Hot Rods Rough running engine such a simple thing should have checked that first

I've been chasing this for awhile....a long while. I got the Vicky together enough to drive, about a year and a half ago. It has a B engine with a Cragar/Miller OHV. The engine was "Rebuilt" but had a multitude of issues and worn out rockers was one of them. I went thru the head and it got BBC valves and a 2:1 Austin Healy rocker assembly.
It got 2X2 Zepher intake with Stromberg 97's. New English ones that a HAMBer had sold because he couldn't get them to work for him
Mallory dizzy, 12V coil
It always had a miss, not a dead hole but a intermittent miss and couldn't tie it down to a specific hole.
At full throttle it would disappear...you drive a banger under full throttle a lot. It would buck at idle and light throttle in first gear. You could feel this under light throttle cruising down the highway.
Start with checking for vacuum leaks, carb bases, manifold to header plate, header plate to head, no leaks. It does have tubular headers, not cast iron exhaust.
Swap out with new plug wires...nope
Different plugs....nope
Rejet carbs....nope
Think I have too much carb for the engine so swap for 81's and set them up similar to a good running Miller/Schofield I have...nope
Swap from the Mallory to a good B dizzy....nope and there is a real steady timing mark with a timing light...not jumping around, no slop in the drive
Drive it lots but it doesn't run right, especially at light throttle
Adjust valves, check compression 72 to 75 psi, dry cylinder which is good for what is usually a 8000 to 9000 ft density altitude here...nope
Now I really want to drive this to the Gathering at the Roc the end of October and I go thru everything again...it is worse and start to look at manifold heat and cam.
Nope

 

The problem child

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I can't help, but I gotta say, that is a great looking car! Love the paint, stance, everything about it.

 

Why, thank you. I appreciate it and that is why I want it to run good also!!!
I did, just today do something that made it run a whole lot more good.

 

And that was?

 

My guess is exhaust manifold gasket.

 

Have you tried getting those plug wires in better order?

 

And yes , very nice car.

 

I’m with rustydusty,,,I never did see what he did to fix it !
Just,,,,nope,,,nope,,,nope,,,,,did I miss the explanation?

Tommy

 

Well, I thought that some might chime in with ideas...nope
Spark plug wires are new and in order
I didn't mention that I thought that I was on track when I figured out that there was a 12V coil without a ballast resistor. It measured around 1.5 ohms and I replaced it with one that measures 3 ohms on the primary.
I also ordered up one of @tubman s condensers....nope
Very nice part by the way

Of all things I had gapped the spark plugs at .028" because there was a bulletin out there with a lot of discussion from one of the Model A chapters to do this for higher compression than stock head.
I gapped the spark plugs at .035" today, Henry's stock setting and it settled right down
I would have never figured....it is a hotter spark that way

 

When I said in order , I meant not crossing one another.as in separated from one another.

 

Good guess, it is certainly on the list of things to check.
You've done this before but had to check it off the list.

 

I suspected that...but with dizzy height and plug angle it is a real challenge to get anything that doesn't look disorderly to some degree.
I checked the high tension side at night, in the dark to see if the spark plug wires or porcelain lit up like a light bulb, nothing awry. Even tried different dizzy, cap wires...
Oh for the want of a diagnostic scope

 

That seems odd to me. Back forty or so years ago , I was wrenching on my bosses circle track car, a 350 Chevy, that wasn’t running right. Had some sort of point ignition ( it’s been a while, lol), he told me to regap the plugs from .035 to about .025 or so. It fixed the problem.
Just the opposite of what happened to you! Lol






Bones