Engine Interchangeability

I have a �64 Beetle; the only reusable parts out of it are the motor and transaxle. I think the motor is a 1600cc. My dad works with someone who has a �74 Super Beetle without the motor. I was wondering if I could switch the motor and the transaxle out of the �64 and into the �74 SB. If I did that would I be able to keep the original Super Beetle axles or would I have to keep the axles with the �64 motor?

Almost any VW engine will plug into almost any transmission, so the general answer is "yes" -- that engine will fit, but it may not work. Read on.

You can get a lot of information about what sort of engine it is by looking at a few features.

First -- the engine number. The initial letter tells you what the engine was originally -- D - 1200; H - 1500; B - 1600single port (1970 USA only engine); AB, AC - 1300 dual port (not seen much in the USA); AD, AE, AH, AS - various forms of the 1600 dual port.

For more information on engine types, have a look at The VW Beetle -- Changes Through the Years on our main Web site -- this article gives a complete listing of engine and chassis numbers.

The early (pre-�71) engines have only one pressure relief valve at the rear of the case -- have a look under the rear (pulley end) of the case for a larger aluminium plug with a screw driver slot in it - about an inch in diameter. ALL VW engines have this plug. Now look in the same place at the front (flywheel ) end of the engine. If it's an early engine case, there will be no matching plug there, but the later cases have the extra plug.

Since any of the 1300/1500 engine cases can very easily converted to 1600 and you can't see anything from the outside, the only way to check the real capacity is to remove a head and measure the piston tops -- 77mm for 1200 and 1300sp (different crankshafts), 83mm for 1500s, and 85.5 for 1600s.

The transmission is a different matter. If your �74 has double-joint rear axles (IRS) with a CV joint at either end of the stub axle, then you must use a "one sided" gearbox for a replacement. "One sided" means that only one side of the tranny case has a removable plate around the axle -- the swing axle cases have a removable plate on both sides of the case, and these can only be used with swing axles.

So it's highly likely that your �64 case can not be used in the �74 car, and you can't (without a LOT of trouble) convert a later IRS suspension back to a swing axle suspension (your question about using the �64 suspension).

If the tranny in the �74 is OK, then the engine (whatever it is) will plug into the tranny, but there might be a problem if it's really a �64 type engine.

The earlier engines have a different main seal arrangement behind the flywheel, and since you CAN�T use a 6-volt ('64) flywheel) in a 12-volt Bug you may not be able to make it all work unless you can convert the starter back to a 6-volt unit (which will survive quite okay for many years on 12-volt).

The early engines used a metal/paper seal behind the flywheel, and the later (after about '65) engine have a rubber ring around the shaft and a larger oil seal outside of that.

The clutch throwout bearing is different too. The early throwout bearings have rounded ears holding the bearing in place and these use a clutch plate which has a metal ring in the middle of the clutch fingers. The later style (from about �71 onwards, have a throwout bearing with flat ears and these have no ring in the middle of the clutch plate -- the fingers are bare.

So although the engine will fit, the clutch may not be compatible without changing some components.

And another thing -- if the engine is a �64 model, the clutch is a 180mm version. The 1500/1600 cars use a 200mm clutch. The smaller clutch CAN be used with a 1600 (it is used on the 1600 semi-autos) but it won't last as long, and you'd need to be kind to it -- no hard launches.

Lastly - is the engine in the �64 a doghouse engine? That is, does it have a box-like structure on the outside front (front is front of car) of the fan shroud, on the left side, or is the front of the fan shroud flat from one side to the other?

The �71 and later cars are all designed to have the doghouse engine for better cooling. If your engine is the earlier variety it would still work, but pushing the heavier �74 body around it will be working harder than it was designed for and you might get overheating problems.

If your case has an engine number on it - that will tell me a lot. I'd be able to tell you if the engine is a straight swap or if some work on it would be needed.

We recently bought a rebuilt "long block" via the net, and made the mistake of thinking the engine that was in my son's '68 bus was "stock". What we have is engine type "AD", dual port --apparently 1971. The carburetor is Solex 30/31 PICT.

The engine we received is what SHOULD have been there -- a single port. While it has no engine ID stamped, it has all the earmarks of a 1968-70 Type 3. The vendor says that as well.

Rather than pay shipping to send it back I'm looking to see if we can adapt the carburetor to a single port manifold...or do we need a different carburetor AND manifold? Also, do you think the flywheels are interchangable?

If I remember right, the H30/31 carburetor has a small flange so it can directly replace the 28 and 30 series carbs which use the small flange manifold. From �71 onwards a larger flange manifold was used which suits the 34PICT/3 (for the 1600s) and the 31PICT carbs (used on 1300s and very common in Europe).

The H30/31 can be used with a dual-port or any large flange engine by sitting it on a 30/34 adaptor (available at any VW shop). (Or if I am wrong and it has the larger flange it will sit DIRECTLY on the large flange manifolds).

If it's a 68-71 Type 3 engine, the flywheels should be the same -- both later T3 and 68-71 bus flywheels are 12-volt (130 tooth) and have a 200mm clutch.

Some earlier Type 3 engines ('65/6'6) were 6-volt (109 teeth) but still had the 200mm clutch, and this one can NOT be used in your 68 Bus unless you convert the starter and pinion bearing to the 6-volt variety (which will survive happily on 12-volt if needed - that's common practice with converting 6-volt Bugs/Buses to 12-volt).

I have a 1600 DP engine in my �68 Bug, with a 30PICT/2 sitting on a 30/34 adaptor so it works with the dual port manifold.

No problem in using this Type 3 case in a Bug -- the only "curious" part is the missing dip stick hole, but yours probably now has a plastic fitting on the back of the case (close to the original position) for one -- that's how they usually do it with the Type 3 case.