The Stovebolt Site Forums The Shop Area Engine Shop I need some Distributor education

>> Do I have a problem inside my distributor?

I cannot turn the distributor breaker cam in my '54 235 to check the automatic advance. Am I trying to turn the wrong thing? I can turn the entire distributor counter-clockwise to check the vac advance.

According to the '54 Shop Manual page 6-18, I should be able to grab the rotor and turn the distributor cam clockwise, then release to check the automatic advance (weights/not vac). If the cam does not return, then the distributor should be removed and repaired.
> Shop Manual 6-18, "Ignition Distributor" step #3

>> If I have a problem - can I fix it without removing the distributor?

My distributor is #1112403, serial #9D15. The '29-'57 MPC shows #1112403 is for a '55-'57 6-cyl 12-v. A '54 distributor is #1112388.
> Distributor breaker plate numbers

The 1955(second) Shop Manual (same distributor as mine) shows the same proceedure.
> 1955 Shop Manual

The block is 1954. Flint Michigan plant. Heavy duty clutch. 0369873F54U

The engine hasn't sounded "quite right" lately. I haven't noticed any spark ping.

Background:
I started to install new points, condenser, and rotor in my '54 235 yesterday. I first checked the existing timing to serve as a benchmark when I finished installing the points and timed the engine.

According to my $25 HF timing light, the timing is currently set at 24-deg advance. I posted a Stovebolt question regarding the reading. I am starting this new "Distributor" thread eventhough it may be connected to the 24-deg advance question.
> Stovebolt post

Today I started a basic distributor check before I proceed.

>> Question about the BB on the flywheel:

Is the BB on the flywheel at 2-deg after TDC?
GM Resto Pack page 154
Engine Timing - Ignition
235.5 Engine Timing spark advance initial setting 2-deg after TDC
Timing mark location: Steel ball in flywheel
> 1954 Resto Pack p.154, bottom of first column

Thanks for your help and education,

- Lonnie

If the dist is the motor you are not going to turn anything much. The ROTOR is going to be stopped by the camshaft gear.

You're not going to get half a turn out of it... maybe a FEW degrees. I think that's what they want to see... if you turn a will it spring back.. ANY spring back is good. NO spring back is bad. Its a half [censored] way to check the springs... kinda like 'are they even there'.

The only way to really test a dist. is on a dist machine that can test the advance curve under RPMs.

There is a centrifugal advance under the plate the points are screwed to.
http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm1228.htm
This will get you started. I would think you will need to pull the distributor to do it properly. Many thanks to Kieth Hardy for the manual.

The tip of the rotor should be able to move clockwise about 1/8"-3/16", and spring back CCW to its original position when it is released. That equates to about 7-8 degrees of distributor rotation, or 15 degrees or so crankshaft degrees of advance. Add another 10-12 crankshaft degrees with the vacuum advance under high speed and light throttle conditions for best cruise performance. A distributor tester or a delay-flash timing light is best for checking actual engine performance.
Jerry

>> Where did I screw up?? The engine won't start.

I retarded the timing on my '54 from 24-deg advanced to 4-deg advanced before I installed the new points. Engine ran well. Maybe not quite as peppy as before.

I installed new points @ .019" gap, new condenser, and new rotor. Lubed the points cam. Dusted the inside of the cap. Returned all plug wires to the original ports on the cap. Installed the cap in the same position as when I removed it. Now the engine won't start. Turns over easily but no hint of even trying to fire. Probably a rookie mistake. Could I have gotten the distrib or cap 180-deg out of sync? Don't know where to start looking.

When it didn't start with the new points, I turned the distributor a little counter-clockwise to advance the timing a little. I thought that maybe the previous 24-deg advance was because of the old worn points, and that now the timing was retarded almost 24-deg with the new ponts. The spring arm on the old points bent easily when I removed them. No change.

Possible problem(?) The distributor does not have an insulator on the outside where the coil connects to the points and condenser. A cork and a fiber washer insulate the distrib on the outside. I believe that the extention on inside insulator through the hole in the distributor case prevents the connecting screw from contacting the case.
> Outside insulator shown in Shop Manual pic
> No outside insulator on my distributor pic

Jerry, Steve, and pfarber - Thanks for your help. I can turn the rotor an eighth inch clockwise at the most. The distributor raises up a little when I turn the rotor. Rotor springs back into original position when released.

I want to get it started. Then I can start checking the performance of the advance mechanisms.

Thanks for any suggestions that you can give to me.

- Lonnie

When a person says the engine won't start just turns over, it does not tell us anything except the battery, starter and solenoid are working. Need to know if you have spark at the plugs or gas at the carb. Need to know if it fires a little but does not start or no fire at all. First check spark at spark plug and work backwards till you find spark. If you have spark and no gas at carb, work backwards til you find gas. If you have both, check timing. If it won't even fire, something is way off or disconnected.
Sounds like it was running but not perfect, then you tuned it up and now it does not start. You did something. Forget advance for now, don't need that to fire up. Start with the basics first. If you have approx. timed spark and gas squirting down the carb, it will start. You DO have to know if you are on compression stroke or exhaust stroke to time or you WILL be 180 out. Search here, the many ways to find the compression stroke for no. 1 cyl.
Somebody lost/broke the outside insulator I guess and used a "cork"? You may want to revisit that fix and use a few nylon washers. The terminal stud does need isolated from dizzy body. You'll get it running next try.

I always set the distributor in the motor so the #1 plug is set to fire at 1 oclock..see how easy that is to remember.. plus the rotor is physically pointing at the #1 cylinder... makes it easy to know where the wires go.

You have to start at the beginning. Set the #1 piston to TDC (use the flywheel or a TDC gauge of some sort), set the points, run the wires, hit the starter.

Did you compare the new rotor to the old rotor to make sure you have the correct part?

I'm back on the road!

The problem was at the insulator on the distrib case between the coil and the points/condenser.

A 5-cent shouldered nylon washer to substitute for the "MacGyvered" cork outside insulator fixed the problem.

Don - The first thing that I did in my trouble shooting this morning was to replace the new rotor with the old one. Although that wasn't the problem, we were thinking along the same line.

Timing was at 5-deg advanced beyond the BB. Ran sluggish; stumbled on acceleration.

Hooked up a vac gauge and advanced the timing for max vacuum. Son-of-a-gun ... at max vacuum, the timing at idle was 22-deg advanced beyond the BB. Same as the timing when I first checked it before installing the new points.

I backed off the timing to 10-deg. Vac gauge fell from 22 In Hg to 21 inches.

Checked the advance.
Timing at idle = 10-deg advanced
Timing at higher RPM = 20-deg advanced
Timing at fast RPM = 25-deg advanced
(No tach)

Truck ran better in road test that at 5-deg advanced. Still seemed to be lacking power on full pedal acceleration in high gear. No spark ping.

I'll leave the timing at 10-deg until I can test it with another timing light. The dial on my HF light may not be correct.

Thanks to everyone for your help. Sorry for the fire drill.

- Lonnie

Lonnie, glad you found it. You can advance the timing until it pings a little under load. And be quite sure you have it right. Fixing the short at the distributor was a very good bit of trouble shooting. No power to points = no spark. You have a base line on your timing light so I would use it just think in terms of a "correction" chart. Subtract 10 degrees from indicated and use it. Just my 2 cents.

Jerry -

RE: weight and vac advance -

I appologize for being so thick. I'm still trying to learn.

Are you saying that the timing should advance 25-deg at speed vs the timing at idle? (15-deg weights PLUS 10-deg vacuum)

My HF gauge shows 10-deg advance at idle and 25-deg advance at speed / no load. That's only 15-degs difference.

Do I have a problem? If so, how can I find the problem?

Thanks,

- Lonnie

I was just using a "for instance" example. Most engines get their best full-throttle power/performance at around 36-37 crankshaft degrees of advance at high RPM, (centrifugal only) and best gas mileage at light-throttle cruise with another 10 degrees or so of vacuum advance added on. As soon as load increases, such as pulling a hill or passing, the vacuum advance goes away- - - -it's just not there with even a moderate amount of load applied. Differences such as camshaft grind, type of transmission, intended use such as load-pulling versus quick throttle response, etc. all factor into an engineer's choice of a particular advance curve. The biggest mistake most folks make is getting too much advance too soon- - - -engines don't like trying to run backwards when too much spark advance gets dialed in.

A series of chassis dyno tests we did on the 1934 Ford coupe family race car with a flathead V8 back in the mid-1950's showed that the power loss from 1 degree too much advance at full throttle was the same as the loss from 5 degrees not enough advance. If you err on timing, too little is not as detrimental as too much!
Jerry

Thanks Jerry,

I always benefit from your explanations. I'll keep playing with my timing.

- Lonnie

This wraps my thread about timing my '54 235 ...

The engine is running good. I didn't hear any spark knock.

I used a vacuum gauge to set the timing. I checked the BB with a variable timing light. I had to advance the knob to 24-deg to see the BB. I backed off to about 20-deg and tightened the distributor. The BB is at 2-deg after TC. So the 20-deg reading minus 2-deg = actual ignition time 18-deg before TC.
> 20-deg past BB

I compared my results vs the 1954 GM RestoPack:

> Ignition timing at idle in RestoPack = 2-deg after TC
> My actual ignition timing at idle = 18-deg before TC (20-deg beyond GM specs)

> Centrifugul ignition time at 1,500 RPM in RestoPack = 12-deg before TC (+14-deg over timing at idle)
> My actual ignition timing at fast idle (est 1,500 RPM no tach) = 28-deg before TC (only +10-deg over timing at idle, but I'm not sure about the RPM)
I assume that the vac advance was not activated because there was no load.

Jerry - Now I understand what you told me about the vac and centrifugal advance.
> GM '54 Spark Advance - bottom col 1, top col 2

I believe that the engine has the correct 1954 flywheel. Here is a pic of the BB; it looks like a "2" imprinted on the flywheel.
> My flywheel

I'm closing the hood on this one, unless you have some suggestions or ideas.

Thanks for bearing with me while I'm learning.

- Lonnie

Sounds like you got it figured out, the old spec's are a good reference to start at, but with todays modern fuels, they are not always correct. Seat of the pants usually wins out when it comes to setting the timing. I run my 250 with a lot more timing then GM used, it starts better, and gets better milage.

Joe