30/30 crank
Thread Starter
Ben
Joined: Mar 2009
Posts: 1,851
From: Snohomish, WA
30/30 crank
So i'm irritated...
I Finnaly (after 2+ months) got my crank back from the machine shop, and having it drilled for the pilot bearing.
$115 for the grind & polish, $100 for drilling the bearing.
Problem. When i bought this stuff from them (this was an engine/crank/pistoins set that had been left & not paid for at the shop) it was advertised and verbally told to me as a crank needing 10/10 grind & polish.
Now picking it up I see 30/30 writtin on it in grease pen.
The machinist assured me it would be ok... but GRRR...
Is this going to be an issue? I don't want it to be more suseptable to spinning bearings because of the grind.
This will not be a race motor, but i do plan to thrash on it, and wind it up to 5k-5500 more than occasionally.
If this is going to be a problem, i think i will contest it with my credit card. I think i have a copy of the original craigslist ad stating it needed 10/10 grind.
I certainly would not have spent another $215+tax having it ground & bored for the pilot bearing if i had known it had already been ground that much... i would have found a better crank first.
Arg.
I Finnaly (after 2+ months) got my crank back from the machine shop, and having it drilled for the pilot bearing.
$115 for the grind & polish, $100 for drilling the bearing.
Problem. When i bought this stuff from them (this was an engine/crank/pistoins set that had been left & not paid for at the shop) it was advertised and verbally told to me as a crank needing 10/10 grind & polish.
Now picking it up I see 30/30 writtin on it in grease pen.
The machinist assured me it would be ok... but GRRR...
Is this going to be an issue? I don't want it to be more suseptable to spinning bearings because of the grind.
This will not be a race motor, but i do plan to thrash on it, and wind it up to 5k-5500 more than occasionally.
If this is going to be a problem, i think i will contest it with my credit card. I think i have a copy of the original craigslist ad stating it needed 10/10 grind.
I certainly would not have spent another $215+tax having it ground & bored for the pilot bearing if i had known it had already been ground that much... i would have found a better crank first.
Arg.
Registered User
Joined: Oct 2005
Posts: 7,304
From: NJ
Is this a BB or SB crank, not that it really matters. I would be Po-ed as I hate when things get turned around (lied). While a 30/30 crank is not the best I would say its ok. I have not heard of repeat or rash failures of cranks that were 30 under. If it were a race engine I would not use it. My opinion only and preferance.
Registered User
Joined: Nov 2008
Posts: 8,477
From: Central Fl
It's not only the crank thats the issue it's the bearing shell composition. How thick is the steel backing on a .010 .020 .030 bearing? According to Clevite they use 2 different shells, 1 for std and .010 and another for .020 and .030 and .040. You're probably o.k. with the .030, but make sure your clearances are right.
Thread Starter
Ben
Joined: Mar 2009
Posts: 1,851
From: Snohomish, WA
Now that i'm home and i have the copy of the original ad in hand stating:
I will have a conversation with the shop owner/machinist on thursday when i go back down for my crank keyway (they called me shortly after i left saying i forgot it).
I think they owe me some money. Either they lied in their original for sale ad, or someone swapped & stole my crank.
I should have known better and measured the crank when i first bought it (along with my other 1st instinct to not leave it at that shop)... had it been an individual instead of a machine shop i would have taken a caliper with me...
Sigh. At least i have it back and can move on with the rest of the build.
...crank is standard will go 10/10
I think they owe me some money. Either they lied in their original for sale ad, or someone swapped & stole my crank.
I should have known better and measured the crank when i first bought it (along with my other 1st instinct to not leave it at that shop)... had it been an individual instead of a machine shop i would have taken a caliper with me...
Sigh. At least i have it back and can move on with the rest of the build.
Last edited by RAMBOW; Mar 8, 2011 at 10:35 PM.
Registered User
Joined: Mar 2009
Posts: 544
From: Princeton Minn.
I wouldn't think it would be a strength issue because many other engine builds turn the cranks down to use big block Ch3vy rods or even H0nda rods but possibly the thicker bearings are not quite as stable
Registered User
Joined: Oct 2009
Posts: 3,814
From: Erie,PA
I had a 455 crank that needed the rod journals machined to .040 to get it right,and at the time you could get .040 rod bearings,so I did it.That engine consists of reconditioned stock rods with ARP bolts,and Pontiac 400 pistons.It was just something I tried,and it was for a street-driven car.Needless to say,it has been running fine for a little over 10 years now,and the owner is not gentle with it.
The 30/30 will be fine.You can take an educated guess at how much needs to be ground off a crank,to make it right,but you don't know for sure until it's done.The difference from .010 to .030 I'd say wasn;t a very good guess,or they didn't look at it too well,OR it already had a previous grind,making it undersized to start with.That is why you don't order pistons or rings UNTIL the machinework is done.
The 30/30 will be fine.You can take an educated guess at how much needs to be ground off a crank,to make it right,but you don't know for sure until it's done.The difference from .010 to .030 I'd say wasn;t a very good guess,or they didn't look at it too well,OR it already had a previous grind,making it undersized to start with.That is why you don't order pistons or rings UNTIL the machinework is done.
Thread Starter
Ben
Joined: Mar 2009
Posts: 1,851
From: Snohomish, WA
had a long phone conversation with the shops owner... He was very cool about it and very appologetic (as he should have been). Did a bunch of digging through paperwork with me on the phone, and figured out where the problem was...
Originally all this stuff came in as 2 motors, one complete with a bent rod, and another used but matched & balanced set of rods/pistons & crank.
The crank in the block was standard/standard- the 2nd crank was unknown, not measured.
Apparently around 2004, they sold the standard/standard crank, the rest sat until i bought it this year.
Because they had not previously mic'd this crank, he mistook it for the standard/standard one when he wrote the ad.
Anyway- long story short (too late)- he basically asked me what i was looking for to make it right- would take the crank back and refund all those charges, or?
I asked him to refund the $100 spend on drilling the pilot bearing (as i would have looked for a better crank before doing that work on an already 20/20 crank). he was totally cool with that & credited it back to my credit card.
So, thumbsup to them for doing the right thing and being cool about the mistake.
Originally all this stuff came in as 2 motors, one complete with a bent rod, and another used but matched & balanced set of rods/pistons & crank.
The crank in the block was standard/standard- the 2nd crank was unknown, not measured.
Apparently around 2004, they sold the standard/standard crank, the rest sat until i bought it this year.
Because they had not previously mic'd this crank, he mistook it for the standard/standard one when he wrote the ad.
Anyway- long story short (too late)- he basically asked me what i was looking for to make it right- would take the crank back and refund all those charges, or?
I asked him to refund the $100 spend on drilling the pilot bearing (as i would have looked for a better crank before doing that work on an already 20/20 crank). he was totally cool with that & credited it back to my credit card.
So, thumbsup to them for doing the right thing and being cool about the mistake.
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