3.400" Stroke or 3.55" Stroke????

Ken Adams

Member
I purchased a set of used forged 4.1 pistons from a member of this web site. He provided records from his engine builder indicating the pistons were used in a TA 4.1 block with a total deck height of 9.535", rods used were 6.0" c to c and the stroke was 3.400". What puzzles me is the listed compression height of the pistons is 1.757". Would a stroke of 3.55" be the way to go with this compression height.? Or will a stroke of 3.400" work w/o issue with these pistons compression height and 6.0" rods ? Any comments welcome
 
Neither will work with those pistons if my math is correct.
3.4= -.078
3.55= +.067

Somebody else please add this up. Im on my phone and it's possible I added wrong. You could cut the pistons and run the 3.55 depending on the piston design/ting location but then you run into clearance volume issues and may need a thicker head gasket from the reduced dish. I'd order new pistons.
 
I come up with .003 in the hole with a 3.55 stroke. If you have the rods it should be easy to tell, the webber 3.55 stroke cranks were offset ground to a 2.100 sbc rod journal. That would mean the big end of the rod should measure ~2.225.
 
I come up with .003 in the hole with a 3.55 stroke. If you have the rods it should be easy to tell, the webber 3.55 stroke cranks were offset ground to a 2.100 sbc rod journal. That would mean the big end of the rod should measure ~2.225.
The K1 rods did not come with the pistons in question. They were a separate purchase and are Buick spec rods but 6.000"
 
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