sjkimmel99
NAXJA Forum User
- Location
- Phoenix, Az
Posting in OEM Tech cause about half the head casting threads are here but move it if you want.
Swapping a '93 7120 for a cracked '96 0630 head. I noticed a difference between the two heads in that the 0630 has two locator pin sockets on the pushrod side in the corners that fit on pins in the block deck. The 7120 doesn't have these pin sockets.
Here's the 0630 head.
Here's the 7120 head with no socket in the lower right corner.
I can put the head on but the pins contact the inside of the casting as shown by some scuffing at the front corner but not any obvious metal being displaced. This offsets the head horizontally enough to make the front head bolts difficult to impossible to screw in without a ratchet. The back bolt holes are aligned enough so the bolts go in by hand.
With the head on and torqued down (with the pins in place) I'm also getting lifter preload of .150-.165 which is far more than the combined milling of .032 from block and head would explain and am wondering if the interference between the the pins and the head is contributing to the preload reading by keeping the head from fully resting on the gasket.
Fwiw, I had the valve stem height checked and it's within spec so sunken valve seats dosent seem to be a reason for that much preload.
I've removed one of the block deck pins and will probably remove the other before putting the head back on. I'm guessing that since the '93 didn't have the pins they are not critical but a later engineering change (to aid assembly?)
Anyone else experience this before?
Swapping a '93 7120 for a cracked '96 0630 head. I noticed a difference between the two heads in that the 0630 has two locator pin sockets on the pushrod side in the corners that fit on pins in the block deck. The 7120 doesn't have these pin sockets.
Here's the 0630 head.
Here's the 7120 head with no socket in the lower right corner.
I can put the head on but the pins contact the inside of the casting as shown by some scuffing at the front corner but not any obvious metal being displaced. This offsets the head horizontally enough to make the front head bolts difficult to impossible to screw in without a ratchet. The back bolt holes are aligned enough so the bolts go in by hand.
With the head on and torqued down (with the pins in place) I'm also getting lifter preload of .150-.165 which is far more than the combined milling of .032 from block and head would explain and am wondering if the interference between the the pins and the head is contributing to the preload reading by keeping the head from fully resting on the gasket.
Fwiw, I had the valve stem height checked and it's within spec so sunken valve seats dosent seem to be a reason for that much preload.
I've removed one of the block deck pins and will probably remove the other before putting the head back on. I'm guessing that since the '93 didn't have the pins they are not critical but a later engineering change (to aid assembly?)
Anyone else experience this before?
