I have a 426 Hemi with MSD box and old Chrysler electronic distributor with mechanical tack drive. Tried two identical distributors, one with light springs and the other with stock advance springs. With RPM increase neither distributor will advance timing. I set the max timing at 34 degrees at high engine RPM, lower to idle and the timing stays at 34 degrees.The weights in both distributors move freely, so that shouldn't be an issue. Using an old Sears timing light to perform timing checks. Why won't the timing come down? The only thing that is different from past motors is that I used MSD distributors and everything was ok. Trying to keep the engine looking stock on this build except for radiator, driven on road for distances. Any ideas would be helpful. Thanks Gary

Pull the cap off and see if the advance will return the rotor after twisting it forward for the advance, if not fix it .If it returns with the cap on figure out what the heck is going on

have a non dialback you could try. What Cab said either a dist prob or the light. 2&1/4" (2.246") CW from the TDC slit is 35.5 degrees.

I have fluid damp balancer with timing marks. 34 degree point marked with paint. Paint mark stays on pointer all the range of rpm. I pushed advance weights outward with a tiny scwerdriver and they pull back easily to home position on both distributors.

MSD (box) issue?

Sent box to msd to get checked out before I installed it. Called them with issue of timing and they told me the box has nothing to do with timing advance or retard. They said it is a distributor issue.

Gary do you have another dist you can toss in for a test?

In the first thread l noted that I tried two identical distributors. One has light springs on the weights and the other has stock heavy springs. Neither one backs down at idle. Both act like they have locked timing advance. Never seen this before in all my years and I have used many of these Mopar race distributors. I just can' t see two distributors acting the same way.

I agree, we're missing something simple

Are you using a dial-back light and reading the light?
Does the motor act like it's got 34 degrees on a warm startup?

Using two different non-dial back timing lights. Both show the same results. 34 degrees with no movement of timing over the rpm range.

Unless the 34 degrees is giving you a problem starting I wouldn't worry about it. Some people prefer to have it locked anyway.

This is a stumper. If it was me (laz-z-boy tuner giving worthless advice) I'd see if I could find someone local with a distributor machine and have them spin both of them up. And then you can maybe get a better handle on what is happening and take some variables out of the equation.

put the dampener at 15 BTDC #1 compression (or what your preferred initial # is) & turn the housing till the tooth is dead even with the magnet with the rotor under the #1 plug wire dist cap terminal (I'm assuming your Rotor Phasing is acceptable) & lock it down. timing light trigger clamp on #1 plug wire (not being rude just covering everything). fire it up & see what happens. I still think it is a MSD issue.

The car starts and runs perfect. The reason I was looking into timing, the engine is running a little hot. While playing the the timing I noticed the lower radiator is collasping at high rpm. Now another issue needs to be resolved. Also the electric fans are not coming on at 185, bad sending unit. Called the radiator shop that built the radiator for me and they are sending me a new switch.

Do you have a spring in the lower hose?

The weights being free to move will not matter if the advance mechanism is jammed/locked. With the unit installed or the shaft being held, you should be able to turn the rotor/reluctor assembly to some degree (1/4"-3/8") and have it be pulled back to the base location by the springs. Obviously, the unit with the heavy springs will require more effort to turn, but neither should require a lot of effort to move.

rickseeman -No there is no spring in the lower hose. Just orrdered one used on the early small block Mustangs. 1 5/8 X 13" long $6 plus $9 shipping. Found correct one from internet search, used by other Mopar owners.

CMcAllister- Performed test and everything work freely, both distributors perform perfectly.

CONCLUSION-I found information for installing the light springs. It states by installing both springs, total timing is achieved at 1200 rpm. With the crossram intake idle is at 1100 rpm. So full advance is at idle on this motor with distributor using both light springs.. No further advance possible. On the other distributor with the heavy springs. Upon taking apart I found the spring on one end has a long eyelet. The springs are longer than the slots in the advance mechanism. So the distributor is at full anvance at startup. The weights are fully opened without making spring contact. So I believe the reason for no advance has been established for both distributors. Now can address issue for correct springs and timing advance.

Thanks for all suggestions from Moparts members.

Big cam? You may like it better with the advanced all in at idle once it's all said and done.

Just spit balling here but could the distributors be for a small block?
If I remember right the shaft is the same length as an RB or Hemi.....

Digger73 (Mike)