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Interesting video on cylinder head straightening vs flattening/milling. #5341194 02/04/20 07:11 PM
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celicaxx Offline OP
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So, this is a longer sort of vlog video. About 8 minutes in, the man at the machine shop starts talking and that's the important part. The machine shop owner claims heads should not just be resurfaced, but if the head warped, it needs to be essentially heated back up, and he basically torques it down in a specific pattern to straighten the head out. He says if you just mill a head flat, that the bind inherent in the head causes the cam to run offset to the original journals, and grind the journals down, and causes failures like broken cams, snapped timing gears, etc. He even goes as far to say that you should not even mill a head flat unless you straighten the head first, and it's better to just throw a new gasket on unless you want to go through the straightening process. He also showed based on the amount of carbon (I think) that compression was higher on certain cylinders than others due to the inherent bind in the head.

Interestingly, too, he likes that she ran Valvoline VR1, and said her head being in the condition it is was a good advertisement for how good it is.

Any thoughts on his theories? It's honestly something I've never heard before, and "conventional wisdom" is to always mill down your heads when changing head gaskets.

Last edited by celicaxx; 02/04/20 07:11 PM.
Re: Interesting video on cylinder head straightening vs flattening/milling. [Re: celicaxx] #5341253 02/04/20 07:55 PM
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MParr Offline
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This guy is correct. I used to worked for a company that made head straightening machines. It was basically a propane or natural gas fired oven with racks and frames to allow the head to be torqued down on. I worked for the company in the early 1980s and we made several different types of automotive machine shop equipment. The company morphed into producing performance parts for racing go-carts and 1/4 scale drag carts.


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Re: Interesting video on cylinder head straightening vs flattening/milling. [Re: celicaxx] #5341294 02/04/20 08:41 PM
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P10crew Offline
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Straightening heads is common when there is a cam running in it.
Cam bore alignment is not checked with a straight edge it’s checked with a straight bar. His straight edge has been abused bad! Straight edges are to be stored in the vertical position hanging from the eye. I didn’t notice any scuffed paint around the eye. Heads twist as they move around. How did he check that with out a bar? Way back in the late 70’s the shop I worked at used a granite surface plate to check heads for twists and warping. The granite surface plate is also the ONLY way to check your straight edge and must be done occasionally. Based on all the dings in that straight edge im guessing it never gets checked.

Re: Interesting video on cylinder head straightening vs flattening/milling. [Re: celicaxx] #5341318 02/04/20 09:06 PM
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MrQuackers Online Content
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Faye <3


Master the 1000 yard stare

coffeeMobil 1 USA
Re: Interesting video on cylinder head straightening vs flattening/milling. [Re: celicaxx] #5341432 02/04/20 11:33 PM
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oldhp Offline
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Old school experience here. I hope this knowledge is passed on.


"None of us are getting out here alive.....drink that beer.....eat that pizza......drive that Hot Rod"
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Re: Interesting video on cylinder head straightening vs flattening/milling. [Re: MrQuackers] #5341497 02/05/20 04:17 AM
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Linctex Offline
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Originally Posted by MrQuackers
Faye <3


Yeah, not bad at all.

It's cool to see an attractive girl actually CARE about her car.....


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Re: Interesting video on cylinder head straightening vs flattening/milling. [Re: Linctex] #5341568 02/05/20 06:56 AM
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Originally Posted by Linctex
Originally Posted by MrQuackers
Faye <3


Yeah, not bad at all.

It's cool to see an attractive girl actually CARE about her car.....


She is in the new season of "All girls garage"

Re: Interesting video on cylinder head straightening vs flattening/milling. [Re: celicaxx] #5341651 02/05/20 09:09 AM
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Sounds logical. Fine straight edges are precision instruments like this:

https://www.amazon.com/Mitutoyo-528-103-Knife-Straight-Protective/dp/B003VM7XQ8


A granite plate loses accuracy very quickly if objects are slid on them. I worked in crystal optics and I would have to grind and polish the smaller granite plates to recover their accuracy. They were checked with interference using optical flats or interferometers.

Even a finely zeroed quality milling machine does not produce a really flat surface, but probably is good enough to be used on a car.

It seems like the camshaft could be used as a test bar assuming it also wasn't bent. We see the ingenuity of the old school cam in block.

Re: Interesting video on cylinder head straightening vs flattening/milling. [Re: celicaxx] #5341855 02/05/20 12:49 PM
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P10crew Offline
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^ agreed!
I was still in high school when I worked in this machine shop and on day 1 you got the low down on not using any of the machinist tools and a big schooling on the pristine granite plates. Im sure much is different now but I guess there is only so many different ways to check things like this.

Re: Interesting video on cylinder head straightening vs flattening/milling. [Re: celicaxx] #5344758 02/08/20 04:16 PM
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celicaxx Offline OP
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So she posted some sequels. In this video he shows his more mild straightening method using a press and a torch. It's very interesting.

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