Packard Forum Index » Pre-War (1899-1942)

In JBRPackard's Nov 13th post on timing, Snopack remarked on vacuum advance being critical to a properly running engine. I wholeheartedly agree and have a couple of questions. First off, I was lucky enough to come by a NOS distributor for my car (an Autolite IGS 4201) and, while the advance pot works, i.e. the distributor advances when suction is applied to the pot, I have to wonder if, in an advance unit of that age, would the diaphragm be hardened up and not as flexible as when new, thus giving less advance than a new one?? Second question, I found an outfit in Puyallup WA that has a remarkable list of tune-up products for the 245 6-cyl and they list a vacuum advance pot for $60 (VC-3082) https://hagensautoparts.com/packard/41-electrical/13607
I ordered it, but unfortunately they have no stock and none on the horizon. They did say if I sent my old pot in, they could have it rebuilt for the same price, so my question is: Does anyone know if there is a generic Napa-type replacement that has the same thread and movement characteristics as the OEM version or am I stuck doing the rebuild and exchange thing??
I guess if the answer to question one is, if it moves the distributor, it is working and leave it alone, then I don't have to worry about it and question 2 becomes moot. Any thoughts or advice?? P.S. I do not have the equipment or ability to test the AMOUNT of actual advance with the engine running (nor do I know how much it should be) and thus, applying suction to the vacuum advance hose is the extent of my diagnostic ability. Chris

The best test is to see if it moves under vacuum and doesn't leak down quickly which can probably be ascertained by using a simple vacuum tester tool. If there was a pinhole or very tiny crack, then it would return quickly but if it doesn't, then it's fine. Some of it is also to do with how the distributor was stored for all these decades and this one was always kept indoors rather than in the boot of a car!

P.S., I've bought parts from Hagen's and they offer very fast shipping and good quality. Also, Puyallap is right next to Sumner where I stored and worked on my 1941 Henney-Packard for years!

Thanks Don, and good to hear that Hagen's is reputable. I think I will send the old pot from the original distributor down to them and have it rebuilt. Then I will have a direct comparison with the one from my NOS unit and 'fresh new rubber' to see if it changes the performance characteristics. Certainly can't do any harm. I also intend on purchasing a good vacuum gauge, as it seems vacuum tells 'a lot of the story'. Chris.

That's a good plan! I have an inexpensive vacuum test set that also can check pressure, such as fuel pump, which I bought on Amazon.com some years ago. It paid for itself very quickly!