Topic: '47 Radiator Cap


len47merc    -- 09-07-2016 @ 5:22 AM
  Did '47 Fords & Mercs come with 4# radiator caps p/n 41A-8100-C or non-pressure caps 91A-8100? The 'original' on my '47 Merc was of the 2-ear'd non-pressure type which I replaced with new replica as a matter of procedure with a C&G cap ~3 years/5,000 miles ago and, with a 67/33 clean, fresh each year mix of distilled h20 & ethylene glycol in a pristine, cleaned radiator & block, the spring is corroded beyond used and the center shaft separated. The 'original' cap could have been replaced years back but given it is known to have been on the car for in excess of 50 years it held up way, way better than the piece of junk I purchased (as a then newbie to the hobby trying to remain 'original' to what was on the car upon receipt versus what may have been technically correct versus what may 'work best'). The car has ran great and 'cool' with no overflow 'spitting' with the replacement cap including long, several hundred mile tours in southeastern US summertime temps.

So, need to purchase a new one and need to know what IS correct for an early-pre-April 1947 AND from whom can I purchase a quality cap that will better stand the test of time than the cap I have now. Thanks -

Steve

This message was edited by len47merc on 9-7-16 @ 5:33 AM


TomO    -- 09-07-2016 @ 7:44 AM
  The 41A-8100 cap was optional and I don't know the criteria for installing one at the factory and when they started to install them on the line. They were available to the dealers in 1945.

I would go with the 41A-8100 cap, if I could find a NOS one. I have had the one on my 1940 for over 20 years and it still holds pressure. The correct 91A-8100 cap has 91A stamped on one of the ears and they are hard to find these days. I would not want to drive my car with an original cap, as the fiber seal is too hard to give a good seal.

For driving, I would use a 4# cap. The Everseal R4 cap is the closest to the original Ford non pressure cap and the best 4# cap would be the Stant 10281.

Tom


EFV-8 Club Forum : https://www.earlyfordv8.org/forum
Topic: https://www.earlyfordv8.org/forum/viewmessages.cfm?Forum=18&Topic=10058