sparkplugs
• Re-torqued head
• Replaced upper and lower distributor plates, including condenser
• Replaced carburetor

Replacing the plates and condenser had the most significant effect regarding the original symptoms. After all this, it still stalls on idle, but I'm ready to move on to other projects and come back to it when I have fresh ideas.

[30 Closed Cab PU]

I recently installed a Bert's carb, same issue with stalling at quick stops. Instead of trying to get Bert's to send another carb I installed a set of Renner's Corner flow tested jets. Still not perfect, but tons better. Motor stills slows a little, but usually does not stall.


I know it is the Berts carb, swapped in another carb I have and issue disappeared. For now have set this carb aside, is good enough as a spare, but will be tackling it again this summer when I have time and have other things to do on my truck.


Also had an issue with a slight gas weep overnight, even with a known good fuel valve turned off. When I drained the carb bowl very little gas came out so knew the leak was not the float valve. Took all the easily removed jets out, put a minimal amount of non-permanent thread sealer on the jet threads, reassembled- issue solved.

[30 Closed Cab PU]

You did not mention if you adjusted/tuned the new Carb using the carb idle screw and Air mixture screw.

Not uncommon to have do this with a new carb.

[dansluck]

This happened to me in Reno. All of a sudden car started running rough. I checked the electrical ,like you did. Tank was at 1/4 so I bought Clear Gas and drove home. Water in fuel was my problem. Good Luck (think simple it usually is when you find it)

[alexiskai]

Originally Posted by 30 Closed Cab PU

You did not mention if you adjusted/tuned the new Carb using the carb idle screw and Air mixture screw.

Not uncommon to have do this with a new carb.

I did noodle with the idle screw and the GAV, but none of my adjustments seemed to make a difference. Keep in mind this issue existed with the old carb too. The Bert's carbs are road-tested before shipping, so I think most likely the problem is something "carb-adjacent," e.g., poor fuel flow at idle, very small leak in the intake manifold, etc. I'll keep poking at it.

[DDeeD]

I had the same things recently on a good running '15. I did the electrical/mechanical things you did. Finally the car would not start at all......it was out of gas.