The Ford Barn

RonLey · 06-03-2016, 07:11 PM

After getting the engine together it is really tight. Without the pistons I can put my torque wrench on it and turns at less than 30 ft lb. But put the pistons in and it is tight.

The cylinders are bored out .060, the pistons are older with the side split but have never been used and have a have a scraper and expander on the middle ring.

The pistons rings are consistent with the top ring gap is .012, the middle ring gas is .010 and lower .080. So all are at the tighter end of the tolerance. There is not any shiny spots on the skirts, the top slides easily on the wrist pin and is not binding against piston. Measured the width of the connecting at the big end to make sure it wasn't hanging up. The piston clearance is a little tight at .002 (skirt not ring end) but can still pull out the gauge.

I thought I might have a bent connecting rod but all check out. Got a cylinder gauge and checked the bore diameters and checked fine. Loosened the caps just a little to make sure that they weren't too tight and binding. Measured ID of connecting big end to make sure no high spots in babbit.

But still when get the 4th piston in it is almost impossible to turn the crank. I have tried different orders of putting the pistons in. I am out of ideas. I am almost at the point of ordering new pistons and rings but I can't definitely say that it would solve the problem.

What am I missing.

06-03-2016, 07:11 PM	#1
RonLey Member Join Date: Dec 2012 Posts: 51	Engine Tolerance and Tightness After getting the engine together it is really tight. Without the pistons I can put my torque wrench on it and turns at less than 30 ft lb. But put the pistons in and it is tight. The cylinders are bored out .060, the pistons are older with the side split but have never been used and have a have a scraper and expander on the middle ring. The pistons rings are consistent with the top ring gap is .012, the middle ring gas is .010 and lower .080. So all are at the tighter end of the tolerance. There is not any shiny spots on the skirts, the top slides easily on the wrist pin and is not binding against piston. Measured the width of the connecting at the big end to make sure it wasn't hanging up. The piston clearance is a little tight at .002 (skirt not ring end) but can still pull out the gauge. I thought I might have a bent connecting rod but all check out. Got a cylinder gauge and checked the bore diameters and checked fine. Loosened the caps just a little to make sure that they weren't too tight and binding. Measured ID of connecting big end to make sure no high spots in babbit. But still when get the 4th piston in it is almost impossible to turn the crank. I have tried different orders of putting the pistons in. I am out of ideas. I am almost at the point of ordering new pistons and rings but I can't definitely say that it would solve the problem. What am I missing.