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Ignition and Distibutor - Take 2

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C

capitalcitycars

Jedi Trainee
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Well Guys, the saga continues. When we last left off, Jeff road to the rescue and fixed a few problems and taught this young buck a few things. Well, here I am for another lesson.

As you know, I have Jeff's loaner installed temp till my rebuilt dizzy arrives. I took it out tonight for a serious drive. Besides figuring out that the gas guage was off by an 1/8 of a tank, another problem popped up. The car idles fine, compression is good, plugs are not fouled, carb adjusted right, adjusted the points to specs, put newer plug wires on, the wiring is mostly correct thanks to Jeff pointing out I was using the wrong wiring diagram which is the last time I take a Hayes manual seriously. Now, going from a standing start to 1st, then 2nd gear, the car does what it's suppose to due. As the load and sustained higher rpms increase the engine starts jerking, I loose power, and I feather the pedal till I'm safely off the road.

Now, I suspect since Jeff's dizzy is a vacuum advance and my car is set up for a non vacuum advance dizzy, this is the cause of my problem since no hose is running from the dizzy to the carb. The connection on my carb I plugged. The solution would be to hook up the hose from the vac advance to the carb till my non vac advance dizzy arrives. Am I on the right track or should I be looking elsewhere. Thanks! /ubbthreads/images/graemlins/crazy.gif
 
Yes you got it. Hay what the heck. it costs nothing to try anyway. A peice of small hose from auto store will do the trick I should think.
 
Re: Ignition and Distributor - Take 2

Vacuum Advance distributor has an internal mechanical advance built into it. If you timing was set without the vacuum source it will mechanically advance with increased rpm until the weights hit the stops. How much mechanical advance depends on the weights and springs that are installed in the distributor. Don't think this is your problem.

I would check the fuel system from the tank to the pump to the carb(s). Sick fuel pump, partially clogged fuel filter, air leak is most likely the problem.
 
Re: Ignition and Distributor - Take 2

Gang, before we get too involved here, a couple of words about the distributor currently installed. I yanked it out of a '74 1275, that hadn't been started in who knows how long. All I did was make sure the points were functional, and took it along with me more as a diagnostic aid, than a long term solution to the original problem. After I removed the Mallory unit, I just plugged this one in, and turned it while Brian cranked the engine, and it started. I basically did an "earball" timing job, and Brian took it for a test drive.
I'm convinced that this is more than likely the root cause, as the points and condenser are of unknown vintage. The weights were free, and the vacuum unit checked OK.
The coil is a brand new, internally ballasted unit, and the voltage supply to the coil was correct with the engine running.
Jeff
 
Re: Ignition and Distributor - Take 2

Ahh, shucks, points and condenser please.
 
Re: Ignition and Distributor - Take 2

If you let off the revs, does the jerking stop? Is there a noticable RPM where the jerking starts. ie. at 4000 RPM (or any other high RPM) it starts jerking, but stops after the engine falls below 3800 RPM? If so, it may be a distributor advance problem.

But I doubt it is a vacuum advance issue. Vacuum advance tends to be less as load and revs increase.

If the problem only arises after you have been driving at speed for a while, then it is probably a fuel problem.

I am assuming you learned the lesson about the gas gauge being off the hard way. Maybe when you got down to the bottom of the tank, you sucked up some trash.
 
Re: Ignition and Distributor - Take 2

when i had a weak fuel pump, i could drive a ways before my car would sputter and crap out....u might check it out...im running well now.......z
 
Re: Ignition and Distributor - Take 2

Jeff and Jack beat my previous post.. I would go with their suggestions.

But keep Biff's fuel suggestion in the back of your mind just in case.
 
Re: Ignition and Distributor - Take 2

And I would lean on the condencer.
 
Re: Ignition and Distributor - Take 2

The loaner has done the job of figuring out thr problems with the car for which I'm very greatful. My new dizzy is ready to go but Jeff at advanced distributors is awaiting Mo$$ to deliver points, cap, rotor and should be in next week. In the mean time, I'm going to try attaching the cvacuum adanvced, throw a new fuel filter on and see what happens. Thanks Guys and I'll keep everyon posted.
 
Re: Ignition and Distributor - Take 2

don't bother with the vac advance.

Get a timing light and check your timing. I'd set it to around 10-degrees BTDC at 800 RPM. If you push the throttle open, you should be up to around 24-degrees at 3500RPM.

As was suggested, throw a new condensor and points in there for good measure and if that doesn't do it, it's probably your fuel pump or filter.

Mine behaved badly under load and at high RPM for a while, it was a failing fuel pump....
 
Re: Ignition and Distributor - Take 2

oh, one last thought - converting to an electric pump is worthwhile. That mechanical one on the 1500s has never impressed me.

The facet pump will work without a regulator. I've recently switched to a carter rotary vane and holley regulator and it's an improvement, but you'd probably be fine with the cheaper facet pump.
 
Re: Ignition and Distributor - Take 2

Who's to know, some last for decades some don't.

Open fuel line at carbs and crank engine a bit, does it pump a lot of fuel or a trickle?
 
Re: Ignition and Distributor - Take 2

Is this a 1275 or a 1500? If it has SU's then I would look at the dashpot springs (or check the oil in the dashpots). This sounds like a weak fuel mix at cruise (but riches-up on acceleration). If it is a 1500 then check whatever controls the mixture on those.
Bill
 
Re: Ignition and Distributor - Take 2

a car cant run without the proper amount of gas flow....just ask me how i know ; )

besides, i love the warm feeling give a correct diagnosis ; ) could it be the pump? ....z
 
Re: Ignition and Distributor - Take 2

Do Webers have a "running " jet as well as an accelerator jet? Maybe the running jet is clogged?
Bill
 
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