1950 panhead tappet adjustment

Top End (cylinders pushrods etc.)
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doc308
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1950 panhead tappet adjustment

#1

Post by doc308 »

What is the proper way to adjust the tappets on a 1950 panhead, which is equipped with the oem hydraulic pushrods ? Should the adjustment be 3 full turns, 4 full turns ( i think that this is right for hydraulic lifters/solid pushrods), or just get the pushrod to the point of spinning freely with no up/down movement?

Also, if I wanted to convert to the later, hydraulic lifter/solid pushrod set up, would I need to change the lifter blocks?
VT

#2

Post by VT »

Also, if I wanted to convert to the later, hydraulic lifter/slolidd pushrod set up, would I need to change the lifter blocks?
You can use the same blocks. Get the complete Colony coversion kit, pushrods, tappet cups, springs. If your hydraulic units will pull out and leave and empty cam follower, your set to go.
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#3

Post by King »

Hi Doc308

As you noted your 50 Pan engine has the "oil can" hydraulics the ones built into the push rods. They never were too good to begin with and by now are probably completely shot. You can adjust them but they will still not function properly and cause a lot of clattering.

Later Pan motors have the lifters in the tappets and their cases have oil passages to fill the lifters. The early Pan motors are not equipped with those oil passages.

Thus you can not use the later lifters without modifications to your cases to permit oil to service the lifters. Several threads on this site have warned against attempting those mods (drilling the cases) as damage can easily result.

My advise is to remove the "oil can" rods and install solid push rods using the existing tappets. I did that with my 51FL several years ago and have been quite happy with the results.

Adjustments are quite simple. With the valve fully shut, back off the tappet's lock nut, tighten the adjuster up till there is no "shake" in the rod and continue tightening till the rod will spin with two fingers but have a noticeable drag. Then hold the adjuster firm and tighten up the lock nut. Check to be sure the adjustment hasn't backed off and you're done. The reason the rods are adjusted tight is that they are usually aluminum and as the motor heats up the cylinders will expand (extend) more than the rods causing the rods to loosen up and clatter.

One word of caution; when you install the solids check the cam rollers and replace any that are iffy. The solid rods will put a bit more strain on the rollers and they can "grenade" scattering their bearing rollers into the gear case--not good. The are posts on this site with recommended replacement rollers.

Good Luck

King
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#4

Post by FlatHeadSix »

Good advice all around King, I did the same conversion on my '49. Its probably one of the easiest upgrade fixes you can do on a pan engine.

Should probably mention that you can do the whole job without a major tear down. The original "oil can" push rods can be removed by turning the adjusters on the OEM solid lifters all the way down and then simply lifting them out. Slip the new solid push rods into the covers, put them in, and run the adjusters back up. Like you said, tighter is better!, more so if you get a set of aluminum rods. I've got mine adjusted so that you can just barely turn them, they run quiet and have not given me any problems.

My original "oil cans" were so bad that they would not open the valves if the bike had not run for a while. When you tried to kick it through several complete rotations the compression would build up so high that jumping on the starter crank with both feet would not turn the engine over, and I hit the scales at just under 200 lbs. Solid push rods cured it!

I'll also reinforce the need for good rollers in the lifters, if all those little needle bearings ever get loose inside the cam chest it won't be a good thing, for any of the moving parts, and especially for the cam lobe under the lifter that spits the bits.

mike
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#5

Post by FlatHeadSix »

VT,
You don't need any of that other junk, tappet cups?, springs?. All you need is a set of solid push rods. Maybe a new set of cover seals if your old corks and stuff are questionable. Otherwise its just a simple swap out.

mike
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#6

Post by 51Hog »

Great advice King and Mike. Exactly what I did when I rebuilt my 51.
It has worked flawlessly.
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#7

Post by doc308 »

Thanks for the good advice, guys. Until I replace the pushrods, do you know what the adjustment is for the ones that are in the bike now--ie the hydraulic rods?

Also, I'd want to put new tappets into the motor if I change the rods. What is a good source for these? Apprx cost?
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#8

Post by FlatHeadSix »

Doc,
When I was still running the original OEM oil cans I had the best luck by pre-loading them a little more. Give them at least 4 turns after contact, maybe a little more. If they still pump up pretty good you should be able to run that way.

I'll let the parts swappers do the reccomendations for replacement items, you're going to get a lot of different opinions about who has the best or cheapest solution.

mike
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#9

Post by fourthgear »

OK,I'll play the part of "parts swapper " I've gotten pretty good at it any way . There is not going to be a real cheap way to replace the tappets and it depends on what shape your tappet blocks are in . If they will take a stock type replacement ,meaning they are not worn past the tolerances in the manual for spec's. Stock units are 0.730 in dia. ,I believe , I would have to look up the exact play you are allowed ( 0.001-0.002 ,I think ) If you are past that, they make over sized units and your tappet blocks will have to be altered ( honed ,bored , what ever )to get the right fit for the over sized tappets . I have Jim's one piece solids/tappets with the big axles in them and they make them in 0.002 OS & 0.005 OS if needed . These units have the adj. part ,in the tappet and you would need push rods with out any adj. in them , very solid design ( no pun intended ). I have over 10K on mine and unlike the conversion system , they do not need to be adj. as much ( I've had both ) I'm sure you will here more.
VT

#10

Post by VT »

Our method is printed in Vol. 1. It is different that what's explained here. Peace.
**************************************
yes, our Vol. 1 is solids.
The hydraulic is listed in the OEM '59-69 Manual. No need to repeat their method, unless the early hydraulic had a different adjustment. You don't want any obsolete push rods in a perfectly good motor.
Note: There's a reason Harley made progressive changes to the Pan motor - ever so often, until 1958 when it was perfected. Then the motor rode a crest for '59 and '60, then went downhill (losing the 8" headlight) and more complicated with dual-points, dual coil, etc.. imo.
I like adjusting the push rod lash at 2,500 mile oil changes. I can't remember which one of mine was a snag tighter routinely upon inspection, but if I flash to it, my mind seems to go towards the rear intake, but it seems that it would be every other oil change before I'd need to adjust one or two.
Oil change push /rod adj. are a way to check the motors wear pattern and read the tea leaves of filter residue at the bottom of the external chrome cup.
Last edited by VT on Wed Apr 16, 2008 8:09 pm, edited 6 times in total.
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#11

Post by panz4ever »

VT, isn't the adjusment procedure in VOL 1 for solids and later style hydraulics?

When I ran my 49 with old style hydraulics I adjusted per manual (3 turns) and never had a much problem with them. But w/ the rebuild, I am converting to solids becuase I strongly believe for my year motor solids are definitely more reliable and dependable.
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#12

Post by PanPal »

'59 and '60, then went downhill (losing the 8" headlight)


The headlight was gone in 60. along with the V style tins. Both returned, I think in the early 90's.
VT

#13

Post by VT »

Yea, I kept '60 as part of the mix, just because the timer stayed the same. I think the '60 cowling was when Harley started trying to keep up the the Beezers. The '59 damper was gone from OHV.
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#14

Post by Pantony »

VT it's not a simple "swap out the lifterblock, change the pushrods" substitute. I requires drilling the case, there are no feed passages to the lifter blocks in that motor and this is pretty much common knowlege that it is no easy task. Advising someone to do this without drilling the cases is junk waiting to happen. And drilling the cases is a gamble if you don't have the knowlege to do this. If your adivising, then get all the facts out. Could have costed the guy a motor.
VT

#15

Post by VT »

Good you were around to state the facts. I wouldn't drill any Harley case for any procedure.
Go light on the correction though. If you're going to alter a case, and don't know about the drilling procedure, for sure you wouldn't be doing it yourself. :?
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