I try not to dump a bunch of gas past the rings or overheat the catalytic converters and you're fine. Stock timing tables will be safe for now.
I try not to dump a bunch of gas past the rings or overheat the catalytic converters and you're fine. Stock timing tables will be safe for now.
I’m not running a cat.
Call me conservative, but I would back off the whole timing table atleast 4° if not 6° for a startup tune. With the displacement change the compression ratio will likely change as will the dynamic compression ratio and cylinder pressure. Better to kill any chance of detonation than hammer bearings, break ring lands or shatter pistons.
I built an 11:1 383 for my Express van and backed off the timing 6° from the factory Vortec 350 for startup and break-in. Then once I had the rings seated and the fueling close tuned for MBT. Also during intial break-in you will have some oil getting into the cylinders which will drastically decrease the available octane making detonation more of a possibility. I ended up making peak power at only 27° of timing on 93 octane and 31° on E85. With a tight quench distance and a good piston design timing requirements are also often less than a factory engine.
Last edited by Fast355; 10-15-2020 at 08:52 AM.
Thanks for the info. So just high light the whole chart and minus 4 degrees in the spark table and the extended table
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