Hi,

My 371 Dynamic 88 stalls randomly when driving. Rarely when parked / idling. after letting is sit for a while, it will start back up.

It sat for about 12 years and recently was able to get it back up and running.

Things i've done so far in regards to this issue:

Fuel tank boil out and re-seal
Fuel line flush
Carburetor rebuild (Finished last night, nothing major, only discoloration in the gasket, leading me to believe that the previous rebuild did not tighten the screws enough.)
timing adjusted
points replaced
coil replaced
condenser replaced

I have a feeling that the carburetor may be flooding. What steps should i take to figure this stalling issue out? Thank you!

 

I just a newbie here and my experience is limited... but check the gas cap.
We used to have a van that would stall out randomly. Turned out it was the wrong gas cap and causing vapor lock.

Worth a try?

 

Good to know. thanks!

 

Whats your dwell and timing set to, also check your fuel pressure, should be somewhere around 5-7#'s. Have you changed your fuel filter? Also make sure your choke is working properly,

 

recently fixed a 71 corvette that another shop had ton a bunch of work on. it ran like crap and they complained that after a few minutes it would lay down and die. had the same problem, the other shop installed a new gas cap that was not vented like the original and that year vette has no other vent in the tank.

 

I'll have to check the dwell. I think the initial timing is 12* BTDC (not positive)

The fuel filter is a copper mesh, Im not sure if there is one in the fuel pump bowl.

 

There is a vent at the top of the tank with a hose that is clamped to the frame rail. So i know there is proper ventilation.

 

Double check the fuel filter, the engine does not need much to run at idle. Your dwell should be at 30, no more no less. Timing sounds right. How's the choke working, does it engage when it's cold and pull off completely when warm?

 

Are you sure the vent line is clear?
How long does it have to sit before it resarts?
How long does it have to crank before it restarts?
Does choke go fully open and hold open when it is warm?

 

Sounds like a primary side electrical resistance issue somewhere. As the engine/engine bay gets hot the resistance goes up. I would check the points, condenser and coil and the wiring to it as well as all the grounds.
Possible ignition key switch problem?

 

The "fuel filter" in the carburetor is the old brass mesh type type. After the rebuild i just completed, there was minimal sediment in the carburetor bowl.

I will check the dwell and make it 30*

The choke is currently tied off because the thermostat coil was rusted out. Before i tied it off, the choke used to slam shut sometimes when the gas was depressed quickly, as if revving the engine.

So i just leave my foot on the gas until it warms up.

 

1. Yes it is
2. Anywhere from a few hours to overnight. Normally once it has been towed home i leave it alone until the next day.
3. It is tied off in an open position.

 

This is what i may have been thinking as well. However, how can i diagnose this for sure?

I've replaced the coil, ballast resistor and condenser. The points were said to be OK by a mechanic, as well as the distributor.

I have not checked all of the power wires since they run in hard places under the dash and in the engine bay.

 

can someone explain to me how the hoses on the fuel pump should be routed?

One goes through the firewall and into the dash somewhere and i am not sure why.
Another goes to the front of the carb as a fuel delivery line
the other goes to the back of the carburetor vaccum port.

 

I'm not super familiar with your year, but you mentioned a ballast resistor and points. Does your car have a resistor wire and a ballast resistor per chance.

You should not have a fuel line entering passenger compartment of the car, it's possibly a vacuum line. Nor should any fuel lines go to a vacuum port.

 

i'll have to check for a resistor wire. Any idea what it looks like?

I think, from snooping around, that the fuel pump is vacuum operated. I have no idea what there is a vacuum line running into the firewall.

The other line goes to a vacuum manifold port on the carb base. no fuel is entering the carburetor through that line, to my knowledge. Maybe i'll have to pull it off to make sure.

On my 67 buick i have one line in from the gas tank to the pump and one line out to the carburetor from the pump. this 1960 fuel pump is baffling me.

 

I got a new set of points and found some interesting stuff in the distributor. for one, there is a lot of surface rust on the weights. I cleaned them up.

I also sprayed silicone on the lower plate to get more free movement.

There was a small wire that was going from the plate to the vacuum advance that was broken. I added a new one.

I set the gap on the points to .016 but my dwell read around 20*

Why?

did i do something wrong? Do i set the points, install the distributor, then the dwell with a meter? Wouldnt that affect the point gap?

 

also,

when re-installing the distributor, is there an oil "stem" that i need to line it up with? ive seen videos where people stick a long screw driver down the distributor opening and wiggle it. When removing the distributor it was really difficult getting it out. Sometime it came up and then became immovable, however, there was a heavy amount of grease and buildup. I want to think that the buildup was making it hard, not an oil pump part.

Is this process necessary on the 371?

 

Point gap is the mechanical distance for the meter reading of dwell. A dwell of 20, will not work, it needs to be 28-32, with 30 being optimal. Also the dwell must be set first before setting the timing, as dwell effects timing, timing has no effect on dwell.

The distributer need to go back on with the rotor pointing to the same plug it was when it came out. That way everything lines up and your firing order is correct.

There usually is a fair amount of varnish buildup that makes the distributer problematic if it has not been removed for some time.

 

The resistor wire is a heavy almost cloth type covering. If you have the ballast resistor inline with it you've effectively halved the amount of electricity going to the primary side components with the ignition in the run position. Once the temperature goes up the resistance will increase also which lowers the voltage even more. That's the point your car shuts off. I've seen this a dozen times on these forums.
I noticed you said it's a 371. I'm not completely sure these early cars used a resistor wire or a ballast resistor so maybe someone else can chime in on that. One way to check is to start the car and get the voltage reading to the points while the car is running. You should have roughly 8 volts to the points. Some early cars also used a resisted ignition switch (my 65 Riviera had one) instead of the resistor wire or ballast resistor.

 

I took out the distributor then cranked the engine until 1 was on TDC on the compression stroke (using my thumb) Then i put the distributor back in with the rotor pointing at 1.

The gap was set to .016 with the go-no-go method and the car fired right up.

So after setting the points, then aligning the rotor ... Do i then turn the car on and meaure / adjust the dwell to 30?

Or do i do it with the car off and set the dwell?

then time it from there.

 

There was no cloth wire (i know exactly the kind you are referring to) in the engine bay that i could see. Unless it was under the dash or wraped in the wiring harness.

How would i correctly measure the voltage at the coil and the points using a voltmeter? Where do i clip?

thanks for the help guys.

 

The car needs to be running to check dwell. I was just making sure you did not have a resistor wire and the resistor in there. Just check that when the key is in start you have battery voltage at the coil and when it's in run it will be few volts less. You clip on the opposite side of the coil that the points are connected to.

 

"Sounds like a primary side electrical resistance issue somewhere."
+++++++++++++++++
There was a small wire that was going from the plate to the vacuum advance that was broken. I added a new one.
========================
Since that small wire ensures the ground path from points plate to distributor housing, it's crucial for correct ignition operation. Flexed in use, therefore will eventually fail.



There usually is a fair amount of varnish buildup that makes the distributer problematic if it has not been removed for some time.
===============
Agreed. They become stuck to the oil pump drive hex rod.
Also, if your car is that old, and you have occasion to remove the distributor, you should dismantle and clean, inspect, replace bushings as needed, and REFRESH THE "GREASE" for the top bushing. Imagine how much lubrication dry cheese grease does on a 5 degree day... none.
http://72.22.90.30/phpBB2/viewtopic.php?t=84851


can someone explain to me how the hoses on the fuel pump should be routed?
One goes through the firewall and into the dash somewhere and i am not sure why.
Another goes to the front of the carb as a fuel delivery line
the other goes to the back of the carburetor vaccum port.
I think, from snooping around, that the fuel pump is vacuum operated. I have no idea what there is a vacuum line running into the firewall.
=======================
Sounds like you have a combination fuel pump and vacuum pump. A line to the dash is likely to run the wiper motor- not electrical. The pump is mechanical- it's mounted to the engine, right? Half of it produces vacuum even if the engine is not, and the other half moves fuel. Two separate functions.

Don't be insulted, but you REALLY need carb 101 and ignition 101. Get a Chilton's or Motor's or better yet the factory Chassis Service Manual, and spend an evening reading up on the 6 basic carb circuits and the basics of the points ignition system. How dwell affects timing, etc. If you can take a class at your local community college, that would be money well spent. Wiring the choke open is not a repair... adjusting it so that it works as designed is a proper solution.

 

Sounds to me like a classic case of the ignition system grounding out, specifically the breaker plate in the dist. Check the negative wire from the dist to the coil for an open (break), after all its been moving around with the breaker plate for how many years.... Check the condenser wire for the same. Make sure neither is grounding out due to a breach in the wire casing. Verify the forked ends where they attach to the point set aren’t touching the plate. The break (open) in the wire may only show up when the breaker plate moves. This typically occurs when the car is running down the road with a varying engine load as the vac advance will move the breaker plate causing it to ground out on one of the two wires. Whereas it won’t do it at idle because the plates not necessarily moving. You can try pulling the vac advance hose on and off while at idle to induce the problem?

Also check the positive coil wire for an open. This open will only show up when moving due to vibe.

Pull apart the bulk head apart between the engine bay and fuse box on the firewall (with the battery disconnected). Those contacts may be corroded and causing intermittent opens or shorts.

Check the primary (smaller) wires on the starter solenoid for opens and continuity.

How about both ends of both battery cables for the same?
I've also seen a bad point set where the spring for the contacts came loose also grounding the points out. Don’t skimp on points and condenser. Get Blue Streaks (if still available) I recommend Corvette spec points. Clean and re-grease the point bumper and dist cam. Clean and re-grease regularly. Don’t touch the points and make sure the feeler gauge is clean when adjusting.

 

Ahhh octania you type faster then I

 

Cool thanks for the info.

Doesnt changing the dwell widen the point gap? So why even use a feeler gauge prior to changing the dwell? Just a question.

 

Thanks for the detailed information! its greatly appreciated.

I hope that ground wire solves my problem. While i was moving the lower plate i noticed the wire would move and return to the contact on the vacuum advance. This explains the shut off, but does not explain why the car would start back up after sitting for a while.

I would love to rebuild the distributor, however, it is hard as H**L finding a donor and or new parts for this distributor. No one (to my knowledge) makes one for a 371 oldsmobile. In your other post, did you use corvette parts for a rebuild?

I've rebuilt carbs before and done a lot of work on old cars. Learning as i go along. A class would be great, but between family life and graduate school, i simply dont have the time. Thats why i rely *(heavily) on great forums like this one. Just trying to keep grandpas old's on the road and out of the garage.

 

Thanks! This explains the situation perfectly in what im experiencing. I'll check the other things youve listed!!

 

I think i may have narrowed down this problem to the points. Since i've replaced them and fixed the ground wire, the car has ran satisfactorily. However, when i try to adjust them when the car is running, it really messes things up. The dwell reading is closer to 15* than 30*.

Yesterday the car sputtered and died. I was able to turn it back on immediately but it sounded way off in timing. I think the points may have burned from too much play in the distributor or because the cam lobes have been too rounded out.

Any suggestions? Im planning on putting in a pertronix module in the next week or so.

 

If you change the dwell it changes the timing. Dwell needs to be set at 30* first and then go back and set the timing. If you can't keep it running I'd suggest increasing the timing more then go back to the dwell.
If I remember right I think you use a .019 feeler gauge? That should get you close. Also, if your points are pitted it will throw the dwell off also. Since you are using new points that shouldn't be an issue.

 

Setting the point gap results in the proper dwell, they are hand in hand. If you have the cap window, then you can set the dwell while she runs, and get your 28-32 degrees that way. The pts gap is to get close enough to run. One great method for dwell adjustment is to turn the adjuster in or CW until she sputters, then back out or CCW 1/2 turn. Works great.

If you convert the dist'r to electronic, or, really, use it AT ALL... please at least remove it, dismantle it, and clean and refresh the grease. Yes I used the Vette brass bushings on the one dist'r. Pretty easy. I did go to the extreme of good shop practice in procuring a reamer and fabricating suitable guides for it use. I figured I had at least 3-4 to do, might as well get the tooling necessary.

For my rare 1111470 UHV distributor I will be using the best GM bushings on hand. They are steel. Unless the shaft is super worn, or the pts cam worn a lot, a dismantle, clean, and regrease should make it good for years yet. Sometimes the bushing is worn, but the shaft not so bad....

It's really easy to dismantle, not a lot to go wrong. If nothing is worn much, then it's a matter of reassembly. I have 1 or 2 pre-65 distributors for parts or cores.

 

The manual states .016, so i was able to set them and the car ran decently, but my meter read way off of 30* (i double checked it with a second one) and got a different reading too.

The thing is, when i adjusted the dwell to 30* is ran terribly, misfired, sputtered upon acceleration, terrible!

 

Can you post a link to where i can buy these bushings? Are they specific to the distributor in size or universal across pre-65?

I would love to dismantle the whole thing, clean the plates down, the weights, shoot, maybe even mess with the springs then re-assemble.

the cam lobes are pretty rounded, there was some real uneven wear going on, but since im going breaker-less, i guess the cam doesn't really matter.

I found this on autozone, is this what i need? Is it necessary?
http://www.autozone.com/autozone/par...3683_433635_0_

 

One other question, i read over on the HAMB, that Oldmobiles have timing marks on the distributor and instead of pointing them to the #1 piston, you are supposed to point them to the TDC of the #6 piston, them time it... is this true?

here is the link: http://www.jalopyjournal.com/forum/s...d.php?t=715390
maybe im misunderstanding. If that is the case, my car is way out of tune, i timed i like i would my buick.

 

So after you adjusted the dwell angle to 30°, did you then readjust the timing, or did you just leave it alone?

Using a feeler gauge to adjust a set of used points will set them wide, sometimes twice as wide as the specification, which is why you can only use a feeler gauge to set points that are brand-new, never-used.

As points close (as they do with wear), the timing retards.

If you set the points wide, set the timing correctly, then narrowed the points gap to the correct value by setting the dwell, you retarded the timing.

- Eric

 

Yes after bringing it to 30* i had to really turn the distributor to get it to 5* tdc. The only thing is the vacuum advance was almost turned to the firewall and the hose wouldnt reach. I want to take out the distributor and reset it so the advance has more room to travel when timing.

The points i put in were brand new.

 

There's something wrong, then.

If the gap of a new set of points is correct, the dwell angle should be exactly 30°.

Are you sure that you have your dwell meter set to 8 cylinders and connected to the negative coil terminal, with the power wire to a hot terminal (coil or battery) and the ground wire (if any) connected to a good ground, and that you are reading the meter off the correct scale?

- Eric

 

There aren't 3 wires on my dwell meter. I had the positive of the meter on the negative of the coil and the ground wire of the meter - grounded on the block. Both of my meters have 2 wires... crap...

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