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Old 12-06-2016, 02:52 PM   #1
jaredmac11
Wrencher
 
Join Date: Sep 2007
Location: Houston, Tx
Posts: 245
Figuring out Options for E30/E36 M42 build

I am rebuilding an e36 M42 and planned to swap it in to my E21.

I got the head off and took it to a machine shop to run some tests and they verified there is a crack on one of the exhaust seats... No bueno. They have an M42 head for $300 that I could consider.

I also have an E30 M42 in my garage. It sorta fell on my lap mid-build and I couldnt say no to the price. I was just planning to hold on to it for later.

I have all the parts I need for a rebuild for the E36, minus hoses. I have none of the parts needed for a rebuild for the E30 (not including any parts that may overlap), which is what is giving me pause.


The draw to the E36 M42 were the knock sensors, the improved intake manifold, the stonger timing case, and a few other pieces. I think the E36 M42 also gave a few extra HP. But all that doesnt mean much when I have a shot head.

What options do I have here? Could I, for example, take the E30 M42 block and head and plug in the e36 timing case? could I take the E30 head and drop it on the e36 block? I have some time on my hands and I can start trying to see what works, just curious if anyone has already run through this.

Ive done a lot of searching and there are a lot of inconsistencies.. but I also understand this isnt too common of a scenario in the first place.
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