Engine: Running Rough

[cloudy]

I started a 1951 Commander V-8 that has been garaged for over 15 years, the car is in great shape but runs rough. I replaced plugs, points, set the timing and put new gas but still running rough, it has to heat up before even thinking about idling, I adjusted the carburetor the best I no how there is no backfiring but still running very rough. Can anyone tell me what I should be checking or can anyone recommend a good mechanic in the Mass. RI area?

[jclary]

Check your vacuum advance diaphragm on the distributor. If it has deteriorated after all these years, it will cause an intake air mixture leak just like any other manifold leak. There are other things to check for such a vacuum leak, like carb gaskets, manifold, etc.

[5brown1]

Add Seafoam to the gas it will help clean things up like the carburetor which probably needs a good cleaning and a kit. Put a vacuum gauge on it to see it there are leaks.

[Mike Van Veghten]

1. Many small passages inside the carburetor, both gas and air. Anyone could be plugged or "partially" plugged. Clogged/partially plugged air bleeds will cause idle roughness.
Carbuetor / fuel injector cleaners, "Sea Foam", et-al, will NOT clean air bleeds..! And may take a while to clean the smallest gas passages.
Only a proper, take it apart and "soak it" cleaning, will clean everything.

2. When was the last time (miles wise), were the valves adjusted ? Tight valves will cause the low engine speed/idle roughness.

Mike

[mbstude]

Can anyone tell me what I should be checking or can anyone recommend a good mechanic in the Mass. RI area?

Bob Munter at WCD Garage. One of the best Studebaker shops around. https://www.wcdgaragema.com/

[jackb]

I would pour in a bottle of Marvel Mystery Oil in the crankcase and drive it for a couple weeks, especially on the highway @ good 50 mph speeds. There are too many possibilities to name in 1 post.

[TWChamp]

A can of Sea Foam in 10 gallons of fresh gas made my 50 Land Cruiser run great within 20 miles. It was pulsing and missing before this.

[pinehurstbob]

I would do a compression check first to either rule out or confirm problem in the combustion chambers.

[Jeffry Cassel]

What they said! Carb needs a good cleaning and a kit. idle circuit clogged.mb suggestion if you are not super good with carbs. Seriously doubt any additive will help but Seafoam is very popular--might be a reason for it. Gotta find an old mechanic who knows what a carb is.

[PackardV8]

Sticking valves on rusty seats is a possibility. A compression check will give us more to go on.

jack vines

[altair]

I had a banging noise coming from my generator (I thought) so I promptly disassembled and replaced the bearing however nothing visible but replaced it any way. After reassembly the banging was still there I further checked the water pump and fuel pump and the banging was also there and generally throughout the engine and the engine was also running rough. I revved the engine and it smoothed out, let it back to idle and rough again, with a quick burst of throttle it backfired through the carb and continued running rough at idle. I had just recently changed the plugs and inadvertently crossed two wires but didn't notice it. The banging and rough idle was the crossed wires, but I have a new bearing in my generator any ways.

[RadioRoy]

The banging and rough idle was the crossed wires, but I have a new bearing in my generator any ways.

And that is why we should always troubleshoot to determine the actual problem before taking things apart that do not need to be taken apart. Simply removing the fan belt would have eliminated the generator as the culprit.

[altair]

Hindsight is always 20/20 removing the fan belt was my first consideration, however the sound was overwhelmingly convincing from the generator the bearing was grumbling and there was a (banging) sound coming from the generator. The banging sound was being transmitted through the block and with my listening stick (poor mans stethoscope) I was convinced it was coming from the generator.

[RadioRoy]

Not trying to give you a hard time, David. Just using it as an example of how too many of us on this forum make too much extra work for ourselves by jumping to action before giving it extra thought.

I've done it myself several times. But it seems that the more I learn about a particular machine or system, the more efficiently it can be repaired, partly from not doing extra work that was not actually required.

When I got my stethoscope, (they are cheap. BTW - like $6.00 or so) I went around listening to various parts of the engine. I could not believe how noisy various turning surfaces are on my car. They were really noisy! And this was a car that was known to be good.

[chet445]

My newly purchased car with 289 was running rough and difficult to keep going. Had the carb rebuilt and cut the rough down some; replaced gaskets on the intake manifold and the car runs smooth. It had been sitting for quite a few years. One never knows. Chet445