Car won't accelerate past 45mph

[Daly]

I Recently bought a 1954 Savoy Club Coupe and for the most part it runs great, except when getting to cruising speeds. 

When I first got the car and tried to drive it down the road, as I got close to 35mph, the car started surging/chugging and wouldn't accurate any further. After looking around I found a kink in the fuel line and suspected it may be causing a fuel starvation problem at higher RPM. I fixed that and can now get to 45mph before the same thing happens. The carb appears to have a slight leak so I've ordered a rebuild kit for it, and while the filter looks fine, I'm going to replace it as well. 

 

Is there anything else I should be looking into? To me it seems like a fueling issue, but I know I don't know everything. 

I live in the county where the speed limit is 90kph, so I need this car to do 50-55mph, which my 1950 Ford was capable of, so I assume this Plymouth should be. 

Eventually the plan is to swap the rear for an Exploder rear end with taller gear and maybe a 5 speed transmission, but until then I'd like to make the OE parts as usable as possible. 

[DonaldSmith]

How fast will it go in 1st?  in 2nd?  I had a distributor problem that cut out at a certain RPM, rather than road speed.  (Did not anchor the spring of the points.  Dah.).  

Like they say, 90 % of carb problems are ignition, and vice versa. 

[lostviking]

Make sure the point gap is proper. Too much and it won't RPM.

Edited June 23 by lostviking

[kencombs]

Take a close look at the ignition points, especially the closing spring install.  

[greg g]

Assure the wire for the breaker plate is in good condition and not grounding to the distributor body through missing insulation.  Then because all ignition faults are fuel related, do the test for adequate fuel pumping volume.

Edited June 23 by greg g

[FarmerJon]

I would check the float height. I lowered mine recently, and went too far. It caused a very similar condition when accelerating hard or trying to hold speeds 45 and up. 

If the carb is tired and leaky, someone in the past may have dropped the float thinking the leak was the carb flooding over.

If it continues, I would replace any rubber fuel line with fresh. Same for if it has an inline filter.

Of course, make sure your ignition is healthy as well. 

[Daly]

Ok, thanks for the ideas guys. I've already started the carb rebuild, but I will have a look at the distributor while everything is out. 

[Los_Control]

@FarmerJon that is excellent advice ..... I would go further to suggest it might be a failing fuel pump that has a small hole in the diaphragm and no longer produces proper fuel pressure.

1 hour ago, greg g said:

Then because all ignition faults are fuel related, do the test for adequate fuel pumping volume.

 

Seems like there use to be a test where you actually pumped fuel into a bucket and measured performance by volume of fuel pumped by seconds to pump it.

 

Or get a fancy gauge to rate the psi of pump.

[Los_Control]

I just want to add I have had a few electric fuel pumps fail on me ..... one just died and nothing happened period after that.

 

I had one that was failing but worked as long as the weather was cool ..... We nursed that one along from ABQ NM to Seattle. ..... Driving at night and hanging out in the park like bums during the day.

 

I had another one that failed and it simply lost it's get up and go .... could not deliver enough fuel .... but it ran fine otherwise at lower speeds.

 

I get it I'm talking electric fuel pumps, I honestly believe any fuel pump can fail in a different way. ..... There is no set pattern to tell you.

So what you describe could be a fuel delivery issue.

 

I will go as far to say I had a 1991 Dodge Shadow and rebuilt the engine, it just never had the performance I thought it should have.

Then it got worse and I figured out the fuel pump was bad.

Once I changed the fuel pump, it ran like a race car ..... These are symptoms of a bad fuel pump or poor fuel delivery. ..... hole in the fuel line would do the same .... good luck.

[keithb7]

Fuel delivery in the needed volume is aa good guess.  The mechanical advance on the distributor is another good place to look for possible issues. How about a failing condenser? Can't keep up a such short dwell times at high rpm?

 

Ripping down the highway at a steady RPM the engine needs a reliable, steady supply of fuel at a fairly decent volume. If the fuel system cannot keep up that the engine is calling for, it sputters out. You can look at anything related to a steady strong supply of fuel. Fuel delivery lines. Air leaks? A fuel line connection loose? Fuel pump PSI and GPM. Vapor lock? Carb bowl inlet valve? Float level.Plugged partial plugged main jet? Carb air leaks? Fuel filter partially plugged? Good free flowing, fully controlled air intake? Fuel is just one area to look at.

 

Then there's the ignition system. We can come up with a good list of items to check. Dwell. Timing. Advance. Coil. Wires. Cap and rotor. Condition of wires from key switch to coil and beyond. Points & condenser.

 

Then there's mechanical things like, proper valve timing. Valve set. Valve condition and seal-ability. Manifold leaks. Fuel tank venting. Timing chain and gears wear.

 

All this and more should be in good condition for proper engine running and performance. That's a lot, but from here it's hard to pin point one thing to focus on.  All these mentioned systems must work together. 

Edited June 23 by keithb7

[Plymouthy Adams]

have you even looked to see if the throttle plate is fully opening......? its never to late to look...!

[Sniper]

I dunno, seems someone I know was having similar issues, then noticed his parking brake was still on

 

Dunno who that could have been though.

[Plymouthy Adams]

didn't that guy live in Texas?

[Los_Control]

37 minutes ago, Plymouthy Adams said:

didn't that guy live in Texas?

LOL   🤣🤣🤣    you Easteners were always looking for guidance  .....

[Sniper]

44 minutes ago, Plymouthy Adams said:

didn't that guy live in Texas?

 

I'll have to ask my son, he was a witness, lol.

[DJ194950]

Texas maybe, but born and raised in Tennessee ?

[desoto1939]

1 hour ago, Sniper said:

I dunno, seems someone I know was having similar issues, then noticed his parking brake was still on

 

Dunno who that could have been though.

No wonder that you kept getting caught by the Fed's when trying to run the moonshine through the backroads. You made it too easy for them to catch you. Especially in thse dry counties.

 

Rich Hartung

[greg g]

The fuel volume test is outlined in the service manual.  But basically disconect the line to the carb, direct the fuel line into a coke bottle, have some one crank the starter with the coil wire out.  Count the pulses of gas entering the container.  12 pulses should give you at least 6  ounces. Or more.