Engine machine shop destroyed my block

General engine tech -- Drag Racing to Circle Track

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B Original
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Re: Engine machine shop destroyed my block

Post by B Original » Sun May 13, 2018 9:30 pm

MadBill wrote:
Sun May 13, 2018 9:25 pm
B Original wrote:
Sun May 13, 2018 9:18 pm
MadBill wrote:
Sun May 13, 2018 8:48 pm

The heat expansion can be more accurately calculated than measured. The coefficient of thermal expansion for cast iron is 6 ppm, so say a 4.000" bore heated from 70°F. to 200° would expand by (6 x 4 x 130)/1,000,000, or 0.00312".
although your calculation is spot-on what about the thermal expansion of the aluminum piston somewhere between 10 and 13 parts per million per degree Fahrenheit?

By the way my memory does fail me sometimes but I just don't remember posting this?
Sorry about that, in trimming the original, I snipped John@RED out ( his post is a few above), leaving you as the apparent author. :oops:

And yes, an all-aluminum piston will expand at about twice the rate of the bore, but that's really a separate issue.
It's all good bill you're definitely a friend and not a foe LoL

And yes I understand it's a separate issue about the Machining but I was putting it into context of calculating the clearance between the two

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Re: Engine machine shop destroyed my block

Post by superpursuit » Sun May 13, 2018 10:49 pm

Basically you can't measure the bore sizes correctly unless you re-install the torque plate. You could fit the head with the head gasket, studs with proper lube and torqued to spec and fit the mains and torque and then measure from underneath to get a bore size. This may give you some idea but it still does not allow for the hot honing. The expansion rates of this cannot really be calculated either as different parts of the block will have different structure, density and variations in thickness which will all affect the expansion rate. I would be very surprised if a shop, that is so fastidious with their process [hot honing], would give you a crude backyarder result. Any shop that sets themselves up to do hot honing is obviously looking for that last bit of perfection so it does not make sense that they would leave it at .0015" oversize. I hope this helps.

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Re: Engine machine shop destroyed my block

Post by Warp Speed » Mon May 14, 2018 5:53 am

Kind of off subject, but relative. How do.you measure a 200* cylinder wall with any accuracy?
That was the big problem we faced back in the hot honing craze days! Lol
Not saying there might not be something to it, but the challenges are real foe sure.

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Re: Engine machine shop destroyed my block

Post by Warp Speed » Mon May 14, 2018 5:56 am

Warp Speed wrote:
Mon May 14, 2018 5:53 am
Kind of off subject, but relative. How do.you measure a 200* cylinder wall with any accuracy?
That was the big problem we faced back in the hot honing craze days! Lol
Not saying there might not be something to it, but the challenges are real for sure.

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Re: Engine machine shop destroyed my block

Post by gmrocket » Mon May 14, 2018 6:57 am

Was it actually hot honed as in sealed with heated liquid circulating through it or just the tq plate?

On that small of a bore it's more critical to be on the money than if its a larger bore , like in the 4.250" range.. being .001" over spec you can get away with

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Re: Engine machine shop destroyed my block

Post by gunt » Mon May 14, 2018 7:11 am

I'M probably wrong or missed it

is the clearance not different for hot v cold hone as in heated water in the water jacket , and therefore the clearance given on the box would be for the average machinist who is doing it for the average punter on cold hone and this too is a factor ,

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Re: Engine machine shop destroyed my block

Post by Warp Speed » Mon May 14, 2018 7:17 am

.....

Warp Speed
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Re: Engine machine shop destroyed my block

Post by Warp Speed » Mon May 14, 2018 7:18 am

.....

Warp Speed
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Re: Engine machine shop destroyed my block

Post by Warp Speed » Mon May 14, 2018 7:19 am

Sorry, damn phone! Lol

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Re: Engine machine shop destroyed my block

Post by Headguy » Mon May 14, 2018 7:24 am

Warp Speed wrote:
Mon May 14, 2018 7:19 am
Sorry, damn phone! Lol
Sure.....

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Re: Engine machine shop destroyed my block

Post by Warp Speed » Mon May 14, 2018 7:33 am

Headguy wrote:
Mon May 14, 2018 7:24 am
Warp Speed wrote:
Mon May 14, 2018 7:19 am
Sorry, damn phone! Lol
Sure.....
Maybe the tard operating it too...........! Hahaha

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Re: Engine machine shop destroyed my block

Post by MotionMachine » Mon May 14, 2018 8:24 am

I always question someone setting their Mitutoyo or other bore gages with a mic. It's completely operator sensitive for one and how accurate is that mic? If the thread adjustment is loose (mic has backlash), it may measure right on with a standard as the backlash is taken out when the standard is snug between the spindle and the anvil. But if it's just screwed out to 4.280" and locked, is it exactly to size with backlash not removed?

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Re: Engine machine shop destroyed my block

Post by 1972ho » Mon May 14, 2018 9:58 am

Now you all have me really curious as to bore clearances, will a bore that is .0004 or .0007 really cause an engine any real hp problems or sealing and wear problems.

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Re: Engine machine shop destroyed my block

Post by Walter R. Malik » Mon May 14, 2018 10:57 am

JodyB wrote:
Sun May 13, 2018 7:21 pm
Put the tighter pistons close to the water pump, loose ones farthest away. Run it.
That is backwards ... a colder running cylinder wall will want more initial clearance.
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Re: Engine machine shop destroyed my block

Post by gmrocket » Mon May 14, 2018 5:01 pm

MotionMachine wrote:
Mon May 14, 2018 8:24 am
I always question someone setting their Mitutoyo or other bore gages with a mic. It's completely operator sensitive for one and how accurate is that mic? If the thread adjustment is loose (mic has backlash), it may measure right on with a standard as the backlash is taken out when the standard is snug between the spindle and the anvil. But if it's just screwed out to 4.280" and locked, is it exactly to size with backlash not removed?
That's why you torque it against your finger and use a mic stand

crazy but I was told this when I was a student at 14 when I worked in a machine shop...in the 70's
Last edited by gmrocket on Mon May 14, 2018 5:29 pm, edited 2 times in total.

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