Difference in Blocks

[gath]

What is the difference between the block "cast" but not the internals of a US M20 "i" and "e". Does the years matter? am looking at blocks from 1985 to 1991.

[jlevie]

The blocks used on M20B27 and M20B25 engines are same, the internals are different. There might be minor differences in the M20B25 blocks used in an IX.

[acolella76]

There is a changeover in the bearings... early/late. I don't quite remember exactly what the difference is, though. But overall they have the same deck height and all that. There is also a difference between E34 and E30; E30s have the dipstick in the block while the E34 dipstick goes into the pan. That's about all that comes to mind.

[gath]

Thanks guys, I should have specified that it's an e30 and non ix. My block is bust and I was looking at a good condition 1985 m20b27 bear block that I intend to swap "i" internals into. I know the late and early main bearings have differences in the tangs (early = single and late = double). What other differences are there?

[MR 325]

Bearings are the only difference.

[LJ851]

I remember talking to Pete McHenry years ago about building an M20 for my 2002 and he mentioned early ETAs had a large core plug on the rear of the block behind cylinder #6 and was a less strong casting. The later blocks did not have the cast in hole or plug.

[SkiFree]

[digger]

does anyone know how much the bottom of the bore/cylinder can be notched for rod shoulder clearance before you break through?

example shown here is a for M54 block but i assume it is similar on M20?

[einstein57]

I thought the eta blocks had more clearance for the longer stroke.

[LJ851]

does anyone know how much the bottom of the bore/cylinder can be notched for rod shoulder clearance before you break through?

I've got a B25 block that is not getting used, you want me to run a saw down the center of a bore to find out ?

[Minimonkey]

I thought the eta blocks had more clearance for the longer stroke.

This is ture MonkeyMadness and Metric Machinics use the 2.7 block for Strockers due to the internal clearance.

If i remeber right my dad says theres plenty enough meat you can remove from the cylinder base for rod cleance. Even for a 89.6mm crank and M3 rods..

If thats what your going for "storker" than you'll be better off with the 2.7 block.

One other spot your need to clearnce as well is the rear bearing carrier for the oil pump drive Shaft. The belt drivin shaft. The 89.6 counter weight on the on #1 cyl. hits it.. No biggy...;)

[digger]

I've got a B25 block that is not getting used, you want me to run a saw down the center of a bore to find out ?

if you aren't going to use it would be great! thanks

[digger]

This is ture MonkeyMadness and Metric Machinics use the 2.7 block for Strockers due to the internal clearance.

If i remeber right my dad says theres plenty enough meat you can remove from the cylinder base for rod cleance. Even for a 89.6mm crank and M3 rods..

If thats what your going for "storker" than you'll be better off with the 2.7 block.

One other spot your need to clearnce as well is the rear bearing carrier for the oil pump drive Shaft. The belt drivin shaft. The 89.6 counter weight on the on #1 cyl. hits it.. No biggy...;)

they have the same deck height so it would mean the cylinder is not as deep which is not good as at BDC more of the skirt is unsupported if that is true. i though the extra internal clearance on the eta block was in a different area more to do with counterweights as the 84mm big counterweight crank rubs on the sides of the block.

The B25 block i have is 206.2mm deck height and 135 mm deep cylinders. Anyone got a eta block they can measure from top of deck to where the bore finishes?

the auxiliary shaft needs to be machined but not sure how much. it is a fat mother compared to the the actual small drive shaft to the pump so i imagine a fair bit can be machined down

[LJ851]

if you aren't going to use it would be great! thanks

I should be able to do it within a day or so, will post pics.

[digger]

I should be able to do it within a day or so, will post pics.

ok cool cheers