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Old 05-07-2019, 07:22 AM   #1
Terry, NJ
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Default About Detonation ?

OK,I think my coupe's engine has "a head" on it, I think! Just who's head or what the C R is, is anyones guess. But it seems to run strong with a bored out manifold and a B carb. Good acceleration and 65 is no problem. I've never held it open to see what it can actually do, but it's gotta be well over 70. I've wondered just how I should set the timing. Using the admonition, with a HC head, you have to not advance the timing as much as with a stock head. Fear of detonation has me only advancing to a point, about 90 deg (straight out) But I see the adjustment lever will go about 5 deg. further. Am I near to the optimum setting? My hearing is not so good anymore and I can't detect the right setting by ear. When it's running, the sounds all blend together, I can't pick them out. T.I.A.
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Old 05-07-2019, 08:15 AM   #2
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Default Re: About Detonation ?

If you cant hear it,you cant avoid it..you can feel it,the power 'flattens' out,but once its starts detonating its hammering your bearings,so either if you hear or feel it its too late..Try a B distributor,and drive worry free.
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Old 05-07-2019, 10:59 AM   #3
Jim Brierley
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Default Re: About Detonation ?

I think you are doing about right. You could advance the lever, BUT ONLY ON LIGHT THROTTLE CRUISING. This might give you slightly better gas mileage, may not be worth the effort? A Model B or FS ignition is a good option but check them so they don't give too much advance. I ran a B dist on a Sun machine years ago and it had way too much afvance. 26 or 28 degrees is probably the max you should use.
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Old 05-08-2019, 07:19 AM   #4
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Default Re: About Detonation ?

I have a stock head so my advice may or may not apply. You can feel the timing advance as well as hear it. On normal acceleration, as was already mentioned, you feel the power flatten out just before it pings.
"There are some that can destroy an anvil with a teaspoon and shouldn't be allowed to touch anything resembling a tool."
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Old 05-08-2019, 03:59 PM   #5
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Default Re: About Detonation ?

A Mallory distributor from Bubba solved my pinking problems but the distributor did require "tuning" to get the required advance because as supplied I was getting only 5 degrees advance despite it being advertised as set up for Model A's. I think this implied that machining had been done for it just to drop in to the Model A motor?
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