Smoke after thicker head gasket- opinions and observations

[dpuckett]

I put in a . 020 thicker head gasket, and it definitely smoothed out the idle and running, but I have noticed more black/ grey smoke at lower RPMs, and higher EGTs across the board. I know, it isnt entirely unexpected, since lower compression ratio equals less pressure pushing back on the piston, but I am also curious if changing the position of the injector tip in the combustion chamber may have had an effect aws well. I HAD a stock head gasket & . 060" washers. I INSTALLED a . 020 over head gasket, but used . 020 washers, along with getting the head milled . 00925", call it . 010 for simplicity of math sake.



So:

. 060 (washers) + . 020 (HG difference) - . 010 (head mill) - . 040(washer difference) = Injector tips . 030" closer to the piston than I was before I did it all; or having . 030" injector washers (if all had been left the same as before) from a combustion chamber/ injector tip protrusion stand point.



I am thinking of advancing my timing a hair, but wouldnt that negate the benefit of the thicker gasket by increasing the pressures? Or am I missing something here? Could my 1. 55mm timing be too soon to be optimized in the combustion chamber, and actually need retarding for maximum air/ fuel mixing?



One other thing to consider is that my turbo is no longer new, and could use a rebuild/ upgrade (discernable slack in the wheel both fore and aft, and a hair up and down. )



Just trying to get some thinking going on. Some of you in the snow belt can get enough heat going to melt some snow



Daniel

 

[Forrest Nearing]

definately run the thinnest washers you can find for the injectors...



advancing timing will increase cylinder pressure, but you've already decreased it, so...