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'51 Chieftain - Getting back to it


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I adjusted the throttle and gearbox linkage- smooth, gentle gear changes at light throttle are possible.

 

I just need to work on getting the free play out of the connecting rods because they're worn and a number are missing their springs.

 

Phil

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1 hour ago, PhilAndrews said:

I adjusted the throttle and gearbox linkage- smooth, gentle gear changes at light throttle are possible.

 

I just need to work on getting the free play out of the connecting rods because they're worn and a number are missing their springs.

 

Phil

what connecting rods and springs are you referring to ?

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20191016_195445.thumb.jpg.1020aaa96fa21b7453c00d6efb3df852.jpg

Throttle linkage. 

From left to right, R pin, washer, spring, throttle crossbar, rod to carburetor.

 

The spring was missing so the connection was very sloppy. Now it is held in line in normal operation but can still squeeze sideways if things jam up.

 

Phil

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Really bad bogging down and misfire at light to medium throttle.

 

Feathering the throttle generates good running and good gear changes. Flat to the floor provides decent get-up-and-go once in top but the 1-2 change is not happy.

I think it's all yet out of adjustment, but I do need to sort the engine running problems first.

 

--Phil

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Some suggestions:

 

1) Do a compression check. All spark plugs removed, throttle open. Pay attention to the second puff, and also what it tops out at. Don't get too hung up on the actual numbers, you're looking for one that is WAY different than the rest.

 

2) Measure your spark plug wires with an ohmmeter. One of those cheap/free little red Harbor freight digitals will do fine if you don't have a VOM or DMM. I wouldn't even remove them from the cap unless you find something wrong. Measure from the terminal under the cap out to the spark plug end. It is kind of fiddly because you will have to scrape around on the terminals with your probes at both the terminal under the cap, and also at the spark plug end, to get a good connection for the test. You are again looking for something radically different. For instance, if the wire is copper or metallic, the resistance will be really low, it could even be as low as a couple of ohms, or maybe a few hundred if they are spiral core wires. If they are resistor wires (probably), they will have maybe 2k-5k ohms (or more on cars with longer wires than yours). The resistance is spread over the length of the wire, so the longer ones should be higher. A shorter wire with a higher resistance is EXTREMELY suspect. If you find one with way too much resistance, replace it, and replace the rotor in the distributor too.

 

3) Inspect your distributor cap under a bright light, looking for anything that looks like a carbon track (or crack) either between terminals, or down to the edge where it contacts the distributor housing. Look on the outside of the cap as well. Look at the the carbon button that contacts the rotor. Make sure its there. It needs to touch. If it is spring loaded, make sure it moves. If it is the sort of cap that does not have a spring under the carbon button, then the rotor will have a flat springy part at the center to contact it. Just make sure the two are going to touch, and you are not going to have a big gap up there when it is assembled.

 

4) Disconnect the line going to your wiper system. Plug the end that goes to the intake manifold. I am going to guess you have a vacuum booster pump, but either way, plug the line going to the manifold and make sure it seals. A leak in the pump diaphragm, the wiper motor itself, or the hoses can cause a huge miss.

 

5) Try different spark plugs. A cracked insulator can cause all sorts of havoc, and the plug will look just fine.

 

Edited by Bloo (see edit history)
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10 minutes ago, Bloo said:

Measure your spark plug wires with an ohmmeter.

Just to throw in my 2 cents. Even though it may not be the same vehicle or year I just wanted to share. 

I have a '94 Class B camper van that started to mimic a transmission problem. It would shake in overdrive or when acceleration was needed. It also kinda ran crappy at idle but with all these problems, still got me around. I had changed everything but the plug wires so I did that couple weeks ago. Amazing! It starts without hesitation, has great acceleration and the transmission runs flawless. I would have never believed a $65 difference in performance.

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20 minutes ago, Bloo said:

Some suggestions:

 

1) Do a compression check. All spark plugs removed, throttle open. Pay attention to the second puff, and also what it tops out at. Don't get too hung up on the actual numbers, you're looking for one that is WAY different than the rest.

I do need to get a compression gauge. Cranking over on the starter WOT it's pretty even though.

 

20 minutes ago, Bloo said:

2) Measure your spark plug wires with an ohmmeter. One of those cheap/free little red Harbor freight digitals will do fine if you don't have a VOM or DMM. I wouldn't even remove them from the cap unless you find something wrong. Measure from the terminal under the cap out to the spark plug end. It is kind of fiddly because you will have to scrape around on the terminals with your probes at both the terminal under the cap, and also at the spark plug end, to get a good connection for the test. You are again looking for something radically different. For instance, if the wire is copper or metallic, the resistance will be really low, it could even be as low as a couple of ohms, or maybe a few hundred if they are spiral core wires. If they are resistor wires (probably), they will have maybe 2k-5k ohms (or more on cars with longer wires than yours). The resistance is spread over the length of the wire, so the longer ones should be higher. A shorter wire with a higher resistance is EXTREMELY suspect. If you find one with way too much resistance, replace it, and replace the rotor in the distributor too.

I have a decent meter, I'll give that a try. I don't have a megger but my VTVM reads low Ohm range accurately (it's good down to about 1/5 of an Ohm, try that with a cheap DMM)

 

20 minutes ago, Bloo said:

3) Inspect your distributor cap under a bright light, looking for anything that looks like a carbon track (or crack) either between terminals, or down to the edge where it contacts the distributor housing. Look on the outside of the cap as well. Look at the the carbon button that contacts the rotor. Make sure its there. It needs to touch. If it is spring loaded, make sure it moves. If it is the sort of cap that does not have a spring under the carbon button, then the rotor will have a flat springy part at the center to contact it. Just make sure the two are going to touch, and you are not going to have a big gap up there when it is assembled.

Didn't see anything but it's an unknown quantity and I think I'm just gonna shotgun it for a new cap and arm.

 

20 minutes ago, Bloo said:

4) Disconnect the line going to your wiper system. Plug the end that goes to the intake manifold. I am going to guess you have a vacuum booster pump, but either way, plug the line going to the manifold and make sure it seals. A leak in the pump diaphragm, the wiper motor itself, or the hoses can cause a huge miss.

Currently disconnected and plugged with a bolt in the manifold take-off.

 

20 minutes ago, Bloo said:

5) Try different spark plugs. A cracked insulator can cause all sorts of havoc, and the plug will look just fine.

 

Also a genuine possibility, 7 of them are what came with the car.

 

 

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9 minutes ago, Summershandy said:

Just to throw in my 2 cents. Even though it may not be the same vehicle or year I just wanted to share. 

I have a '94 Class B camper van that started to mimic a transmission problem. It would shake in overdrive or when acceleration was needed. It also kinda ran crappy at idle but with all these problems, still got me around. I had changed everything but the plug wires so I did that couple weeks ago. Amazing! It starts without hesitation, has great acceleration and the transmission runs flawless. I would have never believed a $65 difference in performance.

Yeah, I do want to change the leads. I'm trying to find a source of decent phenolic right-angle caps. I'll probably buy a length of wire and make my own wires up so they are the correct length. The insulators rubber boots are shot on a few of them, but do not track visibly when run in the dark. Not to say they aren't but that was the best my eyeball could muster.

 

Also there is a certain amount of energy being lost through the cap because my neon plug tester flickers dim and then goes with a bright flash each ignition stroke.

 

I'm hoping that changing the ignition sundries, giving the carb a decent clean out and another tune-up solves it.

 

--Phil

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For what its worth, I am not running boots at all on my 36 at the spark plug end (as original). I do have them on the distributor end, but that is mainly to keep water from getting down inside the towers and making a corroded mess. Of course it is better to seal things up with boots. I have been out driving in the rain and no issues yet, despite reports of it being a problem when the cars were new.

 

Boots or no boots, it doesn't necessarily have to arc over to miss. It there is an open circuit or extremely high resistance somewhere, like an open-circuit plug wire, or a missing carbon button in the cap, the coil will run out of energy before it establishes a spark at the plug.

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20 minutes ago, Bloo said:

For what its worth, I am not running boots at all on my 36 at the spark plug end (as original). I do have them on the distributor end, but that is mainly to keep water from getting down inside the towers and making a corroded mess. Of course it is better to seal things up with boots. I have been out driving in the rain and no issues yet, despite reports of it being a problem when the cars were new.

 

Boots or no boots, it doesn't necessarily have to arc over to miss. It there is an open circuit or extremely high resistance somewhere, like an open-circuit plug wire, or a missing carbon button in the cap, the coil will run out of energy before it establishes a spark at the plug.

The belt it gave me at the plug end suggests otherwise- it had enough energy to go through the rubber and arc through about 1/4" of air before hitting the spark plug terminal and grounding itself by sparking inside the engine...

 

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

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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)
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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.

 

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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

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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)
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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

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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

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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

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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 

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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.

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49 minutes ago, PhilAndrews said:

Question a deep C type spring compressor

 

 

What's the best type of valve spring compressor for this block? I'm looking at the pincers style ones that wind out.

 

Phil

 

49 minutes ago, PhilAndrews said:

Question

 

What's the best type of valve spring compressor for this block? I'm looking at the pincers style ones that wind out.

 

Phil

 

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I managed to clear up the valves with some gentle persuasion and a bit of lubricant

 

Back now really to needing gaskets because I can't get the mixture to balance across the rev range. I think the carburetor probably needs a good clean because I've had to dial the slow-running jets out quite a bit further than the manual suggests to get it to run without leaning out at light throttle.

 

Phil

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5 hours ago, PhilAndrews said:

I managed to clear up the valves with some gentle persuasion and a bit of lubricant

 

Back now really to needing gaskets because I can't get the mixture to balance across the rev range. I think the carburetor probably needs a good clean because I've had to dial the slow-running jets out quite a bit further than the manual suggests to get it to run without leaning out at light throttle.

 

Phil

 

That shouldn't even work. You just fixed the manifold alignment issue, right? All ports sit flat against the block? I don't recall, but if not, get it faced, and new gaskets. The exhaust manifold will expand with heat and slide on the gaskets a little as it gets bigger. Make sure that your attachment hardware is not going to to restrict that motion, because if it does, the manifold might break or warp.

 

Make sure your wiper system and/or booster pump don't leak vacuum when shut off. If there's any doubt at all, disconnect at the manifold and plug the manifold. Kit the carb if it's not been done recently. The mixture screw on a car that new is only for slow hot idle. The fact that it helps suggests things are seriously out of whack.

 

You just freed up some valves? Did you have the head off? I'm not sure whether you meant you need gaskets for the head, or for the manifolds, but they both need to be perfect, so replace any that are suspect.

 

How is the compression now? Also, if you haven't, check the valve adjustment. I wouldn't tighten any loose ones just yet until it has run a little more, because maybe theres crud on the valve faces. Just adjust ones that are too tight for now. Do the whole job later, after it has run more.

 

Keep at it.. You're close!

 

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  • PhilAndrews changed the title to '51 Chieftain - Valve job

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