Return To Accelerator Start

[Paul Falabella]

I am thinking of returning my 55 Roadmaster back to the accelerator starter from the previous owners push button start. I remember reading somewhere,a problem from accidental shorting would fry the whole front harness and could be avoided by placing a fuse at the neutral safety switch. Which terminal and what size fuse?What else do I need?The carb switch seems to be OK.

The push button works fine, I'd just like the authenticity or is this a project best not to get involved with? Anyone else do this?

Thanks,

Paul

[old-tank]

Yellow wire.  Only a problem of shorting if the key is turned on while the wire is disconnected from the  accelerator switch and grounded.  If you install a fuse put it in more accessible location.  While installing fuses be advised that the red wire to the horn relay is hot all the time too.

[Paul Falabella]

OK, In the yellow wire from the neutral safety switch to the accelerator switch. What size fuse would work? 

 

[JohnD1956]

You could always test your switch before re-activating it.  Hook a test lamp between one terminal and a ground.  Then hook a positive lead from your battery to the other terminal.  Light off?  Good!  Then open the throttle rod 1/2 - 3/4 opening.  Light on?  Good!  then open it full throttle.  Still on?  Better.  Then release it. Light off?  The best! Anything else you'll need to repair the switch first. 

 

BTW, if you decide to take the switch off and clean it internally, be reminded it goes back together dry, no lubricant.  Also be sure which side is top, and that the switch goes back on the right way.

[old-tank]

6 hours ago, Paul Falabella said:

OK, In the yellow wire from the neutral safety switch to the accelerator switch. What size fuse would work? 

 

20A would be plenty since that wire does not carry many amps because the start switch it triggers a relay which triggers the solenoid.

[Beemon]

2 hours ago, old-tank said:

20A would be plenty since that wire does not carry many amps because the start switch it triggers a relay which triggers the solenoid.

Actually, going through this issue myself just recently, you'll want a 25A fuse to the switch. My new relay has a fuse slot for battery positive and when starting, depending on ambient temp, would blow the 20A but not the 25A. The shop manual, at least for 56, states approx. 18-20A goes through the starting system when cranking. The 20.~ is just enough to blow a normal 20A fuse. Back then, according to my Engineering division head, they didn't sweat decimals much and if it was 20.3A, it was 20A or good enough.

 

Is your starter switch just the two wires with a normal push button? If so, you should just be able to push them back through the firewall and use butt connectors or something to re-attach them to the starter switch.

[Paul Falabella]

41 minutes ago, Beemon said:

Actually, going through this issue myself just recently, you'll want a 25A fuse to the switch. My new relay has a fuse slot for battery positive and when starting, depending on ambient temp, would blow the 20A but not the 25A. The shop manual, at least for 56, states approx. 18-20A goes through the starting system when cranking. The 20.~ is just enough to blow a normal 20A fuse. Back then, according to my Engineering division head, they didn't sweat decimals much and if it was 20.3A, it was 20A or good enough.

 

Is your starter switch just the two wires with a normal push button? If so, you should just be able to push them back through the firewall and use butt connectors or something to re-attach them to the starter switch.

That is interesting. I thought this would entail more than just reattaching some wires. Let me get this straight.

Test the carb switch, if it works,

Splice a 25A fuse between the yellow wire and the neutral safety switch

If the push button is a two wire device,

Rout wires back onto the carb switch and I'm back in business?

Am I missing anything?

Thanks

[37_Roadmaster_C]

You really need to check out ALL of the auto start system.  There is more to it than just the carb switch.  There are also lockout and safety switches to keep the starter from engaging when the engine is running or under a heavy acceleration condition.  Normally the push button start modification was done because of other problems.  Just a thought....

 

Robin

[Paul Falabella]

7 hours ago, 37_Roadmaster_C said:

You really need to check out ALL of the auto start system.  There is more to it than just the carb switch.  There are also lockout and safety switches to keep the starter from engaging when the engine is running or under a heavy acceleration condition.  Normally the push button start modification was done because of other problems.  Just a thought....

 

Robin

If I recall the lockout device is a vacuum actuated ball bearing in the carb switch correct?

A few years back, when I had the carb rebuilt, I took the switch apart and cleaned it, and it appeared to be free. I just never got into rewiring it.

Edited August 21, 2016 by Paul Falabella (see edit history)

[old-tank]

5 hours ago, Paul Falabella said:

If I recall the lockout device is a vacuum actuated ball bearing in the carb switch correct?

A few years back, when I had the carb rebuilt, I took the switch apart and cleaned it, and it appeared to be free. I just never got into rewiring it.

That's one 'lockout device'.  The other is the charging generator:  the starter relay must be grounded to work, and this ground is through the armature of the generator which is lost when it starts charging.

[NTX5467]

21 minutes ago, old-tank said:

That's one 'lockout device'.  The other is the charging generator:  the starter relay must be grounded to work, and this ground is through the armature of the generator which is lost when it starts charging.

 

Knowing that "grounds" will seek the path of least resistance, once the generator starts charging, where does the "ground" go when the generator starts to charge?  OR is the "reflex action" of hearing the motor start and backing out of the throttle the "saving grace" of that situation?  But then there are also times of WOT, too. 

 

I can understand the electricity moving in different directions, but what's the "other direction's" destination?  Just curious.

 

NTX5467

[old-tank]

2 hours ago, NTX5467 said:

 

Knowing that "grounds" will seek the path of least resistance, once the generator starts charging, where does the "ground" go when the generator starts to charge?  OR is the "reflex action" of hearing the motor start and backing out of the throttle the "saving grace" of that situation?  But then there are also times of WOT, too. 

 

I can understand the electricity moving in different directions, but what's the "other direction's" destination?  Just curious.

 

NTX5467

You're giving me a  headache.

Study the scan...there will be a test tomorrow

[NTX5467]

THANKS for that additional information!

 

Considering what Beemon's been through and the decreasing availability of good repair parts (although the system can be very durable), I've been considering how to use THM400 kickdown switches and/or "switch pitch" switches to accomplish similar results.  On the fixed-pitch THM400s, there was either a carb stud-mounted switch ('69 Chevy pickups) or an accelerator pedal mounting bracket-attached switch ('70s era cars with cable accelerator actuation).  Haven't looked at the switch-pitch switches just yet, but I know about the kickdown switches.  Everything would be either "on" or "off" and no "floating ball bearings".  The '67 Camaro RS headlight motor system (and probably the Riviera clamshell motor system) uses paddle-actuated limit switches to turn on and off the motors with reversible motors.  They are a good bit more compact than the kickdown switches.    I know this would not be "original", but I suspect it might be better for our more modern world?  Provided existing architecture could be adapted rather than a big replacement situation (in the absence of a kit).  Be that as it may . . .  Just some ponderings.

 

Thanks,

NTX5467

 

.

[Beemon]

 

When the engine fires, the manifold vacuum sucks the ball bearing up into a passageway out of the way from the butterfly shaft so it can never re-engage when depressing the accelerator pedal. Likewise, as pictured above, through the starter relay, the points armature needs to be grounded for the switch to magnetize the armature and pull the contact points into position. When the generator starts charging at engine idle, it shorts the circuit by opening the ground and de-magnetizes the starter relay armature. Since the switch bearing on the carb is now gone, due to engine vacuum, it will never make contact for the wires to back feed on the harness. You just hold the gas pedal down until the generator starts charging and it shuts off for you before you can even take your foot off the pedal. The neutral safety switch also opens the circuit when in Drive so theoretically it shouldn't re-engage while in D because it's just a wire that goes no where at that point.

 

The only time the starter can re-engage during driving is if the contacts in the relay arc and weld together, as in my case, or if the generator is bad and there is poor manifold vacuum at the same time that permits the ball from being pulled into the cut out passage and you're in Neutral or Park for whatever reason. I believe some of the forum members here have converted to alternators and just grounded out the starter relay without issue. I'm not sure how much manifold vacuum is needed to pull the ball out of the way or how much the ball weighs, but they're just a standard 1/2" ball bearing you can get from a local hardware store.

[buick man]

…. yes the " floating ball of love " is the magnetic both breaker and contact point.  Very simple reliable genius applied here …..

[Beemon]

I'm not sure if you're trying to make a point of me not knowing what I'm talking about or not, but I was referencing the wiring diagram posted above, obviously not the carburetor starter switch, which is not the starter relay...

[Paul Falabella]

Test light lit when throttle rod was pulled forward, indicating switch is good. Will splice in fuse and get to rewiring. Has gotten me thinking now, if switch is good, why was it converted to push button?

[old-tank]

If it works, we will never know.  I have seen them rewired many different ways to get it to start with a push button.  The most common is just attaching an extension of the existing wires on the start switch to the push button.  Another way is to have the push button apply 12v to solenoid (black wire on the starter relay).  The least common way was attaching the wires on the start switch together and using the push button to complete ground on the starter relay.

If it does not work as designed, there are ways to determine if the starter relay is the problem.

[Beemon]

Some people may also not like the fact that the throttle blades are open when cranking the engine, or that you have to use the gas pedal in general. If the choke is set properly, the throttle blades being timed to open on start up is irrelevant. Buick was the only car company that I know of that had a less than normal starter system, majority of people who didn't grow up with it or are used to it probably think it's weird or stupid and just re-wire it.

[JohnD1956]

Probably has more to do with a mal adjusted choke than anything else.  But I even wired in a button on my 56  a number of years ago.  It was temporary and had to do with the starter continuing to spin when the engine did not start right away and I backed off the pedal.  Cleaning the switch and putting it back on the carb right side up seemed to fix it for the last 10 - 12 years.

[KAD36]

Paul - late to the game on this - was trying to find the post.  Have had a 10 amp fuse in subject wiring with no further electrical issues to date; keep posted on the debug and good luck

 

Starter Switch Short Close Call

[Paul Falabella]

OK, after installing 25a fuse and carefully tracing every wire in the starting circuit, found the difference from factory was the pink wire from the starter switch to the starter solenoid(just covered with electrical tape), #4 terminal. Car started with the accelerator. The push button is apparently sliced in between the voltage regulator and the starter relay. I will leave it alone for a while. I still need to see if there was an operational problem that may again pop up.

Keeping my fingers crossed!

Meant relay, thanks, Willy.

Edited August 29, 2016 by Paul Falabella (see edit history)

[old-tank]

18 minutes ago, Paul Falabella said:

the starter switch to the starter solenoid

did you mean starter relay?

[Paul Falabella]

Yes meant relay, will correct.

[Beemon]

Terminals #3 and #4 would be obsolete with a push button as they open and close the contacts in the relay (now performed by your finger). The only reason I could see it spliced into the voltage regulator is if they took #3 terminal and grounded the switch with it, just like the relay, so the starter shuts off whether you have your finger on the button or not. Do you have any pictures of the switch and wiring? If there is an issue with the system that pops up, it's most likely the starter relay as it's the only component in the system being bypassed. You already checked the carburetor switch to be good, the shop manual details how you can check and calibrate the starter relay.

 

I'm curious because no mention was made prior, but did you pull the starter switch off the carb or just check the terminals?

[Paul Falabella]

The carb switch was R&R'd and cleaned as per the book. The push button is mummy wrapped in electrical tape and I don't really want to mess with it. So far as I can see,the way it was done, if something goes wrong, I can remove the pink switch/relay wire and I'm back to push button. Sounds weird huh?