I question alot of work that is done in other machine shops, mainly head work.
I get several heads that were supposed to be set up with +1mm valves, performance springs, valve tip height set,ect ect ect....
I have had 5 heads this year, that were recently rebuilt, had issues, pulled and sent to me to find out what is wrong with them.
I will say that any head can be torn apart, and found fault with it, guides is a big one, one machinist will say its marginal on wear, another will say it needs replaced. The cust budget may not have allowed for the guides to be changed, or the shop may not have had the tooling to do it.
But certin things HAVE to be right! Spring installed height, seat pressure, and valve tip height
The head below was done at one shop that is supposed to specialize in the 4g head. I spoke with the shop, and they have no real clue how this made it out the door.
I was sent a head that had recently been done at another shop.
The issues with the head were 0 compression.
What I saw when I opened the box.
Pull the head out of the box, and start to remove the packing.
The customer taped a 1 x 10 board to the surface to protect it.
I cut the tape to remove the board and the first thing I see is oil and sand.
More sand on the bottom of the head.
Head must be fully disassembled and cleaned.
Getting the towel from around the head, I find a cam gear was busted in shipping.
Looking at the bottom of the head, notice the valve placement.
Also Notice the head was belt surfaced.
The Intake valves are in the exhaust seats, and the Exhaust valves sunk into the Intake seats.
Customer supplied pic
Putting the proper valve in the proper seat should fix the issues with this head.
Next is to pull the cams… So remove the cam caps, I notice that the caps have been swapped sides and backwards.
Intake side is to the bottom of pic, front is to the left
I mark the head casting, the cams, and the caps with a letter to ensure the same caps end up back on the same casting.
With the caps, cams, followers and HLAs removed, I check the cam bores
Notice the grey black oil, this is from the cam trying to self-clearance.
Next remove the oil galley plugs.
I find grit and rust on the backside of the plug
Rubbing oil from the galley between my thumb and finger I feel grit, I cannot see it tho.
I did this several times to make sure it was not grit on my fingers I was feeling.
Next I remove the springs and retainers.
Stock retainers and locks.
Aftermarket Manley Valve Springs.
There was no need to check valve tip height, due to the valves being in the wrong seats.
I measure the head for thickness
Exh Rear 5.194 Int Rear 5.193
Exh Front 5.190 Int Front 5.200
New head spec 5.205 Min 5.185
Roll the head over and inspect the seats.
All the exhaust seats were ground, appox seat width is .095
I also noticed hard carbon build up between the guide and head casting.
On the intake side Cylinder numbers 1, 2, and 3
The seats were appox ground halfway around.
With Intake side facing, the ground area runs from appox 9 to 12 to 3.
The seats were fully ground on cyl #4 Intake
Intake seats were appox .095-.125
IMO, the seat widths are to wide, and should be .030 on the intake and .040-.050 Exhaust.
I decided to check valve seat run out
On cyl #4 intake seats, I found .004 and .006 on the other.
I will fully go thu the head, clean, Valve job, surface and oil port mod 1, New valve stem seals will be installed, and spring installed height will be checked, and shims will be used as needed.