I have an E 30.

[Nader393]

Just noticed, there's a divot in an unshaved stock head that disappears when it's been decked. See? It's under the exhaust side coolant passage for the first and sixth cylinders. #6 is shown here. So you can tell at a glance if a head's been shaved.

[nbridgema]

Looks good; have you calculated the new CR?

I did this [decades] ago on a 1969 M30 2.5L, which BMW rated 9:1. It measured 10:1 :up:

Helps explain why it pinged so readily... ;)

[Nader393]

Looks good; have you calculated the new CR?...

Yes, but it took some doing. I had all the necessary values to plug into a compression ratio calculator, except for piston dome volume for these new 85mm Mahle Powerpak pistons.

So, I called Ireland Engineering, because these pistons were made by Mahle for them. An older gentleman answered the main line, and told me he didn't have the dome volume, that it wasn't available. Strange. When you order custom pistons, the maker always includes a spec card with all the measurements.

Soo, I called MAHLE North America, got rerouted a couple times, and eventually connected with a helpful tech guy that was able to use the laser etching number on the piston to look up the specs. Long story short, the total dome volume on these pistons is only 0.9cc. Ostensibly, the deep valve pockets offset the piston dome volume.

Sooo, I plugged that into the CR calculator for the 2.9L stroker specs, and with a stock unshaved head (41.7cc), I get the expected 9.7:1. If I use the shaved head with the reduced combustion chamber volume (37.5cc), I get 10.4:1. Whew!

Soooo, anyone curious about component weights? Here's a comparo between stock 2.5L 84mm piston+pin+rings with m20 rod, versus Mahle 85mm piston+pin+rings with S52 rod:

[Nader393]

These pictures are mildly interesting, too:

[Nader393]

I looked a little closer at this extra head, the shaved one, and noticed something off. Can you see it? Hint: It's the rockers.




Here, have a closer look:

[Nader393]

Well, someone went through the care and trouble to engrave the rockers (and rods) with their respective positions (intake vs exhaust, and cylinder #), but the last person to reassemble this head put the intake rockers on the exhaust side, and vice versa. Theoretically screws up the cam break-in and wear patterning.

I went ahead and stripped it to reassemble correctly. Along the way, I notice that this is the third head I've encountered that shows evidence of rocker rod abuse. What manual describes pounding on these things as proper procedure for removal and installation? If you take a little care, you can slide the rockers off the springs a few at a time as you rotate the cam, and work your way to alleviating all tension on the rod, so it slips out by hand. Same when it goes in. Jeez.

[Nader393]

This was supposed to be a 284 cam. But it says 280.

[Secniv]

I have an E 30.

These pictures are mildly interesting, too:



[ATTACH]124523[/ATTACH]



[ATTACH]124524[/ATTACH]



[ATTACH]124525[/ATTACH]



[ATTACH]124526[/ATTACH]

Wow that’s some serious reciprocating weight saving. I’m def going this route when I stroke the b25. Do you need to bother balancing the rods?


Sent from my iPad using Tapatalk

[Nader393]

Wow that’s some serious reciprocating weight saving. I’m def going this route when I stoke the b25. Do you need to bother balancing the rods?

The rods are a nicely matched set, about a gram or so off between them. I might balance them down to zero if I run out of things to do while waiting on the machine shop.

Speaking of which, I've selected one and will be dropping off the block in a couple of days. When I called the shop a few days ago, and told the machinist that I wanted an M20 stroker block machined and the rotating assembly balanced, he seemed interested. When I told him that I had acquired a mishmash of parts to make it happen, he balked lightly and insisted on measurements of:

A. Piston compression height
B. Connecting rod length
C. Crankshaft stroke length
D. Block deck height

Rather than be irritated, I found that response reassuring. You want your machinist to be exacting. I took the measurements, and they were spot on within a fraction of a millimeter to fit. For the record, add A, B, and C/2, then subtract from D:

A. 29.8 mm
B. 135 mm
C. 84 mm
D. 207 mm

This whole process is a bit different from the machinist that is doing the head. He also does my Alfa race car head, and I consider him my friend. How good is he? He does heads for the private mechanics that maintain multimillion dollar car collections. He has a 1-2 year waiting list to do work. I don't mind waiting since I have another head ready to go, until "the good one" is done. His is an unassuming hole-in-the-wall shop, but he has heads stacked up from here to there, super exotic stuff including Le Mans winning Ferrari heads, and occasional vintage Formula 1 stuff. Always pulls out something crazy to show me when I stop in.

While I wait to take the block in to this other shop, I decided to clean up the threads for the head and main caps in preparation for ARP studs. The tap did a good job, but didn't go deep enough for studs that need to bottom out, so I ground down the tip of the tap to go deeper. I made it into a bottoming tap. See the pictures for comparison. Sure enough, it found more carbon and grunge down deep in the threads. Satisfying.

[2mAn]

Im very curious to see what the block makes when you're done. What cam are you going to run with the 2.9?

[ahrensNW]

Love the car.

But seeing that damn buret makes me want to cry.

Now my nightmares will be filled with titrations again

[Nader393]

I hate it when people name their cars. I think it's stupid. Especially when it's a powerful, really fast sports car, and the owner names it "Bella" or some other fanciful, dainty woman's name. Does the car not have muscle? Balls?

So, I don't anthropomorphize my vehicles. Until now, and just this E 30. Here's why:

The car seemed to do its best to impress me, even with the prior imposter engine that never really delivered. Car still felt and sounded fast. Now, after the engine transplant to a verified 2.7 stroker with a hot cam, the car definitely feels faster and entertains me even more. After sorting out the throttle position switch issue, the car seemed to be making every effort to win back my trust.
I've driven it a couple hundred fun miles without issue.

Importantly, it's taken me to work reliably, as one of my daily drivers. I have an unforgiving kind of job where I can't be late, and this car performed reliably for my week of shifts. Then the other day, after my last day of work before my extended time off, it took me a bit farther to drop off parts at the machine shop for the next engine (the 2.9).

On the way back, I was within three miles of home, when I thought this would be a good time to pick up some beer for my time off. I pulled off the highway, and the car started to stumble badly, like it wanted to stall. Had to keep the revs high to keep it from dying. Now, I drive this car hard, and had a hundred thoughts going through my mind of how I might have broken it. Like busted rockers, skipped tooth on the belt, dropped a valve, etc. All kinds of potential catastrophes.

I managed to limp the car home the remaining 3 miles on slow surface streets while it stumbled and backfired, very low on power. I kept saying, out loud, "Come on, baby, just get me home." And it did! Whew!

I've experienced this before on cars that didn't fire on all cylinders. So once I got home, I quickly popped the hood, and used an infrared temperature gun to check the headers. Cylinders 1, 3, & 5 were cooler than the rest. That tells me I lost an injector bank. Poor car struggled to get me home on 3 cylinders, and did it! Good car! My buddy! See, now it's more than a car, it's a being.

At home, the car was able to run on 3 cylinders while I futzed around the rest of the day trying to diagnose it. The next day, however, it wouldn't start at all. At this point, though bummed, I felt even a bit luckier, and grateful to the car, that it got me through work and errands far from home, and managed to conveniently die in my driveway after its final struggle. Poor thing!

I did a bunch of diagnostic testing, and ultimately discovered that there was a short in the harness between the injectors and the Motronic. I undid the injector harness plug (the one under the intake manifold) to find a bunch of dirty water in there. I had to pour it out! Cleaned the terminals, reattached it thinking that was the solution, but no go. I got mad, pulled back the rubber boot from the bottom connector, and found this:



Those happen to be the two wires for the two injector banks going back to the ECU. The #1, 3, 5 wire must have snapped on my drive, and the #2, 4, 6 broke after I fiddled with the harness while diagnosing the problem. Like I said, that plug retains water, and the wires eventually corrode from the inside out until this happens. I think that explains why the harness on the previous engine was "hacked" as I described it, and had spade terminals instead of this miserable, non-waterproof plug. So I cut off the plug, and peeled back the harness cover. I'm sure the muck and corrosion goes farther back than this:

[2mAn]

I had the same issue with mine, huge pain in the butt.

SO what did you name the car? Buddy?

[CubbyChowder]

I hate it when people name their cars. I think it's stupid. Especially when it's a powerful, really fast sports car, and the owner names it "Bella" or some other fanciful, dainty woman's name. Does the car not have muscle? Balls?

So, I don't anthropomorphize my vehicles. Until now, and just this E 30. Here's why:

Haha this statement hits close to home, here's an excerpt from one of my past E30 build threads as I was introducing the car:

"I've never named one of my cars before, to be honest I just think it's weird. Like an E39 M5 named Tatiana is just weird to me. With that said, Golden Boy seemed fitting."

I thought the similarities were amusing :nice:

Just read through this whole build and thoroughly enjoyed it! Very informative and motivating. I'm currently refreshing an M20B25 for my '73 2002 and this thread is giving me all sorts of bad ideas but I'm doing my best to contain myself...

Looking forward to updates :up:

[Nader393]

Got the car's injector harness rewired. I used brass bullet connectors that are correctly crimped and sealed with marine grade heat shrink tubing, then encased in water-tight vinyl sleeves. Car fired right up. Whew!





As for naming the car, I'm over that. I did call it "Baby" a few times in moments of panic and darkness. Then while working on it today, I heard this song on my shop radio while tuned to KEXP:

https://www.youtube.com/watch?v=ONIJXHvoynw

Interesting story about the Emerson brothers. They grew up on a large farm outside of Spokane. As teenagers obsessed with composing their own music, their father believed in them enough to mortgage the 1600 acre farm to produce the album. This was in the recession-era mid-Seventies. Obviously, the album went nowhere, and the most of the farm acreage was lost, down to about 65 acres.

But, no, I won't be referring to the car as "Baby."