With the interest recently of how to convert a Type 4 engine for use in a Type 1 (Beetle, KG, 181, etc.) and in the early Type 2, many of the Type 3 owners have wanted to join in on the fun.
Actually, it's a natural curiosity, as both the Type 3 and the Type 4 engines utilize a lower profile cooling system (often referred to as a "pancake" cooling system) with the fan bolted to the end of the crankshaft and the shroud bolted to the end of the crankcase. They are on the opposite end of the engine from the flywheel. The fan blows the cool air over the cylinders and head and the shroud and engine direct it to the hot spots. The low overall height of the cooling system allows for a second trunk: one in the front (like in the Type 1s) and another trunk over the engine.
So, being the eager Type 3 owner, you want to know if this conversion is possible. Yes, it is possible, though it's not as easy as unbolting the Type 3 engine and bolting in the Type 4 engine. There are a few areas of concern when doing a Type 4 conversion into a Type 3 car: flywheel/clutch, intake, exhaust, engine/transaxle mounts, engine support bar, dipstick, fan intake boot, and oil filler. Each area will be a cause of interference, but most of the time it's relatively minor. Now let's look at each point and see how we can overcome them.
Because the Type 3 transaxle is basically identical to the Type 1, there's no point in me restating what I've already discussed in my flywheel and clutch tech articles. Please refer to these articles for what you'll need to do in this area.
The added weight and torque of the Type 4 engine puts quite a strain on the engine and transaxle mounts. If you drive your Type 3 hard or if you modify the engine, you'll make the situation even worse.
The early Type 3s used a front transaxle mount (commonly called the nose cone mount) and two bell housing mounts (the same ones as the Bug cradle mounts). The transaxle is mounted to frame horns essentially identical to the Beetle. This method suspends the engine without any support on the shroud end. It is suggested that you provide support additionally with a rear engine support bar. This bar is bolted to the case underneath the fan shroud and is then bolted to the body.
Those of you with Type 3s with IRS (double joint axles or the tranny with CV joints) don't have the transaxle mounts at the bellhousing. These cars relied on the nosecone mount and a rear engine support bar. This setup works for a stock 1600cc Type 1, but additional support is recommended when doing a Type 4 conversion.
To support a full on Type 4 in an IRS equipped Type 3, it is suggested to get the torsion housing out of an swingaxle Type 3. It's a direct bolt in, but you will have to weld in brackets for the IRS diagonal arms. This will provide you with a nose cone mount, two bellhousing (cradle) mounts and the rear engine support bar.
For the really hot Type 3, other means of transaxle support are required. My personal favorite is the Gene Berg Enterprises's intermediate mount. It will provide a solid third mount for the transaxle and keep the nosecone end from lifting under those hard starts or power-shifting. This mount is only usable with a Type 3 with frame horns, so the stock setup on an IRS car will not be able to use it.
Now that you understand the importance of the engine support bar, we can look at what is required to make it. This bar requires some fabrication skills. For most Type 4 conversions, the stock Bus bar is more than adequate. You will have to cut about 1" off of one side of the bar, and provide some kind of bracket to mount the bar to the body.
If your plans call for a lot of horsepower (like 200bhp+), I would suggest that you look into fabricating a larger, and stronger bar. My suggestion would be to manufacture it out something large like 1" square tubing. Pay particular attention to how the bar is mounted to the body; too weak a mounting and the next burn out you'll have a project for the next weekend. So, for the hot street crowd, I'd have a heavy duty nose cone mount, heavy duty cradle mounts, a custom engine support bar, and a rubber mounted Gene Berg intermediate mount. This combination should provide all of the support you'll need for spirited street driving.
The difficulty here lies in your choice of intake systems. The easiest way (in terms of fitting to the engine) would be to use the stock dual carbs from the 411/412 station wagens. They used really short manifolds and 34PDSIT carbs (the same carbs found on the '72-'74 US market Transporters). This would be an easy way out if you're in Europe, but these manifolds are basically non-existent here in the US.
The best option is to use the Weber IDF and Dellorto DRLA series carbs. There are readily available manifolds for the Type 4, but that isn't the end of the story. The problem with these manifolds is that they are too tall. These manifolds, with carbs and 1.75" tall air cleaners will rise above the trunk floor of your Type 3.
The solution to this problem is to cut the manifolds down to a much smaller height. FAT Performance and Eurorace have done this modification in the past, so they are the ones I would contact for getting this done. The people I've talked to say they've paid about $250 for new manifolds that the shop modified appropriately. It's not cheap for manifolds, but the IDF/DRLA carbs allow for a lot of tuning adjustability.
These manifolds could also use the IDF/DRLA style throttle bodies that are commonly available. This provides the best of both worlds. You can use off-the-shelf components for the throttle bodies, standard linkage, and get the power and tune-ability of a programmable electronic fuel injection(PEFI) system.
The next option requires a lot of skill and knowledge. This option uses the stock fuel injection manifolds and throttle body. It would require a total adaptation of the stock Type 3 fuel injection parts and the stock Type 4 fuel injection parts. The other alternative is to use the stock manifolds and adapt aftermarket EFI components. Either adaptation is difficult to do, so it should be left to an experienced tuner.
The saying is "what goes in, comes out", and that's how we start the section on the exhaust system. I would first recommend that you read my tech article on exhaust systems. It will give you some background information concerning selecting exhaust systems in general, particularly size and type.
What makes this part of the conversion difficult is that there are no readily available exhaust systems for the Type 3/Type 4 conversion. You will have to be creative with the stock pieces and the readily available aftermarket parts. We'll look at the exhaust in two pieces: manifold (usually referred to heater boxes or jtubes) and the exhaust system itself.
The exhaust manifolds bolt to the exhaust ports underneath the heads and generally do a 90° turn to exit back. There two basic manifold suitable for the Type 3: the Bus/Type 4 heater box with twin port flanges (used through about 1974) and the later Bus single port manifold that exits towards the front. This later system merges the two exhaust tubes into one flange. Either system should work for a mild street application.
If you are looking for a higher state of tune than that, with a large camshaft, large valves (48x38, 50x40) and an insane displacement, you'll need to make a manifold out of larger tubing. This is best left to an exhaust shop that knows what they are doing.
It should also be mentioned that one difficulty you may run into with the exhaust is the header/muffler clearing the rear body. The modified j-tubes mentioned above have been shortened 1" to bring the header closer to the engine and away from the body.
All of the people that I've talked to have used exhaust systems designed for the Bus. The Bus exhausts are designed to clear the fan shroud and still not stick too far beyond the body. For most Type 3 conversions, the header/single quiet pack muffler for the '72-'74 Transporters seem to be the best option. It features a 4-1 collector, inexpensively priced and easily modifiable for different muffler.
The Bus Monza system is also usable, though the exhaust tips seem to stick out a bit too far and it's way too restrictive to get the most power out of your engine. I'd stay away from these exhausts, even if you are not looking to win a drag race, as the most efficient exhaust will reward you with better gas mileage, better smooth drive-ability, and cooler engine temps.
So, for the exhaust system it pays to do some careful measuring and trial fitting. This careful preparation will ensure that you have less problems after the engine is installed and running.
It's been found that the easiest way to accommodate a dipstick in this conversion is the use the long dipstick from a 914 case. A Bus case could also be used, but a machine shop would have to install the dipstick tube in the same location.
If you are looking to do an ultra clean conversion, it would be suggested to look at using the Type 3 oil filler and dipstick mounts on the body. It would probably be possible by modifying the Transporter oil filler/dipstick tube. That way you can check the oil and add oil to the engine without opening the engine cover. Some careful planning and a little fabricating, and no one will realize that deep rumbling in the back is a Type 4 engine, even at the service station.
My personal recommendation is that you also look into using one of the Gene Berg Enterprises oil temperature dipsticks. It is an inexpensive tattle tale to tell you when the oil temperature rises to the 227°F range. This dipstick, in conjunction with the stock oil pressure switch provides basic engine monitoring for an insignificant amount of investment.
WIth an air cooled engine, it is critical that the engine be fed a diet of cool air. On the Type 3 (and the Type 4 station wagen), this air was pulled in through vents in the rear fenders, direct to a rubber boot that connected the body to the fan shroud. Without this boot, the fan will pull in the hot air surrounding the engine, and will not properly cool the engine. You will want to mock this setup with your new Type 4 engine.
After a lot of research, it has been found that the 411/412 station wagens (Variant) used a very similar setup that is handy in this conversion. The boot flange that bolts to the Type 4 fan shroud is quite rare. A VW parts manual shows the part number as 021-119-609A and was installed on all years of 411 and 412 station wagens (variants).
The most difficult part of solving this problem is locating this flange. You will probably have to check local wrecking yards, eBay, or maybe see if you can get your local VW dealer to check their shelves for an NOS one. Use this flange with the rubber bellows and clamps and your engine will be getting a supply of fresh air.
The various Type 4s used two different types of oil fillers. One was a plastic funnel bolted to the breather box on top of the crankcase, and the other was bolted to a flange on the rear of the case, just to the right of the oil pump. The easiest solution in this case is to take the breather/filler, cut down the filler and re-attach using a putty bonding agent like JBWeld. A fresh coat of black paint and no one will be the wiser.
1). Submitter Steve Glavas made the suggestion to use the Type 4 fan shroud from either a 914 or a 411/412. These shrouds had a screw plug on the top of the shroud that allows easy access to the timing mark on the cooling fan. If you don't use this particular shroud, it will be necessary to remove the air intake boot to check the ignition timing.
2). Submitters Nate Morse (Nate's Aircooled Tech) and Greg McGee have designed and templated a piece that allows you to mate the Type 4 fanshroud to the outer half of the Type 3 housing. This allows you to use the stock Type 3 cooling bellows boot. <I will post a link to where you can download the template as soon as I can find it.>
3). There is a great discussion thread on the Type 4rum on Shoptalk Forums entitled "Best Type III Conversion Factory Parts" that includes a lot of great information in doing a nice looking Type 4 conversion in a Type 3 along with pictures.
4). Nate Morse has another discussion great discussion the Type 4rum entitled "New Project: 914 2.0L into '67 T-3". He shows how he is building a Type 3 with a Type 4 engine. His goal is modern performance with factory looks. The thread shows how he designed and assembled the bellows adapter mentioned above. It's a must read if you are considering putting a Type 4 engine into your Type 4.
I want to thank Dan Zink, Tom Notch, Nate Morse, Piledriver, and Steve Glavas for their help with this tech article. I don't own a Type 3 myself (though I plan to someday), but these great guys do, and have done this conversion. They were kind enough to answer my questions and share their experiences. Thumbs up guys!!