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Detonation - 1950 263


1950SuperBlueBuick

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I'm reading in my 1950 Buick Shop Manual that 'light detonation' is normal in the 263 even when timing is correct and also using premium fuel.

Would that be a slight 'rattle' in the exhaust when the engine is under load above 30 mph? Other than the knocking, it runs & idles very smoothly. The temp. stays 1/3 from "C" unless poking along in a parade. Mileage averages 12 to 14 mpg.

Anyone else with this same engine have these issues?

When I push the gas slowly to the floor, the knocking gets much more severe. The book indicates premium fuel for the 263 Dynaflow 7.2 compression ratio.

I'm pretty sure todays 10% Ethanol gas is rated differently. Is 93 octane today sufficient to run a 59 year old engine smoothly? Or is there something about Ethanol that makes my motor knock? Several car club friends have indicated so and I should go back to 87.

I could start retarding the timing back from 4BTDC at the expense of less power and lower mileage. Anyone else try that and get any results? :confused:

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No amount of knocking ( detonation ) is good for any engine, most will tolerate some, but at higher rpm`s or loads there is a real risk of engine damage; the simple solution is to progressively retard the timing until it goes away.

If there is a risk of losing performance / economy that would be a small price to pay, finding the sweet spot however is a bit of an art.

Considering that in an original engine there is likely to be considerable wear in the distributor / cam drive train, this will make the timing marks somewhat unreliable, then of course you have to deal with modern fuels and their different burn rates etc.

So the best approach is to experiment with different timing settings on a road that will give you a variation in engine load / speeds until you can eliminate the knocking; just bear in mind that the original manufacturers settings may not be the todays best settings.

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That engine should never knock...I have my 53 263's ignition way advanced over factory and I run 87 octane--never a ping, ever. Premium back then was way lower octane than premium today. My understanding is that octane didn't really get up in the 90-100 range until the '60s. 7.2:1 compression should run on pond water. You need to figure out what's wrong with the car. Check your ignition timing. Make sure the mechanical advance is not frozen up or sticking in your distributor, same with vacuum advance. What type of spark plugs are you running? I run AC 45S in mine. Something is making that thing ping, because it shouldn't. Good luck--let us know what you find.

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i also have one of the old cars=55 and it runs GOOD. no pings at all. these old cars need lead in the gas. did you put an additive in your gas? i had my valves redone so it runs on no lead.you also have to use sae oil in them.the oil have lead treatment in it. hope this helps you .danny

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