[Spridgets] Is anyone running a 649 cam?

fastvee fastvee at yahoo.com
Wed Dec 16 15:32:49 MST 2009


Hi Mark.
The 649 is way too much cam for a street 948. The smaller the engine, the
higher the rpm where it "comes on the cam", which would be more than 3000 rpm
in a 948 with a 300 degree cam. You will need to set the compression ratio to
12:1 or higher or you would have less torque in the lower rpm range than a
stock engine. I suspect the 295 chambers are much larger than the 1098 heads
we raced with, and I don't know if you could mill enough enough to get what
you need without complications. We milled .125" from a 185 head, brazed up the
oil galley, and still needed a .100" dome on the piston to get 12.5:1. David
Vizard says the 649 cam could be a fast road cam in the over-bored 1400 and
1600 cc engines. The added displacement has the effect of taming long duration
cams.
We recently discussed street cam choices on this list for the 1275 I am
building. The consensus was that even a 286 degree cam is too much for the
street, and that was my first choice. We tend to over-estimate how much time
we spend at high rpm on the street, and 276 degrees is good for a street 1275.
Based on what I said about displacement, maybe 266 degrees would be ideal for
a 948?
John
Fogelsville, PA


--- On Wed, 12/16/09, Mark Haynes <haynes386 at netzero.net> wrote:

From: Mark Haynes <haynes386 at netzero.net>
Subject: [Spridgets] Is anyone running a 649 cam?
To: spridgets at autox.team.net
Date: Wednesday, December 16, 2009, 2:27 PM

I have the Kent grind of this waiting to be installed in my 0.020 over 948, I
was going to run Hepolite Flattops (already on resized rods) and a 295 head
milled as far as it can go without breaking into the oil line, with rimflow
valves. Does anyone have any experience with the 649 cam on the street? Does
it have too much overlap and thus too little low end? I drive the BE like I
stole it, so below 2K rpm isn't much of a problem usually.


Mark Haynes
HAN6L12779
HAN5L8016

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