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.


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


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 .



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

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.

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.

jeeez look how shallow the tear drop is

Yes, that oil transfer port is way thin, can you say lifter tic? Or improper oil flow to the head?

This is why your probably going to end up with a much bigger customer base.

Most likely when the time is right, I'll be sending you a block to set-up. Seeing your threads really settle my worries when it comes to my next build. The shop I use is pretty good, but I don't trust them with setting up what I have planned.

BTW, I love the guides. That's the funniest thing I've ever seen. How dumb do you have to be to mess that up. "huh, one long one short, odd, well I'll just throw them in"

Hey Dale! This is my head prior to Dale building me one of his big mouth head setup for 737/2000, this is the same head that the local "guru" assured me was better than new... It wasn't as shown.

Dale your the man, the replacement is a work of art and I can't wait to see the short block your working over for me. New turbo is on the way and injectors coming to feed the new beast your building.

Prove it you were right about what was wrong with my car a while back, that and several other issues as dale has shown here. You and dale are true assets to our community, thank you both.

The new turbo for this car should do 500 whp on pump and 625-650 whp on meth. See in a few months. As Dale and I spoke earlier it is being assembled to be street able (for a toy not daily driver) car but stupid fast on the track.

Dale you'll have to get some teasers up of the block in a few weeks when you get it started and I'll put the photos up of new turbo and related parts. Maybe a proper build thread even. Sent a contact me about the trans builder we talked about today, hopefully hear back shortly from him.

another great post..

Great informative post. All new to me.

Quoting prove_it:
This is why your probably going to end up with a much bigger customer base.



I concur.