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Crankshaft polishing? (update, machine work costs)

casadejohnson

Bronco Alchemist
Joined
Jan 21, 2005
Messages
3,587
I currently have my 200 six Block at the machine shop to be bored. I had planned on totally disassembling it before dropping it off complete with crank, cam and pistons. The shop said they would pull it apart for me and let me know how much I would have to bore it. They mentioned that they would also let me know if the crank needed to be polished. I'm no engine building expert so enlighten me on what polishing the crank does for me. I have assembled several engines in my time and have never had any work done on the crank but none of the engines have been in service as long as this one (Engine is out of a 68 Mustang). I know polishing is common on newer engines and high performance / racing engines due to the tight tolerances but is this something I need to worry about on my daily driver?
 
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73azbronco

Contributor
Bronco Guru
Joined
Nov 11, 2007
Messages
7,796
more polish, less friction. of course, it needs to be the proper size/clearance. Did he use the term grind or turned?
 

JGbronc

Bronco Maniac
Joined
Mar 30, 2007
Messages
6,211
You would probably be okay without it, but it wouldn't hurt to go ahead and have it done. You don't need a bur or scratch or anything to hurt the contact to your rod bearings or main bearings. Unlikely to be a big deal, but it wouldn't be a bad idea just to be safe.
 
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casadejohnson

casadejohnson

Bronco Alchemist
Joined
Jan 21, 2005
Messages
3,587
more polish, less friction. of course, it needs to be the proper size/clearance. Did he use the term grind or turned?

They have not recommended anything yet, They were just cleaning it up and disassembling it today. He just mentioned that the crank may need to be polished or possibly need to grind it. This was before they looked at it, I think he was just saying it was a possibility. I'm mostly curious as to how far I need to go with this for a daily driver. I had the head done a couple months ago by the same shop. We put in all new valves, added hardened seats, and milled it down 60 thousandths.
 

ken75ranger

Bronco Guru
Joined
Jan 27, 2002
Messages
5,069
Loc.
Troy, NY
If your old bearings were very warn it will leave a spot on the crank. Many time polishing is enough so the new bearings have a good surface to run on. If it's very bad wear then they would have to turn the crank.
 

7elk

Sr. Member
Joined
Feb 13, 2006
Messages
369
Loc.
Albuquerque
The enginges that I have done recently, I have had the crank ground 10 thousandths. This gets all burrs and slightly uneven spots for smoother operation and longer life. Just my opinion, it's already apart, why not do it right?
 

needabronco

Bronco Guru
Joined
Jul 2, 2004
Messages
6,411
Loc.
Prescott/Farmington
It is my understanding that the quality of the steel that Ford used on their crankshafts was very good, and from what I've been told about 90% of the time the crankshaft journals only need to be polished. If there's too much wear then they will grind it .10" over. Polishing gives the new bearings a smooth hard surface to ride on, so it's a good thing and costs less than grinding... Ask them to chamfer the oil holes before they do it, my guess is they'll do it anyway but you never know.

I would have it polished. It should only be around $50-60 or so, versus over $100 to regrind and polish.
 

blubuckaroo

Grease Monkey
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Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
You'll need to mic the journals to see if they are round. If you don't see lines or waves in the journal lots of guys just polish it with a strip of 500-600 grit emery cloth to give it some tooth for the oil to hang on durring break-in. If that's all it needs you can do it at home. If you see lines or unevenness of any degree, get it reground. That only costs about $65 around here.
 

ft bronc

Jr. Member
Joined
Feb 25, 2008
Messages
143
Loc.
Greater Cincinnati
Can't tell anything without measuring the rod & main journals with a micrometer. The shop should be able to determine how much wear it has, and then grind to 0.10 under if necessary. You're replacing the bearings either way, so if you're planning on keeping the motor for any length of time, don't hesitate to have it ground.
 
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casadejohnson

casadejohnson

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Jan 21, 2005
Messages
3,587
This is why I ask. I don't mind paying to have the job done right, I just needed a little schooling on the matter. I did not talk to them today so I don't know the condition yet but at least now I know what I'm talking about when they tell me what it needs. The machine shop is about a block from work so once I hear back from them I'll stop in and have them show me the condition of the crank before I have them do any work. I plan on keeping this engine and the Bronco as my daily driver so I want it to last. With any luck, I'll know more on Monday.
 
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casadejohnson

casadejohnson

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Jan 21, 2005
Messages
3,587
Looking for Machining recomendations.

Ok talked to the machine shop.

The crank is out of spec and they recommend grinding it. I think its $120 to grind it. Is that reasonable? I'm a little disappointed in the quote I got but maybe I had my hopes too high. I'm looking at around $1100 out the door on a complete rebuild of the short block. Including the Magnafluxing and cleaning ( Blocks good), bore and hone 30 over,grind crank, recondition rods (?), R&R pistons and rods, install cam bearings,install freeze plugs, R&R cam gear, Assemble short block, also includes the complete rebuild kit with new pistons,cam,gasket set and new timing set.

I was thinking I was going to come in closer to $800. Am I out of line or is this a good price?

The shop already did my head work a couple months agoand it cost me about $300. All new valves, hardened seats , milling the head etc.
 

gearida

Bronco Guru
Joined
Jun 8, 2007
Messages
1,428
Loc.
Newburgh, IN
Including assembly, wow I think that is a great price. I paid $1,800 several years ago for boring, pistons, crank work. Then had to take it somewhere else to fix that work. But that is another story...
 

VT_Don

Sr. Member
Joined
Aug 16, 2001
Messages
365
You don't even want to know what I spent having my side oiler freshened.
 

bmc69

Contributor
Bronco Guru
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Jun 11, 2004
Messages
11,852
Excelent pries and good call on what work should be done.

Reconditioning rods,btw, is the rather tedious process whereby the caps and rods are ground slightly at the bolt interface and then re-sized back to original spec. Used rods are typically 'oval' somewhat due to stretching/stress over time.
 
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casadejohnson

casadejohnson

Bronco Alchemist
Joined
Jan 21, 2005
Messages
3,587
OK, I'm feeling a little better about this. I'm still not excited about breaking the news to the wife about going over $1000. She gets testy when the projects get a forth digit in the price. I did look at the options again and Its actually a closer to $1200 than $1100. I could also spend about another $100 if I went with another engine kit available but they seem to think this ine is just as good. I believe the only difference was the brand of gaskets and bearings. Shop guy said they were good brands in both sets and reccomends the less expensive kit. The good news is, They are willing to do the work and let me pick it up when funds allow. He went so far as to say that it would be fine if I waited several months to pick it up. They showed me another ford straight six they built that they are hanging onto for a guy who lost his job ( Nine Months ago). The shop has a good reputation and the guys seem very nice but its still a pretty good chunk of change!
 

phred

Contributor
Bronco Guru
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Aug 25, 2006
Messages
3,432
Loc.
Earth
good advice and good price. Just got one back and the prices you are getting are in line with what I paid.
 

ryoungbronco

Bronco Guru
Joined
Jul 4, 2007
Messages
1,748
Loc.
Belmar, NJ
Ok talked to the machine shop.

The crank is out of spec and they recommend grinding it. I think its $120 to grind it. Is that reasonable? I'm a little disappointed in the quote I got but maybe I had my hopes too high. I'm looking at around $1100 out the door on a complete rebuild of the short block. Including the Magnafluxing and cleaning ( Blocks good), bore and hone 30 over,grind crank, recondition rods (?), R&R pistons and rods, install cam bearings,install freeze plugs, R&R cam gear, Assemble short block, also includes the complete rebuild kit with new pistons,cam,gasket set and new timing set.

I was thinking I was going to come in closer to $800. Am I out of line or is this a good price?

The shop already did my head work a couple months agoand it cost me about $300. All new valves, hardened seats , milling the head etc.

That sounds about right. I also have my engine, a 351w, at the machinist. The block was stripped down to just the crank, rods, and pistons. I am getting less done than you and I'm figuring $1500 with forged pistons. $1100-1200 sounds like a fair price if you are able to drive the truck home.
 

needabronco

Bronco Guru
Joined
Jul 2, 2004
Messages
6,411
Loc.
Prescott/Farmington
That sounds reasonable. Just wondering, did they offer a reman. crank as an option to grinding yours? If you need to shave a few hundred off, you could always assemble the short block yourself. There's really not much to it, and could reasonably be done on a Saturday. I would have the shop fit your rings, and everything else can be done with hand tools and a torque wrench.

Do you know what pistons they are using? I would recommend the hyperutectic pistons with moly rings for a daily driver. Also stay with a standard volume oil pump, there's no need on a sbf to use a high volume pump...
 
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