VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1933-1936 enough spark? 36

Last fall I got some good advice from you guys about starting my rebuilt engine (36 Master). Got distracted with some other repairs, and now I'm back at it. With some Marvel mystery oil in the cylinders, I took out the plugs, and with a 12V battery, it turned over very fast. Having loosened everything up, I put the plugs back in and it turns over well enough that it should be starting. But it's not firing at all. I checked spark at the plugs, and there is a spark, but I'm not sure if it is enough. I'm used to the bright blue spark in newer cars, but how do I know I've got enough? Any simple way to reliably test the coil?

I'm relatively certain I'm getting gas into the carburetor, and I primed it with a small amount of gas.

I would appreciate it if you could point me in the right direction.

Are you checking the spark at the end of the grounded spark plug wire or grounded plug? Weak spark can be caused by a weak coil, bad points,a leaking condenser or bad spark plug wires. Are you sure you have It timed properly? Is the gas fresh? Try turning It over on 12 volts and see If It fires.
Richard

I agree with P.U. Guy.

Also, check to see if the valves are adjusted properly. After having my 30 motor rebuilt, I couldn't get it to fire either. Turns out I had the valves misadjusted and was not getting much compression. For the coil, the 30 owners manual says;
"In order to determine if the coil is operating properly, secure a piece of wire, attach one end on the frame of car or motor casting or other metallic "ground", bring the other end to within 3/16" from the point where the high tension wire (running from coil to the central terminal on the distributor) leads from the coil and crank the motor by hand with the switch on. If a spark occurs at this point, the coil is operating properly."
Although this is for the 1930, the method should work for the 36 also.

Good luck,

Dan

Spark plugs, distributor, cap, rotor, condensor, spark plug wires all new. The only thing I haven't changed is the coil.

I checked the spark with the spark plug attached and body of the plug grounded. Seemed like a weak spark to me, but I'm not quite sure how to judge this. Checked the coil the way the manual you quoted suggested, but even if there's a spark, I'm concerned that the coil could be weak.

I'm going to double-check the timing and valve adjustments tomorrow.

Are you sure that the case on the condenser is grounded? If not you are likely to get a weak spark. Making sure of grounds is critical in these old Chevys.

Will check this. Thanks Chipper.

Take an old (or new) spark plug of any kind and increase the gap to about 70 or 80 thousands. Ground the side of the plug to a good ground (any place on the engine) and attach the plug wire and then test the spark. If its healthy it sould jump the gap.

Great idea, Gene. I'll let you know what happens.

The spark jumped the gap just fine at 80 thousand. That's one possibility eliminated. Will proceed to double-check timing.

If it were mine I would jump it with a 12 volt booster pack or 12 V battery to get it going. But do recheck the "other things" first.

Yes, I'm using a 12volt battery and a charger in start mode.

Probably unrelated, but should I be getting oil pumped up to the valves/rocker arms when just the starter is operating? Or does the engine actually have to be running?

Oh, well. Two steps back... While checking the timing, etc., I heard a sizzling sound, and smelled something burning. I left the 12 volt battery connected with the ignition switch on a bit too long, and it looks like I burned up the coil. Bad move. Live and learn. At least they're not very expensive.
Will update after getting a new coil from the Filling Station.

Fortunately, it looks like the coil still works, but I've ordered a new one just to have it on hand. Valves have been re-adjusted, but I think they were set ok to begin with.

My 12 volt battery and an 80amp starter/charger in start mode turns it fast with the plugs out, but still slow with them in. When I try again, I thought about also getting a compatible 12 volt starter to use temporarily to get it running. Any value to doing this?

Hi Randy,

Good to hear you didn't completely fry your coil.

Have you checked compression in cylinders? No compression = no running. Also, are the spark plug wires connected correctly? Possibly 180 degrees out? That is, set to fire on number 6 when it should be firing on number 1. I only suggest these things because of some embarassingly similar difficulties.

I don't know if hooking up a 12 volt starter will help. It seems that the 6 volt starter would spin the motor much faster with the 12 volt starter pack. On mine, when everything is tuned up just right and it's not too cold, it will fire up with about half a rotation of the motor.

Keep on tryin' and good luck.

Dan

Thanks, Dan. This is a freshly rebuilt engine. Compression is definitely not a problem. I believe the spark plug wires are correctly installed, as they are just like they were in the picture I took before disassembly. Looking at the distributor from the side (passenger side), #6 (nearest the firewall) plug wire is at about 12 o'clock, and the order is 6,2,4,1,5,3 proceeding clockwise. If that isn't correct, please let me know. I've made lots of embarrassing mistakes, and expect to make lots more! As long as I learn something...

Randy,

I think you're 180 out on the firing order. Mine is set up with #1 in the 12 o'clock position and #6 in the 6 o'clock postition. I'll email you some pics of what mine look like. Of course, our distributors could be set 180 opposite each other, in which case your's is correct as it sits.

Dan

I would like to think it's that simple. But it is the same way I had it before disassembly (and running).
[img]http://www.flickr.com/photos/14907429@N00/4718572049/[/img]
This seems to be the same as the arrangement on other 36 Chevys I've seen on the web. Not sure why they're different.

Sorry, should show up this time. Click on link to Distributor.

Distributor

Right you are, Randy. If it worked that way before, it should work again. Starting to sound like a mystery wrapped in an enigma. Not to mention frustrating. These old engines are simple enough that if they don't run it is either because of no gas or no spark. Are the plugs wet at all and/or smell of gas after you've cranked on it a bit? I'll keep pondering about this one for a while. Don't give up.

Dan

One other possibility. When mine was rebuilt, the machinist recommened towing the car up to second gear speed and then easing out the clutch to get it to start. He said it would probably be too tight to start it initially with the starter motor. He was right.

Dan

There is some smell of gas, so it could be flooded. Not surprised if that's the case after so much cranking. But the plugs are still dry enough that I can get a spark with the plug out and grounded to the engine. While I wait for a new distributor, and locate a stronger charger/starter (or maybe another 12 volt battery, with 2 in parallel) so I know it's cranking fast enough, I'll give it a few days to dry out (plugs out) and try again.

Are you going to replace the distributor, or did you mean coil? Sometimes, just walking away from these for a while helps.

Good luck, you'll get her going again,

Dan

distributor is brand new, as well as condensor, rotor, cap, spark plug wires, plugs. Starter has been rebuilt. Only thing original in the ignition system is the coil.

By the way, drift starting it on a hill is not an option right now. Don't have the steering completed yet. Oh, and the transmission is not in, no seats, etc. So going down a hill could be challenging. Might have to do more of the assembly if that becomes the only option.