M20B29 w/ Triple Webers into my '71 2002

[kid325e]

Can't wait for a video to hear this thing sing!

[TimeMachinE30]

Is it singin' yet?

[indecline]

Impressive feats thus far. Let's see something happen!

[TrentW]

Oh yes, we're all in need of some news Andrew.

[SkiFree]

Dang it! I've got some really good news coming in about two weeks (no, car's not running but some major steps forward finally)!

Rear axles are done, will post more on that this coming week.

Side note, Jeff's number 5 car is out from hibernation to be worked on this winter. Working on a drysump M10 with 336 hollow cam. Should give the 510's a run for their money. Will try to start a fresh thread for that car.

[SkiFree]

Can't resist a nice wood steering wheel, this one's out of Sweden; a period Personal Autostrada (oem option on a couple Italian clunkers).

[kid325e]

Love it. The cutouts in the spokes are pretty cool!

[deutschman]

Good stuff Andrew. Cant wait to see and maybe hear more ;)

[SkiFree]

I don’t have much free time again, so this’ll be kind of jumbled together. Cylinder head rebuild is finally done! Working on another piston option that should be kind of neat (hint: involves Mahle Motorsport)!

Cylinder head rebuild (strangely this was spread out over a year-ish)

Goals: In line with everything else, going for a fun hot-rod 91octane street engine. The idea was to port-match the exhaust ports while cleaning up both the intake and exhaust bowels.

New parts list
-IE 284/272 dual-pattern new cam
-IE HD Rockers
-oem dual valve springs
-valve guides
-IE SS Intake Valves
-IE SS Exhaust Valves
-OEM Rocker Shafts
-Elring Upper Gasket Set
-rocker hardware+eccentrics
-OEM Oil sprayer bar
-OEM Spring retainers (top and bottom)
-OEM valve cover studs (with M30 acorn nuts) Intake Studs (with thin IE 11mm nuts)
-Allen-head exhaust studs w/ copper nuts
-Freeze plugs

Tools:
Die Grinders
6”mandrell
carbide bits
80 grit cartridge rolls
120 grit cartridge rolls
rubber hammer
Bearing, Seal, and Race Drivers Kit
wrenches/sockets

First thing was sending the head to the machinist to have the guides punched out, head checked for cracks and warping, and lastly cleaned!

Port matching the exhaust side

Pretty straight forward. Painted the port with some trusty dykem lay-out fluid, 2)lined up a head gasket and scribed the ID with an exacto knife.







Started with a pretty beefy carbide bit, as long as I kept it lubed it made short work of the aluminum.



Next I wanted to clean up the intake and exhaust bowels. Mainly the casting ridges you can see here and the small edge immediately inside the short side of the port (you can feel it pretty easily when hooking your finger in there.

You can see how this was MUCH easier with the guide removed.

Casting ridges


First pass with the carbide bit



Stepped it up to 80 grit cartridge rolls on the end of a 6” Mandrel

Ended up with a 120 grit and went ahead and polished the combustion chambers for good measure.



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Next step was sending the head back to the machinist with new guides and valves. The machinist then did a nice 3-angle valve job, punched in the new guides, and resurfaced the head.



Before dropping off at the machinist.



After picking the head up from the machinist.





From this point it was all basic reassembly work.

Valve Stem seals went back in using the little sleeves supplied in the upper gasket set to keep the valve edges from cutting into the seal. Using the OEM stem-seal tool was kind of neat, didn’t know it existed..




On to the new springs, retainers and collets. Broke out the spring compressor. Compressed spring/retainer right before slipping the collets in.









Cam’s turn.



Rockers and rocker shafts were next. I could slide all of one bank on pretty quick. Pushing in the second shaft however meant that I was going to reach a point where the cam would need to be rotated for the rocker to go on.




Made up a handy head stand from some aluminum around the shop (in hindsight I should have moved the dowels farther forward).




Kind of neat but the M20’s rocker shafts are interchangeable from intake to exhaust while those found in the M10 and M30 are not. Rotated the shafts and snapped the rocker retainer clips in place.



Last major step, studs, oil sprayer bar, freeze plugs, cam seal/o-ring.

When installing the seals and or freezeplugs...
1) On the OD of the seal, run a thin layer of good gasket sealer (I like Dirko).
2) On the ID of the seal, run a smear of good synthetic wheel bearing grease.



Already to go!





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After thinking long and hard about it I made the call to switch to throttle bodies instead of carbs. My dcoe manifold wasn’t panning out and the more measurements I took the more I realized that carbs just wouldn’t work without compromising somewhere.

Went ahead and picked up a Racehead 40mm ITB setup.



With the ITB’s in hand I wanted to at least replicate the look of an old Alpina setup (red stacks, grey valve cover). Sent the parts of to Nick at Rodini up in Fremont for powdercoating.

Once the bits were back from powdercoating I mocked up the new setup ….

[DER E30]

\
Once the bits were back from powdercoating I mocked up the new setup …

That's gonna look amazing !

[mr2peak]

Very clean work. Are you planning on an MS setup?

[MR 325]

Looking good Andrew! 8)

[CorvallisBMW]

Holy shit, beautiful!

[LJ851]

Very nice, Andrew !

I think it's time to update the thread title, though...

[ForcedFirebird]

HA! You mentioned you might pull the plug on the carbs. Good choice.