I bought a spin-on Kit from Deve's technet using a WIX 51515 filter and installed it. Everything seemed to be fine last summer when it was hot except that the oil pressure is a bit lower than with the previous engine; about 28PSI compared to 35PSI. I'm also running 15/40 oil rather than 20/50. The engine has a new Melling oil pump and tight bearing clearances, low end of spec. In summer, the oil pressure does not vary much whether cold or hot except at hot idle (250 deg oil temp) pressure is ~15 psi. I interpreted the change in oil pressure to the fact that the gauge connection is on the low-pressure side of the filter so there is the pressure drop across the filter to consider. I'm also running a Franz toilet paper bypass filter in parallel with the gauge connection. Franz paperwork says it has a restrictor.

Now the real head scratcher and cause for concern is that now it's winter (high for the day was 15 and the low was about 5 and it's been like that for 3 weeks now) and it takes more than two minutes for the oil pressure to come up. The gauge shows nothing for 30 seconds or so then slowly creeps up. It seems to me that the filter's bypass valve should open under these conditions and provide flow despite cold oil. I'm assuming this filter has a bypass valve and one spec I found indicated that it filters something like 11 to 15 microns. That's pretty fine for a full flow filter, so I can see where there might be considerable pressure drop with thick oil. But running all that time with no indicated oil pressure bothers me.

Anyone have any experience with full flow filters on Stovebolts? Should I just not worry about it or go to a coarser filter?

1951 3800 1-ton
"Earning its keep from the get-go"
In the DITY Gallery
1962 261 (w/cam, Fenton headers, 2 carbs, MSD ign.), SM420 & Brown-Lipe 6231A 3spd aux. trans, stock axles & brakes. Owned since 1971.