53 Merc flathead with power engine miss

[Dynaflash8]

I was looking at a very nice 1953 Mercury 2dr hardtop pretty seriously.  The brand is way off my knowledge mark, being I'm a Buick guy.  That said, I've eyed this car for a number of years.  It belongs to a friend of mine.  In the picture, no skirts....but, they are in the trunk.

 

So, I drove it to a car show, following him in another of his Ford-brand cars, an original 1941 Mercury.  So, I wanted to put it through it's paces.  The car is a flathead with Merc-o-matic transmission.  It also has power steering and power brakes (I think it has the brakes, not sure, but one or both maybe aftermarket) It is all original specs.

 

So, we were driving along about 50 mph and the Mercury was running great.  So, I decided to try the passing gear.  Now Ford guys, does a 53 Merc-o-Matic have a  passing gear?  Anyway I floored it and it started to break down like the points were too close or something.  I let off of it and it straightened itself out and we went on.  I tried it again and the same thing happened.  Hmm....so we finally arrived at his storage site and as I slowed down, before turning it, I got down to about 35 and I floored it again (just trying a short spurt) and it started breaking down again. 

 

The owner has driven this car 125 miles each way to a car show numerous times.  Now it is 85 years old and doesn't horse the car and he's never had any complaint.  Despite his long life of owning probably hundreds of Fords and even having been into auto racing, he didn not have a plausible answer to what I found.  Another friend, a retired lifelong mechanic, said the valve springs were weak (right off the top of his head).

 

I still like this Mercury.  So I'm asking all of you Ford guys all over the world here.  What's wrong with this Mercury.  I've also heard that transmission doesn't even have a passing gear!  Wow. 

 

I asked a couple of other Ford guys I know and got a different thought from each one.

 

Edited July 26, 2018 by Dynaflash8
another thought (see edit history)

[Bloo]

Start with the ignition. Maybe there is some slop in the breaker plate allowing the points to close up as it moves. Maybe the points are just set too close.

 

Maybe there is a bad rotor or missing carbon button in the distributor cap or something like that, causing the spark to run high and then just fail under load. A scope could suss this one out pretty quick.

 

Maybe the supply voltage to the coil is weak?

 

Did I hear aftermarket brakes or steering or something? If you don't mind small changes, the distributor in those late flatheads is a Holley Loadmatic, and didn't work right even when new. I might consider dropping something else in. You will most likely have to change the carb too if you want a functional vacuum advance. It will run better with one than without.

 

In 53, I believe the transmission has 3 speeds but only uses two. The only way to get low is to manually select it. That said, I would be really surprised if there is no kickdown to second gear when passing.

Edited July 26, 2018 by Bloo (see edit history)

[Dynaflash8]

All of those distributor ideas sound rational except maybe the Loadmatic suggestion sounds odd to me.  The car runs and starts perfect.  I'll think this over.  Come on, somebody else out there must have more ideas. 

[vermontboy]

Well we know it's either spark or gas - if it's spark it's most likely the distributor - could also be bad plugs. If it's gas it's the furl pump or carburetor settings (most likely an adjustment or the accelerator pump). If it's getting good spark at the right time and the proper amount of gas it will run as intended. Something is (or isn't) happening when you step on the gas. It's a shade tree mechanics dream ....

[AntiqueCraftsman]

12 hours ago, Dynaflash8 said:

So, we were driving along about 50 mph and the Mercury was running great.  So, I decided to try the passing gear.  Now Ford guys, does a 53 Merc-o-Matic have a  passing gear?  Anyway I floored it and it started to break down like the points were too close or something.  I let off of it and it straightened itself out and we went on.  I tried it again and the same thing happened.  Hmm....so we finally arrived at his storage site and as I slowed down, before turning it, I got down to about 35 and I floored it again (just trying a short spurt) and it started breaking down again. 

 

The first thing that came to my mind when I read these symptoms is the accelerator pump in the carburetor isn't working properly.  In the carb there should be an accelerator pump that gives the engine an extra squirt of fuel when the gas pedal is depressed quickly.   If that extra spurt of fuel is not there the engine will bog down because it's running out of gas too quickly before it's had time to accelerate up to speed.

 

I'm not even sure that a 53 Merc has an accelerator pump on the carb, but that would be my first guess.  That's exactly what the accelerator pump is there for.  It's supposed to give the extra shot of gas that the engine will need to accelerate.   Especially when you're putting your foot into it hard to get a quick acceleration.  Without that spurt of gas the engine gets too much air and not enough fuel and bogs down.

 

Just a guess.

[Dynaflash8]

Wouldn't it eventually catch up?  This car just kept breaking down until I let off the gas.  It sure felt more like a distributor problem to me, but experience tells me it's sometimes hard to tell the difference.

[Bhigdog]

Insufficient voltage at the spark plug gap.......bob

[28 Chrysler]

You may also check the vacuum advance. 

[vermontboy]

Another possibility is a bad fuel pump - easy to check the pressure

[TerryB]

Fuel filter need replacing?  I suspect the car’s owner rarely if ever does the same test you are doing.  I would be looking at both fuel and ignition as the source of the problem.