I'm sorta stumped.....

[bob w]

All the symptoms tell me you have a vacuum leak.
Intake manifold gaskets, carb base gaskets, a vacuum line unplugged, a bad vacuum modulator or something you're overlooking.

I agree.

 

[kenny c]

All the symptoms tell me you have a vacuum leak.
Intake manifold gaskets, carb base gaskets, a vacuum line unplugged, a bad vacuum modulator or something you're overlooking.

Have you tried spraying a little carb cleaner around the intake area while running to see if the idle picks up or changes?

 

[Bamamav]

After spraying starting fluid all around the intake, carb, and blocking all vacuum ports, it looks like the carb spacer is not sealing. One spot when I spray it dies, does it every time. Going to get new gaskets or make some and try again.

 

[Old Iron]

If you have an adapter under the carb make sure it seal if not get a steel plate that goes between the adapter and the manifold.

 

[Bamamav]

No adapter, I have a stock fiber looking spacer about 3/8" thick, not even sure where it came from or why I used it. [S I've got another one, not quite as thick that looks unused, maybe it's the one that came with the carb, I dunno. May just use it with a gasket top and bottom.

I think I may have found my water leak on the passenger side, it's either the freeze plug in the end of the head has a pinhole in it, or the head gasket has went away on the corner. Alternator bracket covers the freeze plug, so I'm gonna try to get it running first before I tackle the leak....
cause if the trannys no good, it all has to come back out anyway.....

 

[Dr Crankenstein]

I suggest you "true" the spacer before you replace the gaskets and reassemble. Chances are good, the spacer isn't dead flat on either mating surface, carb to spacer on the top, spacer to intake on the bottom.

Back when we were running a fuel funny car, our blower to manifold seal was a large perimeter o-ring. No gasket otherwise and the tolerance was small between manifold and blower, something like .009, however, spread over a much larger footprint than a four barrel carburetor...

Anyhow, out of necessity, we carried a low-tech hand operated surfacer. It was nothing more than a slab of machined aluminum plate with a pair of handles attached. Glued to the plate was a common sheet of 80 grit emery cloth. A little machinist's blue and a few strokes would tell. A few incidents proved the tool and method accurate, repeatable and good enough for 54 pounds of boost.


Dumb and memory challenged as I am, I somehow retained a few things from days gone by. I've "trued" a few surfaces using the lessons learned above... I've glued a sheet of emery cloth to my table saw's (machined flat) table and sanded the piece fore, aft, left, right, 45° left and 45° right until the rattle can paint disappeared. Low tech for sure, but flat as can be without visiting the machine shop...

.

 

[Bamamav]

Well, that was a waste of time. New carb gaskets, different spacer, torqued intake bolts again to be sure, same $hit. Did manage to take the choke off, but still won't idle below 2000 rpm. Retarded timing a bit, no help. The sob may sit there and run 30 minutes at 2000 rpm, then again it might shut off after one minute. Tried backing off the idle speed screw, as soon as it gets below 2000, it quits. Never had one fight me this bad.

 

[Old Iron]

Take a few pics of the engine and carb at different angles and post them so we can see what you've got.

 

[Bamamav]

OK, put my Rochester 2bbl on, getting the same results. Looking now toward the HEI. Is it even possible that it could work above 2000 rpm, but be dead below that? I thought they either worked or didn't? Could be the module bad I guess.....
May try my points distributor again. Can't be much worse.

 

[Dr Crankenstein]

I also wonder if that's possible... do you have a weak battery and the voltage is too low, until the alternator spins up and joins in? That would make some kind of sense, I suppose...

Grasping at straws... does the distributor body ground properly at the hold down clamp? Good motor to chassis ground? Are your mechanical advance weights stuck "open"?

.

 

[Bamamav]

Well Dr C, ground cable goes directly to alternator bracket, also have a braided wire ground from an intake bolt to the firewall, distributor is clean aluminum, bolt and clamp are paint free.
I even tried a hot wire direct from battery to coil, no difference.

I'm wondering about that module. It isn't flat like a GM module with the 4 wires, 2 on each end, it has all 4 wires on one side, but probably works the same. I don't know about the advance, it's down under the pickup wheel, can't really see it.

It has started when it shuts off to spit fuel back out of the carb, that makes me think ignition is giving up, if it was working that should be a fireball, not raw gas.

My chinese distributor may just be junk. I should've just went ahead and bought a 85 Mustang GT carbed distributor and ran it off a GM module, but I got in a hurry trying to make a self imposed deadline. Live and learn....

 

[Burgerman]

Think you're on to something with the consistent drop off at 2000 rpm and the fuel spit up as the engine dies. I've replaced stock ignition parts to "upgrade" and ended up going back to them. Hang in there Bama. This is gonna get figured out.

 

[Old Iron]

Go by Occam's Razor
"The simplest solution is most likely the right one."

 

[Dr Crankenstein]

I would still verify voltage... measured at the ignition, car running.

I'm simply suggesting, your alternator/regulator may be providing too much voltage, or none at all.

A GM HEI will run on low input voltage, but it's hard on components... too much input voltage will kill the module in short order. Your present ignition may be more sensitive, or not... regardless, I'd want to know what the ignition is seeing for actual input voltage, both static and running, if you can keep it running long enough to measure!

Kindly disregard this message if you've done all that already...


P.S.: What coil are you using and what's your spark plug gap?

.

 

[Bamamav]

To answer best as I can Dr C:
New fully charged battery
Alternator is same Delco 35 amp I had on other engine, putting out about 13.6 volts
Read 13.6V at coil static, haven't checked while it's running
Put a jumper from battery direct to coil 13.6V
Coil is used 12 volt taken off a 8N Ford tractor, I had thought it was getting hot causing problem on tractor so replaced it, turned out not to be the cause.
Plug gap is about .035, I had set them to that for the points and haven't reset them yet.

Didn't get a chance to work on it today, maybe tomorrow I'm going to put the points dizzy back in and try it again. If that works, I'm putting my 4bbl back on to try.

I have began to think something is amiss in the HEI, pickup, module, something that works weakly at low RPM's, just enough to fire it off but not enough to keep it going until it spins faster. I mean, when you start letting off the pedal, it gets down to around 2000 rpm, it just shuts off like you turn off the key, and with it spitting gas out as it spins down, the fire has to be out because it doesn't even pop out the carb or exhaust, it just quits and spit gas back out. If there was fire there, it should spit a fireball. It's a magnetic pickup, maybe the magnet is too weak?

 

[phil cottingham]

Bama, I had something similar years ago with a points distributor and it was the weights or springs in the distributor.

 

[Bamamav]

Too busy today to try anything. Tomorrow looks busy, too, got 20 ton of gravel coming for the drive and carport. I see a lot of tractor and box blade time for a couple of days...

 

[Dr Crankenstein]

Your dilemma has been burning a hole in my head, so I did some research...

As you might expect, real technical information for knock-off ignitions is virtually non-existent, so I read up on GM's HEI, which might shed some light on the subject...

A GM HEI control module increases dwell as RPM increases. (I'd expect aftermarket/copycat modules do the same.) The increased dwell ensures adequate time for the coil to fully saturate and deliver the appropriate amperage. (We're talking more camshaft degrees and milliseconds here.)


Here's my theory... good, bad or shotgun fodder...

Your coil's resistance is probably too high. If that's the case, it's too slow to saturate and therefore, can't reach the demand at low RPM. If your module acts like a GM module, more RPM brings more dwell, which could (potentially) allow your slow coil to "soak" long enough to fire above 2000 RPM. [S

Am I nuts? Probably, but one thing is for sure... an electronic ignition requires a low resistance coil to accomplish "high energy". I'm guessing, your points type 8N coil measures something like 2.5 ohms resistance, which severely handicaps an electronic ignition designed for a "fast" coil measuring anything between .3 and .7 ohms resistance.

Sorry for the long-winded post, Bama... just sharing what I believe is the root cause of your failing ignition. I'll bet you a dollar, a proper coil will cure your issue...

https://www.ebay.com/itm/Small-Bloc...-Cap-HEI-Distributor-ELECTRONIC-/321833728989

https://www.ebay.com/itm/BLUE-45-00...NEW-/191987405441?vxp=mtr&hash=item2cb3575281


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[26Troadster]

doc may be on to something there.

 

[Old Iron]

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