3900 headgasket on 3400 head and other lz9 info

[The Dark Side of Will]

Well... yours is mounted and running.

Looks like the bracket could be offset forward by the hole center, so the forward stud of the engine mount would go through the rear hole of the bracket. Sandwich a piece of 1/4x2 flat bar between the mount and bracket to pick up the rear stud on the mount and the forward hole on the bracket.

[Shaun41178(2)]

I wanted to post this pic here for front bolt hole location for Eric.

IMG_20220922_195335595.jpg (3.34 MiB) Viewed 3433 times

[ericjon262]

I wanted to post this pic here for front bolt hole location for Eric.

IMG_20220922_195335595.jpg

can you measure the distance from the oil pan rail to the bolt hole for me? that should tell the whole story by itself.

[ericjon262]

I dragged my LZ4 out of the corner, and snapped a picture of the mismatch, it's off, but it actually appears to be rotated off, maybe the boss on the side of the block is at a different angle? I'll have to measure it tomorrow.

[Shaun41178(2)]

I tried to get a center to center estimate since the bolt location for the front oil pan bolt is the same between the two blocks

IMG_20220922_212723403.jpg (3.27 MiB) Viewed 3427 times

[Shaun41178(2)]

Yes I believe the boss on the side of the block is at a slightly different location, which will effect the angle

I believe this because I used my stock 88 front mount bracket on the lx9 I had and the front mounting holes lined up.

Also used the same 88 bracket on my lz9, and the lower bolt hole lined up, but obviously the second one just above is missing on the lz block

[ericjon262]

Yes I believe the boss on the side of the block is at a slightly different location, which will effect the angle

I still don't think that bolt hole is in the exact same spot. I think I'll revise my design to bolt the engine mount to the oil pan, hopefully that way more than one engine can use one mount design, this finding may mean I need 2 different alternator brackets, but I would most likely need to make 2 different mounts anyways.

[ericjon262]

I took the timing cover off of my LZ4, peeled the gasket off, and laid it on my LX9 block:




the bolt holes are in the came place, but some of them are smaller on the LZ



on each block, I put three bolts in, two in the lower timing cover bolt holes closest to the motor mount boss(es), and one in the mounting point that is being debated. I them measured the positions of the bolts relative to each other.

LX9










LZ4











the 1" mark on the tape is approximately centered on the head of each bolt it is over, it's not exactly precision, but close enough to show there is a difference in the position of that bolt boss relative to the timing cover bolts. I also measured the angle of the block side bosses, they're 60 degrees from vertical on both blocks.

[The Dark Side of Will]

the bolt holes are in the came place, but some of them are smaller on the LZ

As far back a the 2.hate, the front cover had 10mm bolts on either side of the water ports on the block, with 8mm bolts everywhere else. I guess this new style of gasket allows them to back off the clamp load around the water ports so that they don't need 10mm bolts in those locations anymore. Also on the 2.hate, the waterpump was bolted to the block only in those four locations, so the belt drive loads on those four bolts may have warranted larger fasteners.

The FWD engines spread belt drive loads across all the front cover fasteners instead of mostly on those four. Somebody eventually realized that they could use smaller bolts at those locations, which also simplifies assembly since they're now the same as the other bolts.

on each block, I put three bolts in, two in the lower timing cover bolt holes closest to the motor mount boss(es), and one in the mounting point that is being debated. I them measured the positions of the bolts relative to each other.

Calipers are a good tool for that

[ericjon262]

Calipers are a good tool for that

I do have a set, but they weren't in the garage with me, and I didn't feel like making another trip. this was accurate enough to show there is a measurable difference.

[The Dark Side of Will]

Calipers are a good tool for that

I do have a set, but they weren't in the garage with me, and I didn't feel like making another trip. this was accurate enough to show there is a measurable difference.

Did you think your mount bracket wasn't enough?

[ericjon262]

Calipers are a good tool for that

I do have a set, but they weren't in the garage with me, and I didn't feel like making another trip. this was accurate enough to show there is a measurable difference.

Did you think your mount bracket wasn't enough?

Isolating variables, I didn't know if the block side bosses had been changed.