1961 CB72 Project

G-Man · Post by **G-Man** » Sat Oct 17, 2015 6:37 am

Rich

Nice to see someone else having a go. A clean straight crank is critical to these engines. Something best not left to chance. Enjoy the workshop fun!

After you've trued it you'll appreciate the care you need to apply when putting on the outer mains to avoid putting it out.

G

rpr851r wrote:Thanks Jerry and G-Man. Unfortunately I pressed up my crank yesterday and the clearance ended up a little tighter than I was aiming for at .about 004. I don't have a great way to control the final clearance but will try and bump the clearance to .008. The good news was the crank was much straighter than I expected right out of the press with .007 runout being the worst. I am letting it set for a few days before trying to bring it in.

Thanks again for the feedback.
Rich

Tim Miller · Post by **Tim Miller** » Sat Oct 17, 2015 9:00 am

You could press crank back apart slightly. I use two feeler gauges on each side of rod when pressing together to control desired clearance.

Tim

rpr851r wrote:Thanks Jerry and G-Man. Unfortunately I pressed up my crank yesterday and the clearance ended up a little tighter than I was aiming for at .about 004. I don't have a great way to control the final clearance but will try and bump the clearance to .008. The good news was the crank was much straighter than I expected right out of the press with .007 runout being the worst. I am letting it set for a few days before trying to bring it in.

Thanks again for the feedback.
Rich

rpr851r · Post by **rpr851r** » Sat Oct 17, 2015 9:05 am

G-Man,
I was a little apprehensive disassembling the crank but figured I didn't have much to loose. You're right. I'll admit to not completely stripping the crank all though I was advised to. I don't have a fixture to put it back together and keep the cam gear in the right position. I did remove the oil passage plugs and spent several hours getting the internals clean including the slingers. There was a bunch of crud in there just like what you and others have shown. The original reason for taking the crank apart was to get the little ends of the rods resized which was accomplished at the local machine shop. I ended up using parts from a few cranks to get good rod needle rollers and cages. If there is a next time I am going to completely strip the crank and see how close I can get it back.

You're right. The crank will move with just a little abuse. I will be very careful putting the bearings back on.

Cheers,
Rich

G-Man · Post by **G-Man** » Sat Oct 17, 2015 9:32 am

Tim

Good advice. I've noticed that they spring back a little when you take the pressure off so shouldn't be possible to pinch the feelers.

I was pondering making some adjustable spacers to put between the webs.

G

Tim Miller wrote:You could press crank back apart slightly. I use two feeler gauges on each side of rod when pressing together to control desired clearance.

Tim
rpr851r wrote:Thanks Jerry and G-Man. Unfortunately I pressed up my crank yesterday and the clearance ended up a little tighter than I was aiming for at .about 004. I don't have a great way to control the final clearance but will try and bump the clearance to .008. The good news was the crank was much straighter than I expected right out of the press with .007 runout being the worst. I am letting it set for a few days before trying to bring it in.

Thanks again for the feedback.
Rich

G-Man · Post by **G-Man** » Sat Oct 17, 2015 9:40 am

Rich

I'm building up quite a collection of spare crank parts and am looking at several possibilities for reclaiming some of the damaged pieces. I hate to see parts being thrown in the scrap bin...

G

rpr851r wrote:G-Man,
I was a little apprehensive disassembling the crank but figured I didn't have much to loose. You're right. I'll admit to not completely stripping the crank all though I was advised to. I don't have a fixture to put it back together and keep the cam gear in the right position. I did remove the oil passage plugs and spent several hours getting the internals clean including the slingers. There was a bunch of crud in there just like what you and others have shown. The original reason for taking the crank apart was to get the little ends of the rods resized which was accomplished at the local machine shop. I ended up using parts from a few cranks to get good rod needle rollers and cages. If there is a next time I am going to completely strip the crank and see how close I can get it back.

You're right. The crank will move with just a little abuse. I will be very careful putting the bearings back on.

Cheers,
Rich

rpr851r · Post by **rpr851r** » Sat Oct 17, 2015 5:21 pm

G-Man,
I'm like you, I hate to trow parts away.

Tim,
Thanks for the feeler gauge suggestion. I thought of that but was worried that somehow I would pinch the feelers or worse damage the rod shoulders. Now you confirmed it works that's what I'll try.

Thanks again everyone for the help.

Regards,
Rich

rpr851r · Post by **rpr851r** » Mon Oct 19, 2015 8:17 pm

I got my rod side clearance adjusted to .007 and bumped it around until I had .0007" runout on one end and .0015 on the other. The wheel swash or wobble is under .0005. The high spot in both cases correspond to the pin location so I don't think there is much more I can do with it. For comparison I put another crank in between centers on my lathe and it had similar runout. I also checked runout by supporting the two center main bearings and checking the ends like Gram and got similar numbers to what I got not the lathe. Are the numbers I am getting reasonable for a street engine?

Thanks,
Rich

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