Collapsing lifters or weak oil pump

[jack moghrabi]

Hello everyone,

A while back I wrote about the "engine rebuild" I had done once I recovered from my motorcycle accident with an automobile. My "rebuild" consisted of honing out the cylinders, cleaning the pistons without removing them from the connecting rods, taking out and cleaning the valves and then lapping the valve seats by hand with the stick and the rubber plunger and putting everything back together.
I figure I have about 1000 miles on the new rings and I've been breaking her in easy. I don't have a speedo or a tach on my bike so my mileage is a guess and frankly I don't need either one because I scoot down the road without a too much of a fuss. I'm really pleased with the results. My "63 starts easy and runs nice. The throttle response is nice and crisp. I think she runs pretty cool because I check the cylinder head temperature by laying my left hand on the valve covers while I'm motoring and the valve covers stay warm to the touch--I can pretty much keep my hand on the covers indefinitely as long as I'm in the wind..... Like I said, everything is nice except for one thing:
After I've been riding a half hour and I pull up to a long stop light the engine feels like she's collapsing with the increase in temperature. She doesn't miss or quit. She just feels like maybe a valve or more aren't opening up all the way? When the light turns green and I get her going she clears back up and runs great.

While doing the "rebuild" I did pull the tappet blocks off to replace the gaskets and I did check the lifters and OK to the best of my knowledge I thought they ranged from marginal to still serviceable. At the time I decided to go ahead and use the old lifters (how old I don't know). One of the tappet rollers was pitted and I did change that. The other rollers were smooth and the cam lobes were nice. I thought with a bad tappet roller I'd see corresponding damage on the cam lobe but no, cams were good.
Am I getting a collapsing lifter or more once the motor's hot and then idles at a long red light? Another symptom I get as the motor "sags" is that I do get an exhaust that "pops". She'll "pop" "pop" softly and intermittently until I get the green and get her going and everything clears back up. It's nothing like a backfire or a shotgun blast....just a soft "pop".
Is it my old lifters or my old oil pump not delivering enough pressure under the conditions outlined above?
What's the best way to check? Also, if it is the lifters I'm considering the solid conversion kit. As always any thoughts and advice are highly appreciated.

[fourthgear]

Do you get good oil flow back to the tank at idle when you have sufficiently warmed her up? The lifters do get less flow at idle and are notorious for collapsing when aged. Another thing is it is very hard to decipher cam lobs with out removing the cam and Mic 'ing the lobes(even tho they look good they could be worn or unevenly worn ). I have used solid lifters on all my Harley's and with stock cams or solid cams . I just believe they give better performance( I know they are opening and closing the proper amount when adj. correctly ) nothing really wrong with hyd. when they are working PROPERLY. my two.

[DuoDave]

If you have a lifter collapsing on you, you will hear it tapping as the clearance increases.

[Cotten]

Jackmo!

I must ask: You aren't running an andrews "a" cam, are you??

...Cotten

[jack moghrabi]

Good morning everyone,

Thanks for the comeback.....

Fourthgear, I believe I do get good oil flow back to the tank. I actually get so much pressure that a while back I stuck a vented cap in the tank hole because I felt the tank was being pressurized. I've been running her that way for a while now. With the motor running and the tank cap off, you can see quite a bit of oil/air mist being kicked out. Set me straight if I'm doing something wrong!

Hey DuoDave, Yes, my valvetrain does "tick" away going down the road so I suppose I should take out the old lifters. I kinda get a "kick" out of stretching the serviceability of the parts by I guess enough is enough here.

Mr. Cotten! I believe everything in the motor is stock except for the new rings and the pistons are .10 over. As I mentioned earlier I use the bike as my primary transport and I do baby the bike although I guess I am tough on the machinery by pushing the serviceability of the components probably beyond what most people will do...... For the first time yesterday afternoon I started to open up the throttle more than I've done before. I did get hesitation and lag at about half open throttle so I made the high speed jet a bit richer on the Zenith/Bendix and that improved the response.
This morning driving her to work (about 20 miles) everything was pretty good. The motor didn't "sag" or "collapse" (I can't think of any other words to describe the condition) even at a couple of the longer red lights. That's pretty much were I'm at now..... waiting to see were things go.... Any thoughts you all?

[Cotten]

"Sagging" isn't how I would describe collapsing lifters ("Clatter and banging" is.)
Although it is natural to accuse the motor immediately, if you do not hear a change in sound, I would look for something taxing horsepower somewhere in the powertrain or even the brakes first, just to avoid tailchasing. Especially if it is intermittent.
And don't forget fuel supply. (I once had a plastic filter swell shut and become my highspeed mainjet. Drove me nuts.)

Good luck,

...Cotten

[jack moghrabi]

Good morning Mr. Cotten. Thanks for the reply. To tell the truth, over the last two days things have come together quite well as far as running my '63 goes. Like I mentioned earlier, now that I've got over 1000 miles on the new rings I'm beginning to rev her higher going down the road. After I dialed in a slightly richer mixture to the high speed circuit on my Zenith/
bendix things have gotten better. Now, except for the increase in valve train clatter once the engine is hot and I find myself idling too long at a red light, the motor really runs great! The motor feels real solid and strong. Over the past two days (since the carb adjustment) the weakening lifters under hot conditions doesn't seem to be as pronounced as say a week ago.

It did also take a bit of tweaking with the intake manifold set-up though. I'm running the aircraft style flexible clamps that hold the fat rubber bands in place over the hard round thin plastic inserts that go over the lips on the carb intake manifold and the cylinderhead intake ports. To make it short I always found the clamps gradually creeping their way off the rubber bands towards the center of the cylinder jugs. Finally I stuck two pencil pieces, cut at the right length, and wedged them between the clamps and so far it's been doing the trick. It might look a little odd to see two pencil pieces wedged into my motor, but that's all right, I know I've got the coolest ride down here and I always feel like nobody can touch me going down the road no matter how slo' I go.

As I have mentioned so many times by now, I really ride this bike....everywhere all over Palm Beach County. And frankly, for me, there aren't that many other things l'd like to do than be out on my '63. I'm sure everyone gets something different from owning an old Harley, but for me it definitely has something to do with a sense of antiquity, old time and earlier times. Maybe its even got something to do with what seems like quieter times. And a Panhead definitely is the ticket, rather than some old European or Asian bike, not that there's anything wrong with them.....you get my drift I'm sure.

I'm hoping to be able to ride my bike up North from S.Florida this summer by way of Appalachia. Down the way I'd like to take her further, like out west and like everybody else maybe to alaska one day.

I hope I didn't take to much space expressing my appreciation to this website and all of its noble participants!