crack in cyl?

[crazyhorse]

has anyone ran across this problem?
on 3 different 2500 ford engines in the #1 cyl crack up and down the cyl.
all 3 were 30 overbore with wiseco pistons.

[84Dave]

Were the cracks on the left-right sides of the cylinder bores, or the fore & aft sides of the bores? Were the cylinders in all engines sonic-tested for wall thickness? -Dave-

[crazyhorse]

looking from the front it is located on the left side at about the 10 oclock position and none were tested.

[Racedad]

Are these actual 2.5 Ranger blocks or stroked 2300's?

[crazyhorse]

2300 blocks

[84Dave]

Thinking out loud here....... looking from the front of the engine to the rear, the left side wall of the cylinder bore would be the 'major' thrust side when the crank is rotating from TDC to BDC on the 'combustion' cycle. Pressure highest on the piston crown & side-thrust on the piston the greatest during the 720-degree '4-cycle'. The stroke length versus the rod length obviously dictates the rod-length-to-stroke ratio. The lower that number, the greater the rod angle on the down-stroke of the combustion cycle. So...... the possibility would exist that there could be excessive side-thrust of the piston onto the cylinder wall, which could cause a cylinder wall to crack if the cylinder wall was too thin. However, one could also suggest that if there was no excessive core-shift when the block was cast, a +.030" bore should not produce a thin cylinder wall. And if there was excessive core shift, producing a thin cylinder wall, why the cracking on #1 cylinder only? Why not other cylinders? Generally speaking, the #1 cylinder runs the 'coolest' with #4 running hotter, assuming the coolant system is working properly. UNLESS, there is/was a lubrication problem to the #1 rod bearing in all engines, potentially causing at least a partial 'seizure' problem @ the #1 crank journal. If so, that could be part of the problem. Bottom line? Without close inspection of the hardware...... I have no frikin' idea!! Sorry! -Dave-

[Robertms]

Greg, are you concreting your blocks? Also, you may be running too fast. If I come over Sunday I will look you up. Robert

[runyou-2]

Is there stress on the block from the top motor mount design?

[crazyhorse]

no on the concrete and i've been letting off the gas and slowing down!! not sure on the engine mount.
i'll be in the stands this weekend Robert.