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On 15 Jan 2002, at 12:28, Brian Schlepp wrote: > From a technical side, the increase in displacement from 1585cc to > 1679cc is only 6%. I don't think it is to much to ask of a set of > single port heads and a single side draft carb to compensate for > this. Plus with the higher ratio rockers and different cam, the port > velocity would be increasing, which would fill the cylinders better > and increase the throttle response because of the small port heads. > The restriction with the heads will only be felt probably above > 5,000rpm which is seldom seen on a daily driver or even street car. The single port heads are much more restrictive and you will feel the difference long before you get to 5000 RPM. The engine will certainly do the same RPM, but it just won't have any power getting there. No matter how you look at it, the cylinders can't fill as well when they're sucking thru a long straw. There are certainly a few nice parts here, but the heads and carb make much of it pointless. BTW, most people don't realize that the biggest real advantage of the roller crank is that it will survive running "dry" for longer than a standard journal bearing crank. The main bearings of both are the same: standard journals, but it's the rod bearings, which get oil last if you power up after a corner which left your oil pump sucking air for a few seconds. A few seconds of no oil to the rod big ends at full throttle can make a difference. We had a VW beetle race car here in town a few years. It had a SPG crank and was almost unbeatable in its class. Unfortunately these cranks have full circle webs between crank throws, so they aren't counterweighted and aren't any better than a stock crank at high RPMs. I believe some shops worked out ways to maching away part of the full circles to make counterweights, but this was not common and was expensive because the cranks can't be disassembled to do the work, so you have to be REALLY careful to keep all the cuttings out of the rod bearings. - ******************************* Jim Adney, jadney@vwtype3.org Madison, Wisconsin, USA ******************************* ------------------------------------------------------------------- List info at http://www.vwtype3.org/list or mailto:help@vwtype3.org