Sunday, April 10, 2016

Quality time with Winston, Part 2

It's taking me forever to get anything done with anything VW related.  I have decided the best use of my time is to focus on projects that result in a significant reduction in the use of storage and garage space.  VW engines are fairly compact packages when built out, but not when strewn about in pieces.  And I think we can all agree that the best storage place for a Karmann Ghia engine is when it's correctly built and installed within its respective car.  So, I'm getting on with it then. Two engines to build.

I next decided to 'warm-up' my engine building skills with Winston's 40 Horse.  When last we checked in on Winston and his 'freshly rebuilt--though seriously ailing' power plant, it had a significant oil leak.  It was misfiring, had an exhaust leak or two, and was just generally unhappy with its lot.  In the three years since then, I've collected a bunch of parts and should have some good options for this rebuild.  As mentioned, I found enough wrong during the main seal replacement with the flywheel and its shims that I decided a complete teardown would be a good idea.  Again, that big puddle of oil developing under the car after each run really drove my decision.  I also felt a little excessive heat, saw a fluttering oil light and some disturbing ping'ing during hard acceleration, even with modest distributor advance.  Made me wonder if the installation of the Mahle 40 Horse Big Bore kit and previous head flycutting resulted in an excessive compression ratio.  Lots of concerns and time to lift the veil of mystery and get my hands dirty to resolve it all.

I chose to use the original heads, case, 180mm flywheel and hardware.  The heads are square boss '65 heads and they cleaned up real nice.  The flywheel was already done.  The case was sent to three different places to check for cracks--with none found.  It was then sent on to RIMCO to again check for cracks, then machine for double thrust cam bearings.  It also got ANOTHER line bore!  Because after 375 miles it needed one!?!?  And that line bore also went along with a custom thrust cut to #1 main bearing.  The lifter bores were surfaced/clearance.  The case already had the inserts for the head studs and cylinder deck seemed ok.  I had RIMCO send along a set of Silverline (#2 steel backed) main bearings and found that they are really, really nice bearings.  Dare I say nicer than the Mahle/Kolbenschmidt bearings I've seen of late?  I was worried about Silverline--but no longer.  Cam bearings are Mahle double thrust, because they were locally sourced at NuVintage.  I chose a set of Bugpack lightweight lifters and a Norris 329S cam, with a Webcam bolt on gear I had laying around.  The pump is a nice old Schadek 21mm.  I found a set of 6mm sealing nuts and a real nice stock cover for it, then blueprinted the pump.  No clearance of the pump body was required, otherwise.  I did have to work over the cam bearings to give the cam a little endplay in the case, but the lifter to lobe clearance was plentiful.  The crank was NOS 64mm.  The rods were the original to the engine, balanced end to end and for total weight.  New pressure place was sourced, because that's what you do.

I then decided to have the engine parts dynamically balanced, but I made a mistake by not using Denver Balancing for the work.  The shop I used instead found a bent crank pulley, so I had to source one and this turned into a year long inexplicable ordeal to find the correct part and have it powder coated.  The second round of dynamic balancing went well--until I checked the shop's work.  Let's just say that I might as well have not bothered with balancing because their idea of balancing is not mine. and had to fix some of it.  I've got to check and see if Denver Balancing is still in business and use them instead.

Anyway...all seemed in readiness...until I requested a re-hone of the cylinders.  The shop delivery person accidentally dropped them onto the shop parking lot and made quite a mess of them.  I don't know the whole story, but a scramble ensued to find me another set.  These pistons and cylinders were the old style Mahle 83mm 40HP big bore with ~350 miles on them, so they were essentially like new.  I paid good money for them.  However, what I got back was...well...I don't know their provenance, really.  They aren't well balanced.  I don't like what was done to the piston pins to clean them up because they are really sloppy in the rod bush.  It's not the stuff I sent them and I kind of feel cheated, really.  And, they are not easily replaced with as new parts.

The 'cylinder kit incident' happened easily two years ago, but it sort of left me a bit disinterested in the project--that is, until I purchased an  'AA Pistons' 40Horse Big Bore 83mm kit shortly thereafter.  Yes, they are Chinese parts and I was afraid of them.  It served to stall the project, further while I half heartedly looked for NOS Mahles.  Only recently did I actually pull one of these AA pistons out of its liner and take my first look at things.  Let me say that I was really impressed and unimpressed, all at the same time.  The cylinders are great.  I ran calipers, tested ring gaps (Deves), and used an internal bore gauge to measure everything, and was quite happy with the cylinder.  The piston rings seem like they might be Grants--or, clones.  Completely usable, but I'm going with Deves.  The piston pin retainers are decent circlips and completely usable.  Now, what I did not like at all was the casting and machining of the pistons themselves between the crown and the first ring land.  Two pistons were scratched and pitted, where it seemed they didn't get the machining correctly done to remove all of the casting recesses in the raw piston.  I'd classify these as 'Seconds' and not necessarily something I'd want in my freshly rebuild engine.  Having discovered this well outside of my warranty period, I ordered another set of pistons from 'AA Pistons' for $100.00, shipped.  We'll see how these look, and then go from there.

While I'm waiting for the pistons, I've decided to get the deck height sorted using the pistons I have.  I'm assuming that AA Pistons hasn't made any broad and sweeping changes to their piston design in the past three years...and probably is a rash assumption on my part in any case...but what I found is that the AA Pistons do not like my '65 Type 1 case.  The case at the case webbing at the #3 spigot interferes significantly with the piston side skirt at the flywheel side and I believe I will have to crack apart the case to do some grinding.  The Mahle pistons don't have any problems, here, and when comparing the two pistons I can see why.  The Mahle's have a shallower side skirt by quite a margin.  So...there's that.  I also compared the deckheight measurements for both the Mahles and the AAs and now have an idea of the cylinder base shims I need for piston to head clearance for each, but need to 'cc' the heads to adjust that to reduce the compression ratio to sane levels.  In the AAs favor, I was given a more consistent deck height measurement across all cylinders.

This is getting fun!

UPDATE:  The pistons arrived today and they are excellent.  No casting marks, scuffs or other abnormalities.  Unfortunately, the piston design remains the same and there's still the interference with the case at #3--and possibly with at least one other cylinder spigot.  Deck height remains unchanged with these new pistons, so that's good, but weights are all over the place.  Piston pin weights are nearly 20 grams more than the Mahle pins. I use the old Mahles, or crack the case and clearance it, then go with the new AAs?  Hmmm....

1 comment:

Aaron said...

Fantastic work. Keep up the updates. I will upload some images of my 2 x 1500cc based engines also under construction. Regards- Aaron Britcher.