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Discussion Starter · #1 · (Edited)
I am moving onward on my Giulia 2L project and I am starting by getting my crank checked and balanced. I have Jim K's book and I like the idea of putting threaded studs in the plug holes and I will attempt that very carefully.

At first inspection my crank looks pretty good, no scores in the bearing races, and I think it's never been cut but one thing I was wondering about that Jim's book doesn't cover is the dimensions of the bearings. How can i tell whether or not I need to over/under size my bearings? Does anyone have numbers they can provide for the "stock" uncut sizes?

Thanks!
 

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just remember that the crank is hardend and u should use a tap for that spec or probably easier thing is to have a machine shop do it as they do these things all the time for a minimal cost.
 

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Here's some received wisdom from someone (not me) who's built many, many Alfa engines.

His view is that struggling with tapping a nitrided crank isn't really worth the effort.
Instead, remove the almuinum plugs and thoroughly clean the passages in the crank.
Then hammer in new aluminum plugs coated liberally with loctite red or blue. Problem solved.
 

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What shop manual are you using?
 

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Discussion Starter · #6 ·
I have an old hanes manual.

Anyone know what the standard main and standard big end dimensions are for a 2L crank?

It'd be very helpful.
 

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Discussion Starter · #8 ·
Thanks! I looked on the IAP site and didn't look at Centerline. Funny my manual has different specs.
 

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Not always minimal cost; the local race shop that drilled & tapped a crankshaft for me last year had a very hard time, and charged $100. Also, one of the respected West coast engine builders claims the threaded plugs are not necessary if the factory plugs are inserted correctly.

Regarding bearing clearance, be sure to use plastigauge to check clearance once you buy new bearings (as they say; ask me how I know).

just remember that the crank is hardend and u should use a tap for that spec or probably easier thing is to have a machine shop do it as they do these things all the time for a minimal cost.
 

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It's rare to grind a 2000 crank, because they're so durable and don't need it, and because if you grind it you remove the nitriding, as I understand it. If your crank needs work you might be money/durability ahead to find another that retains the nitriding. There are tons of 2000s around.
Andrew
 

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Discussion Starter · #11 ·
Yes, strangely I think my crank has been undersized at some point because they the main bearings seem to be measuring in smaller. I will re-chech tonight with the Centerline numbers. Luckily i have a spare 2L bottom end laying around, perhaps that has a virgin crank inside.

To get things straight an uncut 2L crank should measure between 2.3606 and 2.3611 correct?
 

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That's what the specs on the CL site say. That's for the main bearing; you'll want to measure the rod bearing journals too. Measure them all, not just one.
You can look at the back of the bearing shells; they should have the oversize (010, 020) stamped on it if so.
Andrew
 

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Discussion Starter · #13 ·
So upon closer I found some engravings on the crank that indicate -10 on both the mains and journals, which seems to be what the crank is measuring in at.....now I'm wondering if it was re-nitrided after being cut. It does seem be be because after scratching at the bearing surfaces with a carbide tip, the metal did not scratch at all. Although knowing for sure that has been nitrided might be difficult.
 

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Shouldn't it be pretty certain whether it's stock size or 10 under? .010" relatively speaking is a big distance in crank measurements. Did you look at the back of the bearing shells?
My understanding is all 2000 cranks were nitrided. Papajam or someone more definitive than me may chime in. But I don't think it was just some, I think it was all.
Andrew
 

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Discussion Starter · #15 · (Edited)
Andrew yes I checked bearings and they are over sized accordingly. Now I'd really like to know if my the crank has retained it's nitride coating, one of the engineers at work knows about chemical metal treatments says that nitride hardening penetrates about .003-.005. But I'm going to research this a little further. I also have another crank sitting in a complete 2L engine that I'd have to disassemble, as much as I wanted to avoid splitting yet another engine, I may have to.

 

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all 2l cranks were nitrited. but if your crank was machined 010 , it will remove the nitriting and should be checked and or re done. cleaning and installing the aluminium plugs with red locktite is a good thing, however, they still have a minimal chance of coming out even under the best of cases.
 

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Crank plugs

If you or someone else replaces the original alu plugs with threaded cap bolts may I suggest using pipe type ie tapered bolts plus loctite so that they "bottom out" at the base of the threads. In this way you will have both a mechanical and chemical attachment.
 
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