How To:
Type 4 Conversion: Where to start

This page was last updated Tuesday, September 15, 2009

Ok, you are now thinking to yourself, "I'm convinced a Type 4 is right for my car. Where do I start?". Well that's where this page comes in. I will show you, step by step, the simple process of converting a Type 4 for use in your Bug. This is not intended to be a shop manual replacement, just a broad overview of what's involved in the conversion.

Throughout this page I will be assuming that you will be converting a good running stock longblock for use in a street Bug. For the most part this article will apply to most other VWs, but for the sake of simplicity, I will assume the Bug.

Step 1: Finding and purchasing a Type 4 longblock.

The first step in the Type 4 conversion is to find a good running longblock. This can happen at a junkyard (wrecking yard), through word of mouth from a VW or Porsche club, or online at places like eBay, Shoptalk Forums, or Pelican Parts. If you can see/hear it run, at least you know it's in good condition.

It really doesn't matter what car the engine came from originally. A 914, 411/412, or Bus engine are, for the most part, identical. There are some minor differences, so it's good to know which chassis it came from. Generally the 914 engines have lived the easiest life, as the 914 is a very lightweight and aerodynamic car, whereas the 411/412 is quite heavy for a car its size, and the Bus is both heavy and unaerodynamic. You can look up an engine serial number at this page. I've found that many 914 enthusiasts will sell you a running 1.7 or 1.8 for a very reasonable price, as they want the 2.0 for a little extra power.

Stay away from engines from a Vanagon. Their breather tower is enclosed and would require disassembly and machining to match the tower of the early cases. You need the tower to be open for mounting your alternator stand.

Step 2: Inspection and detailing.

Ok, you've got your first Type 4 engine. It's sitting on the floor of your garage and you're thinking "What next?!". My first recommendation is to strip the engine down to the longblock. This means removing the stock exhaust system, the stock intake system (whether FI or carbs), cooling tin, fanshroud, cooling fan, etc. I'd leave the distributor in, as it's not really in the way and it will help you when you install another distributor and time it.

The next step is to take the engine to the local car wash in the back of your pick up and remove the dirt, oil, and road grime that's accumulated on the engine over the years. This way you don't end up with this gunk on your garage floor. It's much nicer to work on a cleaned engine, and it makes it easier to see what you are doing. Make sure you plug all of the holes leading inside of the engine, like the exhaust ports, intake ports, breather tower, etc., just be careful to not spray the water into the engine. The water, if allowed to enter and set, can rust the carefully machined internal parts.

Make sure you get everything clean, including underneath the engine. The reasoning for this cleaning is it will allow you to clearly inspect the engine for any missing bolts, damage, etc. It also gives you an opportunity to familiarize yourself with the Type 4 engine. A clean engine will allow you to track down any oil leaks that may occur later when you install the engine.

The final reason is who wants to look at a dirty engine? After you are through with this conversion and the word gets out among your VW buddies, everyone is going to want to see your masterpiece. Take pride in your hard work and share the virtues of the Type 4 with your VW buddies!

Step 3: Freshen the cylinder heads.

Technically this is a purely optional step, but it is one that I highly recommend. The Type 4 has a reputation for losing stock valve seats, causing a disaster. There are many head rebuilders out there that have come up with the solution to this problem. They replace the seat with a newer material and install them with a tighter fit. I won't go into the details here, but suffice it to say that this problem has a cure.

With that said, it is my recommendation that you remove the cylinder heads and have the heads gone through by a machine shop that does Type 4 heads all of the time. Most of the shops I've talked to will upsize the valves and seats for no more money, so increasing the valves to 41x34 or 42x36 would be advantageous.

If your budget doesn't allow for that, I would suggest you at least have a machine shop drop in new OEM exhaust valves (they live a hard life and are the first ones to fail), inspect the seats for recession/loose (the valve in the chamber will be lower than all of the rest), check the valve guides for wear, and lap in the valves.

The only way I'd skip not having the headwork done is if you really trust the seller who's told you a reputable VW Type 4 shop did the heads recently. If in doubt, do the valve job! It's cheap insurance for down the road. Check out my technical article on cylinder heads for more information on the Type 4 head.

Step 4: Sealing the heads.

Once you get the heads back from the machine shop there are a few points about assembly. VW published a bulletin back in the '70s to remove the head gaskets. The stock gaskets were a source of leaks between the cylinder head and the cylinder. Removing the head gasket (a metal ring) will increase the compression ratio slightly, but this is a desirable side effect for a Bug-Type 4 conversion. In order to get the maximum seal from your heads, it's suggested to lap the cylinders in to the heads with some valve grinding compound. This will make sure that the two surfaces are parallel and promote a good seal.

A common oil leak can be found at the pushrod tubes. The Type 4 tubes are not wedged between the head and case like the Type 1, but actually slide into the heads and on through to the case. As the engine grows and expands, the pushrod tubes slides inside the opening in the head.

To keep the pushrod tubes from leaking, it has been found that you need to polish the bores in the head and case that the pushrod tubes reside. A few suggestions to polish the bores included the use of fine steel wool with solvent, or a scotchbrite pad. You want the bores smooth, free of any roughness or nicks that could stop the tube from traveling as it was designed. Use a teflon sealant on the stock o-rings, as the teflon provides lubrication for the seals. I also must emphasize not to use any silicone or RTV based sealants here.

Step 5: Prepping the longblock.

So now you have this sparkling clean Type 4 longblock with freshened up cylinder heads in front of you, what next? The next step is changing the oil, oil screen, and oil filter. Make sure you inspect the oil for any evidence of metal particles, a sign that something is wrong internally. I'd also replace the oil pressure switch, as it can be a source of oil leaks, and a warning that the oil system isn't right.

It is also advantageous to adjust the valve clearance now, as it's a lot easier than later when the engine is in the car. Purchase a couple of valve cover gaskets, check the adjusting screws for wear, and the valve tip for wear. You might also want to inspect each pushrod for abnormal wear.

Step 6: What kind of transaxle do you have?

Now we turn our attention towards your Bug. The first thing we need to know is about your transaxle. Is your transaxle a 12V or a 6V model? The 12V models came mated with a flywheel with a starter ring with 130 teeth, whereas the 6V models came with a 109 tooth starter ring flywheel. The 6V bellhousing is smaller than the 12V, but careful use of a grinder can make the 6V housing accept a 12V flywheel.

What you are looking for is a transaxle that can take a 130 tooth flywheel. So if your current Type 1 engine has a 130 tooth flywheel, then you are one step closer to sliding that Type 4 into your Bug. If your transaxle is an earlier model for the 109 tooth flywheel, you must clearance it to clear the later flywheels.

A stock transaxle can live with a Type 4 conversion, but it will only survive if you drive it with respect. Don't attempt a drag race start or power shift too hard. Ease away from the stop sign with a gentle foot, and a normal shift will get the job done.

It's also worth noting that the increased torque from the Type 4 engine will require increased support of the transaxle. I'd recommend replacing all of your tranny mounts with heavy duty rubber mounts. This is a worthwhile conversion as you can cause a lot of damage if the tranny mounts aren't up to the job.

You can find more information about the Type 1 transaxle in my technical article on Type 1 transaxle modifications.

Step 7: Flywheel

For the Type 4 engine to properly mate to the Type 1 transaxle, you will need to have one of four different flywheels for the Type 4. They are the stock 200mm (from the extremely rare '69 411 sedan), a stock 210mm (from a Bus or 411/412), a stock 215mm (once again from a Bus or 411/412) or a 200mm adaptor flywheel from Kennedy Engineering Products (KEP). Any of these flywheels will slip right into the 12V bellhousing and will mesh effortlessly with the stock Bug starter.

Any of these flywheels will work fine, but here are some thoughts on selecting one. The stock 200mm flywheel is extremely rare to find, as it was never sold here in the US and the '69 411 was made in very low numbers. The 210mm and the 215mm flywheels are more common and their larger clamping surface area makes for better holding power with no increase in pedal pressure. Locate a Bus 1.7 or 1.8 with a manual transmission and you'll find one of these flywheels.

The KEP 200mm, although being the most expensive option, makes installation and selection easy when it comes to pressure plates and discs. You can use your favorite pressure plate and disc combo from your Type 1 with this flywheel.

If your engine originally came with a 228mm Bus flywheel or a 914 215mm flywheel, you will need to get one of the above flywheels. Both the 228mm and the 914 215mm can be used, but require a lot of work and specialized machining to work correctly. Unless you know what you are doing, I'd leave these two flywheels to someone else.

One final modification must be made to the flywheel before it is ready. The input shaft, the shaft coming out of the transaxle, is longer on the Bus trans than it is on the Bug trans. As a result, the bearing that supports this shaft is deeper into the crankshaft. It's location, if left, will not support the shaft, causing a premature failure of your transaxle. The fix is to buy a new bearing (which is the same bearing used in the Type 1's gland nut) and install it into the center of the flywheel. This places the bearing in the ideal location and is an easy and economical modification. The KEP flywheels already have this modification done to them.

More information can be found in my tech article on flywheels.

Step 8: Clutch and throw-out bearing.

One other thing to consider when selecting the flywheel is the transaxle's throw out bearing. If your transaxle has the early style throw out bearing with two removable clips, your pressure plate must have a ring in the center for the bearing to ride on. The later model throw out bearing, the one with a three bolt sleeve on the trans housing, rests directly on the pressure plate fingers.

The reason I bring this up is that the stock 210mm and the 215mm pressure plates do not have the ring in the center for the early throw-out. They do make adapters to use an early trans case with the late throw out bearing and sleeve. I recommend that you convert your throw out bearing to the late style, as the early style is prone to losing clips.

I've also been informed that aircooled.net sells a 210mm and a 215mm pressure plate with the center ring, so you can use them with the early throw out bearing. These pressure plates will allow you to retain the early throw out bearing, but you will still have to deal with broken or dislodged clips someday.

The point is to make sure that you have a matching pressure plate and throw out bearing combo. A mismatched combo will lead to rapid premature failure.

More information can be found in my tech articles on clutches.

Step 9: Cooling system.

You've gotten this far and the fun part is now upon us. The fun part is converting the engine to use "upright" cooling, just like your Bug's Type 1 cooling. There are many options to consider, ranging from dirt cheap to "hand over the credit card". I cover the different conversions in my tech article on upright cooling. I highly recommend you read the article to fully understand your options.

For me, there are only two options for an engine like this. Either make your own cooling following the directions outlined in Joe Cali's book or get the DTM conversion and have a system for your next Type 4. Joe's way of cooling works great with a mild engine like this, but it can't keep up with hotter running engines. If you foresee yourself building a larger and hotter Type 4 later, invest yourself into a DTM shroud from massivetype4.com. This shroud has been well designed and has proven itself in many large cc Type 4s.

Whichever conversion you go with, make sure your engine has engine tin to seal off your engine bay from recirculating the hot air. If the cooling fan is allowed to take in the hot air expelled underneath the engine, it will compromise the fan's ability to cool the engine.

Step 10: Intake system.

Once you have the upright cooling system installed, you'll realize that the stock intake system will not fit. This means that you will need to invest in a set of dual aftermarket carbs. The most popular carbs are the Weber IDFs, Dellorto DRLAs, and the Kadron/Solex kit.

For those of you doing the Joe Cali cooling conversion, any of these carb kits should work fine. The price winner is the Kadron kit, as they can be purchased for about half of the price of the IDFs and DRLAs.

The best intake system is a pair of Weber IDFs or a pair of Dellorto DRLA carbs. These carbs will get you the most power from your engine. They also lend themselves quite well for any future upgrades. For my money, this option is what I recommend. My tech article on intake systems is worthwhile reading to further educate yourself.

Step 11: Exhaust.

Up until a few years ago there were very little options when it came to the exhaust part of this conversion. The options have increased, with many shops offering well designed systems for the Type 4. Instead of writing a ton about the systems available now, I will refer you to my tech article on exhaust systems. I will recommend that you go with a tube style header, as they provide the best flow that promotes lower head temps, excellent performance, and increased mileage.

Step 12: Ignition.

Now that we have a way to get fuel into and out of the head, we need a way to ignite it to get power. The stock Type 4 distributor is a great distributor, but at first it appears that it is unusable, as it appears to require a vacuum source from the carbs. Aftermarket carbs generally don't have a vacuum port, so they'd have to be modified. Upon further examination of the stock distributor, we discover that we can still use it. The vacuum pod is not an advancing device; it is designed to retard the distributor in the upper RPM range. Without the vacuum pod hooked up, it functions similar to a 009, but of better quality.

Sticking with the stock distributor, I highly recommend adding an electronic point conversion, like the Pertronix Ignitor and Compu-Fire. These conversions replace the points and condensor and provide right on timing. For those rare moments, it's still advisable to carry a set of points and a condensor, along with a screwdriver in your Bug, just in case.

The other option is to go with a Mallory Unilite Recent reports have shown that the Mallory is the winner when it comes to power, but it's price tag is higher. I feel that it's a wise investment, as the quality is second to none. I recommend that you read my tech article on ignition for the Type 4 for more information.

Step 13: Engine mounts.

Ok, the engine is assembled and inside of the car. You've got the tranny mounted with heavy duty rubber mounts and you're itching to take it for a spin. Well stop right there. You are almost done, though some people have done without this.

As you engage the clutch, the engine's torque causes the engine to travel down, towards the ground. This will destroy your new mounts and will bend your tranny horns. To counteract, you will need increased support for your drivetrain.

There are couple different devices on the market, the engine support bar (or traction bar) being the most familiar. The traction bar runs underneath the engine and is supported on either side with rods and brackets. This support can "preload" the engine so it won't move (or minimize the movement) when the clutch is released. This bar can be a modified Type 1 bar, a modified Type 4 bar (rubber mounted) or you can fabricate something yourself. Whichever you do, make sure it can tolerate the weight of the engine along with the torque of the engine.

I can not emphasize how important this step is. Having a frame shop straighten the horns after you dumped the clutch at the stoplight is something I don't want to spend my hard earned money on.

Well, that's it. You now have a great engine that will last you for many miles and will provide you some of the parts you'll need when you decide that you just have to 2.3L (or more).

I hope you have found this guide helpful. Stop by the Type 4rum at the Shoptalk Forums and let us know how you like the Type 4 conversion.