VW Type 1 Engine


WARNING: I am not an expert on cars, automotive engineering, VW Beetles, beach buggies or anything else discussed in these pages. What I have written is my current understanding of the issues involved in building Tina's buggy. These opinions are based only on my own research in books and on the web. They, therefore, have no basis in fact, may well be wrong and potentially downright dangerous if taken to be gospel truth. If you intend to use any of this information for any purpose other than pure entertainment, then please get its validity confirmed by someone who knows what they're talking about! You have been warned...

This page contains the following Sections:

Long Block

VW Type 1 air cooled long block

The long block is the fundamental basis of the engine and consists of the crank case, flywheel, crank, bearings, connecting rods, pistons, cylinders, cylinder heads, cam, valve gear and valve gear covers, as pictured above.

Whilst building my buggy, I have aquired a number of 'spare' long blocks that could be used for Tina's buggy:

Whilst choosing a suitable long block for Tina's buggy, I considered the following options:

I didn't consider anything less than a 1600 TP, as Tina wants her buggy to be pretty quick. I have not considered any non-VW or non-air-cooled options, even though these can potentially deliver more power and better reliability than an air cooled VW, as I know nothing about water cooled engines and I want to minimise the complexity of Tina's buggy by keeping as many components stock VW as possible. All of the options I considered are designed to run on unleaded petrol.

My main considerations in selecting the type of long block for Tina's buggy are that it should make good power, look good, utilise one of the long blocks that I already have and not be too expensive. Having bought a long block for my buggy, I also wanted to build an engine from scratch as a learning exercise for me, Tina and Laurie. I, therefore, decided to build a 1641 TP long block out of the 1300 TP given to me by Zane, as I'm unlikely to use this engine for anything else and it's just cluttering up the garage.


Bosch 009 Distributor

Having chosen to build a 1641 TP long block, I now need to choose a distributor.

There is a wide choice of distributors available for the VW Type 1 air cooled engine, ranging from stock to high performance. Some of these options are listed below, in increasing order of (approximate) price in GB Pounds:

The major choice to be made between distributor types is whether they are of the centrifugal or vacuum advance type. With the former type, the ignition timing is advanced, as the engine revs rise, by centrifugally operated weights within the distributor body. With the latter type, the vacuum in the inlet manifold is used to advance the ignition timing via a diaphragm on the outside of the distributor body. Of the above listed options, only the ACN SVDA Distributor is of the vacuum advance type. Note: Stock VW distributors are normally of the vacuum advance type but since the 1302S donor Beetle engine is a remanufactured unit, it has a reproduction Bosch 009 centrifugal advance distributor and I don't have any stock VW vacuum advance type distributors.

The choice of distributor type must be made in conjunction with the choice of carburetor, as some carbs are designed for vacuum advance distributors and have vacuum take-off points for this purpose, e.g. the stock VW Solex PICT carbs, whereas other carbs don't have vacuum take-off points and must, therefore, only be used with centrifugal advance distributors.

It is possible (but sometimes not advisable, depending on the carb type) to use any type of carburetor with a centrifugal advance distributor but impossible to use a vacuum advance distributor with a carburetor without an appropriate vacuum take-off point. Using a vacuum advance distributor without a proper vacuum feed will result in an engine that will only run properly at tick-over :-(

The choice of carburetor configuration is also linked to the choice of exhaust system, in that many after-market off-road exhausts don't have the necessary manifold heat riser ports for use with a single centrally mounted carburetor, which means that you must use dual carburetors with this type of exhaust system in all but the hottest of climates.

Since Tina wants to use a shiny after-market 4-into-1 or dual-cannon exhaust system, and these are likely to come without the heat riser ports, I will need to use dual carburetors. My choice of dual carburetors are Dellorto DRLA 40s, which although they do have vacuum ports on them, these are meant to be used only to balance the carbs, rather than to work with a vacuum advance distributor. This in turn means that I need a centrifugal advance distributor. Further details about the choice of exhaust system and carburetors are given in their respective sections.

Having chosen the type of distributor that I need, the choice of make and model is basically one of price vs. performance/sophistication. You pays your money and makes your choice :-)

The Bosch 009 is probably the most widely used distributor on VW replacement and performance engines and whilst it isn't the 'best' quality unit available, it is generally considered to be adequate for most applications, provided that it is timed dynamically, with a strobe, rather than statically with a timing light, due to its erratic advance curve. Bosch have recently stopped making the 009 distributor and, whilst they are still available (at time of writing - Oct '06), stocks are now dwindling.

In order to obtain reasonable performance as cheaply as possible, I will use the Bosch 009 distributor from the 1302S donor Beetle on Tina's buggy. This will use the standard points ignition system.

Fuel Pump

VW Type 1 mechanical fuel pump

The fuel pump draws fuel from the fuel tank and supplies it to the carburetor(s) at a suitable rate and pressure. A fuel pump is required unless the fuel tank is high enough in relation to the carburetor(s) to supply fuel by gravity alone. Since the fuel tank will be in the front of Tina's buggy, at a similar height to the carburetors, a fuel pump will be required.

The basic choice with fuel pumps is between the stock VW mechanical fuel pump and after-market electrical fuel pumps.

The stock VW fuel pump is both simple and reliable and supplies fuel at a suitable rate and pressure for the most commonly used off-road carburetors. The stock VW fuel pump is driven by an eccentric cam on the distributor drive shaft.

Electrical fuel pumps, on the other hand, are typically able to deliver more fuel at a higher pressure and so tend to be used in very high performance engines. However, since they require an electrical supply (by definition!) they are likely to be less reliable than their mechanical counterparts and will not work with a flat battery. Also, electrical fuel pumps are not self regulating and so are generally used with a separate pressure regulator between them and the carbs.

In order to obtain reasonable performance as cheaply as possible, I will use the stock VW mechanical fuel pump from the 1302S donor Beetle in Tina's buggy.

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