What do I have here?

Nigeldtr said:

Matt Spencer said:

See a post recently where someone used a durometer , and found the new crank studs softer , so used the originals , with the new nuts .

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when it comes to big end and crank nuts and bolts, I think I'll use the old ones with loctite. I have had too much crap replacement parts recently to ever believe they test the tensile strength!

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I just got a set of those studs etc so the tensile test was ...................... interesting.
To be truthful if they are around Grade 5 the supplier should be notified,a bolt up crankshaft with hardware store spec fasteners is not very comforting.
I have my 71 750 on the bench also,same pistons as yours,same journal measurement but it still has the original shells and MRJ crank roller and ball bearings. (New crank bearings have arrived)
I have a jewelers type eye glass which makes detail examinations easy for most things.
The sludge trap is worth checking,the Norton's was quite clean,the 73 Moto Guzzi's (no oil filter either) had sludge that needed picking out.

DogT said:

I'd punch them again. Loctite may not hold up to the temp.

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Loctite seems to hold up to around 200 C, if my crank gets that hot I am in trouble anyway Concerning nuts bolts etc I really have lost faith, as mentioned, I had an engine blow up and make a real big mess after a rebuild where the big end nut split into two pieces - the top lock part came off and then the nut unwound itself and the big end bolt came out and bang! I'll look at my shells tomorrow I suspect they are standard, I was surprised to find rollers on both sides of the crank?

>>I have a feeling its been sitting round for a good few years! Its actually all reasonably clean but someone has already had it apart and taken out the old cam. I'll take the crank apart next week (away for a few days on business) and see what is in there. Journals seem to be standard as I measured 1.749".
I assume the main bearings are the newer ones - seem to be in good condition - chunky Thanks for the tip, I'll check out crank polishing.<<[/quote]

Your bearings do look to be the "superblends" that replaced the early problematic ones according to
Beltdriveman's info, the standard MRJA30 bearing had eleven rollers and yours have 12!

Your bearings do look to be the "superblends" that replaced the early problematic ones according to
Beltdriveman's info, the standard MRJA30 bearing had eleven rollers and yours have 12![/quote]

I just had a look and the bearings have NJ 306 E marked on them - are these the right ones?

Nigeldtr said:

Your bearings do look to be the "superblends" that replaced the early problematic ones according to
Beltdriveman's info, the standard MRJA30 bearing had eleven rollers and yours have 12!

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I just had a look and the bearings have NJ 306 E marked on them - are these the right ones?[/quote]

Once it was figured out that the original MRJA30 bearing was problematic Norton worked to develop the Superblend type with rollers with a very slight taper towards their outer edges. Actually slight enough that just looking at bearing it really isn't obvious. They wouldn't have put a non-superblend in to replace the originals so yours should be fine, however I'm not sure which exact number should be on it. Maybe someone else hear will tell us.

Nigeldtr said:

I just had a look and the bearings have NJ 306 E marked on them - are these the right ones?

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FAG NJ 306E.M1 (C3) is the correct bearing. Andover Norton part number 06-4118

So split the crank and found a little dried out sludge in there but nothing dramatic - So Matt it was worth while

L.A.B. said:

Nigeldtr said:

I just had a look and the bearings have NJ 306 E marked on them - are these the right ones?

Click to expand...

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FAG NJ 306E.M1 (C3) is the correct bearing. Andover Norton part number 06-4118

Hi LAB, Thanks for the picture - clear now!

I had a look through the box of bits and found some cam followers/tappets which show some wear, there seems to be plenty of meat on the tips and the marks are not deep. Do you think I can just have them reground - I want to fit them with the new 560 ss camshaft?

Nigeldtr said:

I had a look through the box of bits and found some cam followers/tappets which show some wear, there seems to be plenty of meat on the tips and the marks are not deep. Do you think I can just have them reground - I want to fit them with the new 560 ss camshaft?

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yes

Yea , std proceedure if the engines down , is lap them flat . Might even pay to P O L I S H the things . Cam Lube for reassembly too .

While we're there , you mayaswell polish the rods & check the cases for flash / daggs / burrs . You can polish the insides of them , too .

And bore Oilways Oversize if youre planning on running it flat out , or over the ton continuous on visits to the wide beyond . At least giveing
the OIL PUMP a detailed inspection & lapping the body for One Thou endfloat at the gears , sees that at its best & stops the tank draining
back through the sucker . Done real well & 2/3 to 3/4 thou , and a burn up with the electric drill with assembly lube will see it right .

Gentle de dagg on the rocker arms , with emery paper & maybe grinding a smidgeon off the ends past the adjusters cant harm , & solid spacers
rather than the el cheapo split washers for end clearance .

good to see all is in order , and nobodys throwing things .

I'll give the tappets a go with some fine wet and dry on the surface plate - I'll soon see how hard they are! I would have thought that emery or wet and dry would not touch them. If it does, then I would think they are too soft - perhaps I am wrong here. The rods look in very good condition, not bashed about and should polish up easily. The cam lobs hit the crankcase when turned so I will need to remove some material to get it to spin freely. There is a "ring" cast around the camshaft in the case which seems to have a thin wall, if I bore it out, there won't be much left?

I won't really be zooming around too much just the odd blast to frighten myself. I will stress the engine a bit but probably me more I need to pull the head apart but so-far-so-good. I have a mill and lathe so making the spaces will be no problem. Oil pump was missing but I gave the same treatment to my 850 and worked well at reducing the wet sumping! I am reluctant to change out the mains as they seem fine I might drop them out for a good clean and inspection but seems a same to throw if they look good

Nigeldtr said:

I'll give the tappets a go with some fine wet and dry on the surface plate - I'll soon see how hard they are! I would have thought that emery or wet and dry would not touch them. If it does, then I would think they are too soft - perhaps I am wrong here.

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Stellite is very hard. Maybe not damn hard, but darn hard approaching 50 on the rockwell scale.

Even if you could polish these, you shouldn't. Short of crank journals, I think this is the second most criticle area of the motor. Not only do they have to be perfectly flat, they also have to be perfectly square. No hand jobs here, so to speak. Being shiny is a moot point

pete.v said:

Nigeldtr said:

I'll give the tappets a go with some fine wet and dry on the surface plate - I'll soon see how hard they are! I would have thought that emery or wet and dry would not touch them. If it does, then I would think they are too soft - perhaps I am wrong here.

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Stellite is very hard. Maybe not damn hard, but darn hard approaching 50 on the rockwell scale.

Even if you could polish these, you shouldn't. Short of crank journals, I think this is the second most criticle area of the motor. Not only do they have to be perfectly flat, they also have to be perfectly square. No hand jobs here, so to speak. Being shiny is a moot point

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I had a local camshaft shop grind mine for about $20 so a very cheap refurbishment to new.

Egar . lapping on a good stone is possable , with a steady hand . ' mirror finish ' comment was spur of the moment .

Oil Retention , or Anti Scuff / Oil Retention . fancy pants might put a V groove to feed oil into contact patch . maybe :? perhaps :|

ANYWAY , ' One ' has NOTICED youve Two Pair there :!: if the workin pairskis are togtherski , :?: Two ODD Pair . :shock:

chamfer at edges for and aft on the one , clean through flat on the other . Thus not the same , dissimilar in detail . Not Quite Matching .

WHAT is the meaning of THIS . maybe some picked up and were replaced . The o.h.c. pintos did this , metalurgy & oil feed tube were causes .
The later if blocked , coked , or ignored on overhaul .

Dead Square & no rocking if refaceing by hand . any more than a few thou & youd machine them , but light scouring SHOULD be eradicated
if one has them in ones hands . not to mention heavy scouring . Clean Unworn Mateing Faces , Cam to Follower . and Elsewhere too . 8)

Looking atem the shaft needs polishing clean too . Maybe you could make some lightweight Titanium replacements . :?

They came in the bottom of a box all mixed up so I don't know what order they were in! I suspect the cam was shot probably due to the setup with the combat head etc - I will check all the clearances and valve geometry on the bench just to make sure the clearances and angles are OK. I have a measuring surface plate here that I use for finishing cylinder head and barrel faces (extremely well looked after) and I will give them a light clean on it just to see where the high and low spots are.

I can take them to the shop but who is to say they will do a perfect job! I doubt that they have a gig for holding them so they will probably clamp them in a vice, hopefully setting them square and run a grinding wheel over them. Well I can probably do the same on my mill table and use my grinding attachment from the late.. Obviously, there are some enormous pressures and forces at work and presumably the idea is the oil shears and not the surfaces of the tappets/cam lobs. So, how do we ensure there is no metal to metal contact?

Moreys Heavy Duty Oil Stabilizer . 8)

Nigeldtr said:

They came in the bottom of a box all mixed up so I don't know what order they were in!

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If you mean the followers/tappets/lifters you can look with a magnifier to see which were together but you won't know which cylinder.
Main thing is to have the beveled sides together and facing the front of the engine. ?