Up the creek without a crank

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70spider
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Up the creek without a crank

Post by 70spider »

Well I took the block and crank into the machinist yesterday. He took some preliminary measurements and the main journals were right at the lower limit, 1.9990 in. The connecting rod journals were within spec. He said he wouldn't be able to work on it for a couple of weeks but I am a bit worried. Also I didn't do very good job on storing the crank after removing it and the journals rusted a little, who knew. I cleaned the rust with some WD-40 and fine scotch pad, but there was some small pitting on a few of the journals, the machinist didn't like this. So as it stands right now my crank is in bad shape. I am debating on jumping the gun and getting a 1608 crank from Midwest-Bayless while they have one. If the worst happens and the crank needs to have the main journals cut, is running oversized bearings a detriment to the motor? This project is going to kill me :D , but I'm loving every minute of it :wink:
1970 Fiat Spider 124 Sport aka "Pesto"
2002 Mazda Protege5
2013 Buddy 170i
So Cal Mark

Re: Up the creek without a crank

Post by So Cal Mark »

we've used up to 030 over bearings with cut cranks without any issues
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70spider
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Re: Up the creek without a crank

Post by 70spider »

Thanks Mark, when he calls to let me know what he found I'll let him know it is ok to cut it, but during the initial meeting he didn't seem keen on the idea.
1970 Fiat Spider 124 Sport aka "Pesto"
2002 Mazda Protege5
2013 Buddy 170i
So Cal Mark

Re: Up the creek without a crank

Post by So Cal Mark »

as a last resort you can send your crank to me and I'll get it done and supply bearings
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RRoller123
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Re: Up the creek without a crank

Post by RRoller123 »

A related question: I was advised that after removal, the crank should be held during storage in some sort of a supporting frame, like a plywood box, or similar, that supports it evenly across its length at regular intervals? I know nothing about any of this of course, but it surprises me that the crank, being such a large heavy piece, would be subject to movement?
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focodave
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Re: Up the creek without a crank

Post by focodave »

Hey 70spider,

Your original question has been the topic of some previously "spirited" debates on the forum.
I was tortured by the thought of running a crank that was ground, after reading some of the opinions I've seen here.
But after many sleepless nights, I decided to give it a try.
I am running a fuel injected, 2-litre with both mains and rods ground to .030 under. My engine is bored .8mm over and runs 10.2-to-1 compression pistons.
I've been running this engine for about 2 1/2 years, with about 6000 miles on it now.
Runs great, holds perfect oil pressure, smooth and quiet as can be.
Mine is strictly street-driven and never sees over 4500 RPM.
I think all of the negative comments on grinding cranks comes from folks who are either racing their cars or driving their street cars like race cars, pushing the limits of everything mechanical.
My opinion -- as long as your machinist does quality work, thoroughly cleans the internals of the crank when done, etc, I would go for it and not lose any sleep over it.
1980 Spider 2000 F.I. (my hobby)
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70spider
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Re: Up the creek without a crank

Post by 70spider »

as a last resort you can send your crank to me and I'll get it done and supply bearings
thanks for the offer it gives me a lot more peace of mind. Could you PM me a price for the service?
10.2-to-1 compression pistons
what octane fuel do you run with those? my pistons are 9.8:1.
1970 Fiat Spider 124 Sport aka "Pesto"
2002 Mazda Protege5
2013 Buddy 170i
djape1977
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Re: Up the creek without a crank

Post by djape1977 »

2 liter cranks are nitride treated, meaning that hardened surface layer is very thin.
when machined down to undersize, they usually last about 10-15k kms

older cranks were heat treated and hard layer is much deaper
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124JOE
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Re: Up the creek without a crank

Post by 124JOE »

Ok so i guess i should pull out my spare block and crank check it for rust and how straight it is
It is a 1592 block and i have no need for it but i keep it around any way
when you do everything correct people arent sure youve done anything at all (futurama)
ul1joe@yahoo.com 124joe@gmail.com
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SP3
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Re: Up the creek without a crank

Post by SP3 »

70spider wrote:Thanks Mark, when he calls to let me know what he found I'll let him know it is ok to cut it, but during the initial meeting he didn't seem keen on the idea.
why would be not be 'keen'? what kind of machine shop is it? this is (still) an every day kind of thing in the automotive world not some super-exotic process. odd. or, am I missing something?
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SP3
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Re: Up the creek without a crank

Post by SP3 »

djape1977 wrote:2 liter cranks are nitride treated, meaning that hardened surface layer is very thin.
when machined down to undersize, they usually last about 10-15k kms

older cranks were heat treated and hard layer is much deaper
I think this just answered the question of whether I am missing anything. However, there are plenty of shops that can nitride so this still ought not be a huge issue.
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70spider
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Re: Up the creek without a crank

Post by 70spider »

why would be not be 'keen'?
Maybe I over stated it, he was concerned about the mains and the pitting left behind by the rust. I have no doubt he will do the work that is necessary. This is the first time I have ever used a machine shop so my mood is that of a new father in the waiting room :lol:
1970 Fiat Spider 124 Sport aka "Pesto"
2002 Mazda Protege5
2013 Buddy 170i
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joelittel
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Re: Up the creek without a crank

Post by joelittel »

RRoller123 wrote:A related question: I was advised that after removal, the crank should be held during storage in some sort of a supporting frame, like a plywood box, or similar, that supports it evenly across its length at regular intervals? I know nothing about any of this of course, but it surprises me that the crank, being such a large heavy piece, would be subject to movement?
Anyone have any insight on this? I've got a crank to store and I'd like to go about it the correct way.
fiatfactory
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Re: Up the creek without a crank

Post by fiatfactory »

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Last edited by fiatfactory on Tue Jul 02, 2019 12:30 am, edited 1 time in total.
nothing to see here... move along.
djape1977
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Re: Up the creek without a crank

Post by djape1977 »

new fiat cranks came from factory in wooden crates, laid flat, on a soft wood support. box and supports were not precisely made, so my conclusion is that fiat didn't think they could be bent.
crate and supports in it are there to prevent tumbling and impact damage
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