M30 vs M90 or combination of both?

[Good & Tight]

Are you sure it's not just a 4-speed g262? That was the stock transmission for the e12 (assuming that's where the M90 came from). I guess the easiest way to tell would be to check the shift pattern. Found this golden nugget floating around mye28:

Just checked it's a 5-speed but not a dog leg. oh well.. :-(

[bataangpinoy]

the g262 is actually a g265, if it came from an m30 powered e28 or e24.

[LowR3V'in]

262 is a 4spd, 265 is 5spd.

[george graves]

Ok, found all the info, this should answer most of the transmission related questions:

http://www.m30swap.com/index.php?title=Transmission

Ahh that's great. Who running that little wiki?

[4drPwr]

Let me jump in here since I have the M90 and the actual dogleg , both from a euro 1980 635csi. For N/A purposes only, what benefit, if any, would I gain from dropping the B34 head on the M90 block? If there is no benefit, but no detriment either, would it be advantageous due to the B34 head having a more updated distribution system? My M90 has some sort of cap and rotor that are at a 90 degree angle to the head. I'm not sure if this will "jive" properly when converting the engine to M1.3.

[BenM]

Let me jump in here since I have the M90 and the actual dogleg , both from a euro 1980 635csi. For N/A purposes only, what benefit, if any, would I gain from dropping the B34 head on the M90 block? If there is no benefit, but no detriment either, would it be advantageous due to the B34 head having a more updated distribution system? My M90 has some sort of cap and rotor that are at a 90 degree angle to the head. I'm not sure if this will "jive" properly when converting the engine to M1.3.

All M30 heads from '69 to '87 use the same combustion chamber. However, the earlier pre-80 heads were more prone to cracking in between the water jackets, so it would be beneficial to upgrade if yours has a casting date of "80" or earlier.

Of course you can't use the L-Jet/mechanical Distributor for the M1.3 conversion, but its relatively easy to swap over to the later electronic distributor. All you need is the later upper timing chain cover, cam conversion nut for using the electro distributor (or just a B35 cam) and the associated cap, rotor, etc.

[4drPwr]

All M30 heads from '69 to '87 use the same combustion chamber. However, the earlier pre-80 heads were more prone to cracking in between the water jackets, so it would be beneficial to upgrade if yours has a casting date of "80" or earlier.

Of course you can't use the L-Jet/mechanical Distributor for the M1.3 conversion, but its relatively easy to swap over to the later electronic distributor. All you need is the later upper timing chain cover, cam conversion nut for using the electro distributor (or just a B35 cam) and the associated cap, rotor, etc.

I'll definitely check the casting date tomorrow when I have a chance. If mine is a "good" casting and worth keeping, is it really that easy to convert the distributor? The M20 and later M30s have that rounded, circular shape on the end of the head for the rotor to sit in, whereas mine seems to have no provision for such a conversion due to the shape of the actual head itself. Thanks for the help Ben, we spoke on the phone several months ago about this and I'm sure I'll be pinging you for info often when the time comes to dig into this as you seem to know a lot in an area where I don't. Also great to be in the same state, you never know.

[BenM]

I'll definitely check the casting date tomorrow when I have a chance. If mine is a "good" casting and worth keeping, is it really that easy to convert the distributor? The M20 and later M30s have that rounded, circular shape on the end of the head for the rotor to sit in, whereas mine seems to have no provision for such a conversion due to the shape of the actual head itself. Thanks for the help Ben, we spoke on the phone several months ago about this and I'm sure I'll be pinging you for info often when the time comes to dig into this as you seem to know a lot in an area where I don't. Also great to be in the same state, you never know.

Hmm, not sure what you mean by the circular shape in the head, maybe I just need to see it in person. I currently have 2 M30 heads (one of an M90) and my E28 has an "81" cast head. The M90 head was cast "82" and I believe was a replacement for the original that cracked, but was running the L-Jet/Mechanial distributor no problem. Maybe your talking about the actual timing chain cover? Anyways, yes it should be that straightforward and feel free to give me a call during the week to pick my brain. I recently picked up an M90 for a friend and we are converting it to carbs and running a Hartge cam in it. It'll go into his '69 2500.

[4drPwr]

Hmm, not sure what you mean by the circular shape in the head, maybe I just need to see it in person. I currently have 2 M30 heads (one of an M90) and my E28 has an "81" cast head. The M90 head was cast "82" and I believe was a replacement for the original that cracked, but was running the L-Jet/Mechanial distributor no problem. Maybe your talking about the actual timing chain cover? Anyways, yes it should be that straightforward and feel free to give me a call during the week to pick my brain. I recently picked up an M90 for a friend and we are converting it to carbs and running a Hartge cam in it. It'll go into his '69 2500.

I'll get a picture for sure tomorrow of what I'm trying and failing to describe. PM me your number so I have it, I'll definitely give you a ring next week to talk M90 conversions.

[ChaseN]

All medium case except for the ///M cars which had large case diffs. Obviously you will need to use the back plate from an e30 to make a e24 diff fit on your e30.

And axle drive flanges from an e30.

[4drPwr]

So I'm an idiot, I can clearly see now where what I was trying to describe is simply the upper timing chain cover you were describing, and can easily be disconnected from the head and replaced with the later style components.