When Driving a Model A?

JOES31

JOES31

Senior Member
Been driving the 31 Tudor since I have it 99% finished. When I come to a long signal light I smell gas fumes. Even when I have it idling in the driveway I can smell the fumes. No smoke coming from the exhaust and it has a new stainless exhaust system from Snyder's. I checked for leaks and there does not seem to be any. I installed new floor boards and they are pretty well sealed with the new webbing. Carb is adjusted properly with the float set to specs and I drive with the GAV about a half turn open. If I close it down to 1/4 then it has a tendency to stall at stops.

So is this just the way Model A's run? It doesn't gas you out but you can smell some of the fumes. Is this normal? In 50's and 60's cars we get this but not as bad and they don't enter the vehicle when you come to a stop.

Again any information is appreciated,

Joe
 
Do you have blow by from your oil filler tube? If so you will also have oil on your engine parts.
 
you should not stall with the gav open 1/4... actually i run mine cracked open..
get yourself a set of flowed jets from renners and go through the carb.. if you have play in the throttle shaft install an oversize..
 
If I have the windshield open past the factory detents on the windshield swing arms ,I get the gas smell in mine , if at the factory detents or closed , no fumes at all .
 
I drove a 1930 Town Sedan for many years and if I did not have the windshield at the detent, I would get very bad head aches. Obviously, I was getting some carbon monoxide. The idea is to slightly pressurize the cabin from the air coming in the windshield to prevent the exhaust from coming in any place it wants to!
 
No blow by. I made a cap that has a stainless steel filter insert to keep any oil from coming out of the cap. Just rebuilt the Zenith carb. Used Snyder's kit. I checked the size and they were correct. I have a Tillitson that will run with the GAV at any setting. I thought I would rebuild one of the three Zeniths I have and see if it runs any better than the Tillitson. It runs much better than before I rebuilt it. I will try the flow tested jets.

Thanks
 
Gas cap good? Vented properly? fuel shutoff valve good? Fuel leak at the steering column? Park the car outside with it closed up in the sun. Wait an hour or so and slowly open the door to grab the first clean whiff of inside air. If you have an inside gas leak, it will smell.
 
Ok how could a gas cap, fuel valve have, steering column have anything to do with exhaust fumes?? Car smells like new upholstery that I put in when I first open the door. Maybe it's because the newer cars burn so much cleaner than the A. I only get it when it runs.

Mitch just ordered flow tested as you suggested.

gpits good idea about the windshield.

Thanks Guys
 
JOES31 said:
Ok how could a gas cap, fuel valve have, steering column have anything to do with exhaust fumes?? Car smells like new upholstery that I put in when I first open the door. Maybe it's because the newer cars burn so much cleaner than the A. I only get it when it runs.

Mitch just ordered flow tested as you suggested.

gpits good idea about the windshield.

Thanks Guys
Click to expand...

youll see it makes a night and day difference to get properly calibrated jets. ....the jets from all the suppliers are generic uncalibrated garbage which makes the carbs run to rich

use this excellent source from berts as a guide going thru the carb
on the L/S of the page it lists the jets and how they should be orientated
http://www.modela.org/lower_carb_assembly.html
 
How far from the back of the car does the tailpipe end? Unless it is back far enough the fumes will be sucked back into the cab.
 
It is running to rich, if it stalls you may have to adjust the float. 1/2 turn is way to rich for a warm engine. The exhaust should have very little smell.
 
My own experience with exhaust smell may be of use.

I was having problems with exhaust smell. I must have re-done the connection between the manifold and the exhaust pipe half a dozen times and used three different clamps to make it right. (Clamps DO matter - early ones are the best, the intermediate 1960s-1990s clamps not so good, the latest quite a bit better but not up to the old ones.)

After discovering how to "plug" the exhaust pipe with a towel on the end of a broomstick, I worked at finding the leak. The engine wouldn't slow down a smidge even with the exhaust fully blocked.

I had developed the technique to put 30W oil with a bump bottom can on the exhaust clamp to confirm it was tight. With the pipe plugged as I describe I started at the clamp and worked my way up the exhaust manifold. Lots of smoke as the oil burned off, but about a third of a way up all of a sudden bubbles BIGTIME as the manifold crack became visible.

The exhaust manifold was cracked - and QUITE cracked at several locations. All sealed nicely with rust - at first - but my resurrection and work must have opened them up.

So I took off the manifold - and just "touched" it with the ball end of a ball pein hammer - it promptly fell into about 6 pieces.

Heh. More than one leak. You could tell the cracked portions had been cracked for a while by the rust pattern.

A newish manifold cured the problem.

Joe K
 
Joe my thought is you could very well have a leak where the muffler pipe flange meets the manifold.
The clamp used there often is installed upside down contributing to leaks.
Perhaps you use the same method but here is how I install a muffler to the manifold with good success.

Attach rear tail pipe bracket and hang the tail pipe in it. Using a floor jack raise the front of the muffler up until it contacts the manifold and adjust for a perfect fit. Once it is all set like you want very carefully lower the jack just enough to allow room to apply muffler sealant past to the female lip of the muffler pipe. Raise the muffler back into place and attach the clamp. If this connection is good about the only things left would be a bad seal between the manifold and engine, a cracked manifold or exhaust gas swiriling back in from the tail pipe.
 
If you determine problems with the exhaust system leaking and you remove the muffler, then I would go to the extent of pulling the intake and exhaust and trouble shoot the manifolds.
I have seen: loose stud bolts, hidden holes, cracks, drooping, bad gaskets, non-flush surface of the manifolds when they are bolted together, corroded bell contact surface where the muffler clamps to the exhaust manifold, poorly fit exhaust clamp install, rusted clamp bolts, or at least loose clamping bolts.
take you time, and be systematic.
Bob
 
You must log in or register to reply here.
Back
Top