E30 Touring 3.0L M20 Stoker Build

[digger]

im not sure what you mean for that first measurement

but top of block ( HG gasket face) to bottom (sump gasket face ) is 266.1 to 266.2mm

the main cap part line is 60.0 mm from the sump skirt so add the 206.2mm deck height and that gives 266.2 above.

Measure the deck height (from main cap part line to top) this is the key. Yours looks like it will come out at 203.x in Which case it looks like someone skimmed 3mm off yours

[E30-TourZing]

i measured 225.5 and 141.6 with a vernier depth gauge on a b25 block (no HG) obd2 b28 crank which aligns pretty well with the theory

Sorry for my late response guys. I have been pretty busy with the M6, Christmas and skiing. This evening I had to move my block off the stand to make room for a subaru motor I am rebuilding this weekend, and I was inspired to spend some time measuring the block. I need to get a vernier depth gauge, or atleast borrow one to get 100% accurate measurements on the crank throw, but I feel my measurement is pretty much on-point.

My two block measurements are (from the top of the main bearing cap - Top of block) 172.14mm

Bottom of block - top of block) 263mm

Can anyone tell me their block height for reference. Beyond the crank throw, I am worried my block may be decked to far... I will have to measure everything up, but I hoping this will be the first step.

My block is from a 86' 325E

Thank you!

[digger]

the nominal dimensions should be

206.2+84/2-22.5 = 225.7
206.2-84/2-22.5 = 141.7

but the delta is the important part

does it have a machine step for the tooth wheel on number 6 counterweight?

i measured 225.5 and 141.6 with a vernier depth gauge on a b25 block (no HG) obd2 b28 crank which aligns pretty well with the theory

[ForcedFirebird]

I love speedtalk! Been a member for many many years, probably longer than here. Curtis, AFR, Vizzard, CamKing, Knight etc are extremely knowledgeable, and so willing to share with competent inquisitive minds. Many if those guys compete in the EMC.

TractorSport waalso an excellent wealth of information, but probably haven't been there in about a decade - the site changed hands and names and is now flowbench.com or something (out of town to attend first born's collegiate graduation, going on memory)
. TS.com /FLB.com was the first group that designed pass around plates so many of us could calibrate out flow benches so numbers are more universal. That's the guys that caused me to learn boundary later, Coanda effect, the importance of shirt side radii and valve angles/back cuts. Mostly just PM on those sites, rarely post.

I use KS bearing often, unless a customer requests OEM shells (stupid expensive and buying one shell per box...), I can say early shells are 360° groove, late is single 180. Assembled enough m20's to know that much. Also in a pinch, you can miss and match the shells for desired results if you have multiple partial sets. ;) All the 24v engines have 180 and work just fine, all the GM and other US domestic stuff we do are all smooth.

However, I do prefer a 360° thrust. Thrust clearance and contact is ignored by many, but even when replacing the bearings in my Ford Excursion V10 haul vehicle ("gasser" we call them in the States, you might call the "petrolers" rofl) I went ahead and purchased a second set of shells just to make it 360° and it's approaching 300,000mi of severe duty. Seemed silly to have the caps and block recessed for a 360, but install a 180 in something that can haul 8-9 tons, and weighs 3.503 tons empty (yes I weighed it, 7,007lb no driver, 1/2 tank if fuel). Thrust bearings don't really rob any power and have the same "skim board" effect referenced earlier. Also fun note, my truck prefers 0-20w oil, 30w or more and I get piston slap at light throttle no load, specially on lower octane (87 vs 91). Heavy loads and high TQ low RPM engines need the thrust as the cranks tend to walk back, adversely cams tend to move forward.

[digger]

There is a thread on speed talk about grooves 180, 360 etc. same with the thrust. 360 groove are old school thinking was the outcome. 360 are Rarely if ever needed infact the opinions were they are actually worse (and not from the obvious negatives to the mains which on an online 6 are not an issue)

I thought KS twin tang were 360 but glyco were 180 could be mistaken

[ForcedFirebird]

To add, I have never had any clearance issues with b28 cranks in m20 blocks - even the one I built without turning the crank weights (I modified the piston skirts), the customer car has been daily driving it for over 2yr now (plus the 3yr it was a track car was before cutting the cage out and installing an interior). It's the 217whp/202wtq b28 we did in 2014 and 16 with stock .5mm over slugs, 130mm rods, .5mm off the deck, IE 272 cam, RHD ITB.

[ForcedFirebird]

The single tang bearings have a 360° oil groove.

I am not sold on the modification, many high HP OEM designs have smooth shells. Having been a beach bum skin boarder for quite some time (many years ago, tho), I feel even the 180° grooves are unnecessary.

[digger]

I have a M52B28 OBD2 crank in a M20B25 on a stand. I can measure this weekend rather than do the maths.

What’s the deck height (top of block to crank c/l) on yours? Mine is like 206.2mm

Why do you want single tang? I thought there were less bearing options for those? My current engine is a single tanger B25 from 87 iirc.

The crank C/W won’t hit the actual intermediate shaft the connecting rod will. The big counterweight hits a bit of the block in a couple areas, near the block main web areas that bulge out a bit, one of which is near the intermediate shaft. It does this on b27 blocks but not b25. One of the sticky threads regarding the block has the pics

You will want to pay a bit of attention prior to final assembly with mocking up and seeing where the pistons comes at TDC to optimize the combustion chamber, CR etc. If you don’t have a selection of gasket thicknesses it needs to be in the deck height machining. also check the angle of the piston chamfer and see how it mates to the head

[E30-TourZing]

Thank you everyone for your input!

The crank I have does not have any connecting points on the counter weights like OBD2 M52B28 cranks do.

I am intrigued about the numbers you have digger. I am fairly sure the ETA block I have has only put on roughly 60,000Km's, so I doubt the block has been decked. 2mm of difference it quite a big step. Rather puzzling. I am trying to be as accurate as I can be with two straight-edge rulers.

The smaller counter weights do assist me quite a bit. With a standard OBD2 M52B28 crank, the counter weights run into the auxiliary shaft. This is fixed by machining 8-thousands of an inch off. I am pleased I do not need to do that anymore.

While Canada does likely have more euro spec vehicles per capita vs the states, we still do not see many around here. To touch on 'Betz' comment, I have looked into all the BMW wreckers within a 1000 km's of where I live and no one has one available unless I purchase an entire motor. The cheapest option I could find was $500. Buying from the states has literally been eating my project funds like an obese child and cake. By the time I cover shipping, duty and the + 30% increase in the US dollar, it hardly makes it worth it to just buy one off ebay. This is why I am quite excited to officially find what I am looking for. Not only that, I feel like I have been thrown a bone considering its better setup for my application.

I also lucked out on my 86' ETA block. It has single lock tang main bearing caps which saves me from sending out my caps to M/M. Jim thought that was the only M20 block year to have this from the factory. I got this block completely by chance.



This is what the top of my piston looks like. There are big valve reliefs as you can see. Hopefully the block height issue as mentioned above will not impede this build. I have a metric mechanic improved coolant flow head gasket. I am not sure the thickness, but its certainly not as thin as MLS.



P1011349 by Jan Willem Wilderom, on Flickr

[ForcedFirebird]

Oh Canada!....well a lot of grey market cars here in the states come from CAN as the have much looser import restrictions. Prior to the 25yr rule, the only "easy" way we could get tourings (as well as real e36m3's) was import from CAN. The only other way I know is when Military brings cars home, and immigrants are allowed to bring certain vehicles once brought up to US DOT standards.

[digger]

Euro spec b28's had the crank sensor in the front, like the early USDM cranks. Only know this because a local has a z3 coupe that was sold by BMW as a motorsport-only car (no title, BMW USA couldn't even decipher the VIN). It had an m52, but since it was imported, it used the Euro DME and harness. The crank sensor went bad and had to order it from Europe. Aslo, the Euro cranks have smaller counter weights, no need to turn them down and re-balance.

EDIT: Also it appears in post #10 that the pistons do in fact have the proper squish dome.

yeah that's exactly that's why i mentioned it if it doesn't have it then its one of the OBD1 crank. He is in Canada so would be pretty rare? Europe and Oz its very common

i don't think the dome on those exactly matches the OE there is some kind of chamfer though. My Rally slugs were similar, the new rally lugs are like flat tops

[ForcedFirebird]

It's really not hard to find a good 84mm crank. Mine was like <$100 shipped on eBay and similar price at any local auto dismantler. And also not that hard to turn down the counterweights from the US one to clear your pistons. I took mine to a run of the mill machine shop and they charged me like an hour including all of my 325i pistons skirts getting shaved and their weights matched. You're gonna regret not having the stroke and compression, and I would kill for those MM pistons, they're pretty much the best you can get. I would use what they were designed to be used with.

The OP is in Europe, they got a different crank as they stayed OBD1 for a little longer than the states did. Their crank does not need turning.

[betz]

It's really not hard to find a good 84mm crank. Mine was like <$100 shipped on eBay and similar price at any local auto dismantler. And also not that hard to turn down the counterweights from the US one to clear your pistons. I took mine to a run of the mill machine shop and they charged me like an hour including all of my 325i pistons skirts getting shaved and their weights matched. You're gonna regret not having the stroke and compression, and I would kill for those MM pistons, they're pretty much the best you can get. I would use what they were designed to be used with.

[ForcedFirebird]

does it have a machine step for the tooth wheel on number 6 counterweight?

Euro spec b28's had the crank sensor in the front, like the early USDM cranks. Only know this because a local has a z3 coupe that was sold by BMW as a motorsport-only car (no title, BMW USA couldn't even decipher the VIN). It had an m52, but since it was imported, it used the Euro DME and harness. The crank sensor went bad and had to order it from Europe. Aslo, the Euro cranks have smaller counter weights, no need to turn them down and re-balance.

EDIT: Also it appears in post #10 that the pistons do in fact have the proper squish dome.

[digger]

the nominal dimensions should be

206.2+84/2-22.5 = 225.7
206.2-84/2-22.5 = 141.7

but the delta is the important part

does it have a machine step for the tooth wheel on number 6 counterweight?