1973 Dodge SB Distributor will not seat against block

[1970FuryConv]

I have a 1973 Dodge with original 360 V-8 engine. The car starts and drives okay. However the base of the distributor does not seat against the top of the block. There is about 1/8 inch of clearance between the top of the block & bottom of the distributor base. Further the distributor is very hard to turn when I set timing.

Thus far I have tried removing the distributor and tapping down on the oil pump driveshaft to see if it is not fully seated on the bushing. I also cleaned out the slot at the top of the oil pump driveshaft. I’ve removed the oil pan, 1st and foremost to clean out debris in the oil pump pickup, but also to see if pulling down on the oil pump driveshaft would help lower the slot for the distributor shaft. The oil pump driveshaft is fully seated against the bushing and pulling on the bottom of it does nothing.

I cleaned the base of the distributor on a wire wheel and installed a new O-ring. I lubricated the O ring with light oil, but still the distributor base will not seat against the top of the block. Yet, when driving the car, I would never know that this problem existed. The distributor does not make noise.

Is distributor driveshaft set up wrong in the housing? How would I fix this issue?

Wrong oil pump driveshaft bushing?

Has anyone run into this problem and what did you do to fix it?

Thanks for your help as always!

 

[CBODY67]

Just curious . . . when did you notice this situation? Has anything changed or has been done to the engine before you noticed this?

Thanks,
CBODY67

 

[413]

Had it happen, tried several things like you did, changed the gear, no change. Made a round spacer to fill the gap between the block and distributor with a gasket on each side. Works fine now.

 

[1970FuryConv]

Just curious . . . when did you notice this situation? Has anything changed or has been done to the engine before you noticed this?

Thanks,
CBODY67

1. Bought the car in January 2021
2. Top front and rear of block covered in sludge. Original 2bb manifold still on car. Front and rear seals gone. Badly deteriorated RTV.
3. Pulled intake to change to 4bbl.
4. Noticed the problem with distributor then. Removed distributor.
5. Cleaned and painted top rear of block
   
6. Distributor: Vacuum advance diaphragm did not hold vacuum. Removed vacuum advance. Purchased new unit from Halifax Hops. Installed and lubed components per FSM. Did not remove shaft from housing or do anything to change position of shaft in housing.
7. After intake installed, reinstalled distributor per OP. Still have original problem.
8. Could PO have purchased a distributor improperly rebuilt? What do I do to properly orient shaft to housing?

Thanks!

 

[CBODY67]

Sounds like the shaft is too long, as there is usually only ONE way it can be installed and work. Like putting an RB distributor in a 361-383-400 without the Direct Connection spacer.

What is the stamp number on the side of the housing? Which might lead to a Chrysler dist number so that the orig application of the distributor might be determined?

Just some thoughts,
CBODY67

 

[Big_John]

In the dim recesses of my mind, I recall some earlier distributors having a metal gasket instead of the o ring. Or maybe along with the o ring.

There would be a height difference to let you use the gasket.

 

[CBODY67]

On our 383s, the '66 had the metal shim gasket and the '70 has the o-ring seal. Both go in the same place at the same flanged installed height. LA motors different?

FWIW,
CBODY67

 

[1970FuryConv]

Sounds like the shaft is too long, as there is usually only ONE way it can be installed and work. Like putting an RB distributor in a 361-383-400 without the Direct Connection spacer.

What is the stamp number on the side of the housing? Which might lead to a Chrysler dist number so that the orig application of the distributor might be determined?

Just some thoughts,
CBODY67

I have owned 9 LA motor Chrysler corp cars/trucks. 1st time I've run into this problem. Wish I had a spare LA distributor. I'd measure the length of the shaft from the bottom of the housing and compare.
ID # below:

 

[halifaxhops]

Make sure you have the right o ring on it to wide will cause this. Easy check remove it and see if it seats now.

 

[halifaxhops]

Mopar Distributor Shaft Lengths


Mopar Distributor identification guide by measuring shaft length, measured from mounting surface to lower end of distributor shaft.

Mopar LA engine – 3.875”
Mopar B engine – 3.5″
Mopar RB engine – 4″
–
Chrysler 331/354 Hemi – 4.25″
Chrysler 392 Hemi – 4.5″
–
Dodge 241/260/270 Hemi – 3.875”
Dodge 315/325 Hemi – 4.25″
Desoto 276/291 Hemi – 4.00″

 

[commando1]

There is about 1/8 inch of clearance between the top of the block & bottom of the distributor base.

Mopar LA engine – 3.875”
Mopar B engine – 3.5″
Mopar RB engine – 4″

4.0 - 3.875 = 0.125 = 1/8
Nah... Impossible. Can't be.

 

[Big_John]

4.0 - 3.875 = 0.125 = 1/8
Nah... Impossible. Can't be.

B & RB run counterclockwise. A runs clockwise.

So you look and there's a left and right hand distributor and one would run like crap if it was switched.

Unless the shaft can be interchanged! With a rebuild, you know Jose may have dropped the box of shafts yesterday and that could happen.

 

[halifaxhops]

Pretty hard to mistake that one it is different length, rotaion and weights also. Unless there was zero testing afterwards hard to do by mistake.

 

[commando1]

& RB run counterclockwise. A runs clockwise.

I was joking John.
I wanted to see who caught this. Damn you.

What happened to the reply that showed the shaft lengths?

 

[max1196]

There isn't by chance just a piece of crap that has fallen into the intermediate shaft slot and now won't allow the distributor to seat properly?

 

[1970FuryConv]

THE FIX
· Rotor: 3 o’clock position, front of car 6 o’clock

· distributor remove: I got my 1st big shock of the day because the distributor was very difficult to pull out even when the base was clear of the block. It turned out that the oil pump driveshaft came out with the distributor. I have removed and replaced a lot of distributors and I’ve never seen that happen. Don’t think shaft fully seated in slot of oil pump driveshaft. Part of problem.

· Oil pump driveshaft: on examination I saw that somebody had bunged the slot, presumably while trying to hammer the shaft in place from above.

at least bushing looks OK

· Oil pump driveshaft: I went through my spare parts box and found an oil pump driveshaft from a 1990 318 that I disassembled 11 years ago. The shaft and slot were in perfect condition. I cleaned the shaft on a wire wheel. Used Q-tips and screwdrivers and CRC brake cleaner to clean out the slot.

· 1990 oil pump driveshaft install: the slot turns about 1/8 inch counterclockwise when you install it on a 360 LA block vehicle. I positioned the slot at approximately 430 and used a long screw driver, with a broken flat blade that I had ground on either side to gently maneuver the driveshaft until it engaged the gear at the end of the camshaft. I pushed down with a screwdriver, the driveshaft turned 1/8 inch CC, and was slightly advanced from 3 o’clock.

· Distributor: shaft play. 4” base to end of shaft with shaft pulled out. 3.75” with shaft pushed in until pin contacts washer at bottom of base. 3.875” attainable by pushing down on shaft where rotor mounts, after distributor installed.

 

[1970FuryConv]

Pin that limits upward travel

· Distributor: I looked at the position of the tang at the bottom of the shaft versus the position of the rotor tip. I think the tang is slightly advanced from the rotor tip so the rotor position should be about 3 o’clock.
Hard to reach that distributor. Foot stool helps.

· Distributor install: even with a correct oil pump driveshaft, the distributor would not push down into position. I took Halifax Hops advice and removed the o-ring at the distributor base. The distributor went easily into the oil pump driveshaft slot and the base seated against the top of the block. He was right, NAPA I had sold me too big an o-ring. I found a different O-ring that was approximately the same size but a smaller width and installed that on the distributor. I used sil-glide around the O-ring at the distributor base. I installed the distributor by pushing down and rocking slightly side to side until the base was seated against the top of the block. Push down on shaft to assure fully seated in slot. Rotor installed at 3 o’clock. Vacuum advance pointed to 730, which was approximately the position before I removed the distributor.
Too big

Narrow o-ring on left from spare parts box

Distributor fully seated, rotor 3 o'clock

· Timing: Somehow the orientation of the slot in the 1990 oil pump drive shaft changed the position of #1 tower. I manually turned the motor until the Harmonic balancer timing mark was at 5° before top dead center. I made a chalk mark on a hose above the intake manifold to indicate where the rotor was pointing. I installed the distributor cap and spark plug wires. I oriented number 1 tower such that the coil tower, number 1 tower, and the mark I had made on the hose were lined up. I started the car. Despite my best efforts initial timing was 10° after top dead center. I turned the distributor until timing was 5° before top dead center.

· Test Drive: OK

 

[Big_John]

Collar missing here. Those were often plastic and broke in half...

 

[Big_John]

Hughes Engines has new steel one.

Plastic v. metal.

 

[halifaxhops]

Use that style not the ones with the set screw thay can come out! Not a good thing in a engine.