Topic: Detonation


carcrazy    -- 05-04-2015 @ 5:36 PM
  Recently bought a '53 Ford with "original powertrain". Was told the engine was stock with just some dress-up items. The engine has Offenhauser finned aluminum heads and Fenton cast iron headers with dual exhausts. The carburetor that came on the engine is an ECG with 56 main metering jets. Once the engine reaches operating temperature and the ambient air temperature is 70 degrees or so the engine has heavy detonation when accelerating or climbing hills. I have been using 91 octane premium gasoline and tried STP octane booster but the detonation remains. The ignition timing has been checked and is to specs. What is the best way to proceed to reduce or hopefully eliminate the detonation? Any information will be appreciated. Thank you.


cliftford    -- 05-04-2015 @ 8:42 PM
  The aluminum heads I'm sure have a higher compresion ratio than the stock ones, which would cause the detonation. As for the timing and carburation, I'll leave that one to those with more experience than I on these things.


ken ct.    -- 05-04-2015 @ 10:16 PM
  The carb you have on there is for a Y-block 55-56 yrs IMO too big especially with .056 MJ's Normal carb for a 52-53 is an EAB with 50-51 MJ's. I would try a correct carb on there if I were you. ken ct.


pauls39coupe    -- 05-05-2015 @ 9:55 AM
  The 8BA engines used at least two different front covers and pulleys. If these were mixed the timing marks could be off by a bunch.
Check the engine to be sure the pointer on the cover lines up with the pulley mark at top dead center. If it does not your timing settings will not be correct leading to detonation.
The load-o-matic distributor should be connected to the vacuum port on the side of the carburetor, not direct manifold vacuum. Perhaps the correct carb would cure your problem.
Be sure your vacuum advance is working correctly. Use a power timing light to check the advance from initial to full advance.



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