165-170F and above spark issue?

R

RickMcK

Member
I have 36 pickup. I'm struggling to fix a issue when the Radiator is about 170F The engine runs great below about 165F. Above about 165F it feels like it is loosing spark. Here is what I have tried thus far:



  1. Several distributors and rotors (distributors set up by Skip)
  2. 2 round top coils (were evacuated and tested in 2014 at 30KV, then in storage) and 2 external coils (one brand new)
  3. If I bypass the ignition resistor I can get maybe 10F more.
  4. I backed off the vacuum brake adjustment and it helps, but not enough.

  • Starts great below 150F
  • Distributor caps look good and are fairly new
  • Plug wires are 15 YO with near zero miles on them (truck was in storage for 10+ years). I think they are the kind with solid wire cores
  • 40 year old Champion plugs
  • When it's hot (above 165F) it will not start, once it cools to about 130-150 it will start.
  • Will run at part throttle at about 170F, but is mush at full throttle, and will die if at regular idle RMP at +170 with resistor bypassed.
My thinking is the left point dwell (not enough coil saturation), plug wires and or plugs.


Also, what typical max temp at idle?


Any thoughts - ideas to test- try- replace?
 
Take his with a grain of salt but I put an engine in my da's Model a that ran great with the Champion plugs that were in it. At least it did for 100 miles or so. Seemed like a condenser issue but that did not work. Pulled out the champions and put in the 3X that were in the other engine and all became right.
No one could really tell me about a plug just failing and there was nothing really visible to indicate it failed or maybe it was all of them.
 
Champion was bought by NGK and new Champions are made by them and are good plugs, older made ones, not so much.
To me heat related ignition problems usually point at the condenser or coil or both. However, if your underhood temp is high, your fuel pump if old may not be creating enough pressure to keep a steady flow of fuel.
Remember New does not = Good anymore, especially where condensers are involved. (Even Skip has had a few coils fail due to solder connections inside) For starters I would ditch the 40 year old plugs as that is the easiest. Next I would try a new fuel pump since you have tried all different parts of the ignition. Good luck and keep us informed.
 
R&R'ed the plugs with NGK's, and I new IH 200 Condenser.

Coils read 1.1 Ohm across the low voltage terminals, and 8.8 Mega Ohm low to high voltage. With ignition resistor I have 4vdc at the coil with points closed.

Plugs and Condenser helped but not enough. Now it craps out at about 180F. Will restart when hot only by bypassing the ignition resistor. It has a new fuel pump (with glass filter bowl.

Under hood temperatures are about 105F.

Because it will only hot start by bypassing the ignition resistor. I assume (can make an *** out of me), it is still spark related.

Should I replace the caps, rotors and wires? If yes to the wires what kind is best? Currently it has solid wire core type.

Thanks
Rick

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Frank. Good ldea. I have not though of that. I will try it, then I guess I will order some newer : rotor, caps, & wires.

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I would disassemble the ignition switch and clean the contact surfaces. Also disconnect wires from ignition coil, ballast resistor and ignition switch and clean eye terminations and nuts with either a file or fine sandpaper and resemble. That ballast resistor is a sleeper - remove all nuts and the resistor and you will note that the studs sticking out of the black fiber board. Reassemble in this order: you have cleaned the flats on all of the nuts with either the flat of a file or sandpaper, then install a nut on each stud, then the ballast resistor, followed by a wire either to the ignition switch or the coil and finally a nut on each stud and snug each nut with a wrench. What we are trying to do is avoid a voltage drop in those connections for the ballast resistor and at the coil.

Considering the spark plug wire, check them with an ohm meter and you should have zero ohms. The terminals may be giving problems. I am in favor of using solid core wires and retain them if at all possible. If the insulation is hard or cracked, then consider replacing them with Packard 440 (solid core wires.). For the terminals, I strip the insulation back about 1/2 inch, insert the wire thru the terminal, fold the wire back over and insert into the socket. A new cap and rotor is a good idea - hard to see any defects in a cap or rotor. Merry Christmas to ALL.
 
Thank you for the suggestions.

New data. Found 1 distributor cap, and change it out. Got to 180F-200F. I'm more confident that it's the Distributor caps.

Already cleaned and checked the ignition switch, and did a simple bypass. No effect. External coil has an integrated resistor, so I'm bypassing the dash resistor.

Plug wires all measure about 1-2 Ohms, so they look good. They are solid wire type and look and feel new.

I have 5 rotors that I can try after I get new caps.

At 195F, it will barely Crank (turn over). Cranks good and fast when cooler. Battery is brand new running at 6.2V. I'm using a solenoid in the circuit and using the foot switch to activate the starter circuit.

I will try backing off the timing a little bit, and re-clean all the electrical connections.

I will update after I get new caps.

Thanks again for the help.

Rick Seattle.

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Machined a set of distributor caps (see image), and got the gaps to be about 10 thousands of an inch or less. Re-cleaned all the electrical connections.

Now it will run up to about 180F. It improves if I set the timing advance all the way up. Skip H, set up the distrubitor, so I trust the dwell is correct.

Below 180F it seems to Rev fine. Can't take it for a test drive because we have about 3-6 of snow, and the roads are sheer ice (in Seattle).

Is there a way to find #1 TDC, without removing the cylinder head?

Any more ideas thoughts?

Thanks
Rick McK Seattle. 21-12-27_2.11.10PM.jpg21-8-21_12.56.59PM.jpg0821211258a.jpg

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Make a metal strap pointer that uses the two 3/8ths tap holes on front of engine and I put mine on the passenger side. Remove #1 plug and insert a zip tie so that it stops the piston before TDC, mark the crank pulley where the pointer indicates on the rim of the pulley, then turn the motor in the opposite direction until the piston again pushes the zip tie against the head. Again mark the pulley rim at the pointer. Now you have two marks. Go half between the two marks and that is TDC. File a notch on the rim of the pulley. Using a timing light, set the firing point about 1/4 inch (4 degs) in advance of TDC. I have to remove the belt for a better view of the pointer and notch. In your earlier post you stated that the motor would not turn over when hot - you have a rebuild that needs more miles or is it that the battery does not have enough capacity? If you are using a lead acid battery, you might consider an Optima - has a lot of capacity and will last a long time. I installed mine 7 - 10 - still good.

The foregoing represents the zip tie method to avoid pulling the head. When I rebuilt my motor I could use the hard stop method by putting a socket over a stud held down by a nut on the stud and proceeded from there. Hope this helps. And Happy New Year to ALL.
 
Bill. Thank you for zip tie process. I will put a wad of tape on the end to ensure that it does not fall into the cylinder. That is a very good idea. If it warms up some I will try it this afternoon.

The battery is new (interstate). I need to clean all the connections and test it again. The motor has about 15hr on it so I don't think it's overly tight.

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Rick: Get about 5k miles and you should have better results starting. At 50 mph at 15 hrs is 750 miles - guesstimate. Temp will drop too.
 
I agree on giving it more time. I had a Corvette motor that was built so tight that it would overheat if left to idle. I was just about ready to pull it out at about 2500 miles, when it finally got broken in and I have not had a problem with overheating since. 2500 miles at 50mph is 50 hours so you have a way to go.

I have a suspicion that some of the "Race Engine" builders strive to get ALL of the tolerances in the engines they build to the absolute lower limit so they can brag to their buddies, which leads to this kind of problem.
 
Did some more messing around. I found that disturbtor I was using was only giving my 10-15 degrees of advance. I tried a spair I have and It was better (20 degrees advance), but still feels retarded about 175F. I did the wire tie TDC trick and marked the Crank Pulley. Then I groung the mechanical advance stops and get some more advance. It's better, but still feels retarded when hot (above 175F.

The starting problem was a bad connection. Now it starts great hot or cold. Hot idle oil pressure is only about 10 PSI, so I don't think it's tight.

Now with the advance adjustment all the way up (max advance) it starts fine when hot (185F). But still feels retarded. Because it will start really advanced when hot does not seem right. If I remember correctly hot engines don't want to start if the timing is too advanced. Am I correct?

Next, I will check the Dwell. And see if I should open up the Rt points to make the spark more advanced.

Any more ideas?

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That distributor should only have 11 degrees advance which is 22 degrees crankshaft plus 4 degrees initial makes 26 degrees total and that is about right for a flathead. Too much advance and the engine will be running against itself. I would not have ground the stops. Send a good core to Skip Haney in Fl and have him set it up for you.
 
Thanks. Yes I was worried that opening up the advance might be a bad idea. It really didn't make it any better and I only got a few degrees (via timing light) anyway.

I'm getting it hot by putting a plastic bag over the grill.

Skip set them up (3 of them), he said they all checked out OK. I have not tried the 3rd one yet.

But I'm still not sure what to do.

The block has a minor crack at the #3 (torque sequence) stud. When I initially torqued the heads that stud "popped" (heads and block are flat and true. It torqued to 55 Ib, and there was a micro drip next to the exhaust stud. I see some white smoke (steam), but NO bubbles in the radiator so I don't think it's into the cylinder. It's just into the exhaust port. I don't know if the white smoke is a dew point issue (it's cold at 90+% RH) or if it's throwing out water vapor. I don't think this should be an issue, but I might be.

I'm debating if I should start all over again with a new block, try to have this one repaired, or just run it.

Maybe it's OK the way it is. I will have to wait for better conditions to take it for a test drive (snow on the roads in Seattle).

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The more I think about this problem. I'm starting to think that it's a crack leaking water into a cylinder when it gets hot enough. Does this make sense? I'm not sure because at no time do I see any bubbles in the water (radiator).

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I would run it. Wait until the ambient temp gets to 60 F or better and see if the white smoke persists - water vapor is a product of combustion. If you want to make a tiger out of kitty cat, back the vacuum brake clear out, use a 48 Stromberg and install a straight thru muffler with a 1 7/8ths tail pipe or more. Your seat of the pants dynamometer will show you the results. A 221 will run!!!
 
Bill. Thanks. Yes I will stop messing with this issue until the Spring (when it warms up), and see if the white smoke (steam), goes away.

I guess it's telling me to get out of the shop, and go Skiing. [emoji106]

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