Evaluate my 1.6 SNC Miata crank for rebuild

The crank itself is in spec according to the machine shop. My concerns are in two areas.

1. Slight imperfection in the keyway:
   
   Direct link to pic on my album:
   https://picasaweb.google.com/lh/photo/wIMMjNo0tLDzSwpTqyTOU9MTjNZETYmyPJy0liipFm0?feat=directlink

2. scratch at the rear main seal from idiot mechanic's screw driver
   Direct link here:
   https://picasaweb.google.com/lh/photo/orhyD7Z9DaXCTmuNcnJpQ9MTjNZETYmyPJy0liipFm0?feat=directlink

Thoughts?

Why would you bother rebuilding a 1.6?

Smaller motor = lighter parts = faster revs, etc.

The keyway doesn't look AWFUL, i'd probably be more mad about the idiot mechanic screwdriver marks, personally. Then just do the loctite thing as a pre-caution.

That said... if i had it all apart, i'd probably just get another crank.

Or a 1.8.

Loctite fix on the pulley end, speedie sleeve on the other end? Maybe you can burnish out the screwdriver scoring.

Maybe see if you can find a long-nose crank from a core engine and sidestep both issues. Although I do have a built 1.6 short-nose in one of my cars.

Loctite is a decent option for that nose. Note that this is not just Loctite blue, but a mix of a few products.

1.6 because Spec Miata - and I have it in the garage already.

I'm kinda pissed b/c the machine shop cleaned and micro polished the crank and only informed me afterwards of the potential issue... I went and bought a new timing cog and pulley ($200) when they called to inform me that everything measured out ok on the crank...

I can get a long nose crank inexpensively. A local club member has one. What else would I need to change over?

I'm hesitant to piss the money away I already spent if I don't have to.

Thanks.

This is why i usually ask my machine shop to check and recondition parts.

Specifically in that order.

You'll have to piss away some money to make the switch, the long nose uses a different oil pump, timing cogs and pulleys. The question is, would you spend more to fix/recondition this one? If it's for a racer, I'd make the swap. If you miss one event due to problems with this setup, it'll cost you a lot more than $200.

Hmm, I think you can use the higher volume 2001-05 oil pump on the long nose as well. Although Spec guys probably don't want the pumping losses.

Darn. I was hoping you guys would say everything was gonna be alright...

Swank - that was the agreed to plan. They screwed up on that front. :/

I managed to take a better pic of the keyway here:

At the section that is widened out, the thickest feeler I can stick in there and bottom out is a .229 mm w/ the woodruff key installed. It is tight. The .203 mm slides in and bottoms out easily. The rear of the woodruff key does not move. The front can be moved side to side slightly

Can the machine shop weld and recut the keyway? Or just use the appropriate Loctite to fill in that gap?

Couldn't you get a wider key and cut the keyway to size? You would also have to cut the keyway in the pulley to match. I have also seen keys that were of a different thickness to fix this problem. One thickness to fit the wider keyway and a upper narrower part to fit the stock pulley.

I've seen the weld and recut work. It's the smart way to fix it. But you still have that scar on the rear seal - and by the time you're done, are you any better ahead than starting with a different crank?

Keith Tanner wrote: I've seen the weld and recut work. It's the smart way to fix it. But you still have that scar on the rear seal - and by the time you're done, are you any better ahead than starting with a different crank?

Yeah, that's my concern as well. I'm just not looking forward to the $ outlay. Grumble grumble grumble...

I spent some time last night educating myself about the loctite and other hacks, er I mean fixes. The more I learn about them, the less interesting they become.

This SNC motor was the original motor in my really early 90. I have a low mileage 'long nose' motor from a '91 in the car now. I think I may pull that out and evaluate that crank. My only concern with that motor is that I found this chunk of metal on my Dimple magnetic oil drain pan after a weekend where I spun and hit the tire wall with both feet in. I'm wondering if I may have damaged the thrust bearing (and crank by association) when I hit the wall with the clutch depressed.

If I do get another crank, should I get the pistons that were on that crank as well or reuse my old ones?

Thanks.

The piston question is unrelated.

If you're going to have that other engine out, pull the pan and see if you can figure out where the Mystery Chunk came from. If it was the thrust bearing, I'd expect a fairly major engine event to follow shortly after.

The Loctite fix was actually developed by Loctite engineers in Australia. It's been tried quite a few times with success, so I'd rate it a bit above a hack.

Keith Tanner wrote: The piston question is unrelated. If you're going to have that other engine out, pull the pan and see if you can figure out where the Mystery Chunk came from. If it was the thrust bearing, I'd expect a fairly major engine event to follow shortly after. The Loctite fix was actually developed by Loctite engineers in Australia. It's been tried quite a few times with success, so I'd rate it a bit above a hack.

I actually ran a few more events after the mystery chunk incident.

Thanks for the comment on the hack. I had severely discounted it - apparently overly so.