Cool Dave’s 1973 Dodge D100 Club Cab

[CoolDave]

So this thread I will be using to document my progress through the truck and ask a bunch of questions along the way, the first few posts will be catching up from buying the truck to now, I’ll use this first one to just introduce the truck and it’s back story..

So I’ve always some sort of old car or truck to tinker on, my wife is very supportive and also loves old trucks. We finally moved out from the city back in ‘21 and decided on picking up an older truck to use to make the hardware store runs on weekends as my work truck has a topper on it. After scouting around for a while we found the right truck in Oklahoma City..



It’s a 1973 Club Cab, first year for it! The guy I bought it from had, supposedly, been using it every other day until he purchased a new truck to replace it. He had purchased it from its long-time owner of around 40 years, it came with paperwork all the way back to the build sheet, manual and salesman’s business card up in Colorado. With how complete it was and the documented history we went with our gut on it and brought it home.



Turns out, it had probably been sitting a lot longer than we were lead to believe so its become a little more involved getting it to a useable state. We did discover a lot of fun little coincidences with it though, it’s originally from Denver which happens to be where my brother lives, the long-time owners name was a combination of mine and my sons names and it’s been known as ‘Rosie’ for most of its life which was one of my best friends childhood dogs we played with all the time as kids.



I will make my next post about the initial troubleshooting and how the truck is running right now. Looking forward to getting some proper Mopar knowledge and getting this truck running how it should be!

 

[LocuMob]

Best grille for the Tim Grille era trucks, but I'm biased having a '72 crew cab. Look forward to your progress.

 

[318willrun]

Nice Truck!

 

[missing linc]

When I was about 10 my dad bought a new D100 Adventurer truck with a slide in camper. I really liked that truck, but he was not happy with it and didn't keep it for very long.

 

[4spdragtop]

Welcome aboard from Canuckistan! Beauty truck!

 

[CoolDave]

Thanks all!



I’ve been thinking about how to concisely sum up the basic work I’ve done to it since I got it home so let’s just start with a list of new parts..

IGNITION/ELECTRICAL:
Distributor, cap, rotor, coil, wires, plugs, ignition module, starter relay, ballast resistor. I also cleaned and tightened all the contacts on the back of the dash and replaced all the dead bulbs except the license plate.

MECHANICAL:
Oil/filter, transmission pan gasket, neutral switch, shift-shaft seal (don’t even get me started on that), basic carb cleaning and tightened countless loose bolts.

So overall pretty thorough but basic tuneup stuff. After all that I polished it up and took off the big hubcaps, I’m casually looking for some cheap poverty caps or possibly different wheels after I get it reliably useable.



So now let’s get to where I’m at with the truck currently..

Two weeks ago it was running pretty well with the exception of a noticeable flat spot at light throttle causing hesitation. I had previously set timing when I put the new (cheap) distributor in and roughed in the carb using a vacuum gauge and just how the truck felt. The electric choke is wired open but even cold starts were easy, idle was decent and it felt strong at mid throttle. I did have some bounce in the vacuum gauge needle at idle but I chalked it up to maybe not finding all the leaks yet and the cheap gauge.

Fast forward to last weekend, I decided to dig into the vacuum situation. To make a long story short I took the vacuum advance line off and checked it, I can suck air through or blow air back. Little disappointing but not surprising considering the parts quality. That said, when it was hooked up (manifold vacuum, not ported, school me) it still pulled a bunch of advance but I thought maybe it was causing too much of a drop in vacuum when the throttle was cracked open leading to the flat spot.

So kinked the line off and bumped initial timing up to 16-17 degrees. Still fires easy but idles a little warmer. No flat spot accelerating but once the motor has heat built up it starts to run awful. Can’t take a load on the motor unless you give it a bunch of pedal.

And that’s where I’m at, waiting for more time to tinker.. I have two young kids and work pretty long hours so time for the truck is limited. I’m itching to get it going properly.



So school me! Where do I go in my troubleshooting from here? Should I move my vac advance to ported vacuum or just bump up my static timing? I’m here to absorb all the wisdom about these motors.

 

[AJ/FormS]

You don't have a timing problem.
All your efforts are only band-aiding the real problem, which is most likely the carb. and AFAI can tell it has multiple problems. Assuming;
the intake valves are sealing and NOT sticking, and
the gas is fresh and clear, then
the carb will have to taken apart and cleaned, then, the timing returned to near stock.

In addition, you will need to;
make sure the PCV system is functioning properly, and
that the EGR system is Not faulty, and
that the only other air entering the engine, is going past the Throttle valves. and
that the crank is NOT seeing an idle load from other systems like the A/C compressor, the P/S system, a faulty convertor, etc.

AFAI can tell your carb, itself has up to three major issues, but ids not limited to just those three; Assuming that ;
A) the gas is fresh and
B) the WET fuel level is both correct and stable, and
C) most importantly that the cylinder pressure is even, stable, and it takes about the same number of compression cycles to peak the gauge; then, the issues may be/ but are not limited to;
1) the accelerator pump is lazy
2) the Transfer slot exposure under the throttles is too small, and
3) the airbleeds or emulsion tubes are restricted.
4) the fuel is contaminated.
I would start with a compression test, on account of you mentioned the vacuum gauge bouncing, which is a clear sign of something going on in the intake which should not be happening and can almost always be traced to an intake valve; simultaneously I would check every valve spring to make sure each has enough seat pressure, to be able to keep the valves closed and sealed. If you can spin an intake with just your fingers, that is NOT enough, lol.

 

[Max1196]

Gas tank stuff survived? there's some crazy stuff going on there in 72/73. Here, gravel roads made a mess of that tank thing.

 

[LocuMob]

Gas tank stuff survived? there's some crazy stuff going on there in 72/73. Here, gravel roads made a mess of that tank thing.

View attachment 1716163755

View attachment 1716163756

Yep, they kept the cab filler, but went to a tank under the bed in '73.

 

[CoolDave]

You don't have a timing problem.
All your efforts are only band-aiding the real problem, which is most likely the carb. and AFAI can tell it has multiple problems. Assuming;
the intake valves are sealing and NOT sticking, and
the gas is fresh and clear, then
the carb will have to taken apart and cleaned, then, the timing returned to near stock.

In addition, you will need to;
make sure the PCV system is functioning properly, and
that the EGR system is Not faulty, and
that the only other air entering the engine, is going past the Throttle valves. and
that the crank is NOT seeing an idle load from other systems like the A/C compressor, the P/S system, a faulty convertor, etc.

AFAI can tell your carb, itself has up to three major issues, but ids not limited to just those three; Assuming that ;
A) the gas is fresh and
B) the WET fuel level is both correct and stable, and
C) most importantly that the cylinder pressure is even, stable, and it takes about the same number of compression cycles to peak the gauge; then, the issues may be/ but are not limited to;
1) the accelerator pump is lazy
2) the Transfer slot exposure under the throttles is too small, and
3) the airbleeds or emulsion tubes are restricted.
4) the fuel is contaminated.
I would start with a compression test, on account of you mentioned the vacuum gauge bouncing, which is a clear sign of something going on in the intake which should not be happening and can almost always be traced to an intake valve; simultaneously I would check every valve spring to make sure each has enough seat pressure, to be able to keep the valves closed and sealed. If you can spin an intake with just your fingers, that is NOT enough, lol.

A lot to digest here so I’ll dig in properly when I’m looking at the truck. I did pull the carb and crack it open when I got the truck, it was actually pretty clean inside so I threw in the basic seals and slapped it back together. Fuel pump eccentric seems to be shot so I added a cheap electric pump, new hoses and filters. Fuel supply is good, gas is new, filters are clean. The vacuum bounce was a few inches of vacuum until I blocked off that vacuum advance can, now it’s a tiny fluctuation and the gauge shows strong idle vacuum.

I guess I can figure out running a compression check on it when I have time to eliminate it as a cause. In the mean time I’d like to probably try to get the vacuum advance back to working which means a new canister or maybe just a whole new distributor. When I do that what’s the consensus on ported versus manifold vacuum? Then I’ll also check out the carb a little closer, is there a good guide for those 2-barrels somewhere?

Yep, they kept the cab filler, but went to a tank under the bed in '73.

My truck has the cab filler hooked to the under-bed tank but it also has evidence of what used to be a filler on the side of the bed. Still haven’t figured out why that is..

 

[TT5.9mag]

The engine is stock, set the timing up accordingly. Get a service manual and set up timing based on that. The stock distributor probably has a very long slow curve in it and bumping up the initial without fixing the centrifugal will cause problems. The vacuum advance should be on ported vacuum at this point. You don’t need a bunch of initial timing with a stock camshaft and a stock distributor. The best thing you can do is modify the distributor to bring in less centrifugal advance so you can add initial and not over time the total.

 

[AJ/FormS]

If the bouncing Vacuum gauge quit with the vacuum line pinched, and the line plumbed to ported vacuum, then, your throttle is too far open, because at idle, that port should be dead.
But if the line was plumbed to the intake-port, then the possibility exists that the diaphragm is fubarred; you would have to watch the timing light to see if it is similarly bouncing. if it is not, and nothing changes at the timing marks when you pinch the line, then I'd go with a bad diaphragm.
If the carb floatbowl has already been proven clean and uncontaminated;
Then I would just remove and clean the block under the choke plate which carries the emulsion tubes and air-bleeds, and make sure the gaskets are correct, and make sure the Accelerator check-system is complete. Going from memory, Some have a pointy check brass valve like a float valve and others have a ball with a weight above it.

 

[CoolDave]

The engine is stock, set the timing up accordingly. Get a service manual and set up timing based on that. The stock distributor probably has a very long slow curve in it and bumping up the initial without fixing the centrifugal will cause problems. The vacuum advance should be on ported vacuum at this point. You don’t need a bunch of initial timing with a stock camshaft and a stock distributor. The best thing you can do is modify the distributor to bring in less centrifugal advance so you can add initial and not over time the total.

I have the service manual, I originally had it set to factory spec on the timing, I only bumped it up after losing the vacuum advance out of curiosity of how it would respond. I am considering just picking up another new distributor locally as the one I got online is obviously questionable. I will hook it to ported vacuum, is that the small port under the choke on the passenger side?

If the bouncing Vacuum gauge quit with the vacuum line pinched, and the line plumbed to ported vacuum, then, your throttle is too far open, because at idle, that port should be dead.
But if the line was plumbed to the intake-port, then the possibility exists that the diaphragm is fubarred; you would have to watch the timing light to see if it is similarly bouncing. if it is not, and nothing changes at the timing marks when you pinch the line, then I'd go with a bad diaphragm.
If the carb floatbowl has already been proven clean and uncontaminated;
Then I would just remove and clean the block under the choke plate which carries the emulsion tubes and air-bleeds, and make sure the gaskets are correct, and make sure the Accelerator check-system is complete. Going from memory, Some have a pointy check brass valve like a float valve and others have a ball with a weight above it.

Diaphragm in the vac advance is definitely a problem, I can suck air through it or blow through it. It’s not completely blown out as it still pulls in advance but the bounce in intake vacuum goes away with it out of the system.

So it seems like my plan will be to probably buy another distributor. I will reset the timing to factory spec and hook the advance to ported vacuum. I will pull the choke plate and EGR valve (disconnected anyway) off the intake and inspect those also. I will update on the result!

 

[TT5.9mag]

I have the service manual, I originally had it set to factory spec on the timing, I only bumped it up after losing the vacuum advance out of curiosity of how it would respond. I am considering just picking up another new distributor locally as the one I got online is obviously questionable. I will hook it to ported vacuum, is that the small port under the choke on the passenger side?

Depends. What carb do you have? Post a few pictures. No need to get a new distributor just yet, you might just need a vacuum can. And let’s start talking in actual numbers here and narrow down the timing. What is the initial timing and what is the idle rpm? What is it at 1500? 2000? 2500? And so on. What rpm does it stop advancing at? With that info someone like @Mattax can plot a graph for you. All of this should be done with the vacuum advance disconnected and plugged.

 

[Mattax]

Just skimming through. It sure looks like an EGR valve on the intake. Off the top of my head EGR should be closed off when the engine is cold, at idle hot and cold, as well as at wide open throttle. Typcially they use a ported vac source and some sort of thermal switch usually in a coolant. vac diagram should be (was ?) in the engine bay. Some used a venturi vacuum signal. example diagram of venturi signal system

Some info on the EGR systems in the Master Techs series in '74. Can also skim back through '73 and '72 to see what is there.

Browse MTSC by Model Year – 1974 – MyMopar

mymopar.com

Knowing the engine has smog stuff on it, would want to see the carb and check the FSM or Sun cards to see what else it had. Generally trucks has less junk added to them compared to cars of the same year. Shop manual (cars) shows smogged 318 ought to be around TDC to 2.5* at 750 rpm. But that only works at higher rpm with the matching distributor curve. An earlier 318 with its distributor will be more like 5* at 650 rpm. Measure the rpms vs timing and we'll graph it.

 

[CoolDave]

Depends. What carb do you have? Post a few pictures. No need to get a new distributor just yet, you might just need a vacuum can. And let’s start talking in actual numbers here and narrow down the timing. What is the initial timing and what is the idle rpm? What is it at 1500? 2000? 2500? And so on. What rpm does it stop advancing at? With that info someone like @Mattax can plot a graph for you. All of this should be done with the vacuum advance disconnected and plugged.

Here’s the best picture I have right now for the carb, I’ll snap some more next time I have the hood open as there’s a few other things the service manual doesn’t offer much guidance on.



For the distributor I’m sure I could probably get away with just the vacuum can and I may take that route but considering the can was bad on my new part (thanks China) I may just buy one locally that should be better quality.

Just skimming through. It sure looks like an EGR valve on the intake. Off the top of my head EGR should be closed off when the engine is cold, at idle hot and cold, as well as at wide open throttle. Typcially they use a ported vac source and some sort of thermal switch usually in a coolant. vac diagram should be (was ?) in the engine bay. Some used a venturi vacuum signal. example diagram of venturi signal system

Some info on the EGR systems in the Master Techs series in '74. Can also skim back through '73 and '72 to see what is there.

Browse MTSC by Model Year – 1974 – MyMopar

mymopar.com

Knowing the engine has smog stuff on it, would want to see the carb and check the FSM or Sun cards to see what else it had. Generally trucks has less junk added to them compared to cars of the same year. Shop manual (cars) shows smogged 318 ought to be around TDC to 2.5* at 750 rpm. But that only works at higher rpm with the matching distributor curve. An earlier 318 with its distributor will be more like 5* at 650 rpm. Measure the rpms vs timing and we'll graph it.

I will get the book out again and reset the timing to factory, I want to say it specified somewhere around that 5* mark but I will confirm. In terms of smog stuff it seems like it really only has the charcoal canister which has all the lines disconnected to/from it and that EGR valve.

The last point to note for future troubleshooting too, this motor is not original to the truck. I’m not sure what it came from but it was swapped in around ‘05-06.

So questions..

1) Does the EGR need to be functioning or can I simply leave it capped?

2) Heat riser valve on the passenger side exhaust.. how do I confirm it’s working correctly?

 

[TT5.9mag]

That’s a Holley 2210 style carb. You’ll find diagrams with all of the ports labeled
Here;

https://www.carburetor-parts.com/assets/manuals/holley-2210-2245-rebuild-manual.pdf

 

[Mattax]

I want to say it specified somewhere around that 5* mark but I will confirm. In terms of smog stuff it seems like it really only has the charcoal canister which has all the lines disconnected to/from it and that EGR valve.

The charcoal can may need some vacuum for purging.
Main concern functionally will be the fuel tank vents where ?
The carb in the photo has a bowl vent inside the air cleaner, so it will work fine. The charcoal can connection to the carb bowl is typically only for controlling bowl vapor when the engine is off. Nice but but not neccessory (and can be problematic).

The last point to note for future troubleshooting too, this motor is not original to the truck. I’m not sure what it came from but it was swapped in around ‘05-06.

Huge! So its an unknown mishmash of carb, distributor, and emissions stuff.
Block and intake may have casting dates you can see (with some effort).

1) Does the EGR need to be functioning or can I simply leave it capped?

I think the answer is: yes with no vacuum the valve will be closed at all times.
As far we know, it doesn't have the matching distributor so this is the simplest route.
Emissions delete is going to be the easiest route. EGR should be easy enough to hook up later on if you choose to.
If the heads are late enough, they will have air injection holes under the main exhaust ports. They will need to be plugged.

2) Heat riser valve on the passenger side exhaust.. how do I confirm it’s working correctly?

When its cold, see if you can rotate it by hand - it should move and then spring back. Nice but not super critical. Wire it open if/when it fails.

Going emissions delete, but mystery distributors, I'd start with timing around 5 to 7.5* BTDC without vac advance. Note the rpm!
Then measure timing at some other rpms. You will be limited to the timing range on the cover unless you have timing tape, dial back light, etc. Its super important to know the rpm of any timing measurement.

 

[CoolDave]

That’s a Holley 2210 style carb. You’ll find diagrams will all of the ports labeled
Here;

https://www.carburetor-parts.com/assets/manuals/holley-2210-2245-rebuild-manual.pdf

Nailed it, I knew it was a Holley style and started with a 2 but so many variants! I’ll dig through that link. Thanks!

The charcoal can may need some vacuum for purging.
Main concern functionally will be the fuel tank vents where ?
The carb in the photo has a bowl vent inside the air cleaner, so it will work fine. The charcoal can connection to the carb bowl is typically only for controlling bowl vapor when the engine is off. Nice but but not neccessory (and can be problematic).

Huge! So its an unknown mishmash of carb, distributor, and emissions stuff.
Block and intake may have casting dates you can see (with some effort).

I think the answer is: yes with no vacuum the valve will be closed at all times.
As far we know, it doesn't have the matching distributor so this is the simplest route.
Emissions delete is going to be the easiest route. EGR should be easy enough to hook up later on if you choose to.
If the heads are late enough, they will have air injection holes under the main exhaust ports. They will need to be plugged.

When its cold, see if you can rotate it by hand - it should move and then spring back. Nice but not super critical. Wire it open if/when it fails.

Going emissions delete, but mystery distributors, I'd start with timing around 5 to 7.5* BTDC without vac advance. Note the rpm!
Then measure timing at some other rpms. You will be limited to the timing range on the cover unless you have timing tape, dial back light, etc. Its super important to know the rpm of any timing measurement.

Fuel tank has a vent hose that would have run to the canister hanging under the bed to where it can’t get dirt or moisture in it. Trucks parked outside 24/7 so I’m not too worried about it right now. Heat riser moves freely and springs back, in its resting position with the motor off is it open or closed?

Thanks for the insight so far guys, I feel a lot more confident I’ll be able to get this truck working how I want it to now, if I could just find the dang time!

 

[Mattax]

Its super important to know the rpm of any timing measurement.

Here's a couple examples using initial timing and advance from service manuals.

Here's a '69 with CAP/CAS with the gray dots representing measurements on an engine.

With the timing of TDC set at 700 rpm, the rest of the timing is in spec.
With 7*TDC at 1000 rpm everything is the same as as above.
BUT.
If the timing was set to TDC at 1000 rpm, the engine would be a lazy dog.
or
If that distributor was set to 7* at 700 rpm, the engine would likely ping under heavy loads, or even moderate loads once fully hot (long trips).

Finally here's an comparison of early non-emissions vs emisions distributor advance.

Late 70s early 80s distributor advances are probably different again because those had catylitic convertors.

 

[TT5.9mag]

Told ya! @Mattax is always on point. Get some actual numbers for us regarding timing and we’ll get you sorted out.

 

[pauly]

@CoolDave : I have two wiper motors that will fit that truck if you want spares. Both bench test good. Yours for the price of shipping.

 

[CoolDave]

Alright so small update..

Pulled the EGR valve, it actually had a hairline crack between the two ports. Cut out a metal block off plate out of some shim-stock, sandwiched it in with a skimming of high-temp silicone.



Then over to the distributor side.. moved the vac advance line to the ported vacuum on the carb.


I also managed to craft a new connection/wire for my choke assembly so I repaired that and got it back on.

On the timing I do not have a functioning tach or a timing light that reads RPM. I set the idle timing with the vacuum kinked off to right around 5-6* initial. I’m not sure what RPM it is at but the mechanical maxes out at 28-29* according to my Harbor Freight timing gun.

With these numbers locked down I unkinked the vacuum line, it didn’t seem to make any noticeable difference to idle but it did certainly help the low-throttle driveability and idle temperature. I still need to replace the can on there regardless.

One thing I did notice with my timing gun, is that sporadically I would get a timing jump of 3-5* but only for a split second and then it’s back in line, not consistent or engine speed dependent. Typical culprits to check?

 

[AJ/FormS]

timing chain slack. That's a "normal" symptom.
The test is to rock the crank back and forth against the valve springs, without disturbing the cam.
2/3 degrees at idle is not that bad.

The sparkport should have zero vacuum at idle. In fact, if you slowly bring the idle up in N/P, it might take more than 1500rpm before it tickles the port.

That distributor is NOT set up right for your application.
I'm NOT saying it won't work, just that the cam in it is too short.
If yur at 5/6 and only get 28/29, then the cam is 29 less 6 equals 23 degrees. To get to a good number of 34/36 with a 23 degree cam, will take; 35 less 23 equals an initial of 12 degrees of idle timing.
You need to try it. and crank your idle-speed back to something like 550 rpm(A guess will be fine) in gear/any gear. Then twiddle the mixture screws for best quality idle, then add 1/4 turn rich. Then gently drive away.
If the engine, responds smoothly, then yur in business.
Finally, shift from Neutral to Drive several times.
If the rpm change does not bang the trans, or stall the engine, and is in the window of 100 rpm +/- 50 rpm, then, again, yur in business. That distributor may be fine.
The proof will be that the engine does not detonate at any time, especially at WOT, and also not with throttle openings from modest to WOT below about 3400 rpm.
And the final test is that the engine shuts off cleanly with no tendency to run on, which should not be a thing, at 12 degrees.

 

[CoolDave]

Minor updates..

Bumped initial timing up a couple degrees, all-in mechanical is now hitting 30-31 degrees.

So at this point it’s getting to a point where I feel I can start to tinker on improving things and fine-tuning stuff rather than just getting it to a consistent state. Bearing that in mind my first move was a new tach since my factory one does not work and I figured it would also be beneficial for further tweaking on timing, idle etc.

I grabbed a universal 2.5” tach from the local parts store, it’s a hair too small so I had to mess with it for a while getting a setup together to make it fit the factory hole properly. It still need some fine tuning but functional for now..



So my idle in park sits right around 1000 after the choke has finished backing off. In gear it drops to closer to 500rpm and seemed to have a little miss to it so I think I’m going to bump it up 100-200rpm.

While I was tinkering on wiring I was also joined by, I guess, a neighborhood cat..



Super friendly cat, seen it a couple of times now so my wife named it Maggie. Got to admit I’m happy to have another mouser around with how much the truck and my Mustang sit idle!