Which Block do I have? HELP
 

My 74 seems to have a GB (Bus) Block in it. How can I tell if I have 914 heads or BUS heads? The Fuel injection apears to be 914 stuff. I have heard that the VW heads are a great way to toss away 15-20 HP. Reading the messages on the Hydralic Lifters made me start to wonder... Does the Bus Block not have Solid Lifters? I planed to take the motor apart and rebuild it. Is there anyway to tell how much BUS motor I have? IE: The Pistons etc... I heard they are also heavier units and don't let the motor make the same HP as the 914... I might even have a BUS Cam! I wondered why this 2.0l was so much slower than the one I had previously. Thanks in advance for any replys. dac

Good news...As near as I can tell the GB is a European 2.0L with 8.0to 1 compression compared to the American 7.6/1. However this may sound to good to be true.
Maybe you meant "GE" then it is a bus block, as anything other than "GA or GB" is not a 914 motor (either bus or 411 type IV sedan). Look at the point where the intake tubes go into the head, if you see/feel four bolts they are 1.8 or 2.0 bus heads. If you see three bolts then you have 2.0L Porsche heads which have larger valves and flow much better. To see what cam you have ain't that easy. First pull off the valve cover, rocker arms, and remove one pushrod tube. Now either with luck or a tappet remover pull out a lifter/tappet. Push in the center of it with the push rod, be carefull not to scratch everything up or bend the rod. Or just look real close for a retaining circlip thing in the lifter, if either the lifter can be pushed in or has that clip then it is hydralic. By the way a GE bus motor only has about 67 BHP a 914 1.7L has 80 BHP and a GB should have 100 BHP. So if your car is really a dog even with the motor in tune (you do tune it up regularly don't you?) then it could be a bus block but do a compression check to see if the motor dropped a valve seat or even puked a lung (blew a piston or cylinder). By the way bus pistons are dished (I think 914's are flat) the cylinders should be identical. As for pulling the motor and identifing the cam, look for two rings on either side of the center bearing journal (one on each side) the rings don't always go all the way around but are cast into the cam. If it has these rings then it is a solid cam. To ID the crank (with out a measurments) look at the rods, if the small end is smooth at the top then it is a 2.0L (bus or 914, the only difference I can tell is the 914 might be hardened) if the rod has a little flat pad on it it is a 1.7 or 1.8 (identical rods however have diff part numbers).
Oh yeah, if the compression is bad and it isn't the rings or valves it might be a stuck lifter.

Many 914 pistons are dished. The US-spec ones have a dish with a beveled edge, while some (many? all?) of the Euro-spec ones have a dish with a curved edge. The factory manual has drawings of the cross-sections.

I'm not sure how you tell the difference between Bus and 914 pistons. I do hear that the 2.0 bus heads have square exhuast ports, while the 914 heads have oval ports. I didn't know that the 2.0 bus heads had the four intake studs. (Thanks, JP!)

Let's not forget the "GC" two-liter 914 case. That's the one that came with the 75-76 cars. And the smaller-displacement motors had different serial numbers, of course.

--DD

Well Dave, the car I bought had a 1.8L with a S/S exhaust system from a 2.0L Porsche. I knew the guy with the 2.0L engine (he had the thing in a bug, it could pop wheelies!). When I put the S/S in on the 1.7L it fit fine except that the mufler bracket only ataches to one (driver) side. I had to extend the bracket on the passenger side (don't know if this is normal or if some other structural part of my frame is tweeked)and with those nasty four tip Monza exhaust(hey, it came with the car) everything fits O.K. Soooo as far as I know, Porsche 1.7, 1.8, and 2.0 all have the same ports and exhaust width and length. The 2.0L is different in that it goes straight instead of bending. The bus 2.OL heads are the same casting as the 1.7 and 1.8, and appear to be the same exhaust ports, oval. As for the piston dish. On a 2.0L bus you could use the piston as a cereal bowl. I "think" there is a compression ritio number on the top of the piston along with the size in mm and direction to flywheel.