4 tec crank tunnel repairs

[Sportster-2001-951C-Stock]

Yep, also custom bearings can be made if necessary. Make sure the crank spins easy, the bearing can get oil and the clearance is within spec. Luckily it's just one journal, that makes it a lot easier.

http://www.obbco.com/
http://www.obbco.com/custom-babbitt-bearings.html

 

[Steven Mace]

Ahh i like it!, well just waiting on a call. Bloke in sydney australia said he has a bearing that will fit the 4 tec crank and is .090 over standard size (56.286mm bore for the tunnel). just found a machine shop that will tunnel bore one main as well. fingers crossed its the right bearing.

 

[Sportster-2001-951C-Stock]

Yeah, ask the guy who tunnel bores it for you if he wants to assemble it too. They usually don't charge much to do that and it's really kind of a courtesy. Besides, he might catch some other problems while assembling that you might overlook and those guys are really good at what they do, can do it better than you.

And, there are some machine shops that will destroy a motor too, but usually they don't stay in business long.

 

[Sportster-2001-951C-Stock]

Here's the method I originally learned for fitting bearings (before plasti-gauge was available, LOL), we kept a variety of pre-cut shim stock of known thickness to choose from based on the clearance we were attempting. I'm not sure what the spec is for the 4-tec mains, I guess maybe around 0.0005~0.0020" but be sure to consult the 4-tec machining spec:

 

[Steven Mace]

haha that’s handy. old school but hey, if it works.. one thing I have noticed over here (Aus) not sure about over there but with engine machinist and even other odd jobs like car super chargers and transmissions, today’s generation are very limited and I always find that the best guys are from word of mouth and it just seems like it’s just an old bloke that’s semi-retired working in his shed full of 1970's machine gear and has been doing it since he was born. it’s hard to find people with experience and knowledge hey. most shops are just people bolting go fast parts off eBay and want to sit there car on a dyno and say look at me.

 

[Sportster-2001-951C-Stock]

Yeah, not so different here! Necessity remains the mother of invention as always, it helps to have been around the block a few times.

 

[Sportster-2001-951C-Stock]

Here's a dude who does custom work like that but only on rare$$$ and museum type restorations, for some of the outrageously exotic/nutty tractor collector and restorers around here, like maybe Smithsonian annexed stuff too?

http://www.georgemillermachine.com/

I noticed you said the journal was being welded, I dunno about that surviving but interesting.

 

[Steven Mace]

The case being welded not the crank sorry. Just spraying some alloy on it to machine back to standard size. Deck both case sides and bobs our uncle I'm hoping. It's only got to clamp a bearing true and square

 

[Steven Mace]

I'll put up some pics when I get it back

 

[Sportster-2001-951C-Stock]

Cool, that's what that over guy does too, he spray welds and can add metal to block saddles.

I'm interested in how it works out, hopefully a pleasant surprise.