VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 Troubleshooting the S.B.6

Hello Gang, I continue to work on my '30 Sedan but frustration can sometimes run pretty high. Right now, the car refuses to start putting me back in testing mode. One needs only compression, charge and spark -- all timed to happen on cue, for a motor to run. Yet, cruising evades me. Here's progress to date:

+ Compression tests are complete verifying that the cylinders, rings and valves are healthy. BTW, cylinder pressures were ~80psi except for cylinder #1 which measured 76psi, dry and wet. That implies a valve seal that is a tiny bit less that optimum but running-in will solve that. It is not enough of an issue to cause poor starting.

+ The ignition works but I suspect that the spark is weak. I'm just not familiar with 6-volt ignition strengths. There is also a little more sparking at the points than I would expect if the condensor was doing its job. I have since bought <another> new one to test and swap. There is also a 'ticking' inside the coil when the points open. That may be normal for this vintage of coil but I picked up a new ($12) 6volt coil today to compare. If there is an internal spark occuring, the output would be greatly diminished. Testing will tell.

+ After re-rebuilding the ignition and verifying that it is once again timed correctly, I will move on to the fuel supply. There is a little discoloration in the fuel left over from the oil that the PO put in the fuel tank. I don't 'think' that that is enough to cause problems but I will drain, flush and refill the tank -- again. I also plan to rebuild the carburator -- again -- but this time I will soak it in carb cleaner and remove the jets for cleaning. They are pretty soundly stuck in place and before, to avoid damage, I cleaned them in situ.

Hopefully, I will then have stumbled on to the problem with this old guy. Given the condition of the rest of the car, I suspect to find something stupidly wrong and have the engine come right back to life. The rest of the car is too nice for a major neglect problem to have corrupted the whole engine.

Thanks for listening...

Rick

Hi Rick,

Not sure I understand the point at which you have arrived. You mention 'crusing' does that mean it runs (the engine), but won't go as expected, or now it won't start?

I'll assume that it won't start. After all the projects you propose to do don't work, take a spark plug (either from the engine or a spare) connect one of the spark plug wires to the plug and place the plug on a good engine to plug contact so you can see the tip. Try to start the engine and watch for a strong spark from the plug. If no spark, time to work on the ignition circuit again. Perhaps dirty points, a shorted point plate, or other problem. If good spark, time to do more work on the fuel system. Perhaps take the gas line loose on the TANK side of the fuel pump. Fabricate a connection to pump and a separate source of good FRESH gas. This all assumes the distributor has not been molested. That is, the timing is still set as it was when last run.

If you still have problems, post your results, and we will GUESS at the solution again.

Hi Rick - on my 1930 chevy - I had a similar hard start problem with a weak spark. When I hooked up the output of the coil to a spark plug and applied 6v to the coil intermittently - I had good spark. Points looked good - drove me nuts with the weak spark at the plugs when everything was hooked up. The points looked good. An old friend of mine remembered a similar problem in the 50's on a chevy six . He said - no matter how the points look - give them a light filing and spray them with brake cleaner. Did it and the engine roared to life. The car was sitting for 3 months in damp weather and ran before. I guess a thin layer of corrosion formed on the points causing the problem. By the way - the spark at the points was weaker before I cleaned them. Now the spark is bright and the voltage at the plugs makes a nice blue spark. Hope this helps.

If that does not help, try this for carb problem - I found that the carb was gummed up from old gas and the car would run a while then stop and no matter how much cranking - it would not start. I took the suggestion of spraying carb cleaner into the carb while cranking the engine and put 2 cans of carb cleaner in the tank. Then let it sit a while and try again - it worked!! The car has been running good ever since.

Ray wrote, "Not sure I understand the point at which you have arrived. You mention 'crusing' does that mean it runs (the engine), but won't go as expected, or now it won't start?"

Sorry to be vague, Ray. The engine won't start but I WANT to cruise. :-)

I will win the battle. It is just a matter of going through each system, one by one, and making sure that each one is doing it's job and doing it on time. :-P Somewhere along the way, I will find a stupid little glitch, eliminate it and THEN get to go for a little drive. :-))

Happy Tuesday! Rick

Using an ohmeter, carefully check the low tension wire from coil to dist. wiggle it vigoursly. A shorted wire here will do odd things. Good luck

An easy to check out the low tension wire disconnected from the (-) side of coil thru distributor terminal, points to ground and thru the condenser and to ground is to hold the points open, you should then read the wire and thru the condenser to ground, there should be an open circuit with some capacitance (small amount) if there is low resistance remove the condenser and check again. Then close the points and check , you should have a low resistance (1/2 or 1 ohms)if not if high resistance the points probably are corroded or the lead wire is open.
However this is probably already known by Rick, and the really modern way is to replace parts, coil, condenser, points, rotor, leads both low tension and high tension. and if you don't find the problem take it some old codger like me, or Chevy Nut, JYD, Chipper, or Raymundo. I would rather check out ignition circuits than eat!

"Rather check out ignition systems than eat...", LOL! We are of the same breed. For me, it is dynamic systems -- which ignitions are. That is part of why I can't leave this problem alone! Let me tell you what I have done and then brainstorm a little:

Last night, I installed a new 6v coil (one not requiring a ballast resistor), cleaned the NEW points with #400 grit emery paper and washed them with brake cleaner (tri-chlor) then measured the resistance from the coil's negative wire (before connecting) to ground. With the points open, the reading was high; closed it was about 0.3 ohms, which translates into about 0.6 volts drop. These are of course, static readings. The leak-down on a new condensor (also designed for a 6v, non-balasted ignition) was similar to that of the new one I previously installed in the car. Once connected, the new coil produced a noticably hotter spark. I felt good. I timed the ignition, installed the plugs and wires (1-5-3-6-2-4, counting clockwise from #1), gave the carb a blast of starting fluid and cranked it over. Nothing. Not one of the cylinders tried.

So now we come to brainstorming. With the engine timed at 12 degrees before top center (pointer aligned with the 'line' in the " |12 " mark on the flywheel) the distributor rotor points toward the notch in the distributor where the cap 'key' fits to guarantee proper alignment. This COULD be 180 degrees out of phase as I don't have the valve cover off to guarantee that #1 is on the compression stroke. However, it IS the alignment I observed when the car was first delivered to me and it matches the pictures.

I did observe that the tip of the rotor does NOT align with the contact in the cap. Rather, it is at the extreme end of one side with only the opposite corners of the contacts aligned. This of course allows for centrifugal advance. It also says that any "Spark" retard added must be done so with the engine at speed or the contacts will be very far apart. In the engine design world, this is called 'phasing'. It is most used with optical interupters whose position on the breaker-plate is adjustable. The only way for that to be an issue on our old cars is from installing incorrect points -- which may be possible.

Okay, I have dumped my brain and have nothing left inside my skull. Sounds like a good time for me to get back to work. :-P

Best regards and thanks, my friends,

Rick

Rick, in the system you have I would suggest that first we need to be sure that you have a system that produces a good hot spark all the way to the sparkplug, a simple way to do that is to clamp a good sparkplug , gapped to recommended gap, to the engine (good metal to metal contact ) with a pair of visegrips or C clamp where the #1 plug wire will reach, and have some one run the starter with the ignition on, you can observe the spark, I grant you it isn't the same as whenthe plug is in the cylinder (compression etc.) But that will give a good test of the high tension circuit. After we produce a good hot spark, then do the timeing of the spark to the mark on the flywheel first static then with a timeing light. I don't know any way of being sure #1 is on compression stroke without useing a whistle, or pulling the valve cover and observeing the rockers, to insure both valves are closed and there is no tension on the rockers. There is a great deal of lattitude in where the #1 plug wire should go, I get # 1 cylinder with the piston TDC on compression, and then place the plug wires in the cap with #1 at the rotor, you may need to turn the body of the distributor by hand to line up the rotor and plugwire contact, then tighten the clamp. Then plug the other wires in the cap according to the fireing order. Then the engine should run. Now I fine tune with the timeing light, loosen the clamp holding the distributer body, turn the distributor body to line up the timeing mark, as per the shop manual, and as soon as I get the timeing set I use a dwell meter to check the dwell, and if it is off, reset the point gap, dwell check , adjust the gap till the meter reads correctly for the number of cylinder engine. set the carb idle jet and idle speed, and stand back and listen, hopefully you will be pleased with what you hear!

Rick, If you have spark, try this. remove #1 plug, remove the dist cap (to watch the rotor) loosen the screw on the right side of the distributor so you can turn the dist.

1. Hold your thumb over the #1 plug hole
2. Crank the engine until you feel the compression coming.
3.check to see where the rotor is to #1 wire on the cap.
4. If its not close to #1 position remove the screw (the one that holds the dist. to the block) and bring the rotor as close to it as possible. It will not go all the way down at that point because the oil pump will not be lined up.
5. Holding the dist.down crank the engine again until it goes down.
6. now one more time crank the engine watching the rotor with thumb over #1 hole to check for compression.
7. If its close to #1 button it up and give it a go. It should start or try to, then you can advance or retard the spark and bring it in.
Hope this helps, it works fine for me.

Thanks all, for the ongoing good advice. Please take a look at this picture and tell me what you think: http://www.stoolhead.com/IgnitionGraphic.jpg

The rotor rotates CLOCKWISE, right? (I am at work, the car is at home.) Therefore, why is my rotor so misaligned -- to allow for advance, one would presume? One would think that any more retard (like touching the SPARK control) would prevent the spark from making the jump. Am I timed to the WRONG side of the cam lobe?

It's funny how the binary things are the most confusing. 'Right versus left', 'before versus after', etc..

Your comments are encouraged and appreciated...

Rick

Rick, regardless of the direction of rotation loosen the clamping bolt that keeps the distributor body from turning and rotate the body of the distributor into alignment with the rotor with #1 plug wire contactor when @1 cylinder is at tdc and on the compression stroke.

Now all you Grurus, when does the plug fire?

(1) When the points open?

(2) When the points close?

(3) the plug fires independently of exactly when the points open or close?

(4) Only, and not untill the contact of the rotor aligns with the plug wire contact allowing the spark to jump to the plug wire completeing the connection to ground?

(5) None of the above

(6) several of the above must be in the correct position.

:confused: :( :p

answer, 'true', never did like multi-choice.

MrMack, I'll go with #6....Points open, coil fires,rotor points to right plug

Rick - before you go this route - please try the following first to make sure you are getting the proper spark to start with. Hook up a spark plug wire directly to the output of the coil and ground the body of the plug hooked up to the other end of the wire. Put the ignition on and remove the distributor cap. Manually open and close the points and observe the spark at the spark plug. If it isn't bright blue - you still have a problem other than timing. If the spark is healthy - the motor will still try to fire even if your timing is off. If the rotor is in either of the positions shown on your diagrams - a healthy spark will still jump the gap and the engine, while it may not run will still try to start and if too far advanced will backfire. Once at this stage - then work on the timing.

I'll take MrMack's quiz, even though my gruru-status is in peril...

> Now all you Grurus, when does the plug fire?

> (1) When the points open?

The field in the coil collapses, after the appropriate DWELL, when the points OPEN with the primary circuit being completed through the condenser -- but that doesn't guarantee that the plug will fire. For that to happen, the rotor must also be aligned, to some degree of precision, with the pole in the cap. That is called 'ignition phasing'. The high tension wires must be in good condition and connected on both ends, and the plug, any plug, must be gapped correctly and in good working order; BUT, none of this requires the piston to be in the correct position on its stroke. This, my friends, is the essence of 'ignition timing'.

> (2) When the points close?

When the points CLOSE the coil's primary winding saturates and induses a magnetic field. This change causes a voltage to flow in the secondary but it is not the high tension event that fires the plug.

> (3) the plug fires independently of exactly when the points open or close?

This only happens with British cars with Lucas ignitions. :-P

> (4) Only, and not untill the contact of the rotor aligns with the plug wire contact allowing the spark to jump to the plug wire completeing the connection to ground?

If (1) and (4) are satisfied, the plug should fire -- but not necessarily at the right time.

> (5) None of the above

See (3) above.

> (6) several of the above must be in the correct position.

Vague, but true.

Last night I verified that the distributor rotor rotates clockwise and that centrifugal advance turns the rotor counter-clockwise. All is right with the world.

Okay, I have a hot spark, it occurs at the right time and I have compression. That leaves 'charge' to be the problem. I have NEVER seen an engine with compression and correct ignition that would not at least TRY to start when charged with ether (starting fluid). Mine won't. Ideas? From here, my next step is to pull the carb off and rebuild it -- again.

Rick

Wow, now it's an essay test, which I dislike even more.

But I like your answers.

Yeah, You have the right answers, the final event required is that the saturation must have taken place just in time for the "switch" (which is the rotor aligning with the plug wire contact )to be thrown. as to the proper charge, try spraying WD-40 in the intake rather than ether, it is not so harsh on the gasoline engine, It works on a hard to start lawnmower also.

Have you tried a timeing light to check the timeing? do you get any reaction at all maybe a backfire or any indication of fireing?
the next thing I would be concerned with is if by chance the timeing gears have jumped a couple of notches. ( Do you have good vacuum at the top of the carb? otherwise will it suck the starting fluid in as you crank?)

Well, it's Monday and I've had a weekend to work on the old Chevy. I am happy to report that the ignition is in great working order and producing a hot spart at the plugs -- and on time! The confounding problem was TWO problems interacting. (1) The coil was very weak (how? I don't know.) plus the plug wires are less than optimal. And (2), The carburettor is hosed.

Sorry to use the technical term on you there but the carb is beyond my level of expertiese. The jets, air and/or fuel, are frozen in place and refuse to come out without damage. Therefore, I have decided to send it off to The Carburetor Refactory to be professionally rebuilt. I have used Merrill before and he does quality work. The cost is about the same as quoted elsewhere but I know Merrill's work. Complete job is about $235, including shipping.

While the carb is off getting pampered, I will flush the fuel system properly in preparation for it's return.

Yesterday, I removed the fuel pump again. I rebuilt it a bit ago but I had noticed a small leak from the diaphram where the upper part of the casting wasn't sealing properly. It is now nicely sealed.

I also took the opportunity to clean the pump valves again and cleaned the fuel bowl. When I took the 2" OD rubber seal out of the fuel bowl screen area, it expanded by almost 1/4" in diameter! It is not reusible! I have never seen a rubber seal expand like that before. Gaskets shrink but this is a first for me. Fortunately, I still have lots of time to get a new seal before the carb comes back.

That's it for Monday. I am getting more comfortable with keeping the car now that I have a storage area for it. I just have to get it out of my wife's side of the garage!

best, Rick