Paul L

Apparently the 1218 has some form of check valve that provides superior performance (?) to the old standby PF35. Is anyone familiar with this subject? I will switch to the 1218 if it indeed provides some upgraded advantage.

mark79,80

Posted this question on the NCRS site several months ago. Was told
difference is the check valve prevents oil from running back out of the
filter, useful on installations where the filter is mounted horizontally.
Mounted vertically on the corvette so the check valve is not needed.

Paul L

Its on the NCRS Tech Board again. But no explanation was available when I posted here. I was puzzled because as you say, the filter is vertical and the oil cannot run out :confused: . Perhaps newer Vettes use a horizontal installation??

Twin_Turbo

weird, even the LS1 has the filter mounted vertically.

Paul L

Perhaps this is a non-issue. They do look identical.

ED DINAPOLI

Could this filter have been used on the 90-95 ZR1 as they had their filters mounted horizontally?
Ed

Paul L

It looks like it comes down to that. Here is an answer from one of our Forum colleagues on the NCRS Board:

"Only engines that have the filter in a non vertical postion need a check valve. the ZR-1 needs one because even though it is mounted vertical it is up side down and it will empty when you shut off the engine.i found this problem back in the 60 with a caddy that i bought used that had a horizontal mounted filter. it had lifter rattle when started but it had a pennzoil filter and as soon as i change to the correct AC filter the rattle was gone. the "iron duke" 4 cylinder engines had the filter mounted horizontal and GM speced a PF51 which had no check valve but the PF 52 did. GM later speced the PF 52 for the engine did away with the PF 51. this new filter may also be used on a engine that does not have a vertical mounted filter."

So another Corvette mystery solved.

Big Fish

Paul, what this person said makes good sense, but if the only difference between the PF35 and the 1218 is the check valve, why is the 1218 the one specified for engines that don't require the check? My 94 Suburban uses the 1218, is mounted threads up just like most other small block Chevys. It does have an oil cooler, but the 1218 is specified for all. Would seem to me like a non check valve filter would flow better if everything else was equal. :confused:

Paul L

I really do not know the answer :confused:.

ddecart

It was making sense until you mentioned your Suburban. Hmmm....I wonder if it was a volume thing where they spec'd that engine with it to get volumes up and costs down for production with that filter on other vehicles. That makes little sense though. Weird.

A filter that sits vertically like in our vettes, there is no need for a check valve.

chuck d

Hi Guys:

My 90 350 powered truck is equipped with a factory oil cooler, a Gm fix for low oil pres. at start up was using the PF1218 instead of the PF35. The reason they gave me was the check valve was installed in the 1218 .

Chuck D

Paul L

I have heard that also. But I cannot figure out how a vertically mounted filter with the check valve in the up position can compensate for low pressure at start-up :confused: .

chuck d

Hi Paul:

I don't know, but it works.

Chuck D