Joined the local Alfa club for a "Dyno Day". Thought some of you might
be interested in the results.
the car is a 74.5. I have milled the head for a 9.5 compression ratio.
Have an S2 cam [270 degree]. Triple 40 DCOE webbers. Crane 700 optical
ignition and their Electronic Capacitance hi spark ignition. Engine
bore .03 over. Flywheel lightened to about 20 pounds. Electric fan.
Crank balanced.
The results: 128 HP@5200 RPM at the rear wheels [anybody have a guess
what that equates to at the flywheel?].
148 ft/lbs of torque. Torque curve pretty flat from 3000 to 4800 then
falls off. HP curve pulled to 5200 and then dropped off to the 6000
where I backed off the throttle.
Ideal shift point for working the car out on the track, about 5500 RPM.
I had been shifting at about 4800 so it will be interesting to see what
happens with higher revs.
Between runs we changed the main jets from 130s to 120s. This leaned
out the over rich condition the 130s caused at full throttle. I have 27
mm chokes which were deemed OK for the amount of air this cam and lift
setup allowed the engine to breath.
If I had known I was going to put on this much carburation when I bought
the can I would have gone to a higher lift/longer duration one [290
degrees]. Maybe next winter's project will be a hotter cam and Mr.
Goodparts roller rockers, and a little more shaving to get to about
10.5:1 compression. [course then will need to mix a little aviation fuel
into the 92 octane stuff I can get at the pump in Washington].
Question, if I go that route, what should I do about valve springs
[current duel ones came with the head from BRNW as a rebuild last year]?
[demime 0.97c removed an attachment of type text/x-vcard which had a name of
Chuck.Arnold.vcf]
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