The Stovebolt Site Forums The Shop Area Engine Shop Oil pump modification

In an tech tip from Jim Langdon he makes this statement, refering to the oil presure relief valve,

"I suggest plugging the end of the bore and drilling a .060” vent across into the inlet hole
of the pump. Be careful not to cover the vent hole when installing the plug."

I can't seem to understand just what is plugged and where to drill. Does anyone have pictures? Thanks

Is this the Tech Tip from Tom Langdon's website? I do not understand exactly what Tom wants done to the oil pump. Do you have hydraulic lifters?

I would give Tom a call before any holes are drilled.

Hoyt

The information did come from Tom Langdon's web site. It is directed at air entering the oil and causing problems with hydralic lifters. Actually, I am using solid lifters so the lifters wouldn't be a problem, however I don't like the idea of air in my oil, so am interested in this mod. I'll give Tom a call.

Hi Will,
I'd also be interested to hear Tom's reasoning on this modification. I was all set to do it and asked the same question over on the Chevy Talk board http://www.chevytalk.org/fusionbb/s...1/hl/oil+pump+modification/fromsearch/1/ and it was agreed that plugging vent was unnecessary. Sealing the pump at the inlet is crucial however. Do let us know what Tom has to say!

I talked with Tom yesterday about the plug and vent. The presure relief valve is left just as it is, a .060 hole is drilled at an angle into the pickup tube side (probably with the pickup tube in place); the pressure valve opening is then pluged (maybe one of the small drive in freeze plugs or he even suggested silicone.) Careful not to cover the hole you drilled.

The idea being to eliminate air being pulled into the pump through the pressure relief valve as this is supposed to cause hydralic lifter problems

No, laws of physics have nothing to do with oil pumps: air always flows from low pressure to high pressure.

I looked at the picture you posted on the other forum; Tom Langdon's modification is on the later 235/261 pump. Not sure if the same can be done on the older pump as you picture. I do see that air could enter the suction side of the pump by way of the relief bore vent. As I understand it, Tom recomends the mod as a cure for engines with noisy hydralic lifters.

Thanks Will, after all of the opinions I decided to leave it alone, especially since I'm running solid lifters. I did check the gear clearance and seal up the pipes pretty well. Let us know if it makes a difference on your motor.