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E: Engine Comet Mongrel



Cyborg

Well Known and Active Website User
VOC Member
#1
There are a couple of other Comet specials in the works, but thought I should create my own thread so I'm not polluting theirs.

I assume this is the original outer bearing race and those are the factory punch marks. What does the little round stamp that says HRD 10 mean?

Case main bearing bore.jpg
 

Attachments

Cyborg

Well Known and Active Website User
VOC Member
#4
I now know why that race is the only one still in the cases. I heated the cases to 200c and the race wouldn't come out even with some careful encouragement from a slide hammer/puller. Although I've never tried it, some on here have mentioned running a bead of weld around the inside of the race.
 

davidd

Well Known and Active Website User
VOC Member
#6
This is a wheel bearing, but I have done case bearings also. It is pretty ugly, but with the wheel bearings some of the residual grease drips down as you are welding.

Brearing Removal 1.jpg

You just need a bead, which will contract more readily than the race and it will pull the bearing race inwards. If you still have some trouble with it not dropping out then weld a piece of scrap from bead to bead. I use 1/8" strap.

Brearing Removal 2.jpg

You can push it out or smack it from the other side. This one broke out on the first smack. The race is quite brittle and will shatter. I gobbed it up with weld and hit it again. It is easier on a bigger diameter, cleaner race.

David
 

Cyborg

Well Known and Active Website User
VOC Member
#7
I ended up welding in a piece of round MS because the race seemed so tight. Then I was able to tap it out from the other side and keep it from going cockeyed in the bore.
No signs of locktite or ever being removed before. These cases seem really nice, so hopefully there won't be any surprises when replacing the spindles, bearings,pump, etc.

Case bearing race removed.jpg
 

davidd

Well Known and Active Website User
VOC Member
#8
A job well done! The only surprise I ran into the last time I did a Comet timing chest was that the rear follower spindle was too long. I set all the spindles to the height of the large idler stud with the ET173 installed because that is where the bottom of the steady plate rests. All the other spindles (with their various washers) are set to that same height so the plate is flat. When I installed the rear follower spindle it would not go in far enough. This is very annoying with everything hot! The spindle was hitting the cylinder stud. The photo below shows the new spindle on top and the old one below:

100_2682.jpg

It is worth looking at before installing the replacement. A bit of grinding may be necessary.

David
 

Cyborg

Well Known and Active Website User
VOC Member
#9
A job well done! The only surprise I ran into the last time I did a Comet timing chest was that the rear follower spindle was too long. I set all the spindles to the height of the large idler stud with the ET173 installed because that is where the bottom of the steady plate rests. All the other spindles (with their various washers) are set to that same height so the plate is flat. When I installed the rear follower spindle it would not go in far enough. This is very annoying with everything hot! The spindle was hitting the cylinder stud. The photo below shows the new spindle on top and the old one below:

View attachment 17929

It is worth looking at before installing the replacement. A bit of grinding may be necessary.
The
David
Thanks for the heads up about the spindle. I'll check it before I heat the cases. I don't have the cylinder studs in yet, so I wouldn't discover a long spindle until later on when I installed the stud..... that would be a PITA.
I ordered a new ET162 spacer for the steady plate, but it seems a little short when I check it against the position of the existing spindles. I had planned on using the large idler spindle as datum. I'll make a new spacer if necessary. Not sure why I bought one in the first place. Probably thought it would save me some time.
 

chankly bore

Well Known and Active Website User
VOC Member
#10
From what I recall the ET 162 should be about .447" wide, at least that's what I got when I measured a new original (with the part number stamped on it)! They obviously had too much time on their hands in 1947.
 

davidd

Well Known and Active Website User
VOC Member
#11
I set the height of the steady plate on the large idler and make everything else fit so that it remains flat. That means I had to make two ET162's to fit. The gap to the bottom of the steady plate was .488" for the two ET162's.

100_2690.jpg

If your ET162 depth is too much for the stud, you can remove the stud and use a 1/4-20 Allen instead. I like to set the spindles so I use a few shims as possible, because you almost always need a few to line up the gears. I did try to do it like the Factory stated, but the steady plate would need a stack of shims to keep it flat if I did it that way.

David
 

Albervin

Well Known and Active Website User
VOC Member
#12
This is a wheel bearing, but I have done case bearings also. It is pretty ugly, but with the wheel bearings some of the residual grease drips down as you are welding.

View attachment 17925

You just need a bead, which will contract more readily than the race and it will pull the bearing race inwards. If you still have some trouble with it not dropping out then weld a piece of scrap from bead to bead. I use 1/8" strap.

View attachment 17926

You can push it out or smack it from the other side. This one broke out on the first smack. The race is quite brittle and will shatter. I gobbed it up with weld and hit it again. It is easier on a bigger diameter, cleaner race.

David
Thank you David, I am currently facing the same problem. I heated the hub to 240ºC and it still did not want to come out. I think a quantity of Loctite has been used.
 

Albervin

Well Known and Active Website User
VOC Member
#13
A job well done! The only surprise I ran into the last time I did a Comet timing chest was that the rear follower spindle was too long. I set all the spindles to the height of the large idler stud with the ET173 installed because that is where the bottom of the steady plate rests. All the other spindles (with their various washers) are set to that same height so the plate is flat. When I installed the rear follower spindle it would not go in far enough. This is very annoying with everything hot! The spindle was hitting the cylinder stud. The photo below shows the new spindle on top and the old one below:

View attachment 17929

It is worth looking at before installing the replacement. A bit of grinding may be necessary.

David
Another helpful tip as I am about to instal a couple of new spindles. I will measure twice!
 

bmetcalf

Well Known and Active Website User
VOC Member
#15
Maybe too much variation in our old crankcases for that to be a time saver? I think I asked Greg B. about it and IIRC he doesn't use pre-made spacers.
 

Cyborg

Well Known and Active Website User
VOC Member
#16
I set the height of the steady plate on the large idler and make everything else fit so that it remains flat. That means I had to make two ET162's to fit. The gap to the bottom of the steady plate was .488" for the two ET162's.

If your ET162 depth is too much for the stud, you can remove the stud and use a 1/4-20 Allen instead. I like to set the spindles so I use a few shims as possible, because you almost always need a few to line up the gears. I did try to do it like the Factory stated, but the steady plate would need a stack of shims to keep it flat if I did it that way.

David
I like the safety wire. I have the wire and the appropriate tools, but would probably go mad drilling all the nuts. I'll do OP36 though. I cringe every time I look at one of those.

I measured the spindle. It's O/A length is .005 shorter, but the shouldered area is .005" longer.

What if anything do you use for a generator? Wondering about the chunk of alloy you used to reduce the diameter of the hole.... and wondering what I should use. I suppose Alton would be the easiest and quickest. This critter will spend it's days on the street, assuming it's finished before I am.

Off to the Post Office today to pick up my belt drive.

PS what do you use instead of the breather?
 
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davidd

Well Known and Active Website User
VOC Member
#17
The length of the short spindle above was 2.52", so that was the length I shortened the new one to.

The photo was taken when I built the racer, so it does not have a generator. The generator hole is occupied by a breather, the adapter for the hose being what you see from the inside. I am not sure my breather would help you out, but it is a Ducati reed valve breather, which can be gotten off Ebay. You have to make an adapter for the bottom to run it into a hose.

019.JPG

On the Flash, which I raced also, I used the stock timed breather with the mods mentioned by Irving. Both breathers worked perfectly.

I like the Allen heads as they are much easier to drill. I insert the Allen key into the head when I clamp them in the drill press to make sure I am drilling down through two flats. If you drill through the corners it is hard to get the chip out and the Allen key doesn't fit as nicely. I used Allens on the large idler boss also.

When I installed the spindles I screw them into the end of a slide hammer. On this engine I cut some scrap EMT or conduit to the desired length and installed a large washer before screwing the spindle in. As I remember, it worked fine for the cam spindle, but there are some obstructions in the case wall that prevent it from being done everywhere. Some other scrap that is cut to length can be used as a gauge. I did not want to be measuring with a hot case, just tap and check with the scrap piece, or tape it to the spindle under the washer.

I have not found Loctite on too many parts, but welding a bead on the race should destroy the bond.

The slide hammer/puller. The top adapter I made for the cam spindles and the lower for the oil pump sleeve:

Tools 10.jpg

David
 

Cyborg

Well Known and Active Website User
VOC Member
#18
Would it be possible to measure the fitted length of each spindle then fit a nut, washer and a spacer so you can just push them in to the correct depth.
Yes, I have done it that way before (sort of), but you have to make sure you have the face of the timing chest perfectly flat. The areas around the threaded holes in the case tend to stand proud, so they have to be levelled off and same with any hash marks on the mating surface etc. I use a chunk of parallel cast iron with a piece of tool stock clamped to it and then take measurements starting with the large idler boss. To install the spindles, I used a setup where the spacer was referenced off the parallels resting on the case mating surface instead of up against the case around the spindle bore. It's a but fussy trying to get accurate measurements, but you can make individual spacers.... at the end of the day, you will likely have to adjust one or two of the spindles with a slide hammer. I'm no expert at this, but I think the best thing would be an inflexible chunk of steel made up like a steady plate. When the cases are hot, all of the spindles could be set to the same height as the large idler. I'm not planning on making a plate, but may make individual spacers. Doing these timing chests tend to make my head want to explode.

Sorry for the crappy photo. I also install a ET173 on the spindle to make it a bit easier to get an accurate reading.

My new large idler spindle reads .3755 above the mating surface and the small idler spindle (which I believe was undisturbed) reads .3790 , so not within the "Instruction Sheets" .419 to .424"
Comet T:case.jpg
 
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Cyborg

Well Known and Active Website User
VOC Member
#19
Going to make a mainshaft oil seal holder. Can someone tell me what seal is normally used. I see the holder listed on VOC spares, but not the seal.
The groove for the outer circlip is beavered up a bit, so thinking of machining out the damaged area and using the seal holder to keep the outer bearing in place instead of the circlip.
What is the normal thickness of the flange that screws onto the case?
Please and thank you...
 

Robert Watson

Well Known and Active Website User
VOC Member
#20
Hi Ken
I have one I bought for the Hancock twin but ended up machiinng the cases and making the holder. I could have made you one as I had the mill setup for the bolt circle dia.
I machined the case down to the top of the snap ring groove and made a top hat type insert with 6 8-32 c/s screws as this now holds the main bearing in situ. You then machine the inside of the engine sprocket down to 1.500 in on the boss and just over . 250 deep. The seal is 2.062 X 1.500 X .250

Sorry it is turned sideways




20171117_152141_HDR.jpg
 


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