71 BB oil capacity

[Jeff M.]

When using the full length oil filter, what is the toal capacity of the system? I have always thought that it was 6 quarts, but seems to be too much. The reason for my thoughts are that i had 2 different wix filters, one had the anti siphon valve and one did not. This had me think that the one without it would drain more oil back into the pan and hence make the dip stick reading higher? Did original filters have anti drain back vlaves??

[Joe L.]

Re: 71 BB oil capacity

When using the full length oil filter, what is the toal capacity of the system? I have always thought that it was 6 quarts, but seems to be too much. The reason for my thoughts are that i had 2 different wix filters, one had the anti siphon valve and one did not. This had me think that the one without it would drain more oil back into the pan and hence make the dip stick reading higher? Did original filters have anti drain back vlaves??

Jeff-----


The capacity of a 1971 Corvette big block oil system WITH filter change is 6 quarts. The filter originally used was a PF-25, so the rated capacity included this filter. Using a PF-35 or similar filter would require a little extra. However, the amount is, for all practical purposes, negligible. Especially when you consider that the PF-1218 of today, which replaced the PF-35, is shorter than the PF-35 and really not much longer than the original PF-25.

The original PF-25 and PF-35 did not include an anti drain-back valve.

[Duke W.]

Re: 71 BB oil capacity

This had me think that the one without it would drain more oil back into the pan and hence make the dip stick reading higher? Did original filters have anti drain back vlaves??

The position of the filter on vintage Chevrolet V-8s effectively prevents drainback. The PF454, which also replaces PF25 has an anti-drainback valve. A horizontal or "upside down" (filter base at the bottom) filter orientation will allow drainback without an anti-drainback valve.

Duke

[Jim T.]

Re: 71 BB oil capacity

Jeff the AC filters have made some changes. I used to use the PF1218 until one day I opened the box on one I was going to purchase. The steel at the top of the filter had changed a lot in design. I looked at a AC PF2232 filter that was by comparision about the same size. The PF2232 cost about $8.00 at Auto Zone. Checked on what it was used for on GM cars and found it is the oil filter for GM diesels. I am using diesel oil in my old Corvette and bought it since the design of the top steel construction was like the earlier AC filters I used. The PF1218 does weigh less than the PF2232.

[Joe L.]

Re: 71 BB oil capacity

Jeff the AC filters have made some changes. I used to use the PF1218 until one day I opened the box on one I was going to purchase. The steel at the top of the filter had changed a lot in design. I looked at a AC PF2232 filter that was by comparision about the same size. The PF2232 cost about $8.00 at Auto Zone. Checked on what it was used for on GM cars and found it is the oil filter for GM diesels. I am using diesel oil in my old Corvette and bought it since the design of the top steel construction was like the earlier AC filters I used. The PF1218 does weigh less than the PF2232.

Jim-----


I think we're likely to see a lot of changes in the construction of AC oil filters in the future. GM or DELPHI no longer manufacture oil filters, so all AC oil filter manufacturing is "outsourced". I think that different manufacturers will be making different filter models, although I believe that Champion Labs is one of the major new suppliers.

The PF-2232 is a diesel engine oil filter of approximately the same length as the PF-1218. However, it contains an internal pressure relief valve whereas the PF-1218, PF-454, PF-35, etc. do not. The internal pressure relief valve is set at 15 PSI. I don't know what effect the valve might have on an engine with an external pressure relief valve (like small and big block Chevrolet engines).

The PF-2232 also has a much finer porosity at about 8-9 micron versus 18-20 micron for the PF1218. Theoretically, that should be an advantage. However, I don't know if there are any negative implications that go along with it.