P-Pump timing question

Johndeeretech

Johndeeretech

New member
just seeing if anybody would know off the top of there head what the timing retardation would be degree wise on pump timing for a engine that has a .20 over head gasket installed without the head or block being decked (stock)
 
I guess my question is how many degrees of timing does your engine get retarded by if you use a .20 over head gasket moving the head away from the top of the piston at TDC by .20
 
BluegrassDiesel said:
4.72” stroke divided by 180 degrees
Click to expand...

Not how it works. Piston speeds follow through a sinusoidal wave, peak speed at around 75 degrees BTDC/ATDC (in this given example, depends on rod length), obviously coming to a stop and reversing at TDC and BDC.

Peak piston movement per degree rotation is 1.097mm (0.043")@74 degrees BTDC
0.5mm (0.020") away from TDC would be at ~6.5 degrees BTDC.
0.66mm (0.026") per degree takes place around 30 degrees BTDC and 128 degrees BTDC.
 
If I am understanding the question correctly, then it all depends on what timing you are starting at... So lets say you start at 13.5 BTDC. If I have my values correct, that should put the piston .063" below deck height assuming 4.724 stroke, 7.559 rod, 2.817 piston pin height, and 12.716 deck height. You are wanting to retard the timing to account for an extra .020" over head gasket so you want the piston to be .020" higher in the bore before injection? So that would mean you would need to set timing at 11.803 BTDC.
 
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Your question is still kind of weird to me though. I don't get what you are trying to accomplish or why? You don't "lose timing" because you put on a thicker head gasket. You lose compression and your injection event will be focused on a slightly different area of the piston (possibly even out of the bowl depending on set timing and injector angle). But your injection event still happens at the same time....
 
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