PhilAndrews

'51 Chieftain - Transmission fixed, troubleshooting running

Recommended Posts

I like boots because I have a habit of leaning across plain terminals and that's unpleasant when it's running.

 

F143867458.png

I'm thinking a set of ends like this.

  • Like 1

Share this post


Link to post
Share on other sites
1 hour ago, PhilAndrews said:

 

 

It makes me think that maybe there is too much ability to spark from this coil

 

That isn't really how it works. The voltage the ignition runs at is mainly set by the spark plug gap and the resistance of the spark plug wires and plugs.

 

Distributor_Ignition_System.png

 

This is a secondary ignition pattern on a scope for a four cylinder engine, just a graph of voltage over a period of time. Let's just look at the first cylinder. Imagine this line being drawn from left to right. The spot where the points open is 2.5 milliseconds in. The circuit is open (because of the spark plug gap). You could also look at it as having an extremely high resistance. The voltage rises instantly to 12 kilovolts. In this particular cylinder, 12 kilovolts is what it took to ionize the fuel/air charge inside the spark plug gap. The spark jumps.

 

Once the fuel/air charge is ionized and the spark jumps, the resistance of the gap is MUCH lower. Since the resistance is so much lower, the voltage drops A LOT. You can see it dropped to between 4 and 2 kilovolts for about a millisecond and a half while the spark is happening. Then, when the coil runs out of energy the spark goes out and the voltage goes negative for a little bit. About 7 milliseconds in (on this particular diagram) the voltage is back to zero, and we are ready to start the process over for the next cylinder. The pattern repeats four times here, but would repeat 8 times on your 8 cylinder engine.

 

It takes more voltage to ionize the fuel and air with a wider plug gap, and that will make the spike (12 kilovolts in the diagram) go higher. A problem in the wire will also make the voltage go higher, due to the higher resistance in the defective wire. Electricity always takes the shortest path. As the voltage rises up into the kilovolt range, if it can blow through the insulation somewhere easier than ionizing the plug gap, then that is what it will do.

 

Also, as the voltage rises, if the resistance is too high for the coil to overcome, then the voltage will continue to rise until the coil runs out of energy, never making a spark at all.

 

Edited by Bloo (see edit history)
  • Thanks 1

Share this post


Link to post
Share on other sites
1 hour ago, PhilAndrews said:

I'm thinking a set of ends like this.

 

Nothing wrong with those, although plain rubber boots (especially with a little silicone dielectric grease) will do a little better job of keeping the spark in where it belongs. At the voltage level your ignition will be running at normally, those Champion things will be just fine.

 

Any ignition cables can shock you if you get too close.

 

Share this post


Link to post
Share on other sites

Thanks for that, familiar with how an ionized path breaks down, but it's been a long while since I had to troubleshoot a points system.

 

Looking around and I see NGK do some better right angle boots, they've got rubber inserts, designed for boats.

 

I'll have a look at the wires tonight.

 

Phil

Share this post


Link to post
Share on other sites

Also, off-topic but on-topic, there's mention of the cylinder head castings showing high-comp and low-comp versions. Where's the identifier usually put? 

I don't see any reference on mine, so it may be a replacement cylinder head, as the numbers stamped into the block deck match the VIN. It should be high-comp, A8UH.

 

Phil

Edited by PhilAndrews (see edit history)

Share this post


Link to post
Share on other sites

20191018_162024.thumb.jpg.17d3b5ba06165f14b1daf0f86d038ff3.jpg

As promised, tested all the leads. None are open.

 

20191018_161933.thumb.jpg.ef0b9a916b824149a6509b8b787a1411.jpg

All are 0.2 Ohm or less.

 

Breakdown insulation? Cannot attest.

 

However, I decided for giggles to tweak the timing.

 

 

Result. Problem? Distributor cap needs replacement.

 

Phil

Share this post


Link to post
Share on other sites

High compression head will have a different casting number. i don't have a new enough parts book to look yours up.

Share this post


Link to post
Share on other sites

Mine and others I’ve seen are stamped “high compression” above the temperature sending unit. 

  • Like 1

Share this post


Link to post
Share on other sites

I'm guessing this has a replacement head then because I don't see any signs of that. Anyone has a picture?

 

Phil

Share this post


Link to post
Share on other sites

This is the head I got with an engine someone gave me. The head to the engine originally in my 48’ (that I’ve already had cleaned and surfaced, and thus is going back on) has no markings and is not high comp. So your head may not be a replacement, it may just not have come with it. In somewhat related news, I guess I have a high comp head for sale. 

710120DA-0F5B-4915-9D26-C9FBB7C52B45.jpeg

  • Thanks 1

Share this post


Link to post
Share on other sites

Okay, that's very definitely marked! Thank you.

 

In that case mine may be a low comp head. 

 

I guess I'll just have to do without the extra few horses if not.

 

Phil

Edited by PhilAndrews (see edit history)

Share this post


Link to post
Share on other sites

20191018_203739.thumb.jpg.56fc4ee1e2ef608a1dac5d49331cc9fe.jpg

There's this up at the front, says GM4 513794, and there's also A18 1 in front of the thermostat. 

 

20191018_203751.thumb.jpg.c016d76395dec7801ab8eda839f7b699.jpg

Rear has nothing

 

20191018_203846.thumb.jpg.a56a8a2f6e6e38c5b17e05160507491d.jpg

Can just about make out the A8UH there in the block stamping.

 

Phil

Share this post


Link to post
Share on other sites

20191019_092915.thumb.jpg.6ff8637c4c324734c4edb68ff70ea089.jpg

Nice day today and I'm stuck at home so I broke out the dish soap, 2000 grit and water.

 

20191019_103548.thumb.jpg.f4a134ec60202eafa249b97d79be57c1.jpg

Then got busy with 2 grades of polish.

 

20191019_125611.thumb.jpg.fb2f3788125b68bc5029a1ba3f23331a.jpg

Then a bit of wax.

 

Still got a lot to do but it's looking better.

 

 

Phil

  • Like 2

Share this post


Link to post
Share on other sites

You might just try the polish without the 2000 grit. The sandpaper will take of some of the paint. The car looks good. 

Share this post


Link to post
Share on other sites

I did, it's scratched to billy-o.

 

I appreciate I'm pulling paint off but in this instance I couldn't get a decent shine otherwise.

 

Phil

Share this post


Link to post
Share on other sites

I use a Meguiar's kit that attaches to a drill with a bottle of their polishing compound. Does an amazing job!

  • Thanks 1

Share this post


Link to post
Share on other sites

This ignition system is giving me grief.

 

I wired up my little tacho and it shows an uneven draw in current, the needle periodically jumps up.

 

Phil

Edited by PhilAndrews (see edit history)

Share this post


Link to post
Share on other sites
On 10/15/2019 at 1:21 AM, pontiac1953 said:

i have an extra nos dual point conversion kit, breaker plate with two new points, you would just move the condenser to the outside of the distributor housing. here's pictures of the conversion in my 55 pontiac 287 distributor - same size housing as yours.

 

Would you be willing to part company with it? And if so, for how much?

 

The plate in mine is, for want of a better description, wibbly-wobbly.

 

Thanks

 

 

Phil

Share this post


Link to post
Share on other sites
On 10/19/2019 at 5:17 PM, Summershandy said:

I use a Meguiar's kit that attaches to a drill with a bottle of their polishing compound. Does an amazing job!

20191019_155826.thumb.jpg.9e77f69f830fe137d461c03a7244fb81.jpg

Elbow grease will just have to suffice.

 

Phil

  • Like 1

Share this post


Link to post
Share on other sites

Misfire appears to be predominantly down to sticky valves. I'm going to pull the head off again, lift the valves out and check them for straightness, rust, coke and dirt and clean up the guides.

 

That should help. Is this something these engines are prone to, sticking valves?

 

 

--Phil

Share this post


Link to post
Share on other sites

I have a straight 8 which is almost  like yours. When I bought it , it was not run since 1975. All my lifters were frozen in the up position. Besides pulling the head I took off the side covers. I used Kroil  and a 1/2 wrench and freed them all up.   Mine is in a 37 Oldsmobile 

Share this post


Link to post
Share on other sites

I don't think the lifters are sticking because it gets really loud as if the lifter is being flicked up and down by the cam.

 

Phil

Share this post


Link to post
Share on other sites
On 10/20/2019 at 4:27 PM, PhilAndrews said:

 

Would you be willing to part company with it? And if so, for how much?

 

The plate in mine is, for want of a better description, wibbly-wobbly.

 

Thanks

 

 

Phil

just got home tonight, $35.00 mailed to you, you can text me if you'd like, 4176935219, charles.

Share this post


Link to post
Share on other sites

Charles, thank you. My in house accountant says I must wait this week.

Children are expensive things to send to camp...

 

Phil

  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now