Fall/Winter/Spring Projects for 0248k

[steve lyle]

Steve, you're throwing us quite a curve ball here. I don't recall anywhere in this thread ( but easilly could
be wrong) but is there anyone nearby with a set of Webers to swap out, just to see wherer this thing goes?
That would be easier than a head swap.

Unfortunately, all my local friends run SU's and Strombergs. They've been quite amused by this misadventure, btw.

[steve lyle]

Are spark plugs #1 & 3 wet after running engine, perhaps compare with #2 & 3

Take a look. This was after idling for about 5 minutes. Top plug is 4, bottom is 1. 3 looks a bit damp to me, 1 looks dry.

[h20hamelan]

something is stopping working if it died, maybe old wires (wiring going to coil) or ignition cylinder require renew? wiring going to coil?

can you hook a jumper from 12v solenoid to confirm quality?

[Craven]

#1 & 3 centre electrode looks shiny to me = wet= fuel. Be careful but the exhaust header will be cold if not firing on those cylinders. Reducing plug gap may prove something!

[steve lyle]

something is stopping working if it died, maybe old wires (wiring going to coil) or ignition cylinder require renew? wiring going to coil?

can you hook a jumper from 12v solenoid to confirm quality?

Funny you should ask. Today I got tired of going to the cockpit to start the engine, then running around to the bay. I made up a harness with 2 switches, one to send 12v to the coil, one "push to start" to attach to the starter solenoid activation terminal, both attached to the +B cable at the solenoid stud. So I take the ignition key switch out of the circuit entirely. So, yes, I've used a jumper, and not used a jumper, and gotten the same results.

A few years ago I rewired the car, so generally speaking the loom is in good shape - other than the lo and hi beam signal wire issue I discussed a few pages back.

[Bill36]

Steve I’ve got a spare set Webber’s that I had on a 67.
I live up I-75, give me a call if you want to try them.
918-815-6995

[snowyelan]

I might have missed it, but did you change the distributor cap? Any thoughts on trying my previous suggestion?

[gjz30075]

I replaced the points this morning, and got exactly the same results - runs rough, pulling 1 & 3 leads makes no difference.

So, new coil, new points, new leads, new plugs, rotor from a car that runs great, with surfaces shined up. Induction timing light shows a steady strobe on all leads, as does an inline tester. Lead held against valve cover with removed plug shows a strong spark at 1 & 3. Leads 1 & 3 show 6.3k &. 7k resistance, consistent with 2 & 4. I've tried switching leads 1 & 3 at the distributor. No change in behavior. Compression and leak-down test results in the "it should run" range.

When timing the dizzy after this point replacement, I pulled the valve cover to verify TDC. I also verified a Twink hack that I read about recently - you know that #1 is at TDC by removing the oil filler cap and ensuring that the #4 exhaust cam lobe is pointing "in" toward the center of the engine. Pretty handy.

OK, Team "It must be the ignition" - what do I do now?

.

Snowyelan makes a good point. I don't see a cap on your 'new' list. Make sure the spark plug wires are fully seated in the cap.

[JonB]

Use an ohm meter to test each HT lead from plug socket to distributor contact. I’ve had these problems before, admittedly with old leads, but in the end I fixed it by locating the bad wire and removing it from the cap, cutting a bit off and reinstalling.

I’m sure you tried something like this..?

[steve lyle]

#1 & 3 centre electrode looks shiny to me = wet= fuel. Be careful but the exhaust header will be cold if not firing on those cylinders. Reducing plug gap may prove something!

How about checking the headers with an IR thermometer, vs my hand?

When idling at 900 or so, same symptoms of no change when #1 & #3 are pulled, temps are:
1 - 130 F
2 - 350 F
3 - 170 F
4 - 350 F

Not sure what that tells us that we didn't already know - or at least that I already knew - if 1 & 3 are doing anything, it isn't much. #3 being hotter than #1 makes a bit of sense - it has hot tubes on either side, when #1 only has one on one side.

[steve lyle]

I might have missed it, but did you change the distributor cap? Any thoughts on trying my previous suggestion?

Sorry, inadvertently left it off, though mentioned earlier in the thread. Cost me $55 from O'Reily's.

My interpretation of your previous suggestion was that my test of swapping the #1 & #3 leads from the distributor was basically the same - would you agree?

[steve lyle]

Use an ohm meter to test each HT lead from plug socket to distributor contact. I’ve had these problems before, admittedly with old leads, but in the end I fixed it by locating the bad wire and removing it from the cap, cutting a bit off and reinstalling.

I’m sure you tried something like this..?

I have checked the leads. #1 - the longest, shows 7k ohms, the others are about the same length and each shows about 6.5k. The test was one probe on the distributor contact inside the cap, the other probe on the metal terminal in the plug rubber thingy at the end of the lead. (there must be a better name for that...), AH - the BOOT.

[snowyelan]

Rotating the distributor or rotor 90 degrees changes the known functional ignition path from 2&4 to cylinders 1&3, and vice versa. If there is a fault it should switch to cylinders 2&4.

Swapping just the wires only checks the wires.

Having said that, with all the parts you've replaced I doubt my test would find anything.

One suggestion I have, based on a recent experience, is to check the contact pin in the center of the distributor is present and plunging freely. I had one fall out and, while the engine would run, it ran poorly. The spark was jumping from rotor to the pin spring.

[steve lyle]

#1 & 3 centre electrode looks shiny to me = wet= fuel. Be careful but the exhaust header will be cold if not firing on those cylinders. Reducing plug gap may prove something!

Not sure I'd agree with you on #1 - ok, I don't, since nothing burns when I put a match to it, but even if so, what does that mean? Enough fuel to fire? Or not?

Plug gap is .025" - what would you like me to try? When I pull the plugs and crank. the engine with the plug on the valve cover, I get what looks to me like a healthy spark.

If you or anyone else would like to actually what's happening here real time, FaceTime or WhatsApp me at (01) 918 527 6578 anytime.

It's either got to be timing, only on 1 & 3, or fuel, only on the right throat of each carb. This afternoon I'll replace both the #1 and #3 leads with longer ones, so I can switch them easily, and give that a try. I know for a fact that I'm getting a spark at the 1:30 position on the distributor with the crank at TDC. Right now the lead at that contact is going to #1. I've tried moving it to #3 once, but maybe I didn't do that correctly. Might as well give it another try - I won't have a new head gasket for a few days anyway. I'll pull the cover and check the valve timing, yet again, as well.

[steve lyle]

Rotating the distributor or rotor 90 degrees changes the known functional ignition path from 2&4 to cylinders 1&3, and vice versa. If there is a fault it should switch to cylinders 2&4.

Swapping just the wires only checks the wires.

Having said that, with all the parts you've replaced I doubt my test would find anything.

One suggestion I have, based on a recent experience, is to check the contact pin in the center of the distributor is present and plunging freely. I had one fall out and, while the engine would run, it ran poorly. The spark was jumping from rotor to the pin spring.

It took me a bit to get my head around your suggestion - but I think I've got it now. I will definitely give that a try. If the problem moves, it means we have an ignition issue more likely, if not, then more likely carbs. I like it.

Re: the center plunger - it's definitely there, and plunging - I tested the resistance of that lead as well, from the plunger to the boot contact.