Loose rotor and points/condenser mounting plate

[allinline]

I'm hoping some of the you I8 veterans could shed some light on the subject for me. I've been noticing a miss coming out of the tail pipe when the car is idling and I can also feel it at light throttle. I started with the basics and pulled the cap to check things out and found the rotor to be loose on the dist. shaft(as in the rotor turns a few degrees in either direction without the shaft moving) I tried another rotor that I had and it did the same. Are there any issue that these distributors are know to have? I could also move the points mounting plate around quite a bit and change the gap of the points +/- .005". It's been a long time since I've messed around with points. Any advice or insight would be greatly appreciated!!!!

[suntreemcanic]

The point and condenser mounting plate "pivots" when the vacuum advance works. When you are moving the plate notice if the arm to the vacuum advance is moving as it should in and out. The plate should not wobble. I have a 263 and my rotor slips on and off real easy but it fits the distributor shaft exact and there is no side ways movement. With the distributor in the engine I can turn the rotor counter clockwise maybe a couple of degrees but it bounces back immediately like it is spring loaded. Hope this helps.

[allinline]

Thanks for the input suntree. the vac advance does work and the rotor will spring back when manually twisted but the points mounting plate tips in all directions and the slot for aligning the rotor isn't a tight fit so the without turning the distributor shaft it'll still rotate a little in each direction. Is there a bushing or something that helps support the mounting plate that could be worn? tanks

[GMorse]

Hello. I have a '39 with the 248 cu.in. engine. I have had many problems with the distributor plate. The early Delco dist., up to 1949, allowed the plate to rotate on three steel *****. Long term, this was not good as the steel ***** rolled in a groove in the cast iron dist., wearing grooves that are quite rough. This of course makes for some play, and worse yet, it prevents the vacuum advance from working smoothly ( or not at all).In 1949 ( I think), Delco changed the dist. and plate to get rid of those steel *****. The plate then rotates enough for the vacuum advance smoothly. The 1949 shop manual has pictures of both Delco dist. I am currently using a '49 dist. in my '39 series 40, and it works fine. There are people that say you should not do this, but the only difference is a slight change in the mechanical advance curve. This change is very slight, and not noticeable to the way it drives. As a side light, there were many after market devices to smooth out the old steel ball type of dist. Delco even produced a kit to eliminate the ***** and used a sliding plastic piece for the plate to rotate against Just my experiences over the last 14 years with this engine. Hope this helps. Gary