I believe that is just the natural point of greatest resistance -- where the
paired pistons change direction from "up" to "down" as you turn the crank,
and your leverage at the pulley is the weakest. It may also have to do with
increased valve spring resistance at that point of the cycle (with valves
open). I would say it is nothing to worry about.
You will notice the same thing on a functional engine, in the car, when hand
cranking to adjust the valves, with sparkplugs removed.
on 5/6/04 8:20 PM, David Macedonia at david.macedonia@verizon.net wrote:
> Listers,
>
> While I slowly progress on the re-assembly of my '66B, my restored engine
> still sits patiently on a stand waiting to be put back in and fired up.
> However, today I noticed something that I'm hoping isn't REALLY bad.
>
> With the plugs out, I hand cranked the engine (it's been sitting now for
> almost 7 years...my how time flies...so I like to spray a little lubricant
> in the cylinders every once and awhile) using a torque wrench and a 1-5/16"
> socket. Generally, I found that approximately 25ft-lbs of torque was
> required to turn it except at two short intervals within the complete 360
> degree rotation when the torque dropped almost in half. The two intervals
> were 180 degrees apart.
>
> I had a machine shop overbore the cylinders and turn the crank, but I
> installed the new, oversized (but for the life of me I can't remember how
> much) bearings and pistons (0.030 oversized). I used Plastigauge and
> verified that all the big-end bearing clearances were in spec.
>
> Is this a problem?
>
> Thanks,
>
> Dave Macedonia
> 1966 MGB
> Crofton, MD.
--
Max Heim
'66 MGB GHN3L76149
If you're near Mountain View, CA,
it's the primer red one with chrome wires
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