Crankshaft Crossroads - Now 2027 Build

[Brian_e]

[Rob Combs]

Thanks Brian, that's good to hear

I cartridge rolled the inside of the manifolds with 40 (I think) grit rolls and cleaned them with alcohol prior to applying the steel stick. I was quite concerned with it holding to the interior walls, so I was careful. This was a few years back so cure time is not an issue. This stuff is pretty hard too.

But now I've removed probably 98% of what I originally put in there; kept just enough to shape the end of the manifold to the template I made for the head ports (it's made with regular JB and one of those plastic FI end casting spacers).

So, it should make a good test mule. Got some helicoils coming to repair the manifold tops. We'll know soon.

[Rob Combs]

So I decided to put the original Weber 32mm venturis back in place and go to more standard jetting, just to make any tuning/jetting adjustments more predictable, while I sort the crankcase pressure issue. Went back to 57 idle, 140 main, and ~ 195 air corrector. I think the emulsion tubes are F24s.

The vacuum elbows I put in to route vacuum to the pcv/oil catch can didn't even last until this morning - 3 of the 4 had cracks in them when I took it out again, and were leaking vacuum.

That made slow-speed driveability hell - pops back through the intake until I got those sorted. Just merged them into one vacuum control system for the pcv and the black box.

The pcv system did help quite a bit, with no visible oil smoke even when pushing it, but not completely cure the oil mess. So after fixing the vacuum leaks I bumped the orifice size to 2mm. That helped a bit more with the oil mess, but then I noticed it surges just off throttle. Did this with a 57 idle and a 60 idle, less so with the 60. That's quite a bit of fuel for the slow speed/idle jetting though. I will try a 2.5 orifice in the pcv restriction, but not sure when the calibrated vacuum leak is going to really mess up my slow speed fuel mixture/idle jetting.

Now I have noticed one of the ball joints in the carb linkage is getting way worse, so one carb is leading the other by what might be enough to make it run rough off idle. Working on a set of heim joints for down-rod ends, and will see if that cures the surging before I mess around with the 2.5 orifice for the pcv.

So, it's looking like a proper breather box will be in order soon. JBugs has the Empi tower type on sale, and with 7 screws around the perimeter as opposed to three down the middle, it looks like it might be better built than the CB tower, so might go that direction if my final pcv experiment doesn't work out. The free shipping is a nice bonus, too.

Then we can move on to the ported manifolds. Helicoils for repairing the carb flange threads will be here tomorrow. Need to get oil management and running as smooth as it can with the intakes that are on it before I add another variable to the mix.

All else fails, I can always go the 44 IDF route.

Chipping away at it. One step at a time...

[Rob Combs]

Ok folks, progress

Determined that the pcv system is simply not going to work, at least not without requiring some really funky jetting and tuning. So, I 86'd that idea and plugged it off this morning. As soon as I did, the oil leak came back, even with very careful, easy driving. I have a breather on the way.

WRT the carbs, I'm getting close. Got the new linkage rods installed, took it out to a quiet place, and balanced the carbs. Got 3s across the board on the snail with an excellent 900 RPM idle. But, I can hear a difference in #3 (huffing), and it started off with quite a bit of difference between the snail readings compared to #4. Then I nearly had to close off the #3 volume screw to get it to idle nicely.

So, I've got another bent throttle shaft

I suspected this when I put the Berg venturies in, but hoped it was so minor I could tune around it. Apparently not so...

I'm thinking it wants just a bit more idle jet too.

BTW, I'm only giving the play by play so others can hopefully have one more build to go through, and learn from my mistakes, when they do their own.

And thanks to all for the tremendous amount of support they've given, both on and offline. For the offline support, which has been substanitial, I'll only name names once I have those persons' buy-in.

I'm parked while I await a breather tower, but here's some fun stuff for the downtime -

Downrods converted to spherical bearings:

Difference in porting to my old Race Trim manifolds to new Empi IDF manifolds. Here you can really see what Brian was talking about a few days ago:

Happy building to all!

[Rob Combs]

Empi dipstick tube, "reimagined":

Broke the tube off the base, threaded with M11 x 1.5 threads, got a 8mm ID by 11mm OD x 250mm aluminum tube from Amazon and threaded the end.

Now the tube goes into the base without being able to see daylight between the two. Will use thread sealant upon final assy, and cut it off flush with the inside of the base.

First, there will be some hillbilly lathe work to be done to knock down the handle end of the tube so the bug saver temp sensitive dipstick will go on there. 2 pillow block bearings (on the way), some threaded 5/16 rod for tension and to ride in the bearings, some kind of turning motor (probably a drill), and something to use as a cutter (I'm sure I have some junk tools somewhere that can be made into a lathe cutter head), and I should be in business. What could go wrong?

Got the breather today, and some different fittings coming tomorrow, so hopefully by the end of the weekend the breather situation will be resolved.

Throttle shaft due to arrive on Monday, so by mid-week the carbs should be able to be fully balanced as well.

Getting there...

[Michael1]

Get oone of the new csp type3 dipstick adapters …
Much better

[raygreenwood]

[Rob Combs]

Thank you Ray!

I'm really glad you chimed in. I see your points about the Mitsu pcv valve and just how much vacuum it needs. It's a lot. To your point, it also does bleed back some pressure to the crankcase (or valve cover in its intended installation) end when blown through, which is probably not all that helpful in this use case.

My next iteration that I had planned was to go directly to the fuel pump cover, tap a 5/32 vacuum nipple directly into that (I already have one in 1/16 NPT), rig it into the oil catch can to use as a separator, then back to manifold vacuum. I could plumb an orifice into that system to regulate volume.

However, for the moment, I am itching to get this thing running well, so I decided to go to what seems to be working fine for most people - a well-vented breather tower. I will put that in place today or tomorrow, depending on how the rest of the day pans out.

That way I can concentrate on getting the throttle shaft replaced on the 3 / 4 carb this week, then onto the manifolds themselves to rule them in or out as the main cause of being so far down on power.

Crankcase pressure mitigation first, then a good carb tune, then on to getting my replacement manifolds iinstalled and carb linkage re-adjusted to the longer manifolds. They're ported well above and beyond what I did to my Berg manifolds, which by all practical measures, were in retrospect honestly just barely beyond a port match to the heads.

I seriously underestimated two things here - crankcase pressure mitigation and intake tract sizing requirements, both length and diameter.

One can read really good instructions, results, and opinions here until they're blue in the face, but there is no substitute for experience, so we can expect a learning curve even when studying this stuff for well over a year prior to building. Because we don't know what we don't know, we are just going to have to accept missing something along the way until we actually go through it.

That's where I am now, and am still enjoying the ride, with everyone's help through these pages. The only bad part was actually installing the engine, due to not really having a lift, high enough jack stands, etc.

I will get back to the pcv system after all of this is resolved. The 2mm orifice wreaked havoc on my lower end fueling, so I need to have it pretty well tuned before returning to that experiment. Introducing something like this with a twisted throttle shaft and other issues was a fool's errand.

One day at a time...

[chrisflstf]

I would do a compression and more importantly a leak down test to see if the rings are seated.

Where is the oil coming from? Pulley, breather?

[Rob Combs]

Thanks for your interest. I do understand the value of the leakdown test. Not going there just yet.

Most of it is coming from the dipstick tube (I think), but some dripped out from around the oil cap area the other day too, after I defeated the "pcv" system I fabbed up. Not sure if the oil cap was on there properly at that time; it's a reproduction cap and filler tube, and has a strange feel to it when you tighten the cap.

No one around here seems to be getting away without a separate breather system, or at least a properly vented tower, with 2 liters(+), unless they run a late style filler, but even then probably needs to be run to a breather box or vented catch can.

All of this discussion does make me wonder, however, about the duckbill seal at the end of the road draft tube - if that rubber is harder/less compliant (again, reproduction parts) than the original material, would it take more outbound pressure to open it? Probably. (Yes, I did cut the slit into the end of it.) Could this extra resistance to opening cause excessive crankcase pressure? Possibly. Would it be enough to pull the duckbill off the end of the road draft tube, put a vent/filter on the catch can, and run it? Something tells me probably not. I could check for free, but...

Breather tower first, with a drain line/supplemental breather from the fuel pump plate. since I no longer believe the repro filler/draft tube will be enough, the parts are already purchased and delivered, except a 45* angle to come up out of the fuel pump plate to make a soft transition to under the alternator. That part will be here first thing in the morning.

Since I received the throttle shaft in the mail today, I'll go ahead and put that in too. Then we see where we are.

[Rob Combs]

Got the breather system installed - that made a massive difference in how much oil it's pushing out. When I pulled the dipstick with it running, it was sprinkling a little out still, so there may be more break-in to do. Also seems to be pushing some out the crank pulley hub - maybe I'll put one of my factory pulleys in place to see how that does. I also have one more port on the breather box I could leverage (back port could become a road draft tube again), which might help. We'll see. I also have my new threaded dipstick tube/adapter almost ready to go.

Got the throttle shaft replaced, and the carbs, linkage off, balanced up nicely. No more crazy adjustments on the balance needles, and no crazy volume screw adjustments to make it run ok. No more huffing through one barrel at idle, either.

Found out the heim joints I put on the linkage are not going to work out, though. About mid-travel I get a strange feel in the pedal and it stiffens up so much it won't travel the rest of the way to wide open - that's the heims maxing out and binding. So new regular ball joints should be here tomorrow sometime. No more driving until after they're replaced and the linkage is readjusted so it will full-stroke.

Also noticed the used thermostat I put on during the build failed, so I was not able to keep any heat in the engine. Carb tuning cannot progress any further without maintaining reasonable heat (CHT dropped to ~ 150* F during the carb balancing), so I stole the ~2 year old thermostat I sourced from Clark off my 1600 and installed it on the new engine this afternoon. Also tightened up some hellacious rattles from the industrial tins while I was in there.

I've got a feeling the carb down-rods have been shortened for the heim joints so much that the standard-style ball joints might no longer reach the carbs, so that may force me to put the longer ported manifolds on it just to get the linkage to reach. Again, we'll see.

Sneaking up on it.

[Rob Combs]

Well fellas, sorry for the language, but I've got a sinking feeling my aluminum cam gear is fucked.

Strange noise at valvetrain speed getting a bit louder as I go. I'm up to all of ~ 50 miles on the engine now. Sounds like a lot of rocker side play or very loose valve adjustment.

Silvery shit in the oil when I dropped it a couple days ago. Thought it was normal break-in stuff. LOTS of backlash (clunk-clunk) before resistance if I rock the crank pulley back and forth. EDIT - clockwise/counterclockwise

Pulled the valve covers to check valve lash - a couple tightened up a thou or two but nothing alarming.

Will pull the distributor drive in the morning to take a look.

But something isn't right, and judging by the multiple posts about cam gear failures, this seems to be where I am at the moment.

This thing was an absolute MF'r to put in with the facilities I have available to me. Now it looks like it's coming back out.

Think I need a drink, or maybe a couple.



Second edit - if the cam gear is the cause, I will go CB 1399 straight cuts and never look back. If those fail, well, there's nothing minor about that.

[Brian_e]

Pull the oil pump cover, and the top gear. The stick a bigger straight slot in the pump drive hole, and use it to rotate the cam back and forth with the crank at TDC. You should not be able to feel it clunk back and forth much at all. Pulling the rockers off makes it even easier to do this.

Brian
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[Rob Combs]

Brian, what's the benefit in pulling the pump cover & drive gear vs pulling the distributor drive and looking down the hole? Am I missing something important here?

I have already pulled the distributor drive, looked in there, checked the backlash, and put it back together so it can at least run.

Good news is the teeth on the cam gear are not visibly damaged. Nice square tops on the teeth. To the naked eye, and even with an inspection camera for a closer look, it looks like there's nothing wrong in there. Until we actually inspect the backlash. The oil that's in there now looks pretty clean, as opposed to the oil used to break it in.

Bad news is there are 3 full degrees of crank rotation in the backlash. I had about .001" backlash when I put it together. Nowhere near this kind of gear lash. Turned over smooth as butter upon assembly. No signs of binding or foretelling of excessive wear.

The crank gear is a factory vw steel gear that I got from the machinist where I bought the case. He assembled the gear to the crank for me as well.

Has anyone seen this? Does anyone know the likely cause? Shitty gear? Heat treatment/hardening process gone wrong?

It just feels like it shouldn't be driven until it's taken back out, pulled down, and fixed. On the fence as to whether to park it for the time being and freshen up my 1600 to put back in there temporarily, or see if I can find a garage to put it in while I fix the motor.

My parking situation is such that I can't let it sit around with no engine in it for any real length of time. Slipping a motor in there on a weekend evening is one thing, pulling the motor to essentially rebuild it is quite another.

EDIT: am I using too much spring pressure? I have Scat duals shimmed to right at .070 from coil bind, variance in shim thickness notwithstanding.

[Rob Combs]

And this will likely be the last update until I choose a path forward and get this thing resolved.

Popped the distributor drive back out this afternoon and actually rotated the engine through several revolutions - the cam gear is definitely toast. Two sections about 30 crank degrees wide just about 1 crank revolution apart. This is beginning to look more and more like a gear was out of round - whether it's the crank gear forced out of round by a woodruff key (factory woodruff key and factory crank gear on a Scat crank), or it's the cam gear itself. The one crank rotation/180* cam rotation kinda points the finger at the crank gear/woodruff key fit. That's one of only a few operations I farmed out so did not get to feel how it all went together, and will never really know for sure because I wasn't there.

I am surprised, however, that this did not reveal itself during the build.

Now I have a real dilemma; a few options I can play -
1) pull the new motor, reinstall the 1600 as-is. Deal with the cam gear problem at my leisure.
2) refresh the 1600 and find out why the heads run so much hotter than the 2027, re-ring, optimize compression, reseal, maybe put my 2239 cam in it and bump to 9:1, install it in place of the 2027 and rework the 2027 at my leisure
3) go to the (somewhat) local DIY shop, pull the motor and either put straight-cuts in it right there on the spot, jam it back together at their facility, and just pay the hourly usage rate, or
4) pull the motor, bring it home, pay the daily vehicle storage fee, put in the straight-cuts on my own timeline, take the motor back out there and reinstall

Options 1 & 2 require me to be a little discreet, get better/higher/more stable jack stands and work in the shadows
Options 3 & 4 require me to pay up for the time I use and any vehicle storage I might need, but I'd have access to a lift, a properly equipped shop, and since everything is already measured up, broken in, and ready to go, I could probably do the whole thing in a day or so. Take all my own special tools, sealant, and chemicals, and should be just fine unless there is additional damage I do not at this point foresee.

But I think I got it in time to avoid most big problems.

It's a shit situation, but I will find a way through. Actually, typing this out I believe I am beginning to answer my own question.

Time for a cocktail. Gotta clear my head.

Thanks all for the input. And those posters from the past who've been here before but I did not know ahead of this to search for their plight. It's all been helpful.

As I've said before, hopefully someone out there will read this before they build and be able to get in front of these things before they happen.

[dunk]

Sorry to hear of the problems...

You seem to be pretty thorough with things, so....
I would tend to agree with the conclusion... that one of the few things you didn't do.. is more likely, to be the cause of the problem..

I had a similar thing happen..

I built the engine up, tested everything.. fully mocked up.. multiple times... was very happy..

But hadn't had it dynamically balanced...

OK... took the rotating assembly to my local engineering shop that does this, they got it done... no obvious problems..

Was building up the case to seal it up, and noticed the Crank was jamming?!... whaaat?!

took out the cam... it was fine... put the cam back in, it would get so tight it would lock up... hmmmnn....

I just couldn't see what it was.. i was just about to put sealant on the case halves, and now ive got to strip it down?! What the hell has happened here?! ... so, took everything out again, stripped the crank down...

And... after a lot of coffee, found... that the person who'd balanced it.. had put the steel cam gear on with a drift or punch, and a 4lb lump hammer... you could see the "peening" marks on the gear FFS .. that was enough to alter the shape of the gear... and make it jam.. I hadn't noticed it when I assembled the crank for the last time. My bad!

Put another used Crank gear on there... perfect...

I was lucky that time, managed to catch it...

I would think a badly sized woodruff that's then had the crank gear "brute force n ignorance'd" on.. would also do similar...

It's a pain now. But youll find what the exact problem is, and it'll be awesome when it's fixed I'm sure.

"Rebuild, and refuse to lose!...."

I still have that crank gear to remind me to check!

[Rob Combs]

Thank you for the positive comments and your story about how fragile the gear setup can be.

I wasn't in the shop when the gear was put on the crank, so I cannot know if it was gorilla forced on there or anything else about it. But it's sure starting to feel like that's what happened.

I'm not going to give up now, I've gone too far to not see it through. It'll just be delayed a bit, probably into next year.

I have several shelves of good and new parts; I doubled up on a lot of parts when building the 2027. Some by accident, others by design. So I'm leaning toward cleaning up the 1600 I pulled out of there, disassembling, checking it over, re-ringing it and resealing it, make sure the heads are still ok (it only has ~ 4k miles on it but the heads have been over 400* a few times), change the cam to the 2239 that was initially going to go into the 2027, give it a little compression, and take it all down to a place about 20 miles to my east that rents out garage space by the hour with lift and tools included. No sketchy jack stands, tippy floor jacks, working in the shadows, sparse lighting, having to hurry, or any of that BS I went through to get the 2027 in there.

Already have a CSP high-flow muffler, slightly modded CB center section with the gooseneck cleaned up, and a 34 PICT 3 with a 28.5mm venturi. Should run pretty well as far as 1600s go.

I figure if I take my hydraulic lift table, the refreshed 1600, and the car all down there on a flatbed I can probably exchange the engine and have it running again in about 4 hours, maybe a little less. Took me 5 round trip doing the install on my back on jack stands that don't lift the body quite high enough to clear the fan shroud going in.

Then tear down the 2027 and inspect for damage, pull the galley plugs and thoroughly clean it out, probably convert it over to straight cuts, repair everything as necessary, then when it's all done do it all over again.

Just a bump in the road, albeit a big one.

[early]

i had a similar problem with cam gear backlash.

i fitted a Berg vw cam gear drilled for reuse and fitted it to a stock vw crank gear.

within a few months it developed a suspicious rattle, turned out to be cam gear backlash.

but in actuality it was the keyway was too small and worked the cam gear keyway slot larger so the slop was in the keyway slot as well as the magnesium vw gear.

video looking in thru the removed generator stand you can see the slop.

https://youtu.be/rfhYQbqlyF


now replaced with CB 1399 straight cut gears.

good luck it can be frustrating working on these vw engines some time.

i just pulled my bus engine out yesterday to replace a leaking main seal and pressure plate ( the alignment was awful when torqued to the flywheel, so i swapped it, i.e. the ring that rides against the throw out bearing was out of alignment .

put the engine back in today and fingers crossed. so far.
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