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Post by trashman36 on Feb 25, 2020 3:42:30 GMT
I got a 73 oly 340 it has a power block clutch on it. Can't find much info on the power blocks are they good? Would I be better off with an original ski doo clutch? Anybody running these clutches any info would be appreciated.
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Post by olyman on Feb 25, 2020 17:26:33 GMT
I like them. Easy to modify if you desire - change the weights and spring. There are 2 basic styles - 3 puck aluminum style and the older 4 puck steel jobber. Newer one is the best & able to handle decent hp. The old steel ones with 4 pucks in them were still smoother and had better life than the original OEM kidney bean weight clutches were. I would try it out for sure before putting something else on. just my 2c.
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Post by olyman on Feb 25, 2020 17:31:03 GMT
I had this on hand that I sent a friend of mine. He had all of them on his bench at the time, hence the descriptions.
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Post by trashman36 on Feb 25, 2020 22:54:03 GMT
I think I will clean it up and give it a go. Thanks for the info
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Post by ericr on Feb 25, 2020 23:08:43 GMT
I'd never go back to a stock rattly clanger of an original clutch after running a powerblock. Sooo much more quiet.
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Post by buzzard82 on Feb 26, 2020 1:31:37 GMT
Have one on my 775. A whole different sled with that clutch.
An old timer once told me that the reason a lot of those older rotax ,(especially the big twins and 3cyls) bottom ends blew apart was due to the stock clutchs. Those metal dogs and slots would wear all uneven in a matter of no time. Throwing engine balance out of whack. The handle bar vibration on my 775 has improved tremendously with the powerblock.
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Post by olyman on Feb 26, 2020 2:41:30 GMT
Very good points buzzard. On that note, I really like the comet duster too which is just as simple. I have one on my 292 big crank. Very smooth. Planning to use one on the 640 too, and hope it stands up as well.
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Post by 69nordic on Mar 25, 2020 6:34:07 GMT
I have several Power Blocs.They were made in Quebec Canada and communication in english is non existant.I spent countless hours on the internet trying to get some info on setting these up but it seems there are lots in use but no one is sharing any info,The older clutches came with a sheet telling you what color spring and number of weights for different machines.I finally found the sheets I put away for safe storage many many years ago.I have no idea where you would find the old solid color springs now.Back in 82 I bought a 71 Oly 299 with a brand new steel PowerBloc clutch,.It was really smooth but It was not shifting well I tried changing weights but never got it bang on But working on clutchs at 40 below makes for some hasty desions maybe it was the wrong spring? I have a couple one is supposed to be set up for a 71 tnt 340 .I am putting the track and sliders in a 72 399 oly so I will have to do some changes as I do not want an agressive take off I might use the skidoo square shaft from a 75 Oly and then I will be asking the Praire Skidoo expert Bones for help.I really like the look of the PowerBlocs it is a shame the info is TOP SECRET.I am in better shape now that I have the sheets.Anything I learn I will pass on. Kash
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Post by olyman on Mar 25, 2020 12:18:20 GMT
You hit the nail on the head with the Top Secrecy. So hard to find info on them. But it is out there. I just bought a new PB ALT from Recreation Supply in Saskatoon that is specifically set up for my 640 tnt (Powerbloc ALT Clutch 0302-0002 clutch + 0101-7028 calib. kit). They put specific spring and weights into it. The spring is black and looks like it came from the front of a 75 F150. The weights are big machined slugs that don't quite fit snugly inside the plastic sliders, but it works. Its what was "recommended" by powerbloc people. So if thats true, then there is a list somewhere. I will ask again for it.
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Post by olyman on Mar 25, 2020 16:59:30 GMT
I was able to get a hold of the guy I bought the clutch through. They have been selling them through their company since the 70's and he has amassed a list of information for lots of the oldies. He's into old ski-doo's himself. He is also ok with particular questions regarding the clutches so I will ask him what ever you are looking to find out about them. I'll ask about the 299, 340 and 399.
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Post by ericr on Mar 27, 2020 20:20:43 GMT
There is a wealth of information on this board found no where else! I have a powerbloc on my Minnesota '73 Oly 340, was on it when I bought it in '06. But until crank seal issues caused me to pull the mill in the summer of '19, I didn't know it was on there, except I always had a smooth engaging clutch. I have another '73, 340 Oly I acquired a couple years back- in Minnesota and to keep with my lo buck theme, cheap... I brought it back to snowless hot coastal Georgia (but we got shrimps and pecans, y'all!) three summers back to put sprockets in it etc..then the "snowpacolypse" of January 2018 came! OMG a quarter inch of ice followed by THREE INCHES of snow! The city was PARALYZED! which is a good thing as 1)few can drive in it and 2) lots of glare ice on any bridge etc. So the Oly was employed and I was the ONLY SLED out tearin' up the ditches!!! I thought, "this thing sure is noisy, wonder if I have pre ignition going on?" And as it turns out, what I had was the typical rattly stock finger weight clutch! I never ran my other same year same engine size sled with a stocker, so I forgot how clangy and bangy the dang things were!
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Post by olyman on Mar 28, 2020 0:48:35 GMT
Got some info back re the tuning of the old steel powerbloc clutches:
1971 299 single 15 hp 6000 Rpm, X-5243300 spring, X-82-70 slug per block. 1971 TNT single 340 26 hp 6000 RPM, X-5243300 spring, X-82-70 slug per block. 1972 399 fc twin 24 hp 7500 RPM, X-5243304 spring, X-81-3 8 weights per block.
Hope that helps!
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Post by silverbullet on Apr 14, 2020 2:57:55 GMT
Got some info back re the tuning of the old steel powerbloc clutches: 1971 299 single 15 hp 6000 Rpm, X-5243300 spring, X-82-70 slug per block. 1971 TNT single 340 26 hp 6000 RPM, X-5243300 spring, X-82-70 slug per block. 1972 399 fc twin 24 hp 7500 RPM, X-5243304 spring, X-81-3 8 weights per block. Hope that helps! I spent some time today sorting through 5 powerbloc clutches I've accumulated over the years. Turns out 3 are aluminum 3 puck clutches from the 80's (all with differing internals and outer cups); 1 was a steel 4 puck unit from the 70's ( I pulled it off a silverbullet years ago) , and the 5th was identical to the steel unit except it was labelled as made by Eastern industries, Drummondville Qc, but had the same patent numbers as the PB on it. My guess is PB bought out Eastern at some point in the past. When all was said and done, the most immediate challenge we have in sorting out these vintage PB clutches and their parts is there aren't any numbers on most of the parts or the springs. I believe the parts and applications information can eventually be sleuthed out but figuring out the part number of a part you have in hand, or sourcing new springs will be the limiting factor in using these units. CVT only lists the X-81-3 weights in their current catalogue. I'm guessing the springs are obsolete. Maybe there are some NOS ones out here somewhere? Lastly, if anyone as a ALT 1013 (late 80's) or AL 1013 (early 80's) powerbloc fixed sheave to spare, I could use it, lol. Turns out the aluminum units I have are all taper shafts and won't be useful for my old doos.
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Post by bones on Apr 17, 2020 3:36:59 GMT
This help you fellas out with PB clutches. Bones
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Post by olyman on Apr 17, 2020 12:38:18 GMT
Thanks Bones. Like silverbullet mentioned the hardest part would be to identify what someone has in their hand as they weren't too well described. That being said I "think" they still sell the majority of their clutch parts these days. Mind you I don't think you'll be finding any steel 4 puck outfits, but you should be able to get most ALT clutches and even updated parts for some of the older clutches between those 2 styles. I don't know what book you're looking through Bones but I know that Recreation Supply out you're way in Saskatoon is a great source for these things. Randy is the guy you want to talk to as he's a wealth of old doo knowledge, and has a lot of resources at hand.
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