Parade Blues

[BILLF/TRF]

I drove my 1931 tudor sedan to a nearby town (30 miles) to participate in a parade. Fortunately, with the hot weather and stop and go movement in the parade (1 hour), the engine didn't overheat but some people along the route said I was "puffing" black smoke from the exhaust pipe. After the parade I left for home was surprised by an irregular "cutting out" as I accelerated to about 45 mph. I thought it would smooth out shortly as I may have accumulated some carbon build-up and needed to "burn it off". Unfortunately it kept the the irregular "bucking" all the way home--more if I tried to accelerate. Could it be a fuel supply or distributor/plug problem? Thanks for any advice.

[Tom Wesenberg]

I would clean the spark plugs and see if that fixes the problem.

[Mike]

BILL,

Sounds like your condenser is shoring out

mike

[Richard Wilson]

Sounds like fouled spark plugs to me. A rich fuel mixture and very slow (parade) driving will mess up a set of spark plugs in a very short time. I have seen plugs so fouled that they had to be replaced with new ones just to get the Model A back home after a parade.

[nostalgicford]

I agree...I have a hopped up Model B engine with hi compression head in my RPU ...it will foul the plugs so bad I can't hardly get it home....no more parades for me

[Dave in Boise]

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I'd look at baked coil or condensor.. A weak spark will not burn efficiently, leading to black smoke, and would be having issues producing enough power to spin your motor past 2K rpm..

is your coil pointing up or down? The modern coils like to be pointed up (not good for judging standards) as the collant oil will then be over the windings and keep it in better shape..

My 2 cents

ps.. Try sprayng your condensor and coil with brake cleaner (carbon tet/ether), PC Keyboard (pressurized air/freon) or starting fluid (careful!) and see if the cooling of either element helps your performance or spark power.. That might help you find the weak link..

[BILLF/TRF]

Update: Thank you all for your suggestions. I replaced the spark plugs and the car ran perfectly. I ran it about 10 miles out in the country at about 45 mph. When I returned I noticed the beginnings of carbon deposits on the plugs. this happened even though I had the GAV turned all the way off. Do these spark plug deposits happen to all Model A cars or is there still something wrong?

[Geo. H]

You must be running rich, and that's likely a carburetor problem. What kind of gas milage are you getting? It should be close to 20mpg.

[BILLF/TRF]

Originally Posted by Geo. H

You must be running rich, and that's likely a carburetor problem. What kind of gas milage are you getting? It should be close to 20mpg.

My mileage is about 14-15 mpg. This is even with a 3.54 rear end! What can I do to the carburetor to make it run leaner? Thanks.

[Blessyouboys]

Originally Posted by BILLF/TRF

Update: Thank you all for your suggestions. I replaced the spark plugs and the car ran perfectly. I ran it about 10 miles out in the country at about 45 mph. When I returned I noticed the beginnings of carbon deposits on the plugs. this happened even though I had the GAV turned all the way off. Do these spark plug deposits happen to all Model A cars or is there still something wrong?

What plugs are you using?

[Kurt in NJ]

With 3X plugs, and jets that were a little large for pre ethonal gas now can be too lean for today's gas.

I have only used original jets, they have not been touched or re-sized ---the one time I tried repro parts for carb internals it ran bad, leaked, I put the old parts back, it can be leaned too lean, or made too rich with the GAV. ---the shape of the tip of the jet is as important as the size of the hole.

If I am caught behind a rich running car in a parade I will pull over like I am having problems and try another place in the parade.

I have used a 5 gas analyzer to check my mixture under load --the picture of the plugs is from after a run on the dynamometer(CO-0.12,HC14%)---that run resulted in an emission level that would pass inspection for a 1990 car, there were no special preparations for the test, all carb and ignition parts have more than 25 years of use. A CO level of 2-5%is ok, 5% at idle, 2-3% at speed will give good economy and power with a stock engine.

Changing to "hotter" plugs is not a cure for bad mixture.

Your engine needs to be sound with properly sealing valves.

The black on the steel part of the plugs is normal, the center electrode is what you look at, when I have a normal mixture mine have a light tan color with just a little white.

For a walking speed parade I usually adjust my speed with the spark advance --1/4 to 1/2 advance, the GAV is just cracked open --perhaps 1/16 turn ---for speeds above 35 --full advance, 1/2 turn gav, above 55 3/4 turn GAV

My fuel mileage is about 20 mpg--stock engine except for "B" cam.

Another thing to look at on your plugs is where the spark is jumping ---there should be a grey bare steel area where the spark is jumping--the arc burns off all deposits, if the spark is weak it will be small, if the spark is good it will clean a larger area. --3X plugs have a small electrode, it is all clean on mine, more modern style plugs shoud have all the flat surface of the center electrode cleaned off, with a really strong spark ( modern cars ) will clean around the corners some and a larger section of the ground strap.

[BILLF/TRF]

Originally Posted by Blessyouboys

What plugs are you using?

I am using Autolite 3076 which is the same as Motorcraft (according to the local parts store). I gapped them to .032".

[Jack '29 Sport Coupe]

I was invited to a parade event a few years back and I was not only to be part of the entertainment, but I was expected to pay 30.00 bucks for the honor to boot. The proceeds didn't even go to a charity----just the bar that sponsered the parade. Needless to say, I sat that one out. The only parade I ever participated in was on Christmas, and I had one eye on the road and one eye on the temp gage. Never again.

Jack

[Maurer1929]

I have the same question as BILLF, if GAV is nearly closed and still running rich by getting blackened spark plugs, what can you do to the carb to fix it?

[Fred K-OR]

Due to the fact that people said you had black smoke coming out of the exhaust, it would seem like a carb problem. Sorry but I am no expert on carbs but the black smoke to me indicates a gas problem.

[George Miller]

Originally Posted by BILLF/TRF

Update: Thank you all for your suggestions. I replaced the spark plugs and the car ran perfectly. I ran it about 10 miles out in the country at about 45 mph. When I returned I noticed the beginnings of carbon deposits on the plugs. this happened even though I had the GAV turned all the way off. Do these spark plug deposits happen to all Model A cars or is there still something wrong?

Most likely you have repo jets in the carb from the 80ts. They were the wrong length and jet size was to big. Find some good jets for the carb.

[BILLF/TRF]

Originally Posted by George Miller

Most likely you have repo jets in the carb from the 80ts. They were the wrong length and jet size was to big. Find some good jets for the carb.

It is hard to believe that my carburetor, which was recently re-built by a builder recomended by this Forum, would use '80's jets but I suppose it is possible. Maybe I should look for some NOS jets--if there are any available and re-do the carb myself.

[Clem Clement]

Here in DC, some parades now ask for a signature that you are responsible and have your own insurance. I am reducing my attendance to parade/events that charge too much. Their loss in my mind.