1973 Shovelhead Oil Pump Isuues Help ???

[Twister the fitter]

Hey Cotten, according to the clown (mechanic) that just did all that work on it, tearing out, replacing, and putting all back in, claims that's what's causing my troubles ??? Poor oil pressure he says, or clogged passages to the tappets. I don't know how he figures it's low oil pressure, when I questioned him about testing pump with a gauge, he said no, I didn't put one on to check it, seems to me he's just guessing ??? That's when he said to ride it until winter when he can tear into it further. Duffy makes a good point, when he says to check for worn or loose tappet blocks, tappets, etc. You'd think this guy would've checked all that first, before putting in those new parts and all the work involved, right ? Tim

[Twister the fitter]

Thanks for the info Aumick10, I'm on a "mission" now !!!

[aumick10]

There is also a screen before the tappets, just by the rear right barrel stud. Should look the same as the two plugs on the oil pump. Fix the relief valve, clean the screen then you should be able to put in hydraulic tappets.
Make sure you have the correct spring in the relief valve part.
Good luck.

[Twister the fitter]

Aumick10, Have all new OEM parts ordered. I did check the screen, it was ok, but I'm not sure what springs were used, that's why I ordered OEM. Thanks for this info, it sure helps those of us in need, when nobody else seems to have any ideas or answers ! We need to get all of you AMCA guys together, say in the middle of the country, build a huge shop completely outfitted, so that those of us can come and get everything fixed that's needed ! Thanks Again, Tim in PA

[aumick10]

I hope you don't mean work for free, unless there is free beer involved.

I am surprised you were able to get the plunger as a OEM.
There are different springs available to change the oil pressure, but I am not sure they change anything. Stick with OEM when available, no point in reinventing the wheel.
I just put fuel in my 29 JD to start it after maybe 50 years. rebuilt carby pissed fuel out everywhere, so i am dealing with that now.
Cheers

[Twister the fitter]

Got em Robbie, Thanks ! See, this info you provided me proves you're a TRUE "Harley God" !!! Tim

[Twister the fitter]

FREE Beer for sure ! That's why I stated, "completely outfitted". There'd be a Brewery on site (first things first ya know) !!! Good Luck with the Carby, I'm sure you'll figure it out. If not, bring it to that shop we're gonna build and grab a beer while it's gettin repaired !!!

[aumick10]

The float that was fitted doesn't float, very useful for something I suppose, but not carbies.
Installed an old cork float and got the bike running. First time it has run for maybe 50 years.
Set off every smoke detector in the house.
Runs like **** still, but I will keep tuning until it is good.

[aumick10]

Twister,
I was thinking about the oil pumps and remembered the pressure relief valve has another function that might directly affect your problem.
The oil pump is a positive displacement gear pump, which means every time it rotates, it will pump a fixed amount of oil. This generates preesure against the pressure relief valve spring.

When the motor is running at low revs, the oil pump pushes the relief piston up until it opens up the first port. This port feeds the tappets and top end, and is relatively large.

As the revs increase, the pressure increase until the piston is raised a bit more and opens up the second, small, port to the crankshaft oil feed.

As the revs increase further, eventually the pistons is pushed up until it opens up a port that relieves the pressure.
Depending on the year, this oil goes to the cam chest, or back to the oil pump feed line.

Harley used this arrangement to ensure the tappets always had an adequate oil supply to the Hydraulic lifters at low revs

This is part of what the drilling passages, plugging ports etc is about that S&S recommend to update earlier motors.

[Twister the fitter]

WOW Aumick, a 29 JD ? I'll bet it's real nice, wanna make a trade ??? Thanks Again for taking the time to help me, when you're having troubles yourself ! Really appreciate the info and "FREE" education ! Tim

[aumick10]

WOW Aumick, a 29 JD ? I'll bet it's real nice, wanna make a trade ??? Thanks Again for taking the time to help me, when you're having troubles yourself ! Really appreciate the info and "FREE" education ! Tim

Your welcome,
Sometimes it is best to walk away for a while when facing problems.