<VV> RE:Cooling Fins

[Scott Cable]

Joe and others:
Thought I'd add my 2 cents to the previous comments:
So far no-one has talked about detonation which is what the below described "ferocious ping" is about. Basicly, detonation is caused by two flame fronts meeting each other in the combustion chamber. There are a multitude of ways to prevent this, which is beyond the scope of this email. Here are a few suggestions:
1. Since you more than likely have the heads removed from the engine to remove the casting flash,  Polish and cc the combustion chambers. This insures even compression and removes any sharp edges which may be a source of pre-ignition / detonation.  It also makes it more difficult for carbon deposits to get a foothold and start growing in the combustion chamber.
 
2. Improve the exhaust flow. This will remove heat from the engine, such as adding tubular headers, and/or low restriction muffler.  Ceramic coatings are a god send, which in effect remove the exhaust heat from the system by preventing the heat from "soaking" into the metal and forcing the heat to stay in the airflow, and thusly away from the engine. If you wanted to keep a stock appearing set-up without headers, significant gains can be had by de-flashing / porting the inside of the exhaust manifolds.  Again, consider ceramic coating or "Jet-Hot" coating the manifolds.
 
3.  Consider a 5 angle valve job, and adding a 30 degree back-cut to the valves.  Adding the 75 degree and 15 degree angles to the traditional 30 - 45  - 60 degree cuts dramaticly improves the air-flow of the engine and increases horsepower and torque.
 
Joe Potts wrote:
I have a heat-challenged situation in my 66 Corsa 140hp that I like to 
run with stock distributor and ignition timing, and with stock shrouds. The 
car is air conditioned, and that, too, is stock (A/C condenser is upstream 
in the path of the air that cools the engine). I live in a hot climate, but at
least I don't drive up long hills/mountains, and I don't pull a trailer. If
I use regular gas, I get ferocious ping. Premium gets me by with about 
zero headroom on hot days.
     I'm preparing a pair of (stock) heads for use in this situation, 
and I have just "deflashed" them. Naturally, there remains a vestige of 
flashing at the narrow point of every through-passage, and I'm working on 
smoothing these down (not easy, as anyone who's tried it knows). I'm working on 
the understanding (not confirmed) that the closer I can get these flash 
vestiges to disappearing, the better my heads will be cooled. And this exercise
brings me to thoughts about the REST of the cooling fins that the cooling
air passes over (the parts upstream and downstream of the point where 
the flashing is found). Thanks.
Joe Potts
Miami, Florida USA
1966 Corsa coupe 140hp 4-speed with A/C



Scott Cable
Jamestown, ND
s2cable1 at yahoo.com
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