Team Rush wizards please help

So i did this upgrade on my '75 304. A previous owner had put a mallory dual point no vac advance in it. I ordered a reman'd motorcraft for a '79 cj 304. I received what I have read to be the dist. with the least desirable reluctor. It has 16L and 21L. One post I saw by JH said he'd never seen the reluctor that that showed numbers equaling half of true full advance. I believe that is exactly what I got. When I started I switched it over to the 21 side believing that would be my total centrifugal. After a short trip with a ton of initial, I wasn't happy with it. I didn't encounter any pinging but Im not sure I gave it the opportunity. I tried checking total with my dial back light and it seemed to be too much. Timing kept climbing past comfortable revs. At this point I only have the dial back light and no timing tape. I also have a diagnostic tach that only goes to 2000 rpm. I moved the reluctor back to 16L and have initial set at 7. That should be 39. Full timing seems to be about 30 coming in at around 2500 to 3000 with the lightest springs. Tach goes to 2000 so im guessing on the rpms. The numbers aren't working. Vac advance is plugged during testing. What am I missing?

 

The way I understand it, is you want 32*- 36* total without vac advance, currently you seem to be at 39*. You want no more than 52 total with vac advance, these totals are around 2500-3000 rpms. You will probably have to limit your advance can to around 10-15*, many go well over twenty stock. set your timing then rev it up to get a total without vac, then do it again with the vac advance pluged in, if you go over 52 with vac, then you will have to limit your advance can, by making a stop or buying a adjustable advance can. Is you new dist points or electronic ignition?? If points you can limit the amount of timing the dist will give also. By lowering the amount of timing available in the dist, you can raise your initial and stay in the 32-36* total zone without vac. just a FYI vac advance is added on top of you totals, as a example : initial of 10* dist timing of 20* gives a total of 30*without vac, say your advance can gives 18*, that's a total of 48* total with vac. If you are in the safe zone of 32-36 and you get pinging, you will need to slow the advance down by adding heavier spings. Hope this helps some

 

Thank you. Lots of good info. I think im going to get a timing tape and a tachometer, check my tdc zero, and start over so that I know exactly what I have.

 

Did you get this figured out yet?

 

Ok. Im getting farther from figuring this out instead of closer. I moved the reluctor back over to the 16L side. I put both light springs from the Mr. Gasket 925D kit. Now the centrifugal advance isn't kicking in until after 1500. I don't really know what question to ask. Is it possible that it is sticking? It feels like it is operating smoothly by hand.

 

I think I used the same Mr. Gasket kit as you and with the lightest spring, I cant idle the engine without the centrifugal being already kicking in with those springs, I think I have a med and heavy spring on mine.. If in your first post the JH you refer to is John Hinkly then I would suggest you read all of his timing and advance articles, him and another guy named Lars have the best articles I have seen and I learned everything I no about timing from their articles, I read them over and over for a couple years until I finally understood it. Timing is very hard to do over the computer as each requires different settings and what works for one may not for another.. Best article I read from them is "timing and vac advance 101" It takes awhile to grasp what they are saying but once you get it, it all falls into place. And I would have to say yes, its possible you could be hanging up if your centrifugal isn't kicking in until 1500 rpms with the lightest springs on. I will try to help all I can, just ask.