Fall/Winter/Spring Projects for 0248k

[gjz30075]

Steve, for what it's worth, more discussion on speedo location aka, more dead horse beatings.
viewtopic.php?f=16&t=9678

[steve lyle]

55 idle jets seem large. For most engines that aren't to far from standard need 45 or 50. Do you have some shaker jets to test or wind the idle screw in a bit more?

The carbs came with 45’s. When I engaged Weber warranty service, they were practically disdainful of that size for this engine, and put the 55’s in the new carbs they sent. In any event, they sent me back the original 45’s, which I just tried. No difference.

[Craven]

Don’t quite follow your thinking on this, #1 cylinder has it’s fuel feed from the front carb #3 has it’s fuel from the back carb, so unless you have identical fault on both carbs mind you the feed is from the right barrel in both cases so may be. Probably not familiar enough but the exhaust note is always a good clue in misfire issues if you are truly running on just two cylinders it must be very noticeable, listen to rhythm when pulling plug leads, a splashy type erratic note usually a weak mix, a deep sounding regular throb usually rich mix. I always listen to the exhaust as well as engine speed when adjusting the idle mixture.
Firing order 1-3-4-2 may give an indication of a worn distributor.
FWIW

[steve lyle]

Don’t quite follow your thinking on this, #1 cylinder has it’s fuel feed from the front carb #3 has it’s fuel from the back carb, so unless you have identical fault on both carbs mind you the feed is from the right barrel in both cases so may be. Probably not familiar enough but the exhaust note is always a good clue in misfire issues if you are truly running on just two cylinders it must be very noticeable, listen to rhythm when pulling plug leads, a splashy type erratic note usually a weak mix, a deep sounding regular throb usually rich mix. I always listen to the exhaust as well as engine speed when adjusting the idle mixture.
Firing order 1-3-4-2 may give an indication of a worn distributor.
FWIW

What thinking? I’m just reporting what I observe. Absolutely no change in engine speed or sound when either #1 or #3 leads pulled. This is not subjective. Yes, it’s running rough, indicative of missing, which is why I pulled the leads, to isolate the issue. i was as surprised as anyone to find 2 dead cyls.

Distributor was rebuilt by a pro a couple of years ago, maybe 6k miles. Nothing sloppy about it.

[Craven]

As you returned your carburettors to be checked, I wrongly then, assumed your thinking was the problem was caused by a fault in the fuel supply to the engine. Did you then just do that for fun. You also wrote I switched the jets, - #'1's to #'2, and #3's to #4's. No change in behavior. Idle jets are 55 F8's, Mains are 120. Emulsion tube F11, and air correction jets 200's.

[steve lyle]

As you returned your carburettors to be checked, I wrongly then, assumed your thinking was the problem was caused by a fault in the fuel supply to the engine. Did you then just do that for fun. You also wrote I switched the jets, - #'1's to #'2, and #3's to #4's. No change in behavior. Idle jets are 55 F8's, Mains are 120. Emulsion tube F11, and air correction jets 200's.

Not for fun. Because Weber warranty service asked me to. I do not know what the problem is, and am not ruling anything out, including ignition, compression, or fuel. I’ve switched fuel parts, and ignition parts, and tested compression, multiple times.

[2cams70]

Check for a bent distributor shaft. It does occasionally happen and when it does you’ll get uneven ignition timing across the 4 cylinders. Measure the points gap across all 4 cam lobes and check that that the reading is consistent or check with a timing light on each of the plug leads

[steve lyle]

Check for a bent distributor shaft. It does occasionally happen and when it does you’ll get uneven ignition timing across the 4 cylinders. Measure the points gap across all 4 cam lobes and check that that the reading is consistent or check with a timing light on each of the plug leads

Thanks, worth looking into. The distributor shaft doesn't appear bent. I pulled the dizzy and checked the gaps - .015 on all lobes.

Last night, while running the engine, it died suddenly. No spark to any cylinder, per the inline tester. Today I pulled the dizzy after verifying the coil was seeing 12v, and showing a bit over 3 ohms across its contacts, and put an ohmmeter across the points. Continuity was intermittent, so I ran an ignition file between the contacts, which seemed to solve the problem, put the dizzy back in, timed it, and I'm back to where I was - runs rough, no change when #1 & #3 leads are pulled. I'll get a new set of points and put them in. My guess is that doesn't fix the 1 & 3 problem - it's the same points that fire 2 & 4, and anyway, every test I have says that 1 & 3 are indeed firing, since a timing light on each of the leads shows a consistent strobe, identical to what I have seen with the in-line spark tester.

I called Barry Sale, who did the head work. He asked that I do a leak-down test. $80 and a Harbor Freight visit later, I had a new tool in the collection. Results showed every cylinder holding 84 psi from a 100 psi source. Leakage was out the crankcase breather. Pretty much what Barry expected, indicating the the valves are good, and well within the range for an engine that should run. He feels the same about my compression #'s.

Based on the assumption that I'm insane, and knowing 2 & 4 were good, and 1 & 3 aren't, I pulled the cap and switched the 1 & 3 leads. Maybe I have one of those super rare 3-1-4-2 firing oder engines? Or got totally confused when I put in my new leads. In any event, when I did that, I couldn't even get it started. Switched them back and it started right up. A day later, I wondered if I could start it with ! & 3 removed, and I could. FWIW

I called Randy at Weber warranty. He's convinced that they sent me two good carbs.

I called Ken @ DBE. He's convinced I have a fuel issue. Possibly too much. If I take a rag and stuff it into the #1 throat with the engine idling, it comes out wet with fuel. No change in engine speed. When I do the same with #3, it comes out dry, no change in RPM. Again, FWIW. Kinda tells me what I already know - 1 & 3 aren't pulling their weight. Not close to understanding why not.

I have noticed that the spark advance isn't as smooth, or as high, as I expected, when I check it with my timing light at 3k+ rpm. I would expect that it would go to 30+ DBTDC, but it sometimes stops at 20, sometimes 30. And there's a range where the strobe indicates missing, before it goes smooth again. So maybe I do have some distributor advance or other issues. It just doesn't explain my idle problem. But maybe it's time to explore alternatives distributors.

I'm just about to the point of submission. I figure in a few days I could put the Stromberg head and carbs back on. That would be the acid test of whether this is a fuel or ignition problem.

[snowyelan]

Depending on if your leads are long enough or if you have 90 degrees of rotation available in the distributor, you could reposition the distributor shaft or distributor 90 degrees. This would shift the high tension side path one position from rotor to spark plug. If the fault is within this path it should change your faulty cylinders to 2&4. I'd swap the plugs to match as well.

[Craven]

Double check your plug lead firing order, remember the distributor arm is rotating in an anti-clockwise direction and the upper and lower location on outside needs careful tracing to inside the cap.

[steve lyle]

Double check your plug lead firing order, remember the distributor arm is rotating in an anti-clockwise direction and the upper and lower location on outside needs careful tracing to inside the cap.

That’s exactly why tried reversing 1 and 3.

[steve lyle]

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?

Same question to any Team "It must be the carbs" members.

I guess for grins I'll pull the carbs off and double or triple check the mounts and their o-rings. Or go get my Stromberg head out of storage and figure out what I need to do to put it back on. Or get the B ready to go to Fayetteville for "Brits in the Ozarks" in a week and a half.

[gjz30075]

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.

[Craven]

Are spark plugs #1 & 3 wet after running engine, perhaps compare with #2 & 3, you realise that what you describe is an impossible situation,

[steve lyle]

Are spark plugs #1 & 3 wet after running engine, perhaps compare with #2 & 3, you realise that what you describe is an impossible situation,

LOL - I wish it were, but apparently not.