Engine machine shop destroyed my block

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gmrocket
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Re: Engine machine shop destroyed my block

Post by gmrocket » Mon May 07, 2018 10:44 pm

John@RED wrote:
Mon May 07, 2018 3:09 pm
tjz450 wrote:
Mon May 07, 2018 2:17 pm
I took the OP's post as total sarcasm, to bait and spool up the membership. May have worked.
Ah ah, sorry guys for the zero more there.... #-o
I obviously was talking about .0008 - .0015 more than what I asked.
I know it could seem not to be a lot, but in this little engine suggested piston to wall is .0032, so .0015 is about a 50% too much.

As someone wrote in the first page, I was just told by them that heated by the coolant during machining the clearance was ok, and they too see that back to ambient temp the clearance was the same i got:
I know that this may happen in some blocks, but thought .0015 to be too much
sounds like they are bs'ng you..it would be the opposite of that happening. when it cooled down the bores would get smaller.

being too aggressive with stone load etc can overheat everything and give a false plus reading when checking compared to room temp.

some piston skirt coatings can add what you need.

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Re: Engine machine shop destroyed my block

Post by MadBill » Mon May 07, 2018 11:02 pm

Line2line was my choice for same...
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Re: Engine machine shop destroyed my block

Post by John@RED » Tue May 08, 2018 7:47 am

modok wrote:
Mon May 07, 2018 8:44 pm
Just in case, you didn't mention....
Was a torque plate used?
Are the skirts coated?
And have you checked the actual clearance comparing skirts to block bore.... or just bore size?

Pistons are getting really good, but I still like to check each one just to be sure.

I;ll assume at worst there could be .0005 difference in measuring due to being a different hand using different measuring equipment, and on a "home gamer" level that could be twice as much. Nothing personal, but it would not be the first time at all.

If the cylinders were heated....they would be larger. They are blowing smoke. But did you buy that? :)

Giving more info:
a torque plate was used during hot honing.
My digital micrometer correctly reads what manufacturer claims on the spec sheet (3.3925), so my digital bore gauge should really see .0032 more in the bores.
And yes, I was too thinking that they should be larger when heated!
I'm going to get there and see when heated then

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Re: Engine machine shop destroyed my block

Post by Dave Koehler » Tue May 08, 2018 8:36 am

Are you taking your readings near the top where torque plate / no torque plate will make a difference?
Might try measuring low in the cylinder.

Are both parties measuring the piston skirt in the same location?

I will assume that you have some kind of master gauge you set the bore gauge with.
Might take your digital mic and use it on the bore gauge to see if they agree.

Were the pistons soaked in the same heated oil?

If this is a race engine will the extra clearance hurt performance? Doubtful.
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Re: Engine machine shop destroyed my block

Post by engineguyBill » Tue May 08, 2018 12:53 pm

Dave Koehler wrote:
Tue May 08, 2018 8:36 am

Are both parties measuring the piston skirt in the same location?

Excellent point. Piston manufacturers determine the location at which piston diameter is to be measured and the measurements must be taken at this exact location in order to be correct. Just another of the many important details to be considered when dealing with performance engines . . . . .
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Re: Engine machine shop destroyed my block

Post by modok » Tue May 08, 2018 2:53 pm

Since a torque plate was used, the cylinders will not be true without the plate. Right?

Although the HOT honing was a red herring..... It is HIGHLY likely that the top and the main thrust area of the cylinder will actually measure smaller with the torque plate in place. Especially if the head bolts are not directly attached to the cylinder itself, torquing the bolts will COMPRESS the cylinder and make the top half smaller.

If I was asked to measure this for clearance without the plate on it, I would measure the diameter of the cylinders around the bottom third of the bore and call that the diameter. NOW what is the clearance?
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Re: Engine machine shop destroyed my block

Post by Bossman » Sat May 12, 2018 10:30 pm

What did you measure that with you canbarley read that on a bore gage if your that particular i suggest you spend $150,000 by yourself a Rottler CNC machine and do it yourself

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Re: Engine machine shop destroyed my block

Post by Keith Morganstein » Sun May 13, 2018 6:46 pm

When I saw this title, at first I thought it was “Engine machine shop destroyed my back

I was like, oh yeah, my back, my shoulders, my hands, my knees, my hearing...
Automotive Machining, cylinder head rebuilding, engine building. Old school shop, semi-retired moonlighter. Can't seem to quit #-o

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Re: Engine machine shop destroyed my block

Post by JodyB » Sun May 13, 2018 7:21 pm

Put the tighter pistons close to the water pump, loose ones farthest away. Run it.

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Re: Engine machine shop destroyed my block

Post by Dave Koehler » Sun May 13, 2018 7:36 pm

Keith Morganstein wrote:
Sun May 13, 2018 6:46 pm
When I saw this title, at first I thought it was “Engine machine shop destroyed my back

I was like, oh yeah, my back, my shoulders, my hands, my knees, my hearing...
True Dat!
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http://www.koehlerinjection.com
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Re: Engine machine shop destroyed my block

Post by B Original » Sun May 13, 2018 8:09 pm

Instead of suggested piston to wall clearance shouldn't .0032 be the minimal piston to wall clearance with a tolerance of up to.005 +-? It's not perfect maybe even a tad sloppy from some machine shop standards but depending on your RPM range if it's not a terribly high performance Engine I'd run with it

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Re: Engine machine shop destroyed my block

Post by B Original » Sun May 13, 2018 8:18 pm

John@RED wrote:
Tue May 08, 2018 7:47 am
modok wrote:
Mon May 07, 2018 8:44 pm
Just in case, you didn't mention....
Was a torque plate used?
Are the skirts coated?
And have you checked the actual clearance comparing skirts to block bore.... or just bore size?

Pistons are getting really good, but I still like to check each one just to be sure.

I;ll assume at worst there could be .0005 difference in measuring due to being a different hand using different measuring equipment, and on a "home gamer" level that could be twice as much. Nothing personal, but it would not be the first time at all.

If the cylinders were heated....they would be larger. They are blowing smoke. But did you buy that? :)

Giving more info:
a torque plate was used during hot honing.
My digital micrometer correctly reads what manufacturer claims on the spec sheet (3.3925), so my digital bore gauge should really see .0032 more in the bores.
And yes, I was too thinking that they should be larger when heated!
I'm going to get there and see when heated then
This may be a silly question but just making sure did you calibrate your bore gauge with a mic that you measure the Piston with to make sure it was on zero before you measure the bore or are you just using the digital readouts of each to give you the sum of the differences
Without calibrating the two measuring instruments to each other?

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Re: Engine machine shop destroyed my block

Post by MadBill » Sun May 13, 2018 8:48 pm

B Original wrote:
Sun May 13, 2018 8:18 pm
...
And yes, I was too thinking that they should be larger when heated!
I'm going to get there and see when heated then
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".
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Re: Engine machine shop destroyed my block

Post by B Original » Sun May 13, 2018 9:18 pm

MadBill wrote:
Sun May 13, 2018 8:48 pm
B Original wrote:
Sun May 13, 2018 8:18 pm
...
And yes, I was too thinking that they should be larger when heated!
I'm going to get there and see when heated then
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? Approximately twice rate of expansion as the iron

By the way my memory does fail me sometimes but I just don't remember posting this?
Last edited by B Original on Sun May 13, 2018 9:27 pm, edited 1 time in total.

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Re: Engine machine shop destroyed my block

Post by MadBill » 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
B Original wrote:
Sun May 13, 2018 8:18 pm
...
And yes, I was too thinking that they should be larger when heated!
I'm going to get there and see when heated then
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.
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

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