Did Harley "re-tourque" pan motors?

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FlatHeadSix
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#16

Post by FlatHeadSix » Fri Mar 07, 2008 3:55 am

Fourthgear,
I kind of have to go with Cotten on this one. If modern synthetic material gaskets are spongier and more compressable than the original materials then something has to move when you tighten things up. If you get even a quarter turn on the cylinder base nuts the cylinders will move down. Same for the head bolts, it will pull the heads down. If the heads are bolted solidly to the frame rail they aren't going to move. Something has to give, if even a few thousandths, and it will probably be the inserts. When the inserts pull you have not improved your seal at either end of the jugs and eventually you will end up with either an oil leak at the bottom or a blown head gasket at the top, or both.

I think the best course of action when retorqueing is to loosen the top motor mounts first, at the cylinders so they can move independantly, and at the frame. Torque everything to spec and then retighten the top mounts.

it can't hurt!

mike



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#17

Post by Cotten » Fri Mar 07, 2008 1:31 pm

The "pulling' or stretching of the cast-in headbolt inserts results from a combination of all things, but mostly just the millions of compression strokes that 40 to 60 year-old heads have experienced.

Loosening the top motor mount is a good idea, but if you have ever straightened a frame you will find that it is very springy. You can move it with one 7/16" bolt on a turnbuckle, much less ten.

Metal moves. If it didn't, it would shatter.

....Cotten

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#18

Post by Robert Luland » Sat Mar 08, 2008 2:13 am

I agree with Fourthgear. The amount of movement would be so minuet It would make no difference what so ever. If they were loose enough to move they would be going up and down with the pushrods. Fourtgear you bring back such found memories. The old banana caliber. If the rattle didn’t drive ya nuts. The bleeder nipple breaking off in the aluminum would make ya want to kill. Bob

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#19

Post by captainharley » Sat Mar 08, 2008 2:25 pm

I run a "banana" caliper on the rear of my '65 Pan and it works great for
me. They are a little more labor intensive then newer or after market ones but I am able to change rear sprocket ratios if I want to. One thing I had done to the caliper halves to help prevent them wearing out. Is that I had the mount pin holes enlarged and 65A generator end cap bearings pressed in. The bearing ID and the pin OD are very close.
This way the mount pin holes in the caliper halves don't get "wallered"
out. I just replace the pin ever so often. 8)

AMF/Ride Safe :wink:

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#20

Post by Cotten » Sat Mar 08, 2008 2:25 pm

I imagine that the pushrods do make the heads rock to a minute degree.

The pushrods also bend; Connecting rods arch under compression and combustion load, and pistons make the cylinders swell like a mouse running up and down the belly of a snake.

Hitting a good bump could very well distort the bores for a microsecond.

No joke.

The frame is a big spring that absorbs vertical motor vibrations (as well as other shock vectors). Having a pre-load upon it may have an effect upon harmonics, but it is anybody's guess if it would be good or bad, for any individual machine.

Face it, getting at that bolt is an annoyance.
I'll admit to a couple of dozen successful re-torques without loosening it.

....Cotten

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Re: Did Harley "re-tourque" pan motors?

#21

Post by 58flh » Sat Aug 18, 2012 11:56 am

MAN You guys brang a memory back on those Ignitions in the early 70s bikes!---I changed LOTS of those (Prestolite) things!, Some of the bikes olny had 3000-miles or less!--ALL went to points -set-ups! in that time!,,After that change ,it was just your yearly tune-ups!, The motors ran decent!--Shifting however was another -JOB in itself!---I had a 76 shortster I scored for bail-money!$300!--Ran great it was a 1000cc motor,I did the topend over ,A buddy gave me a used set of p-cams-I ran a S&S-B on it ,36inch by inch & 3/4 drags--Barnet clutch--Trock-door,& a Andrews c-box. That turned consistent mid-12second runs on street tires & no wheelie-bar!--(FUN-BIKE)--But to do that work today would cost a bundle just for parts!.-I had a grand into it not including the price for the bike!--Total cost was-($1300)& a Everyday rocketride to beat on!-Oh yea it was KICK-OLNY!--The loong wheelies were a blast!--I do miss that one!--But it dont hold a candle to my 69-shortster!-----RICHIE :lol:

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