1955 Accelerator starter switch

[Paul Falabella]

My 55 Roadmaster has a push-button starter. While I have the Carter carb off, I am thinking about returning to the original circuit, if I can.

Got the two terminal connected to my multimeter(ohms).Reads open at first. When I just crack the the throttle I get 0.2 Ohms(2nd pic). When I advance to the butterfly stop(just opening) the meter swings around but will stabilize around 270 Ohms(1st pic).

Is this correct? Am I barking up the wrong tree?

Leave well enough alone and leave the push button?

I figure if someone put the button in, something was wrong. On the other hand, it looks like a pretty simple circuit, though I've read not protected and a potential electrical disaster.

Thanks

[Leif Holmberg]

0.2 ohm looks good but 0,1 is better , 264.3 ohm looks to much,you need to clean the "push button" parts to 5-10 times higher as 1000-2000 ohm.I should be milli ohm I think to be good enough.

Leif in Sweden.

[TexasJohn55]

Paul,

The carb switch should read open circuit at idle and then go to closed circuit at nearly full throttle and be stable at less than .2 ohm then return to open when throttle is released. It sounds like you need to remove and clean the switch components as per the shop manual.

[NC-car-guy]

Glad to see you're going to get that switch going again. It's one of my favorite things about my 55 Special... everyone else is always "oooo, aaaahh" at the idea that it "starts" with the gas pedal!

[Paul Falabella]

So what's in the little black plastic box on the back of the carb needs to be cleaned and this should give a consistant 0.1-0.2 ohm reading and should be usable in the pedal starter circuit?

[Mudbone]

[ATTACH=CONFIG]238860[/ATTACH][ATTACH=CONFIG]238861[/ATTACH]

My 55 Roadmaster has a push-button starter. While I have the Carter carb off, I am thinking about returning to the original circuit, if I can.

Got the two terminal connected to my multimeter(ohms).Reads open at first. When I just crack the the throttle I get 0.2 Ohms(2nd pic). When I advance to the butterfly stop(just opening) the meter swings around but will stabilize around 270 Ohms(1st pic).

Is this correct? Am I barking up the wrong tree?

Leave well enough alone and leave the push button?

I figure if someone put the button in, something was wrong. On the other hand, it looks like a pretty simple circuit, though I've read not protected and a potential electrical disaster.

Thanks

I used a 12-volt battery with a turn signal bulb to determine start position. I tried the ohmmeter at first also. When you run 12 volts to it, it seemed to be more consistent. Mud

[JohnD1956]

What is in there is a contact shaped like a W. It is pushed towards the cap of the black plastic box where the outside ends of the W touch flat plates attached to the screw terminals your wires connect to. There are a few other parts as well, a spring, a guide block, a ball bearing, a washer and any number of timing shims which go between the guide block and the bottom of the W contact. The 56 manual covers removal, cleaning , lubrication and adjustment in section 10-27. The major thing to be wary of is putting the black plastic casing on the base in the correct orientation. If it's upside down, then the ball bearing gets trapped and eliminates one of the two failsafe systems.

[Paul Falabella]

Got a pretty good exploded view of a 53 switch(55 shop manual does not show switch exploded view). Looks like a lot of tiny parts in small box. What's best to clean this switch with? Don't want to use a solvent that will harm the plastic.

Also 3 shims is normal or is that a variable?

[JohnD1956]

I'm sure the 53 exploded view is good. I would use alcohol to clean the innerds. My 56 manual says lite coat of petroleum jelly in the top of the cap between the contacts. No lubricant in the sleeve where the plunger rides. As to the number of shims, that depends on if it works right. For the 56, the switch should engage when accelerator is 3/4 depressed. I'm not sure that is the same for the 55. But the number of shims will give you that measurement.

[old-tank]

The number of shims are 'as needed', so 3 is your starting point. Clean all contact areas to shiny metal with fine sand paper; I use WD-40 which improves electrical properties as well as lubricates without being gummy. If testing off the car goes well it should work as designed if the push button switch was wired so that it substituted for the carb switch....get back to us if wired differently. Consider replacing the starter relay also.

Willie

[Leif Holmberg]

Here are some pictures .

Leif in Sweden.

[Paul Falabella]

Here is disassembled switch,appears to be 4 shims(1 thinner than the other 3). Seems to be in decent shape to me. So this cleaned up should work and give a 0.1-0.2 ohm reading?

Stains are not from switch.