Why NOT to let your head be Belt Surfaced

[BogusSVO]

Why not to let your head be belt surfaced/sanded


The subject head is a Mitsu 4G63T from an Evo VIII
This head was in very good shape to start.
The head was pulled due to a bottom end problem.
It was not overheated.
It was taken to another shop, NOT mine.
The customer was told it was surfaced .003-.004
It was then run and the bottom end failed, Then came

The first thing I did was to check the thickness of the head.
I know a belt surfaced head will not be parallel nor square along with not having the proper surface finish for a MLS head gasket.




HN# Date
CAST#G6EW NOTES:
IV stock New thickness 5.200
EV stock Min thickness 5.185 (AREA SPEC)
EVO 8

This is the surface finish left by a belt sander

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This is how the surface looked after I milled appox .002

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It did cut most of the surface, but it was still low at one corner, and it would happen to be right around the oil feed port to the head.

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I made another pass of about .002
This is how it looked.

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I made another .002 cut
And was to this

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So one more pass to clean the gasket surface, and proper clamping force will be kept on the head gasket.

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I measured the head again, and it was 5.183 at all 4 corners
When I cc’ed a combustion chamber it was 44cc
I also did “oil port mod #1” before I surfaced the head.
This head is now .002 below AREA min spec, but is still a useable head.

 

[BogusSVO]

Here is another good vid on surfacing a head properly!

Good Video of why you need to resurface your cylinder heads

 

[G-UNIT]

I don't see the vid? What kind of f'ng redneck belt sands a head!?

 

[BogusSVO]

G-unit.. Its a common pratice in alot of machine shops, the equipment is cheap, and easy to use, and fast. Thats why alot of shops use it.

 

[BogusSVO]

A couple of internet pics of belt surfacers

 

[Agent Ezzard]

I think I saw that over on TRF. My ranger head was belt sanded but have since sold the truck to a guy in Ocala.

 

[laserspeeddemon]

Just seems like a sub-par method compared to a milling machine. High end milling machines like the Rottler F65M Machining Center enusre that the head is absolutely square when machining too ensure a 100% flat surface.

 

[BogusSVO]

laser the rottler is a sweet piece of equipment, but the equipment cost is too much for most Local/small shops. I would love to have one, but the $125k+ price tag keeps ot out of reach.

Ill just "make do" with my Comec.


It is not "seems sub par" It is sub par

If you go to have ANY head surfaced and this is the surfacer they have... find another shop

 

[laserspeeddemon]

I'll buy it for you, if you let me co-own the shop.

 

[92AWDHX40]

My head was belt sanded didnt know it at first then i inspected it, and had to have it redone shes all pretty now, i should have asked earlier. Went to a shop i hadnt used before.

 

[BogusSVO]

Laser... you are a bit slow on that offer!

http://www.dsmtuners.com/forums/new...face-4g63t-cylinder-head-mls-head-gasket.html

Thats what I use!

iugrad.... you learned, and that is the point!

 

[92AWDHX40]

Yep they were cheaper still ended back up at my shop i used for years. Happy again thanks for the information.