'73 FLH oil pressure

replace gauge and ?

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1957flhchop
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'73 FLH oil pressure

#1

Post by 1957flhchop »

Just working some bugs out and cleaning some things up on my recently acquired chopped '73 FLH.

I got it running and it had between 20 - 30 lbs of oil pressure(can't recall the exact number) when it was cold(temperature in the 80s around here). After it had idled for a few minutes, I rode it up and down the street a couple times and when I pulled back into the driveway I couldn't read a pressure on the gauge. It wasn't making any abnormal noise(at least it didn't seem to me with only my previous Panhead as a point of reference for the older bikes). So, I was thinking that it may just be a gauge issue. That was last week. I went out yesterday and fired it up again and it had the same 20-30 lbs cold oil pressure. I know my old panhead had very little oil pressure when it was warm idling and I've been told shovels are similar. I am using Penngrade 20w50 oil. The gauge is a 100 psi unit mounted down by the pump. I was planning to replace the gauge anyway since the face is cracked.

So, my first question is: Can I use a 60 psi gauge so that the warm pressure number is more noticeable at a glance?

Thanks
Andygears
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Re: '73 FLH oil pressure

#2

Post by Andygears »

Those gauges aren’t too accurate when new, usually inaccuracy is a percentage of travel. So a 100 psi gauge with 10 % error might read nothing at idle with less than 10 lbs. So, yes, a 60 pound new gauge would be more accurate….. for a while.

Andygears
Eb74UL
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Re: '73 FLH oil pressure

#3

Post by Eb74UL »

I would look at replacing the lifters and lifter blocks, shovel need pressure at the rocker arms and lifters. On my shovel, this is where I was loosing oil press, I replaced rocker arms and shafts to no improvements, then I replaced both lifter blocks and lifters and boom! oil press came right back up. I also run bigger oil lines to rocker arms with 20W50 oil, never had a problem since. No way running straight 50W oil through that 1/8 pipe to the rocker arm will take pressure there, unless you live in southern Arizona!
animal12
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Re: '73 FLH oil pressure

#4

Post by animal12 »

You might see if you can get a liquid filled gage . They seem to like vibrations better than a plain gage .
animal
1957flhchop
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Re: '73 FLH oil pressure

#5

Post by 1957flhchop »

Eb74UL wrote: Tue Jul 05, 2022 3:10 am I would look at replacing the lifters and lifter blocks, shovel need pressure at the rocker arms and lifters. On my shovel, this is where I was loosing oil press, I replaced rocker arms and shafts to no improvements, then I replaced both lifter blocks and lifters and boom! oil press came right back up.
If I decide to replace the lifters, thoughts on solid vs hydraulic?
Mongrel505558
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Re: '73 FLH oil pressure

#6

Post by Mongrel505558 »

Temporarily loosen one of the top end oil feed fitting nuts. You will quickly know whether or not you have good oil flow. These pumps are high volume, low pressure. Plus most of these gauges are pretty much only good for "go/no-go" and their accuracy sucks. My '81 shovel read zero on the gauge when hot. My friend owns that bike now and it has the original oil pump. Bike has at least 150k miles on it by now. I have a gauge that I use when I start an engine after putting it back together just to verify that oil is pumping. It's on my pan now just to plug the hole. It reads about 60 psi when I start the bike cold. I doubt the pump is making 60 psi. The dial also starts at 10 psi (like the speedo that reads 10 mph when the bike is parked), so the gauge is pretty much useless for reading low pressure. For what it's worth, I'm running 60 weight oil now, and 20W50 in the cooler weather, but for that question you'll get as many different answers as the number of people you ask.

Jim
Eb74UL
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Re: '73 FLH oil pressure

#7

Post by Eb74UL »

I see nothing wrong with hydraulics, they are really maintenance free. To me solids are more difficult because the pushrods expand when they get hot so clearance must me set correctly and be aware of the pushrod material (I cannot say if aftermarket aluminum pushrods expand the same as HD). I run hydraulics on my shovel and on my pan and never had to touch them after they were set as per book instructions. If I ever have oil pressure issue again I will first change all 4 lifters and both blocks (this is where you have funky angles) and use hydraulics. I disagree with those who say oil pressure is not needed. Oil pressure is certainly not needed on the crankshaft because everything is on rollers (you could not apply oil pressure there even if you wanted). But on the lifters and rocker arms... sorry guys! You need pressure there. Take a close look at the oil circuit you will see oil pressure going to lifters and rocker arms and going thru restrictions before it reaches the rods and crankshaft bearings (rods through the crankshaft passage). If you have no oil pressure you will wear out your lifters and rocker arms. Take a reading at a rocker arm shaft.
1957flhchop
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Re: '73 FLH oil pressure

#8

Post by 1957flhchop »

This bike appears to have solids right now. The Pan I used to own had hydraulics in it.

I've got a 60 lb gauge coming so we'll see what that reads. FYI I went out a couple days after my first post and fired it back up and the pressure was back up as before when the engine was cold.
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Re: '73 FLH oil pressure

#9

Post by nifty »

57flchop
If your 73 was built Jan 1 1973 or later, it should have all the end oiler modifications.
But we know it is chopped, and almost 50 years old, so anything is possible inside motor.
Nifty
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Re: '73 FLH oil pressure

#10

Post by panheadrider1961 »

So in 1977 unleaded gas was know all over our USA Moco sees big influx in shop for Oil smoking on new scooters ? Top end being flooded by High Volume of oil causing oil to be sucked thru valve guide and burnt ? Solution retro fit orficed fitting in feed line to rear head to stop flooding rocker box with large quantity of oil being to slow to drain down cylinder wall to bottom end to be scavaged back to oil tank by the high volume low pressure oil pump designed in the 30,s called a dry sump system, read the manual find a old shovel head wrencher and he will tell you a gauge will keep you broke and the wrencher rich Evo motor was first v twin to hold 8-10 lbs at idle because it was designed that way
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