1972-1979 Type IV Crankcases and Swap Considerations

by Mike Gensler and John Anderson

"Without major modifications (cutting and welding etc.), what motors can I put into my 1972 1700cc camper bus? "

Mike Gensler writes:

All type IV cases were created equal and are all 100% interchangeable. You can take any type IV long block from a 72-78, bolt on your old intake, flywheel/clutch, and exhaust and off you go. I excluded 79 buses in that last statement because they have 1-year only square exhaust ports on the heads and would require the use of the 79 exhaust system as well.

You can even take a motor from any year (70-76) Porsche 914-4 and bolt it in as long as you use your old intake, flywheel/clutch, exhaust and sheetmetal, but the oil filler and dipstick will be located differently. You can probably use any type IV motor from a VW type IV as well, but I don't have any experience with them.

The intake systems are where the differences really start to add up. The original dual carbs that came with your bus will work, but will adversly affect the power of any engine bigger than the stock 1700. And if you want to switch to FI from a late-model bus, in addition to needing ALL the FI pieces (don't forget the ecu, fuel pump, relays, etc.), you'll have to swap your gas tank so you have a return tube for the gas.

John Anderson writes:

Mostly Mike is right but I want to note some interesting things as I have a 1700 case and a couple 2.0 cases apart right now. All Type IV cases aren't quite created equal. This transcends the previous discussion about Vanagon cases having the obvious breather box, dipstick tube hole, and not so obvious 10mm bearer mounting holes. There are more differences.

First, the 1700 is an entirely different (slightly) casting than the 2.0. If you look at the pictures of the 914 1700 in Tom Wilson's [How to Rebuild Your Volkswagen Air cooled Engine] book you can see what I mean. Observe on page 123 the split line of the case below #3 main bearing bore, just below an M8 stud, where the oil pickup goes into the case. This is a single wall on the 1700 case, but somewhere along the line this becomes a dual wall forming a little resevoir pocket of oil on the suction, a resevoir to which the drilling from the pressure relief valve dumps. I would guess for a VERY instantaneous loss of oil at the pickup, perhaps in high g cornering, the little pocket would provide some buffer, but it is a real small volume. I didn't look but wonder if the length of the oil pickups change slightly as the new wall is forward of the old one.

Another difference is dual oil pressure relief valves. This one I'm not exactly sure on. I don't know if the second relief valve between the #1 lifters disappears between 1700/1800/2000 cases or if it disappears for hydraulic lifters. I do know that hydraulic lifter cases only have the one main relief valve and a plug where the second one would be and of course no drilling for its return into the sump. Perhaps the lifters themselves function as relief at high temp/high rpm? This would would make sense--or perhaps they need all the volume they can get. Also, the fuel pump is not drilled on FI cases and 914 cases feature the same dipstick drilling as Vanagon cases, as perhaps do 411/412 cases.

These are all in all pretty trivial changes but it does make me wonder what would be proper for retrofit of hydraulic lifters to a solid lifter 1700-2000 case, particularly if the second relief valve should be blocked (somehow blocking the return as well obviously) or if a high pressure (longer) piston like [the Porsche aftermarket company] Automotion sells should be used.

One wonders about how much the little resevoir matters. VW installed it as an improvement, but how much of one is hard to say. The pickup tube lengths (if different) could also be an issue.

On a side note, I measured a couple of solid lifter cams at about .290 lift, the hydraulic at .250 lift. Bob Donalds of Boston Engine reports both are used occasionally in hydraulic 2.0's from VW so I also wonder if the solid cam isn't a good idea for a little warmed over engine?

As Mike says, a '72 to '83 block will bolt right in (assuming you're using '79 heat exchangers on the '79 to '83 blocks and kept your original fan shroud). The bearer mounting problem I'm guessing can be cured the same way VW cures it. It appears to me ALL T4 cases are drilled M10x1.25. I guess all from '72 to '79 have helicoils in the 4 bearer holes from the factory. One could simply run 4 helicoils into a Vanagon case for Bus use or perhaps try to extract the inserts for Vanagon use from a Bus case.

"From page 90 [of an edition of the John Muir Idiot book]: "Models after November, 1975 no longer have an oil pressure control valve so don't look too long for it." "

I noted the same in the Bus Bentley in figure 9.1 in the Engine and Clutch section showing the breakdown of the Type IV case. As to what this means for someone wanting to retrofit hydraulic lifters into an early type IV case, I don't know. Again, Automotion sells longer (to increase the spring pressure) oil relief pistons for both pistons for use in the 914/912E (and de facto any Type IV) case.

411 cases apparently come with the Bus style oil fill hole blocked (same for 914 cases?) in the casting and feature a drilling down the breather for the oil fill. To use a 411 (or I surmise, but don't know: a 914 case) would require the annoyance of keeping the existing filler (not bad in a Vanagon, but cramped in a Bus) or carving out the bus fill hole and drilling and tapping for the mounting stud and bolt.

For the record, there is no problem whatsoever using a Vanagon case in a Bus despite what Tom Wilson's book says. Simply use the Vanagon clip on breather, or if you don't have it on hand slip the breather tube directly over the steel pressed in flange (though this is tough) and there is no change. The only problem one will run into regards the bearer mounting holes and for that one must simply be prepared with 10mm bolts. Drill out your bus mount pads or perhaps run a $0.25 helicoil down each hole. I'm not positive that will work-- it would if the Vanagon case is threaded M10x1.25 (fine) for which you would then use the 4 M8x1.25 bolts you have. If instead it is M10 coarse, then you need to find M10 bolts. Offhand I don't recall what the thread is, but I do know it is the same as the rear late baywindow bus bumper mounting bolts. We also experienced something weird on the flywheel end but perhaps that was just due to manufacturing tolerances.

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