Sunday, October 11, 2009

Building a power plant for the Nautilus, Part 1

Time to start building an engine for the Nautilus. After all, I actually plan to drive it, not trailer it. It's been better than 16 years since my last VW engine build and there are aspects of this that I'm certain will be a challenge. I used to put together some very good engines and we'll have to see if my skills remain intact.

The original plan for this engine was to go bone stock with it, but I discarded that notion as purely sentimental. Stock early Type 3 engines are fraught with inherent design flaws. Why reinvent that same old problematic wheel? How about taking the good parts and ideas from the much loved original power plant and marry them to what was good and wholesome in the later engines? Build the 1500S engine, but this time with a few internal improvements. Nothing Earth shattering mind you--just apply the updates that can be implemented simply to improve the reliability.

The Nautilus did not ship from the previous owner with an engine. In fact, it did not ship with much more than a body shell. The transmission and unoriginal front beam where there, but much of the pan was rotted. It was left to me to find an engine. I've searched for a decent core engine for many years, buying up a number of potential candidates for a '64 power plant. For some reason, I always seemed to stumble on '63 model year cases easily enough, however it was only very recently that fate lent a hand and gave me what I sought: a nearly numbers matching engine case with an original Type 34 provenance. The engine number on the case could have been installed in another Type 34 the very same week the original engine was installed in the Nautilus. What an unbelievable stroke of luck! All for a bargain price of $40.00. FINALLY!

Early Type 3 engine cases, unfortunately, suffer from the same pitfalls and weaknesses of their Type 1 40-Horse brethren. Engine cases from this era of VW production actually suck. While you really wouldn't want to base your 2-liter hot rod engine on such a crank case, a 1500cc or possibly a 1600cc engine is just fine. With a few case modifications, you can also work through some of the low oil pressure issues caused by the anemic output from the early oil pump. Cam bearings, head stud inserts, uprated lifters and cam, blueprinted oil pump, balanced internals, using a cross drilled 8-doweled counterweighted crank are all factors that play in the favor of longevity for an engine based on a 40-Horse engine case.

I did indeed decide to go with a counterweighted 8-doweled 69mm cross-drilled crank, with a tapered flywheel junction to allow the use of an O-ring flywheel seal. The flywheel used is an O-ring 12V 200mm flywheel, with the 12V ring gear machined off, and new 6V ring gear pressed on. The rods are brand new VW high performance, with self-aligning caps, balanced end for end, and for total weight. The pressure plate is a stock 200mm unit. The pistons and cylinders are a complete NOS Kolbenschmidt 1500S dome top piston set, with cylinders that have the narrower and more numerous fins for better, more even cooling while under operation. I am intentionally aiming for a compression ratio of 8.5 to 1, which was stock for this engine. To further increase reliability, I have decided on the the use of later square rocker boss Type 3 heads. Cooling on these heads is far better because of the cooling fin configuration. Equally as important is the square rocker boss design that helps to prevent unfortunate valve train incidents as I motor on down the road. What is particularly interesting about the heads I've chosen is that the combustion chambers were cut into a hemispherical shape, similar to those done by Gene Berg. This should allow for a better fuel mixture burn, particularly when coupled with the 1500S dome top piston. This could possibly help keep things a little cooler and possibly reduce the chance of 'pinging'. The problem is that they will need further flycutting to bring the compression ratio into specs and I'm hoping there's enough meat in them to do this.

I used to build VW and Porsche (356/912) engines that would generally go for 100K miles without a lot of fuss. There is always a heavy reliance on quality machine work to make this happen. I chose to go with RIMCO for the case machining. The flywheel, rod and crank machine work was excellent, however the packaging done for shipping was poor. The crank and pressure plate hit each other in shipping and the pressure plate may have been bent a little. It was definitely dented, so I decided not to use it and will use another brand new one I have in stock, along with a brand new set of VW high performance rods I've had around here for years gathering dust. The fan, crank pulley, bolts, pressure plate, flywheel, crank and other hardware were all recently checked and balanced by Denver Balancing. I also had them balance the NOS 1500S dome-tops pistons, too, so this should be a very smooth running engine when assembled.

Compared to a 356 piston, the 1500 S piston is actually fairly tame. The dome measures approximately 5.1 cc's. Regardless, they are plenty cool and being NOS German Kolbenschmidts makes them fairly rare, too.

There are still a few parts to round up, but I'm getting some help with that. Jay at NuVintage VW Parts in Arvada, CO, had a NOS set of VW lifters in stock and also provided me with a brand new camshaft. The rest of what I need is fairly common and I might even have them already in my parts stash, but I need to have a set of carburettors rebuilt.

My hope is that I have the engine ready to bolt up when the car arrives home. I don't think I'll actually make that deadline, but it will be close.

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