Just installed a brand new distributor. For a 327/300. As a final check, I twisted the rotor and let go. It didn't snap back.
I have removed the entire distributor again and it still doesn't snap back. The weights just expand and then stay that way.

Is this a manufacturing issue - or will it loosen up after if runs for a few minutes?

 

The weights should retract on their own.....a bit of lubricant might help....
I wouldn't install it until you get that fixed.... The springs should pull the weights back into position...

 

The weights are free and loose. (The springs are in place.) It's the shaft that won't turn back without some mild effort. In fact the weights don't move until I push them very, very lightly.

You've helped me decide that I need to fix this BEFORE I reinstall it.

One final description. With my left hand, I hold the drive gear at the bottom of the shaft. With my right hand, I rotate the plate that the weights are attached to. I can turn it clockwise, or counter clockwise and it stays where I let up. No spring action even though the weights are FREE and loosely attached - with springs.

 

 

Thanks guys. I realize how late it is for you. It's only 8:30 pm here in Seattle.

I just ran outside again and (per your suggestion) added some 3-in-1 oil between the long plate (where the springs attach) and the larger plate underneath it. While it does move a little bit easier, it still doesn't "snap". I manually twisted it about 30 or 40 times trying to loosen it up.

It appears that the long plate is pressed onto an upper shaft (?). Could this have been too tight? I don't know where, or how that upper shaft connects.

I'm going to try to attach a video that I just took. Oops won't accept it. Wrong file type.
So here's a photo instead.


Weights are "closed".



Weights are "open".

I can only get these two positions by twisting the long plate.

 

Support the distributor at the bottom and knock the roll pin out then remove the tach drive cross gear. You can now remove the main shaft through the top along with the weight base that the springs sit on and find the cause of the interference.

It could be that the main shaft has been replaced and needs some love via emery paper around the diameter where the main shaft sits inside the weight base. When you reinstall the lower gear there should be a drill start dimple neat one hole that lines up with the rotor tip at the top of the distributor. This should allow the vacuum advance control to sit centered between the coil bracket and intake runner after you set the initial timing. Keep in mind if the camshaft has been changed to a non GM part it's not unusual to have to rotate that gear 180* to get the vacuum control to sit centered. It's ok to do this if needed and will not effect anything.

 

My '61 dual point distributor has no vacuum advance; per factory design...

As noted by tbarb -- something is binding....I have heard of the distributor internal shaft being bent in one case (think I heard it on here actually)....I would put a straight edge along it to make sure that hasn't happened...

 

 

If you bought it new why not return it instead of taking it apart and fixing a new part?

 

I've been in the same situation - sometimes its worth taking a stab at fixing a critical part even if its new/rebuilt to get back on the road vs waiting 3-4 weeks to get it fixed under warranty or searching for another piece...

 

Those are some strange springs. Take them off and see if the shaft and advance plate move freely versus one another. If so, don't bother disassembling further. I have found that no aftermarket springs come even remotely close to OE GM springs. Way too long or low a spring rate in any case.

There is always a little play in the weights before the inside of the leg hits the advance cam, but they should always snap back to neutral when you twist the assembly with the springs on.

Forget about the weight and spring kits from Mr. Gasket and others. Go online to McMaster Carr and buy a length of stainless extension spring stock, and make your own springs with a set of side cutters and pliers.

 

The El Cheapo spring sets are not hardened in most cases and quickly go out of spec....
But I'm gonna say I still don't think that's the main problem here...

 

Those spring look like small coil springs! They should snap the weights back quickly.
As stated I would take the shaft out of the distributor and see what type of grease was used in the area in my picture.
If you want I could send you an article I wrote on distributor reconditioning which will help you disasemble and assemble it.
Joe

 

Those springs are gonna be way too stiff for all in at 2500. If those springs can't pull in, then the lighter ones needed aren't going to either.

 

Those springs look like they came off a dump truck. What are the centrifugal specs? What's the number on the VAC? I suspect that this "new" distributor was rebuilt from a junk OE distributor with junk aftermarket parts, and your best option is to return it and find someone who can supply you with a properly rebuilt distributor with a spark advance map that is suitable the 300 HP engine.

Duke

 

Remove those monster springs and see if it frees up. If not follow what tbarb said earlier. There should be zero friction between the shaft and the weight base. If there is, then some fine emery will remove any burs and excess metal. Then lube lightly with white lube.

Get a 928G kit from Mr. Gasket. It has 3 sets of springs and it's OK to mix different springs if need be. This kit uses a brass advance slot sleeve which replaces the junk rubber sleeve. Do not deform the sleeve to hold it in place..........use a tiny bit of epoxy. Lose the paint on the weights..........that will gum up the rub areas and foul the light coating of white lube that should be placed on the rub **** on the weight base. No need for case hardened weights. Overkill and not necessary.

 

 

Post back what you find.

 

Good grief you paid good money for a distributor that is basically broken.
I would def send it back and buy another one from a better source but I always demand what I paid.
I get that you want to drive.
In the meantime, so you can drive, go to Amazon
and by a $50-60 HEI unit and you are good till your replacement comes in.
Keep the HEI unit on the shelf as a back up.

 

Where did you purchase it from. Our M-3933 we build that in house and it is an electronic distributor not points. The only two distributors I do not build in house are the M-199 and the M-199H which are new and built by Chicago Corvette. That is probably who supplied your distributor if it is a new one with points to whoever you bought it from. We disassemble and rebuild these into the M-3933 distributor you mentioned earlier.