Common problems, but still somehow unexpected

capguncowboy

Well-Known Member
#1
We do all we can to avoid basket case engines, but every once in a while, the parts on it require the effort anyway.

I picked up this Lighted H35 from a 1969 Rupp Scrambler project a few years ago. The entire project and of the parts had been media blasted (I think with sand), but the engine looked pretty good. No pitting to be seen, good compression and spark, and as a bonus, it's a lighted H35.

I finally found some time today to go through it. The bore is really clean but during the rotation, it seemed to make just a little too much noise. I planned on redoing this engine anyway, so I took the side cover off. The crankshaft is pretty bad. Not on the rod journal where you'd suspect. It's actually grooved on the crankcase cover journal. It looks like something got inside there and just wreaked havoc.

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Both parts will need to be replaced. I have the cover, but I don't have another 5/8" untapped crankshaft laying around. I probably should replace the crankshaft anyway since it has a groove worn in it from an improperly installed set screw. Looks like it just free spun several times over the years and nearly cut the end of it off.
 

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capguncowboy

Well-Known Member
#2
Since the block was in good shape, I started cleaning it up too. Then I broke this screw off...

View attachment 241241

So I'll have to set up the drill press and clean that out. Not really that big of a deal, but THEN I discovered this.

View attachment 241242 View attachment 241243

The aluminum is oxidized so I think it happened a while ago but this seems like it'll be a problem. The nut is free and turns, but I don't want to try to remove that exhaust elbow for fear it'll break it worse. I can see the threads down inside the hole, and they do appear to thread in past the break. Should I try to address this or is it worth worrying about?
 

delray

Well-Known Member
#4
all that stuff can be repaired,but if you don't have the knowledge to do it your self? it may cost more to fix it all then just finding replacement parts. for the exhaust you would have to get someone to weld some aluminum back on and then mill the top deck to make sure it's true again and the side. then tap threads out again.
crank can be rewelded and repaired,but that will be $100+ just to have someone else fix it.
 
#5
If it was mine, and I had no other pressing projects going... I would shop for a donor parts engine. Measure all the characters, pick the winners and go. If no donor, I would tackle a complete repair. Just because I haven’t tried those repairs recently and I have the tools to give the repairs a shot.
 

capguncowboy

Well-Known Member
#8
I have a 3/4" crank I can use in a pinch, but I want to keep it stock if at all possible. Truth be told, I do have the crank I need in a '68 sidepopper, but it has a pulley stuck on it... and I can not get it off of there for the life of me. I haven't attempted to cut it off yet, but I know I'll screw that up if I try.
 
#9
I have a 3/4" crank I can use in a pinch, but I want to keep it stock if at all possible. Truth be told, I do have the crank I need in a '68 sidepopper, but it has a pulley stuck on it... and I can not get it off of there for the life of me. I haven't attempted to cut it off yet, but I know I'll screw that up if I try.
I would give it the Gibbs for a week with light tapping. Then determine if the key way has spun and seized. Then maybe slit the pulley hub carefully with a cut-off wheel if my fly wheel puller wouldn’t do it.
Hope this helps
 

capguncowboy

Well-Known Member
#10
One I have is 3/4" output, so if its for a '69 or earlier Rupp, you would have to change the clutch in order to use it. but it is NOS :cool:

@markus, Any clue if part number 30946 is interchangeable with my crank (33028) ? I might have found what I need, but I'm not sure if the taper is right or not
 
#13
I have a 3/4" crank I can use in a pinch, but I want to keep it stock if at all possible. Truth be told, I do have the crank I need in a '68 sidepopper, but it has a pulley stuck on it... and I can not get it off of there for the life of me. I haven't attempted to cut it off yet, but I know I'll screw that up if I try.
Drew, I used a MAPP torch and heated the heck out of the pulley multiple times and shot with PB Blaster in between. Finally broke loose after a day or two.
 
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