Rebuild or replace case? (planning 1776 turbo)

[TedzBug]

So, i've torn down the two engines i have, one is beat to death the thrust is really beat bad so i'm not even considering that one at this point.

This is the one i've considered rebuilding... I am not knowledgeable enough to know if i should proceed or should find a better case or new.... I would like to plan on a 1776 turbo, i am going to run a megasquirt 2 for fuel and ignition. I have a welded C/W vw crank that i would like to use (again, if it is in good enough shape to run with...) If this engine isnt a good plan, i may do a quick rebuild as stock and run it for now, then build my plan over the winter...

This one is a factory rebuilt by VW as far as i know by the number on it... Dual relief AS41

Can you guys help me out? I've never rebuilt an engine and would like to move forward, making some educated decisions...











Center Split crank bearings

[Marc]

Well, the case looks pretty good from here. It's been many years since the odds of finding one in really good condition have been better than 50/50, but I think you have a winner.
"AD" codeletter denotes a Euro-spec 1600DP application (slightly higher CR and a few more HP than the "AE" US-market model). Case is identical to the AE.
It's been linebored by 1.00mm on the mains, and the crank is .25mm (.010") undersized. Thrust saddle looks to still be standard (nominal thickness of 22mm = .866") so the real test is how snugly a new bearing fits. There should be no discernible step worn into the thrust face on the flywheel side, and a new bearing shouldn't just drop in - should take a little push to seat it and a little effort to tug it back out. Judging from the wear evident in the photos, this engine hasn't been together very long and I'd be surprised if it needs any restorative machinework. Did they install casesavers for the head studs? The top-front stud at #3 cylinder should be sunken deeper into the case than the other 15 - the stud itself is the same length as the bottom eight. You might get away without it, but I highly recommend the head stud inserts - especially for a turbo. Don't accept a cheap job that flush-mounts that one stud, the reason it's deeper is to stagger the stresses on the case under #3 cylinder which greatly reduces the incidence of cracking there.
It's not likely but once in a great while I've come across factory exchange cases which received a little added attention to make them ready to use. They may be shaved at the parting line, which ovals the openings for the crank, oil pump & strainer plate; they then bore the holes round again but there can be slight abnormalities in the pump and sump stud circles and the distributor drive pinion mesh with the crank gear. The oil pressure control plunger bores can be bored oversize, requiring special larger-diameter pistons, and once in a blue moon they bore the cam tunnel for oversized bearings (I've also found reground cams which had their journals turned undersized). Custom plungers can be made by anyone with a lathe, but the odd-ball bearing sizes are pretty much nonexistent. Sometimes the bottom bore for the distributor pinion gets spot-faced, requiring added shim thickness to shift the pinion back up. These oddities are rarely encountered, but do spend a little extra time checking for them before you commit to using this case.

[TedzBug]

Thanks for the response...

There is a very small step in the thrust as you can see in this pic:


So, I need to get a standard set of bearings and see if it will fit tight? Or plan on a thrust cut? The wear marks in the saddle area are almost not even there when i rub my nail across that surface...

I also have a Rimco Welded CW forged crank that i am hoping to use that i was told is 10/10 (meaning .010" undersize on all journals i assume?) Maybe it needs a polish?

[Marc]

Do you have a machinist who you trust? The crank definitely needs polishing, you could probably do it by hand but it's much quicker with the right equipment. I'm kind of a stickler on thrust bearing fit, because if it starts out with any any slop at all it quickly gets worse. As a rule, if you can catch your fingernail on the wear step a thrust cut is needed. If you aren't sure, maybe you can find someone who'll sell you a set of standard-thrust bearings with the understanding that you can exchange them for oversize-thrust if needed. They come in STD. +1.0, and +2.0 thrust sizes; when a thrust cut is barely needed the best approach is to cut the case until it's flat, then trim the flange of an oversized-thrust bearing thinner for a custom fit. Go a hair too far and you have to start over, though, so you want the guy doing this to know his stuff.
The basic P/N for a +.040" OD, -.010" ID main bearing set is 111 198 483; if the main journals need to be turned to .020" under, it'd take 111 198 485.

Do you have a flywheel that's matched to this crank? You can buy a flywheel that's already lightened to ~12½ lbs, 8-dowelled, and resurfaced (if not new) but be aware that the dowel pins might not align perfectly. All SPG jigs aren't perfectly identical so it's always preferable to eight-dowel them together - if the added 4 holes aren't correctly located, by the time you do enough reaming to successfully mate the crank & flywheel not much strength is added compared to four dowels. You could need to open one or more holes up to make them concentric and fit 11/32" pins...another job best left to a machinist familiar with the operation.

I hope that you are planning on having your parts balanced. You can do the pistons yourself if you have access to a gram scale; rods are a bit trickier to do "right" (matched big- and small-end weights) but still potentially a DIY job. The crank, flywheel, pulley, and clutch cover should all be dynamically ("spin") balanced by a professional. Often the price isn't that much more to have the whole thing done, though.

[TedzBug]

There are 2 shops within about 30-40 miles of me that do VWs specifically... gonna visit the one soon and see what they tell me about the case and crank.

It'll probably need a minimal thrust, there is a very fine ledge there. same with line bore I'm assuming? (the mark you see around the saddle i can feel with my nail... not much but it is there)

As far as flywheel, the crank is rimco so I thought maybe I'd call them for a flywheel, maybe my best chance for a mating part?

Yes concerning balance, I'd like that done real well so its as smooth as possible.... I believe I can handle pistons and rods, but If its not much more cost for the shop to do all, may just hand em all off to them.

Hopefully this will turn into a "build" thread soon. .....


btw, to answer earlier post... yes on case savers and deep stud on #3... (gotta locktite 3 back in that came out with the head stud though)

I've also gone ahead and pulled all the plugs for clean out and going to tap for plugs. I picked up an aircraft drill bit to start on the HVX mods (drilled the galley to the last cam bearing on the one side)

[Marc]

...the mark you see around the saddle i can feel with my nail... not much but it is there...

Again, either see how a new bearing fits by trying a #3 in the three large saddles or leave the call up to your machinist if he knows the breed. He'll probably lean towards doing it anyway (more money for him) so if he thinks it's OK you should have nothing to worry about - plus there'll be one more potential "life" left in the case. Back in the day we wouldn't use a "third-over" (+1.5mm) case for any kind of quality engine because there were no bearing sets available that had steel-backed #2 shells, but after Mahle took over the Metal Leve plant in Brazil they started making them so that's no longer an issue. However, do be aware that sometimes at 3rd-over (and almost always at 4th-over) the alignment holes in the bearings may not be quite deep enough and the dowel pins can bottom out, squeezing the bearing against the crank. Ideally you use a bottoming drill and sink the dowelpin holes in the case ~.020" deeper, but simply grinding a little off of the end of the pin will work too.

[TedzBug]

Marc, Thanks for all of the information... This will more than help me get started. I've been reading posts about rebuilding and also about turbo-ing smaller VW engines for weeks and weeks now... I must have read hundereds of threads and posts by now.

As far as a flywheel, it looks as if i'm going to be able to buy the flywheel that was mounted to this crank previously.. This is good.

I will post as soon as i talk to the machine shop... Or if i have any more pressing questions for the process.

Hopefully soon, as i've been on short hours from work for waaay too long. And because of this, starting a new job on Weds the 4th.
(overtime = more budget to get the car running)

[Phil69]

A good rule of thumb is if you press the no1 main into each of the case halves in turn and then try to pick them up using the bearing to lift them.
If you can lift the case it's good to go. If you can't then it will need a thrus cut and or line bore.