Sunday, April 10, 2016

Building a power plant for the Nautilus, Part 2

As mentioned, I'm building two VW engines right now.  I figured that if I'm in 'engine building mode', I might as well stay with the program.  Besides...there are now some serious space considerations and building and installing engines fits with my goals.

I thought I had a well developed plan for the 1500S years ago.  I found a decent, potentially numbers matching engine case from a completely parted out Type 34 in reasonably good shape.  I had it sent off to RIMCO for double thrust cam bearing cut, line bore, cylinder decking, lifter bore dressing, case savers, oil galley plugs removed and threaded, and to have the top breather port cut to the 'D' shape.  This last bit was to address potential blow-by issues in the Type 3 1500S engine as noted in a factory bulletin from early '64.  I'll have to address this opening a bit because it really isn't the correct shape and needs a little cleanup to allow the metal breather plate to be installed flat and in the correct orientation.  My new drill press will get a workout, I think.  Otherwise, the case just needs a really good cleaning...or, so I thought.

I've never really been happy with the 69mm crank I have.  It's a DPR crank and should be a good fit in the engine case, but I noticed some welding at the gussets that should have been better dressed during its production.  Maybe no big thing, but I'm not happy with it.  The rods I have are reworked stockers and are ok, but nothing special in the balancing.  The flywheel is stock weight, but 8 dowelled/6 Volt/200mm with an O-ring--so that's kind of different.  Nothing really unique in this engine configuration and it really just represents an overall upgrade of the stock configuration.  On the other hand, it could be argued that it comes with a downgrade because the counterweighted crank is heavier than stock.  To offset this, a couple of years ago I decided to have a lightened 13lb flywheel constructed, 8 dowelled/6 Volt/200mm with an O-ring.  I have a tachometer for the Type 34 to monitor RPMs and I figure it might liven things up for the typical driving I plan to do in the car.  If I dislike it and the car bogs like heck on the hills, I'll have the stock weight unit to go back to.  I plan on having both flywheels balanced for this engine so I can do that without throwing things out of balance.

A few months ago I was inspired by Aaron Britcher and his 74mm SPG based engine to purchase from DPR a 74mm plain bearing crank for my engine build.  At the same time, I also purchased a set of 'AA' brand Porsche length (5.325") stroker connecting rods, which should help maintain the external size of the engine given the 'A' pistons I will be using.  A set of ARP 2000 rod bolts was included with the rods, which was unexpected and very nice to find.  The pistons I plan on using are the Kolbenschmidt 83mm dome top 'S' style, so this should essentially give me a Porsche 356/912 internal engine dimension and result in an approximate 1602cc displacement.  This configuration worked for Porsche and their relatively heavy cars, so it should work for me and the Type 34.  With an Engle W100 cam, gear and lifters, I should be all set, but I also plan to try 1.25 to 1 rockers.  None of this is earth shattering, but it should give a little extra grunt to move a heavier Type 3 vehicle.

The heads are square boss single ports with heavy duty springs.  I want to say that these are those that would be found on the '66 Type 3 engine.  I had some polishing done, but their ability to breath might be the weak link in this engine.  I might want to have some more work done to them by folks who know best.  It also depends on what needs to be done to help the carburetors breathe a little more.  I plan to run stock carbs, re-jetted for altitude, with larger venturis.

I'm doing a lot of measuring and gut checking right now.  I might need to do some grinding on the case to fit the larger crank.  Once everything is clearanced, I'll send parts out for balancing--but I think I need to find another shop for that work.

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