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Post by weverat on Dec 8, 2013 9:32:59 GMT -5
What were the 6 bolt Cuyunas, and Rockwells used on besides the Stings, and TK,s ?
I used to think the 4 bolt motors were discontinued in about 1975 (Whips), and all motors were now 6 bolt. I now realize the whips were 4 bolt.
What about the Masseys ?
When were the 6 bolts first used ?
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tkjoe
L3 The Proven Snowmobile that never lets you down
Posts: 117
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Post by tkjoe on Dec 8, 2013 9:47:48 GMT -5
I have a couple of 77 Rangwhips and a 75 whip with 400 6 bolt cuyuna/Rockwells. My 77 MF Chinook 300 is a 4 bolt as is my 77 340 whip. From what I've seen, The 75 and up 400 and 440 cuyuna's are all 6 bolt and the smaller motors are the 4 bolt.
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Post by scorp11 on Dec 8, 2013 12:28:50 GMT -5
From what I've seen, The 75 and up 400 and 440 cuyuna's are all 6 bolt and the smaller motors are the 4 bolt. Winner winner chicken dinner. Also, from 75 and up the only thing that is different between any displacement is piston cylinder and head. All other parts are the same Center plug 6 bolts came out in 79. There were no center plug 4 bolts
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Post by weverat on Dec 8, 2013 14:44:24 GMT -5
Ok, I'm still a bit confused?.
The center plug 6 bolt did not happen till 79.
Was there a point when all Cuyuna's became 6 bolt?.
All the whips I have seen have 4 bolt motors, but at some point did they get the 6 bolt affair as well?
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tkjoe
L3 The Proven Snowmobile that never lets you down
Posts: 117
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Post by tkjoe on Dec 8, 2013 15:38:21 GMT -5
Scorpion made a 340 whip with the 4 bolt head
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tkjoe
L3 The Proven Snowmobile that never lets you down
Posts: 117
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Post by tkjoe on Dec 8, 2013 15:50:34 GMT -5
Also someone could have swapped the motors with a JLO 440 which is a 4 bolt head, they look similar to the cuyuna
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Post by scorp11 on Dec 8, 2013 16:01:22 GMT -5
OK . . . . I try again.
6 bolt motors started in 1975. ONLY 400 and 440's ever went to 6 bolt heads. All 400 / 440 6 bolt cylinders went to the bolt on type exhaust manifolds as well. All 290's and 340's retained 4 bolt heads and the cylinders with the pipe sticking out for the exhaust mount
I believe all 1975 and up 400 / 440 engines were 6 bolt. I am not 100% sure this was true for the 1975 super stingers, but some research could determine that. I know everything 1976 and later was 6 bolt for the 440 an 400's
If you have 1975 and up whip with a 4 bolt 440 or 400, someone replaced the motor.
The 6 bolt head motors have big intake ports. The 340 / 290 much smaller.
to confuse it a little more. . the 6 PORT motors started before 1975 and were available with 4 bolt heads :-)
I really should put something together on my site for this I suppose.
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Post by obj1 on Dec 8, 2013 19:49:06 GMT -5
The 74' 400 and 440's had 6 bolts as well.
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Post by scorp11 on Dec 8, 2013 20:15:23 GMT -5
The 74' 400 and 440's had 6 bolts as well. Did they had two inner bearings and rubber seal on the crank too ? Were there ever any 440 / 440's that had 6 bolt heads and the 1 center bearing ?
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Post by obj1 on Dec 8, 2013 21:03:03 GMT -5
I'm not sure. Ours have the 1 seal 2 bearing design. however, you got me thinking about that. I will check a crank we have out of a early 6 bolt 440.
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Post by kube1 on Dec 10, 2013 23:11:15 GMT -5
When you guys are rebuilding these engines are you replacing the small plugs on the side of the cylinders? It looks like they fill a hole that was machined in to finish one of the ports. Something like a welch plug.
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Post by scorp11 on Dec 10, 2013 23:19:15 GMT -5
I never have. I actually have some original plugs for them, but I have never knocked one out and replaced one.
Tom, have you ever replaced one ?
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Post by kube1 on Dec 11, 2013 11:26:22 GMT -5
I never have. I actually have some original plugs for them, but I have never knocked one out and replaced one. Tom, have you ever replaced one ? The reason I ask is that I was wondering if they have a history of leaking.
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Post by scorp11 on Dec 11, 2013 23:42:17 GMT -5
I have heard some people claim they will leak, but its not something I've ever looked for. It would be kind of hard to test with the engine assembled.
I always figured the odds of my putting new ones in that didn't leak weren't any better than the originals not leaking. Maybe put a little case sealer around the edge for peace of mind ?
Pressure testing would show a leak, but it might be a hard to determine if the plugs were the culprit.
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Post by obj1 on Dec 12, 2013 14:49:18 GMT -5
Replace em with a glass plug. Then you can look in and see whats going on. ;D
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Post by scorp11 on Dec 12, 2013 19:26:44 GMT -5
Replace em with a glass plug. Then you can look in and see whats going on. ;D Then everyone would see all the fancy porting you do to all your high HP race motors
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Post by kube1 on Dec 16, 2013 11:36:00 GMT -5
So I just measured the bores on the cyl. of this 440 and one side measures 0.005 over 2.658 on 1 side. The Bore is still nice and clean. Should I over bore or is this still ok?
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Post by scorp11 on Dec 16, 2013 14:56:04 GMT -5
Have the piston and cylinder mic'd or mic them yourself if you are able. What is the clearance between the two ? And. . is the cylinder round ?
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Post by kube1 on Dec 16, 2013 16:56:40 GMT -5
I just measured the bore here at work and it is not round. I don't have the pistons with me. They run out about 0.003-0.004 in the center of the cylinder. The top of the cylinder is round. I don't think that's good but I'm no expert.
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Post by scorp11 on Dec 16, 2013 22:32:34 GMT -5
hmmm. . I would have thought that to be a bit out of round. . but according to the specs for the ultralight version, that is actually within spec. just seems kinda lopsided to me
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