Head Inspection #10

[BogusSVO]

Head Inspection # 10

I had a head sent in by a customer that just had the head rebuilt through his tuner.
The machine shop that built the head did not have a full understanding of the 4g63 head.
This head was built with SuperTech single springs and Kelford 272 cams.
For the most part the head looked good out of the box when given a very quick look over.
The story as best as I can recall goes like this.
The customer went to several tuner shops wanting springs and cams installed.
He then finds a shop that will do the work and cut the deal to have the work done.
The install the ST singles and Kelford cams.
The shop bent the valves on start up. So now the head comes off and gets to the machine shop for a valve job and valve replacement.
Head gets bolted down, and the car still does not run right.
Now I get a call about a head that dropped a valve.
After a few questions and some base info, I know the spring pack that was installed is not correct for the aggressive ramps of the Kelford 272
Also with the customer saying he dropped a valve, I am thinking the head is well trashed. But that was not the case.

Now with the head at the shop, and a fresh casting being worked up.
I finally pull the head from the box the customer sent in. No dropped valve or mangled head like I was expecting, but it did have a handful of slightly bent valves.
Now that I have some time to really look and check the head out, this is what I find.
First the springs were not even shimmed to set the spring installed pressures.
I flip the head over to check the surface finish, it looks good.
But I see that the head has been milled extensively. The injection bosses are cut flush.

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Now is the time I also notice 12 of the 16 valves have been replaced.

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Now I go and measure head thickness.
It is 5.158 on one end and 5.135 on the other That is a .023 taper
So either the head was poorly surfaced before, or the shop needs to check there level .

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At this point I am fairly sure that the casting is just too thin, and with the lift and duration of the Kelford272 cams that no matter what is done this casting will keep bending valves.

The brad of valves installed I had not heard of before, JMWC or something like that. All I did find out is they are some valve made in China and can be bought in bulk when you join Abina website.
With the minimal run time on this head with these valves installed, the black coating had already worn off most of the stem.

It also had the cheap "red" valve stems seals installed

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I just have a personal preference for the viton "blue" seals due to the higher temp rating they have.

Now for the guides, Looks like the shop did not much care what guide they installed.

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5 of the 8 guides are the short exhaust and 3 long intake guides just randomly installed down the intake side.

This casting will hit the scrap pile or be used for a mock up build. But it will never get bolted down and be run again.

 

[Whophlungpoo]

The machine shop that built the head did not have a full understanding of ANY head.

Fixed it for you. haha


Know your machinist people.

 

[TurboDSM90]

Holy shite!

 

[JacksonAuto]

this is the cheap junk that we have to "compete" with. Hope you get your customer straightenend out.

 

[BogusSVO]

JAM... yes I agree, some of the heads I get have been built by other shops, then get sent to me. I just have to shake my head.

Another I did recently had been ported, but no smoothing and blending done, Every runner loaded with burr marks and snail trails, It is like they had 2 sand rolls to do the head with. tip height off, spring just dropped in, tar balls and metal shaving in the oil galleys.

This head, just was replaced, just no hope on saving the casting.

 

[JacksonAuto]

The underlying problem is that in general, consumers are willing to accept this work as "acceptable" because they don't know any better. So many shops are screwing people over with crummy work that when someone like you or I tries to do it right, we are the bad guy.

 

[BogusSVO]

Jam, it is true.

But the thing is, you and I and a few others, can/will show the customer the what, why and how is wrong. Even go to a book and show them the accepted specs, or the math on how it is screwed.

But by the time they get the head to a shop in the know, the head has been molested by 2,3 or more other shops.

Then we are expected to wave a magic wand and fix it all for a $20.00 dollar bill

 

[636chris]

That is absolutely horrible for anyone to even do that , let alone to a paying customer, I would hope whoever's head that is gets there money back in full.

 

[-red97rum-]

Jam, it is true.

But the thing is, you and I and a few others, can/will show the customer the what, why and how is wrong. Even go to a book and show them the accepted specs, or the math on how it is screwed.

But by the time they get the head to a shop in the know, the head has been molested by 2,3 or more other shops.

Then we are expected to wave a magic wand and fix it all for a $20.00 dollar bill

That must be frustrating as hell for you guys. That's why I don't let anyone touch my car and do everything that I can, myself. As for machine work, luckily I know my guy personally, he's been doing it a long time and has the same mentality as you guys.