Topic: oil pump


svmsr1044    -- 01-21-2015 @ 2:02 PM
  I'm having my original 1940 85hp pass car v8 motor rebuilt. The rebuilder suggests using an 80# oil pump instead of a 50# pump. Is this a good idea? I know I would have to change out the sending unit, but what about the dash gage? Thanks, Steve


kubes40    -- 01-21-2015 @ 5:03 PM
  Hi Steve,
You will no doubt get as many differing opinions on this as there are folks out there offering them.
Me? I have used the 80# pump modification with good results. I have also stuck with the stock 40# pump and had good results. Is the 80# necessary? No way. A properly rebuilt flathead will operate well and for a LONG time with a stock pump.
The bottom line has probably more to do with what makes you more confident.
IF you go to the 80# pump, make 100% certain your rebuilder modifies the baffle in the oil pan to accept the placement of the late model sump. The baffle must not be removed! removal is easier than modifying it properly so many guys do just that... DON'T! Do you think Ford would have spent the money to put a baffle in that pan if it were not needed?

Also, the by-pass located in the valve tappet area must be blocked. If not, it will open at the rating it was designed for and your 80# will never get close to what it was designed to do.

One more thing... the dash gauge must match the sending unit. If not, you will not get an accurate reading.
Kind regards,
Mike Kubarth



svmsr1044    -- 01-21-2015 @ 5:56 PM
  Thanks Kube, as usual, your advise is given with thoroughness and authority.
Steve


TomO    -- 01-22-2015 @ 7:40 AM
  The dash gauge will work correctly with the 80# sending unit. You just need to double the reading to read the true pressure.

The sending unit for 80# has a different diaphragm than the 50# unit. This changes the pressure that it takes to close the contacts. The contact spacing, the bi-metal strap and the heating coil are the same between the 2 units.

I have an 80# pump and sending unit in my 40 Mercury and they work fine.

I agree with Mike that the 50# pump will work just as good as the 80# pump in keeping you engine supplied with proper lubrication.

Tom


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