I have not been able to solve my 67 stalling mystery. I had this problem last fall and received some suggestions from several helpful members. I'll describe what happens and what I have tried so far. Cruising at about 70 MPH for half an hour or so.....car just cuts out for a few seconds....then several small afterfires out of the drivers side exhaust and after I take my foot off the accelerator.....it fires right up again without me doing anything. Then, a few minutes later....it cuts out again.....a big afterfire out of the passenger side exhaust.....it coasts as if it will coast to a stop....and then fires up when I down shift from fourth to third....again without me doing anything. I make it home at slow speed without further problems. It has now done this the last three times I've taken it for a spin. Seems to happen when the car is well warmed up......just after I've accelerated to pass or going over a bump or slowing down after opening her up. Over the winter I cleaned the engine harness connections at the firewall and I changed out the old TI box for a Dave Fiedler upgraded model....no change.... I still have the same problem as last year. I'm thinking maybe...the distributor.....the coil....the fuel pump....plugs or plug wires.....can anyone help me to narrow this down?? Thanks.
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Re: 67 427/435 stall.
I would suggest fuel pump and/or fuel filter.
Most of the time its an ignition problem that acts like a carb problem, but you said it happens after passing or acceleration so that leads me to fuel delivery especially if you say its OK at slow speeds.
George -
Re: 67 427/435 stall.
Pasta has you on the right track with the fuel. Same thing happened to me once in a Goodwood Green Coupe 427/435HP. Believe it or not it was the fuel cap. Someone had substituted the original vented one for a non vented cap and it would build up a vacuum in the tank as the fuel left faster than air was getting in. When I stopped it would start up again and run for a few miles and then repeat.
Also had a Goodwood Green Roadster 427-400HP to clog the center carb fuel filter and act similar.
Regards,
JRComment
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Re: 67 427/435 stall.
Rick, I had a similar condition with my 65 a few years ago and it was the fuel filter-----changed it and solved the problem.
ArtComment
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Re: 67 427/435 stall.
My bet is that the distributor pickup coil is about to take a dump.
Separate the the two wire connector from the distributor, and place an ohm meter across the two leads to check pickup coil resistance. It should be about 300-600 ohms IIRC, but check your CSM.
With the ohmmeter connected use a vacuum pump (or oral vacuum) to exercise the vacuum can, and let it snap back from full advance by quickly pulling the line off when the plunger is pulled to the limit. Do this several times. Wiggle the pigtail, too. If the meter reading jumps around, that's your culprit.
Even if the pickup coil passes this test, it's still suspect IMO because it could be temperature related, too.
The leads from the pickup coil are continually stressed by the vacuum advance rotating the base plate. The HEI on my Cosworth Vega did the same thing except it only gave me one warning - one big backfire. Then 30 seconds later the ignition quit. That was while I was running a track event at Riverside. The first thing I checked was pickup coil resistance and it was open.
Intermittent problems are tough to diagnose, so here's another test that you can do while driving. Attach a dwell or voltmeter to the coil with some long test leads that you can attach to the meter in the cockpit. During normal driving you should see a fairly constant dwell or voltage. If the problem is ignition related the dwell or voltage will change when it cuts out.
Clogged fuel filters can also cause the engine to cut out - and maybe backfire or afterfire - but usually only at WOT at medium to high revs when the float levels drops way off due to fuel starvation, but usually not at cruise speed, when fuel flow is just a fraction of WOT at medium to high revs.
DukeComment
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Re: 67 427/435 stall.
Thanks for the help gentlemen.....a new pick up coil is $225. plus.....I'm hoping this is not the problem. The ignition coil is hot to the touch after driving....is this normal. I'm leaning towards electrcal problem because it cuts out while cruising....... but maybe fuel pump. With the upgraded T.I. amplifier installed can I now use a regular aftermarket coil without damaging anything? I'm going to try the test light connected to the two ignition coil terminals while driving to see if the light goes out when the engine cuts out.Comment
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Re: 67 427/435 stall.
A test light could affect the ignition because it has relatively low resistance compared to the very high input impedence of a meter.
Coils normally do warm up. I don't think a conventional 12V coil designed for a point type ignition would be suitable because the TI has about double the primary current. I think the TI average current is about 8 amps, so that's over 100 watts at typical 14V system voltage.
DukeComment
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Re: 67 427/435 stall.
Thanks Duke...you're up early....can I run a wire from the + side of the ignition coil through a test light that is grounded and see if the light goes out when the engine stalls....Clem had suggested this but I don't know how to ground the test light from the cockpit.....thanks.Comment
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Re: 67 427/435 stall.
You'll need some extension leads, and you can run a ground lead back to the battery or any ground in the engine compartment. A good ground in the cockpit should be the dash cross brace under the glove box - what the VIN and trim tags are attached to.
DukeComment
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Good alternatives...
have been suggested (clogged fuel filter, TI pickup coil 'flakey', Etc.) by others, but here's a 'left field' suggestion.
If you have a battery cutoff switch (I'm refering to the green knob wonder design), it may be going 'south' on you due to mis-use. There is no tactile feedback on these gems as to when they're properly tightend down. If the owner fails to use 'gorilla' strength to REALLY torque that knob down, the contact surface junction can be loose.
Loose contact will result in the grass hex-head nut inside the plastic knob 'bouncing' against the thinly plated top surface of the switch. This creates electrical arcing in a radial pattern outward from the corners of the hex nut and thin plating of the top bar on the switch burns off giving you the underlying steel that'll quickly start to oxidize.
Just before this wear/abuse syndrome reaches critical levels (the engine shuts down permanently), owners get 'advance' notice. They see the engine cutting out in 'random' spurts with self-recovery after a brief period. Acel vs. decel maneuvers act to 'bounce' the switch contacts and either create or resolve the problem for a while.
Checking this possibility is child's play. Simply unscrew and fully remove the green knob. Look at the underlying surface condition of the top bar of the switch and if there's ANY appreciable evidence of arcing (missing plating), it's time to replace the cut-off switch. Personally, I prefer the more expensive knife switch units since both contact surfaces are solid brass and there's good tactile feedback for the switch open/closed positions...Comment
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Re: Good alternatives...
Thanks for taking the time to offer an alternative.....I do not have a cut off installed on this car. I am using original style battery cables which may not be tight enough.Comment
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Re: 67 427/435 stall.
I cleaned and reconnected the pigtail from the distributor to the engine harness. It looks a little old....may be the original. Does anyone in the aftermarket sell these? I connected a volt meter as Duke suggested.....positive lead to positive coil terminal and grounded the other lead using the brace on the passenger side inside the car. I just went for a ride with the volt meter inside the cockpit connected as described. At idle I get just over 3 volts. At 3000 RPM on the highway it drops to just below 3 volts. On hard acceleration to 5000 RPM it drops to just above 2 volts.....and of course the engine won't cut out when I want it to.Comment
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Re: 67 427/435 stall.
Rick-----
My guess is that the problem is TI-related, but I don't know which component is the culprit.
Quite some time ago I considered the possible future installation of a TI system for my "ZL-1" project. So, I set about accumulating all of the parts I'd need if I eventually decided to go that route. I purchased NOS TI distributors, used TI distributors, NOS amplifiers, used amplifiers (for conversion to modern electronics), spare NOS pick-up coils, spare rotating pole pieces, NOS and reproduction wiring harnesses, and numerous TI ignition coils.
After much investigation, research and deliberation, though, I decided long ago that I wouldn't install a TI system in my car under ANY circumstances, whatsoever. In my opinion, there is WAY too much chance for problems and resulting UNRELIABILITY. As I've said many times before, RELIABILITY is my absolute, number one priority. TI is TOTALLY inconsistent with that priority. The system adds all sorts of "failure modes" and, in my opinion, for very little gain. In fact, I believe that you can achieve most of the performance attributes of TI with a modern electronic conversion system like Breakerless. It's true that there is some reliabilty risk with any electronic system, but I would consider the Breakerless system to be FAR, FAR more reliable than original GM 64-71 TI. Plus, if it should fail, conversion back to points is a 10 minute job with only a screw driver.
By the way, even though I've totally abandoned any plans to use TI, none of the parts are for sale.In Appreciation of John HinckleyComment
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Re: 67 427/435 stall.
Could be that the pickup coil connector was the problem. Keep the voltmeter in the car!
DukeComment
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Those poor, lonely parts...
sitting all alone, gathering dust without a good car to surround and 'comfort' them. Oh, the shame of it all!Comment
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