36 Ford truck on Ranger

[Dr Crankenstein]

On the heels of Torchie's question... which electronic module are you using?

It's important to have a properly matched coil, otherwise you'll have a severely handicapped ignition.

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[Torchie]

On the heels of Torchie's question... which electronic module are you using?

It's important to have a properly matched coil, otherwise you'll have a severely handicapped ignition.

.

My experience with multiple carbs is mostly from Brit sports cars as I mentioned in Dons posts about his multi carb travails.
And in that experience I found that many times when owners thought they had carb issues it was really ignition issues. But of course when the cars started to run badly the first thing they did was screw with the carbs.
I know you have a much better handle on your mechanics then most of the owners I dealt with Mac, but given your compression readings as well as the looks of the intake gasket I’m thinking your issue may be electrical.
Just throwing spitballs at you from many miles away. Maybe one of them will hit in the strike zone.
Torchie

 

[MercuryMac]

Good question Doc. I don't know what brand it is, but I'll look tomorrow. I would hope the professional 'tuner-upper' would have caught that 'wrong coil'.
Torchie, I'm really gaining experience on this one. Thank you for naively guessing that I have a handle on this. Most of the people that I've asked, said 'it's that carb set-up, throw it in the bush', so I know what you're saying. I'm thinking the same way you are that it might be something else, because I really want these carbs to work, so that's why I'm so determined.
Keep throwing spitballs my way, as I'm running out of ideas to check out and fix.

 

[kenny c]

I have no advice but I feel for you. Keep at it.[P[P

 

[Torchie]

A follow up question Mac.
Are you running a 6 volt or a 12 volt system?
Torchie

 

[Bamamav]

On the heels of Torchie's question... which electronic module are you using?

It's important to have a properly matched coil, otherwise you'll have a severely handicapped ignition.

.

Listen to Doc, he knows what he's talking about....

Mine wouldn't run worth a crap, I looked for vacuum leaks, changed carbs, etc. Changed from a standard coil to a factory Ford square box coil off a EFI engine, it now runs fine. It's ugly, but I have some ideas for a vented enclosure to hide it...

 

[MercuryMac]

Doc, I thought I could find the box that my electronic pick-up came in but no, so here's a picture of it. The printing on it doesn't give any hints, either.
Torchie, I've changed back and forth so many times between 6 and 12 Volts to the coil that I don't know where it's at now. Tomorrow I'll check my resistor under the dash and make sure the coil is receiving 12 volt. This electronic pick-up doesn't like anything less than 12 volts.
Tomorrow, Bama, I'll try to find out what coil I should be using with that electronic set up.
Today I fished the fan, its shaft, and bracket out from between the rad and the front of the motor. What a horribly impossible job. Now I have to remember every little twist and every jink and reverse them to put it back in. I figure, that while I'm this close, I better check the cam timing. The front timing cover has to come off.

 

[MercuryMac]

I pulled the distributor out and checked the vacuum advance by sucking on it with my mouth. I kept one eye open and bent to watch the breaker plate. It worked nicely.
Then I undid the timing gear cover and took it out. After rolling the engine over until the cam gear 'dot' was at the bottom, I tried to find the crank gear 'dot'. It was right where it was supposed to be. [see picture].
One more possible problem scratched off the list.
In some old mechanics text books I read a section on running poorly at higher revs. One thing I learned that I hadn't thought of recently was maybe I'm vaporizing the gas, as my fuel log is bolted right to one head. Hmmm.

 

[Torchie]

Wouldn’t be the first flatly to suffer from vapor lock.
Torchie

 

[MercuryMac]

I agree Torchie, it wouldn't be the first flattie to vaporize it's gas, but that was in the good old days. It wouldn't happen now, ----- would it? To compound the finicky gasoline supply, I think my electric pump is putting little bubbles in the gas stream. One more thing to check. Also, I'm wondering if any flatheads came with a centrifugal and vacuum advances. This is what is always in the back of my mind. It seems to me that my motor goes out of time at higher revs.
Anyhow, I'm putting the motor back together now.
Doc, my memory is returning, I'm pretty sure it has a Pertronics pick-up.

 

[Dr Crankenstein]

Doc, my memory is returning, I'm pretty sure it has a Pertronics pick-up.

Which version, Mac?

FYI

"The Flame Thrower 40,000V coils have internal resistance rated at 1.5 or 3.0 ohms. The 3.0-ohm coil should be used on PerTronix Ignitors installed on four- and six-cylinder engines while 1.5-ohm coils should be used for eight-cylinder applications. These coils can be used on virtually any inductive (non-capacitive discharge) ignition system.

Flame Thrower II coils have lower resistance, 0.6 ohms for use with Ignitor II ignition systems as well as many other high-energy ignitions. The low resistance helps to produce up to 45,000 V. This higher voltage allows larger spark plug gaps for added power and better fuel economy.

Flame-Thrower III coils were developed for use with the new Ignitor III electronics. The extremely low resistance of 0.32 ohms results in 45,000 V and a coil that charges to peak, current typically 30-70 percent faster the other coils. It should be noted that these coils are compatible with Ignitor III electronics only."

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[Torchie]

I agree Torchie, it wouldn't be the first flattie to vaporize it's gas, but that was in the good old days. It wouldn't happen now, ----- would it? To compound the finicky gasoline supply, I think my electric pump is putting little bubbles in the gas stream. One more thing to check. Also, I'm wondering if any flatheads came with a centrifugal and vacuum advances. This is what is always in the back of my mind. It seems to me that my motor goes out of time at higher revs.
Anyhow, I'm putting the motor back together now.
Doc, my memory is returning, I'm pretty sure it has a Pertronics pick-up.

I would check to see if your carb is producing enough vacuum to actuate the advance. That used to be a problem with the Ford load a matic distributors when people changed out their carbs.
I equate it to the old vacuum windshield wipers. The faster you went. The slower they worked. Again. Just more spitballs....
Torchie

 

[Torchie]

Also Mac ..
Google “Bubbas Ignitions “. If you aren’t familiar with him he is considered a flat head distributor guru.
He talk about each a carb and cam change can do to a full
vacuum advance distributor.
Torchie

 

[MercuryMac]

Thanks Doc, I better match my coil to my pick-up system.
Thanks Torchie, I checked the vacuum advance pot and the steel pipe to it, but I never thought that the carburetor plumbing could be plugged. Better check.
I'll listen to Bubba, and learn stuff.

 

[MercuryMac]

I've pretty well got the motor back together. See pics.
I want to be in control of my choke, so I am making a gismo to hook up to my choke cable. I blew through the vacuum port in the carb and it sounds like it's working. The flatheads didn't seem to have centrifugal advance, and I might need one, so I dug into a Y-block distributor to see if I could adapt something. The Y-block one didn't have a centrifugal advance either. So much for that idea.

 

[Torchie]

I've pretty well got the motor back together. See pics.
I want to be in control of my choke, so I am making a gismo to hook up to my choke cable. I blew through the vacuum port in the carb and it sounds like it's working. The flatheads didn't seem to have centrifugal advance, and I might need one, so I dug into a Y-block distributor to see if I could adapt something. The Y-block one didn't have a centrifugal advance either. So much for that idea.

Mac.
Just for clarification....
My comment about the carb vacuum was not so much about it being blocked as it was about it generating enough vacuum as the RPM's go up to activate the advance. Hence my comparison to vacuum wipers on a car. The higher the RPM's get the less vacuum/the slower the wipers work. It is possible you advance is starved for vacuum.
Torchie

 

[MercuryMac]

Torchie, when I first naively thought your suggestion through, the solution was fairly simple. Unplug the carb orifices and it's done.
Now, when you have clarified the problem and I actually understand it, well sir, the low vacuum problem won't go away as easily. ------- But with a wee bit of time to think, I have maybe got a plan. The 'below the throttle plate' vacuum is about 5" hg low, so the 'above the throttle plate' vacuum will be quite a bit lower too. This weak vacuum won't pull the advance plate in the distributor very far. If I took one of the return springs off of the advance breaker plate, it would pull easier. The 'two thirds' vacuum pressure would overcome the 'two thirds' return springs, and I would have advance coming out of my wazoo.

 

[Torchie]

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Torchie

 

[MercuryMac]

Over the last little while, I broke one of my own rules. I fixed or changed quite a few things, without a test drive. How am I going to guess which fix worked. I changed the intake manifold gasket, the intake itself, the carburetor, the vacuum system, checked the camshaft timing, checked the distributor all over, changed the route of the gasoline, researched the electronics and coil compatibility, [it's OK], and got twelve volts going to the coil. The resistor in the ignition wire was still restricting the voltage to the coil and electronic pick-up, and it was deteriorating a lot with bakelite granules everywhere.
I haven't driven the truck on the road, but I started it up and warmed it up in the shop. The vacuum is even lower at about eleven " of Hg and the miss-firing is still obvious. I have a new vacuum gauge now so it may read slightly different than the borrowed one.
My optimism is a wee bit bruised. [S[S

 

[Dr Crankenstein]

Mac: I zoomed in on your last picture and see you have MSD Super Conductor wires. Those are solid core wires and they DO NOT JIVE with most electronic control modules including PerTronix. Get rid of them before you go any further.

I also see the print on your coil, "USE WITH EXTERNAL RESISTOR". What's that about?

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