1973 Shovelhead Oil Pump Isuues Help ???

[Twister the fitter]

Dear fellow AMCA members, I'm looking to you for help in deciding what Oil Pump to use on my 73 Shovel FLH, as a replacement for my OEM that's not operating properly. I"ve removed the pump and noticed that the body is scored in the areas that house both gears on the crankcase side of the pump body (I've been told this may be the reason for my poor oil pressure that won't operate my hydraulic lifters). I'd like to stay OEM, but from what I've been reading, the 73 shovel pumps seem to have been Harley"s worst ??? I have also been seeing that with some of the aftermarket pumps, that I'd need to drill the crankcase, using a jig to accommodate some new pumps. This is where I'm asking your opinions and/or experience with regards to this action or maybe other recommendations. Thanks for any assistance, she's sitting in my garage and should be riding about now ! Tim in PA

[Rubone]

There were several variations of the pump for '73. Any common replacement type would be fine, S&S etc. This is the factory info.

[Twister the fitter]

Thanks once again Robbie ! What do think about the aftermarkets that requiring the crankcase drilling ? Also, would you have or know where I could get a copy of Harley's #647 Service Bulletin ? It states in my Service Manual that changes in design and parts were made to the 73's listed in this Bulletin ? I've contacted an old local Harley shop regarding the Bulletin, but no reply as of yet. Tim in PA

[Rubone]

I can scan it and send it to you Tim. PM me your email.
Robbie

[Twister the fitter]

Holy Cow Robbie, You are like the "Harley God" !!! I'll have to look into how a PM (private message ???) is done. Tim

[ragsflh]

sns pump the best

[Twister the fitter]

Thanks ragsflh ! But what about drilling the crankcase with the jig? Does the S&S pump require this approach ? I really don't want to do that if there's an alternative option. I see you're an FLH man, what pump are you running ? Tim

[Twister the fitter]

More puzzling pump finds ! Removed both CHECK VALVE PLUG and RELIEF VALVE PLUG and SPRINGS only to find CHECK BALLS in BOTH ports (???). I realize a Check Ball should be in the port closest to the engine, but my service manual shows a #26400-54 Oil Pump Valve in the taller port, NOT a Check Ball, is this correct ??? Confused !!! Another reason I'm looking for that #647 Service Bulletin. Could this be why I not getting enough oil press. to operate the hydraulic lifters, or is this the "so called" mid 1973 design change ? I was able to identify my pump from Rubone's pic as being the Early 1973 version, if this helps ? Thanks so much fella's, she's still sittin idle . . . . ha ha

[duffeycycles]

Are your tappets loose in the tappet guides[blocks] ? Are you setting them right?Are the hydraulics loose in the tappet?

[Twister the fitter]

Hey there Duffy, thanks for the reply ! SORRY this is so long, but I want you to have ALL the info. I can only assume all what you are asking is fine. A Harley mechanic, who took out the solid stuff (existing in my engine) and installed all new hydraulic parts found out that there was a problem with inadequate oil pressure to operate the new hyd. parts and re-installed the solids . He stated that I should replace the oil pump this winter, but go ahead and ride til then. He suggested installing the hyd. units back in, while I was commenting on the tappet/lifter noises when I took him the bike for some other work. Well, this isn't my approach to things not working properly. I brought the bike back home and checked out the push rod adj., only because the lifter/tappet noises seemed worse. I did find the front exhaust push-rod out of adj. and tightened it up. This is when I decided to removed the oil pump (as suggested) by another Harley mech. and my previous post explains what I found. Hope this helps, Thanks ! Tim

[duffeycycles]

It still could be new stuff loose in old lifter blocks or adjusted wrong..i'm done

[Twister the fitter]

Thanks Duffy, really appreciate the info. After seeing what work this clown did on my bike, I'm sure there's plenty that's wrong ! I think I found a new TRUE Harley mechanic, gonna have him take a look. Tim

[Rubone]

Tim, 6 page PDF in your email.
Robbie

[T. Cotten]

I didn't know hydraulics need pressure.

....Cotten

[aumick10]

More puzzling pump finds ! Removed both CHECK VALVE PLUG and RELIEF VALVE PLUG and SPRINGS only to find CHECK BALLS in BOTH ports (???). I realize a Check Ball should be in the port closest to the engine, but my service manual shows a #26400-54 Oil Pump Valve in the taller port, NOT a Check Ball, is this correct ??? Confused !!! Another reason I'm looking for that #647 Service Bulletin. Could this be why I not getting enough oil press. to operate the hydraulic lifters, or is this the "so called" mid 1973 design change ? I was able to identify my pump from Rubone's pic as being the Early 1973 version, if this helps ? Thanks so much fella's, she's still sittin idle . . . . ha ha

The Check ball closest to the engine is a non return valve to stop the oil tank draining into the bottom end when the motor is not running. It has a low pressure spring sitting on top of it.
The other valve is a pressure relief valve. It should have a short "Piston" with a heavier spring on top of it. (Length varies by model) Pt no 26400-54. The piston moves up under pressure, (varies according to the spring rate) and opens up a port into the cam chest that relieves oil from the pump. This piston must slide freely. Even though the engine only sees a low oil pressure, the chamber between the pump gears and the relief valve carries a higher pressure than the engine.
If you have a ball in here, you will probably never get any oil to your tappets. All your oil is probably bypassing the ball and relieving into the cam chest.