1975 Plymouth valiant stalls in gear when hot

[NormalPcGamer]

Hello all,

I've been trying to troubleshoot a fairly new issue with my valiant (past couple weeks)


First off the car

1975 Plymouth valiant brougham

Engine - Swapped 360, stock bottom end (stock flat top pistons), comp XE268h cam, Speedmaster aluminum heads and high rise dual plane intake with a 1" plastic 4 hole spacer, hooker long tube headers, Edelbrock performer 750 carb, about 9.0/1 compression, stock style (new) distributer, MSD blaster 2 coil. Vacuum reading in neutral is about 14-15", in gear its about 10". Electric fan and aluminum rad.

Transmission - rebuilt 904, full manual valve body, stock converter (about 1800ish rpm stall)

Rear end - swapped 8 3/4 with 3.91 gears and sure grip


The issue

When the car gets warm (around 150-180 degrees) the car will stall and shut off when put into gear. (see video - ) I've been driving the car since April and this issue has only came up in the last 2 weeks or so. (note: in the video the amp gauge is pinned, the needle is slightly bent towards the charging side but has always read 3/4 or higher when the electric fan is on)


What I've tried

Timing/ignition
-New cap and rotor, new plug wires and spark plugs (about .036 gap)
-currently its set to 15 initial and 41 all in (I know all in is a lot, the swing in this distributer seems to be about 25-26 degrees, I've tried the FBO limiter plate but had to take it out due to it getting hung up on something and sticking at max advance) (side note I've ran the car at 45 degrees all in and I've never heard this engine ping)
-currently I have one light spring on the advance weights and I removed the heavy spring. issue was the same with both springs installed. issue was also the same with the old distributer.
-Vacuum advance is unplugged (ported vacuum) as it makes the car run worse even before this main issue came up. (manifold vacuum will cause the car to surge while driving)
-Tried both the stock black ignition box and factory Chrysler chrome box with same issues.
-I'm still running the stock quad prong ballast resister, I tried bypassing it today but it got the ignition box super hot so I put it back, issue was still the same either way.

Fuel
-New mechanical pump, new sending unit, replaced the rubber fuel lines front and back, blown air through the steel lines, tank is stock but doesn't deposit sediments.
-I've installed that 3 nipple wix filter in line with a clear glass filter and ran the third line back to the tank to prevent fuel boiling. Fuel pressure is a constant 5-6psi cold or hot.
-Currently I have a Edelbrock Performer 750 (1407) set to #14 on the tuning chart. idle mixture screws are at about 2 turns out. cleaned passages in the carb. idle is set to 900rpm in neutral and about 800 ish rpm in gear
-Found a gas station that sells non ethanol fuel, no change there
-All the rubber line up front has the slip on heat shielding, rubber line doesn't feel hot to the touch



Weird things I've noticed
-The coil when running in idle will read about 2.5 volts. when I bypass the ballast resister it reads about 4.5v. This coil has been on the car for about 5 years now and has never had an issue (maybe going bad? its mounted in the factory location and not vertical like they recommend)
-When the ballast resister was hooked up it would get smoking hot but unplugged the ignition box would get smoking hot.
-When the FBO plate was sticking the engine at 36* all the time its actually the best it ever ran and wasn't shutting off when hot.
-Battery voltage is at 15.5 volts when idling, 12.7 when off, I've replaced the voltage regulator but no change
-I have a A/F gauge installed and when the car stumbles and dies it doesn't go rich or lean, just shuts off.
-When it shuts off it will fire up no problem and sometimes idle fine and sometimes surge in neutral.


Things I'm gonna try next
-I have a Holley brawler 650 I'm gonna put back on the the car and see if that changes anything
-Rewire between the ignition box and coil to bring up the voltage on the coil.
-I'll find the ballast resister that came with the MSD coil and install that (P/N 8202 coil) even though the manual for the coil says I only need the ballast for points ignition.


I'm leaning towards it being something electrical that's causing my issues. The voltage at the coil seems very low so that's gonna be my next step. If anyone has any info on the ballast/coil wiring that I should do please let me know, or if anyone has any other questions/suggestions LMK, I've touched everything on this car so I'm very familiar with the ins and outs with it.

Pic of the car

Thanks!

 

[67Dart273]

If it is really that low, that IS pretty low

Are you sure you are measuring coil POSITIVE and a good ground when you read that? What is the battery at that moment.

Voltage drop in these girls can be a problem. It can be one or two issues and accumulative. The ammeter circuit as will as the ignition "run" circuit, going through the bulkhead, and even the ignition switch itself and the connector.

Do you have an understanding of chasing voltage drop, AKA following the circuit path and measuring points along the way?

Carb too lean or way too rich either one can aggravate this problem.

 

[NormalPcGamer]

I'm measuring from the positive on the coil to the negative to the coil. I haven't done to a different ground (chassis or engine)

I have an understanding on chasing voltage drop. I'll check that this weekend.

Carb is so far around 12afr at idle and cruising will be about 13-14 afr. the carb tuning is a whole other issue but that's how it is at the moment

 

[RustyRatRod]

I don't like the look of the ammeter reading while running, either. It's pretty much maxed out. That's not good. Whether that has anything to do with the stalling, I don't know, but I would certainly want to address that. Bad things can happen with the ammeter maxing out.

 

[NormalPcGamer]

I don't like the look of the ammeter reading while running, either. It's pretty much maxed out. That's not good. Whether that has anything to do with the stalling, I don't know, but I would certainly want to address that. Bad things can happen with the ammeter maxing out.

When I had the gauge cluster apart I accidently bent the needle about one line towards the charging side, but I'm not a fan of it either. I'm sure its because when its running the battery is at 15.5-15.7v, but I've changed the voltage regulator so I'm gonna have to do a deeper dive into why its that high. the battery load tests fine and its never cranked slow so I'm not sure where to look next. I've seen people just jump the wires at the ammeter together to "delete" it but that seems like I'm just ignoring the problem

 

[RedFish]

When the amp gauge is the fault we remove that shunt in the current path and install a volts gauge. If owner suspects the amp gauge will be a problem later, they do the same. I don't think anyone is ignoring a problem, just looking at a different indicator. You aren't ignoring 15.5 vdc. If a resister takes 12 volts down to 9 volts 15.5 goes down to 12.5. Too much for some coils. It might make a mess on your intake. My numbers are generalization. Resistance changes with temperature. Your coil may be seeing 14 vdc at times. Good luck

 

[NormalPcGamer]

ok update,

I took another look at the wiring, looks like I had spliced a wire going into the ballast resister to my aftermarket radio (did this almost 10 years ago), so I took that wire out as well as bypassed the resister again. with that now my coil has 9v measuring from positive on the coil to a body ground. Took it for a drive and it died while cruising. limped it to a side street and took a look and the ignition box is screaming hot (coil temp is warm but nothing crazy) so I plugged the resister back in but there was no power going to the cluster or ignition (wouldn't crank, gauges wouldn't move at all) so I jiggled some wires in the bulkhead and got it to fire up.

I was able to drive the car across the city to a buddy's house to store it but one thing I noticed is that the car never died in traffic, and today was a scorcher of a day (32c, car got to about 200-210F), not a single stumble in traffic. So I'm not sure if the moving some wires in the bulkhead connector was the fix or removing that wire I had spliced into the ballast resister was the fix.

Next thing I'm gonna do is take that bulkhead connector out and either see if I can make the wire connections going into it better or see if I can find an aftermarket bulkhead connector (if anyone has any suggestions on that please LMK) and rewire it

Also if someone can clear this up for me, MSD Blaster 2 coil P/N: 8202, Do I need a ballast resister with the stock electronic ignition? The manual for the coil only says that I need to run one if I have points, but for how hot that ECU got I'm not sure anymore. I've been reading confliction information online.


Thank you all

 

[RustyRatRod]

ok update,

I took another look at the wiring, looks like I had spliced a wire going into the ballast resister to my aftermarket radio (did this almost 10 years ago), so I took that wire out as well as bypassed the resister again. with that now my coil has 9v measuring from positive on the coil to a body ground. Took it for a drive and it died while cruising. limped it to a side street and took a look and the ignition box is screaming hot (coil temp is warm but nothing crazy) so I plugged the resister back in but there was no power going to the cluster or ignition (wouldn't crank, gauges wouldn't move at all) so I jiggled some wires in the bulkhead and got it to fire up.

I was able to drive the car across the city to a buddy's house to store it but one thing I noticed is that the car never died in traffic, and today was a scorcher of a day (32c, car got to about 200-210F), not a single stumble in traffic. So I'm not sure if the moving some wires in the bulkhead connector was the fix or removing that wire I had spliced into the ballast resister was the fix.

Next thing I'm gonna do is take that bulkhead connector out and either see if I can make the wire connections going into it better or see if I can find an aftermarket bulkhead connector (if anyone has any suggestions on that please LMK) and rewire it

Also if someone can clear this up for me, MSD Blaster 2 coil P/N: 8202, Do I need a ballast resister with the stock electronic ignition? The manual for the coil only says that I need to run one if I have points, but for how hot that ECU got I'm not sure anymore. I've been reading confliction information online.


Thank you all

I'm saying it needs a resistor unless you're running an MSD distributor. RIght from the MSD site:

"This Blaster Coil Kit is intended to be used with an MSD Ignition. If installing on a stock, points style ignition system, a 0.8 ohm ballast resistor or resistor wiring MUST be installed."

 

[NormalPcGamer]

I guess the wording of that is what's confusing me, Forgive my ignorance but my car doesn't have points ignition? it is stock style, but electronic ignition. I thought points and electronic ignition were a very different setup. Or are they just saying any "stock" ignition system requires the ballast unless its an MSD setup?

 

[RustyRatRod]

I guess the wording of that is what's confusing me, Forgive my ignorance but my car doesn't have points ignition? it is stock style, but electronic ignition. I thought points and electronic ignition were a very different setup. Or are they just saying any "stock" ignition system requires the ballast unless its an MSD setup?

All of the Mopar and Mopar style ignitions, points or electronic need a ballast resistor.

 

[scatpackbee]

Hello all,

I've been trying to troubleshoot a fairly new issue with my valiant (past couple weeks)


First off the car

1975 Plymouth valiant brougham

Engine - Swapped 360, stock bottom end (stock flat top pistons), comp XE268h cam, Speedmaster aluminum heads and high rise dual plane intake with a 1" plastic 4 hole spacer, hooker long tube headers, Edelbrock performer 750 carb, about 9.0/1 compression, stock style (new) distributer, MSD blaster 2 coil. Vacuum reading in neutral is about 14-15", in gear its about 10". Electric fan and aluminum rad.

Transmission - rebuilt 904, full manual valve body, stock converter (about 1800ish rpm stall)

Rear end - swapped 8 3/4 with 3.91 gears and sure grip


The issue

When the car gets warm (around 150-180 degrees) the car will stall and shut off when put into gear. (see video - ) I've been driving the car since April and this issue has only came up in the last 2 weeks or so. (note: in the video the amp gauge is pinned, the needle is slightly bent towards the charging side but has always read 3/4 or higher when the electric fan is on)


What I've tried

Timing/ignition
-New cap and rotor, new plug wires and spark plugs (about .036 gap)
-currently its set to 15 initial and 41 all in (I know all in is a lot, the swing in this distributer seems to be about 25-26 degrees, I've tried the FBO limiter plate but had to take it out due to it getting hung up on something and sticking at max advance) (side note I've ran the car at 45 degrees all in and I've never heard this engine ping)
-currently I have one light spring on the advance weights and I removed the heavy spring. issue was the same with both springs installed. issue was also the same with the old distributer.
-Vacuum advance is unplugged (ported vacuum) as it makes the car run worse even before this main issue came up. (manifold vacuum will cause the car to surge while driving)
-Tried both the stock black ignition box and factory Chrysler chrome box with same issues.
-I'm still running the stock quad prong ballast resister, I tried bypassing it today but it got the ignition box super hot so I put it back, issue was still the same either way.

Fuel
-New mechanical pump, new sending unit, replaced the rubber fuel lines front and back, blown air through the steel lines, tank is stock but doesn't deposit sediments.
-I've installed that 3 nipple wix filter in line with a clear glass filter and ran the third line back to the tank to prevent fuel boiling. Fuel pressure is a constant 5-6psi cold or hot.
-Currently I have a Edelbrock Performer 750 (1407) set to #14 on the tuning chart. idle mixture screws are at about 2 turns out. cleaned passages in the carb. idle is set to 900rpm in neutral and about 800 ish rpm in gear
-Found a gas station that sells non ethanol fuel, no change there
-All the rubber line up front has the slip on heat shielding, rubber line doesn't feel hot to the touch



Weird things I've noticed
-The coil when running in idle will read about 2.5 volts. when I bypass the ballast resister it reads about 4.5v. This coil has been on the car for about 5 years now and has never had an issue (maybe going bad? its mounted in the factory location and not vertical like they recommend)
-When the ballast resister was hooked up it would get smoking hot but unplugged the ignition box would get smoking hot.
-When the FBO plate was sticking the engine at 36* all the time its actually the best it ever ran and wasn't shutting off when hot.
-Battery voltage is at 15.5 volts when idling, 12.7 when off, I've replaced the voltage regulator but no change
-I have a A/F gauge installed and when the car stumbles and dies it doesn't go rich or lean, just shuts off.
-When it shuts off it will fire up no problem and sometimes idle fine and sometimes surge in neutral.


Things I'm gonna try next
-I have a Holley brawler 650 I'm gonna put back on the the car and see if that changes anything
-Rewire between the ignition box and coil to bring up the voltage on the coil.
-I'll find the ballast resister that came with the MSD coil and install that (P/N 8202 coil) even though the manual for the coil says I only need the ballast for points ignition.


I'm leaning towards it being something electrical that's causing my issues. The voltage at the coil seems very low so that's gonna be my next step. If anyone has any info on the ballast/coil wiring that I should do please let me know, or if anyone has any other questions/suggestions LMK, I've touched everything on this car so I'm very familiar with the ins and outs with it.

Pic of the car

Thanks!

View attachment 1716448261

I had the same car in high school 1986-1988 but in red!

 

[NormalPcGamer]

All of the Mopar and Mopar style ignitions, points or electronic need a ballast resistor.

Sweet, thank you! I've read so much conflicting information so I wasn't sure. I'm still running the factory style quad pin ballast, I will have to find the MSD supplied 2 pin ballast in my parents garage to install and convert to that. I will also be converting the bulkhead connectors to something aftermarket and removing the ammeter

I had the same car in high school 1986-1988 but in red!


View attachment 1716448552

View attachment 1716448553

Hah that's super rad! Love the cragars on it!

 

[Bewy]

Replacing the Edel 750 would be a backwards move.......

Vac of 10" is low for that cam. While it NEEDS more timing at idle [ 15* is waaaaaaaay too low, 25-30* more like it ].

So, what can cause low vac:
- wiped lobes lifters
- PCV not working because of the low vac, it becomes a giant vacuum leak
- poor ign
- leaking valves
- blown head gasket
- cold spark plugs [ should be 4 heat range in NGK ]
- & lots more.

One way to give the engine the idle timing it wants is to use vac adv connected to a manifold vac [ MVA ] source. PVA is a waste of a VA unit.

Examples of success stories & actual #s...

 

[NormalPcGamer]

Replacing the Edel 750 would be a backwards move.......

Vac of 10" is low for that cam. While it NEEDS more timing at idle [ 15* is waaaaaaaay too low, 25-30* more like it ].

So, what can cause low vac:
- wiped lobes lifters
- PCV not working because of the low vac, it becomes a giant vacuum leak
- poor ign
- leaking valves
- blown head gasket
- cold spark plugs [ should be 4 heat range in NGK ]
- & lots more.

One way to give the engine the idle timing it wants is to use vac adv connected to a manifold vac [ MVA ] source. PVA is a waste of a VA unit.

Examples of success stories & actual #s...

View attachment 1716448580

View attachment 1716448581

View attachment 1716448582

View attachment 1716448583

View attachment 1716448584

View attachment 1716448585

View attachment 1716448586

- wiped lobes lifters - I installed these heads at the beginning of the year so I was able to inspect the cam, no wiped lobes at all and lifters are in good condition
- PCV not working because of the low vac, it becomes a giant vacuum leak - I have always been suspect of the PCV, I just haven't found a good (cheapish) replacement/upgrade. I've seen the M/E Wagner one but is expensive. should I just remove the PCV all together? Or is there another option I could try?
- poor ign - That I'm sure is contributing to my issue, granted I've been driving the car all year and this issue has only came up in the past 2 weeks, possible part failing? distributer is new with new plugs/plug wires and chrome Chrysler ign box, Coil is about 6 years old
- leaking valves - Heads are brand new from speedmaster, I really wanted to lap the valves before I installed the heads but I got to antsy to drive the car. When I had the old iron heads on (j heads, 2.02/1.60, lapped valves) it had the same vacuum reading. I will do a leak down test closer to the end of the year when its parked at my parents house (they live a few hours away and have all my good tools lol)
- blown head gasket - New gasket this year, and I haven't got the carb tuned good enough to hold it wide open long. Not burning coolant or oil.

I've also sprayed copious amount of brake clean around everything to find a vacuum leak and I cant fine one. I'll take some pics of the engine bay and post them to see if anyone can see something that I can't.

Spark plugs are NGK RC12YC, what was recommended by speedmasters site for the heads.

I have tried running the car with manifold vacuum but it surges bad while driving, as for the mechanical advance I've found the car is pretty happy with somewhere around 20-23* initial, the problem is the advance in the distributor is about 25* to my total timing ends up being around 45-48* all in

And again forgive my ignorance, but I thought a full manifold advance was the opposite of what you want? if its on full manifold when you open the throttle off idle the vacuum goes down which would reduce the advance vs if its on ported (above the throttle blades) as you open the throttle the vacuum would go up (since above the throttle blades are now introduced to the engine vacuum) and add advance? Does this theory go out the window when an engine has low vacuum to begin with? Or am I thinking of this completely wrong?

From my testing with both I've found that if I have it on ported it will take off nicely and cruise smoothly and get great gas mileage, but will sometime die when waiting at a red light (which could also be my ignition/electrical causing issues), but when I try it to manifold it will go lean on throttle tip in (up to about 17-18 AFR) then smooth out until I'm driving at sustained speed then will start to surge bad (once I remove the vacuum line it will cruise fine)


I think what I'm gonna do first is rewire my ignition system so at least I know that is up to snuff and deal with the PCV then I can try playing around with the advance again. from the last 7 or so years I've been driving the car (with this drivetrain) I've always had more consistent performance with no vacuum advance at all.

Isn't there a saying that 80% of carb tuning is all in the timing/ignition?

 

[RedFish]

When doing tune ups, 80% of time in the bay is ignition related. Points, plugs, wires? Check timing. May need to adjust lean best, curb idle rpm. Happy motoring. Next?

 

[George Jets]

Simple is Good

Simple is good, everything runs cool, no ballast resistor, straight 12 volt supply, 60,000 volt e-core coil, 8° BTDC on initial timing.

(because the HEI E-Core coil burns so fast that in itself advances the timing by 4°, so you have to back it down so that it falls into the 12° BTDC factory specs).

Improves low rpm idle, and no hesitation throttle response.

Yeah, it's in your ignition.


☆☆☆☆☆

 

[NormalPcGamer]

I will look into the HEI conversion, seems pretty nice and simple.

As for now I’m eliminating and simplifying the wiring, anyone know what this would be for? It was on the car with the factory setup so I brought it over when I swapped engines. I can’t find anything in the factory wiring diagrams about it. It attaches to the positive on the coil and gets bolted to the coil mount on the intake

 

[RedFish]

That is likely a noise suppression capacitor. Prevents ignition noise in radio.

 

[scatpackbee]

That’s exactly it.

 

[NormalPcGamer]

That is likely a noise suppression capacitor. Prevents ignition noise in radio.

That’s exactly it.

View attachment 1716448880

Ah neat, I guess I'll leave it on, thanks!



Had good progress on the wiring, removed about a dozen wires that were for old plugs that weren't used anymore. Next step is to repair one terminal on the bulkhead connector that had a loose wire which broke off when I unplugged the harness and to eliminate the ammeter wiring that goes inside the car. Time to order more parts

 

[AJ/FormS]

I can make that thing idle at 550 in gear and pulling itself on flat level, hard ground with 5 measly degrees of Timing advance. Maybe even 500.
If I can't, it will be because the engine has too much internal friction, or crap for cylinder-pressure, or the convertor is bad, or the carb is just no good.
I'm about an hour from Winnipeg.
Fill it with fresh gas, and bring it down tomorrow, I got nothing to do. Come in the morning, it might take a few hours.... at 72, I don't work as fast as I once did.

 

[NormalPcGamer]

I can make that thing idle at 550 in gear and pulling itself on flat level, hard ground with 5 measly degrees of Timing advance. Maybe even 500.
If I can't, it will be because the engine has too much internal friction, or crap for cylinder-pressure, or the convertor is bad, or the carb is just no good.
I'm about an hour from Winnipeg.
Fill it with fresh gas, and bring it down tomorrow, I got nothing to do. Come in the morning, it might take a few hours.... at 72, I don't work as fast as I once did.

Well unfortunately I have to wait on some parts to show up, one of the wires that went into the bulkhead broke so I have to order more of the Packard 56 connectors and re-pin it. That being said once the car is back up and running I will send you a DM and I can come on by with the car. I don't know anyone personally who is well versed in Mopars so I am excited to show the car to someone who knows them and is willing to give me advice, everything I've done to the car has been researched and done by me figuring it out

 

[AJ/FormS]

Alrightee then, Snows coming but I got a nice warm shop. Yur a guy right?
If not, then bring a friend, and cover up yur assets, at 72 I'm easily distracted., lol. I can't think with boobies in my face.

 

[NormalPcGamer]

Alrightee then, Snows coming but I got a nice warm shop. Yur a guy right?
If not, then bring a friend, and cover up yur assets, at 72 I'm easily distracted., lol. I can't think with boobies in my face.

lol don't worry I'm a guy, and hopefully we've got plenty of time before the snow starts flying

 

[Bewy]

The HEI conversion is a good move. Use the MSD #8207 E core coil & the bal res can be omitted.

PCV. A simple fix if you suspect a malfunction. Get a 3/8" bolt [ or 3/8" alum dowel ] & cut off a piece about 3/8-1/2" long. Drill a 1/8" hole through it. Push it into the PCV hose. If you get a substantial change in idle quality, the PCV was causing the problem. Either way, leave the insert in the hose.