0.060 oversize Pistons
- Thread starter Granny
- Start date
tubman
Well-known member
No problem. I have built two 8BA's with a .125 overbore with no problem. I have heard of cases where they have been taken to 3 7/16"+.030 (.280 0ver), but I wouldn't even think about trying that. The only things that could make .060" a problem is extreme core shift or really bad rust.
By the way, have you asked your machinist if he can "sonic test" the block? That will tell you for sure. If he can't, you may want to find one that can.
By the way, have you asked your machinist if he can "sonic test" the block? That will tell you for sure. If he can't, you may want to find one that can.
Bored&Stroked
Well-known member
If your machinist knows this little about flatheads and the blocks, what will he/she know about how to correctly do the valvetrain work?
They should have the correct guide-bore pilots (made specifically for a flathead) and not just use a standard OHV pilot inside a flathead valve guide. Do they have the correct pilots?
Do they also understand that the valves on the Driver's side of the flathead are about .043 or so higher (as compared to the deck) as compared to the passenger side? The valves are all the same length, but the relationship to the deck is different due to the crankshaft being offset. I've seen shops do things like try to deck the block to make "both sides the same", sink the valve seats on one side . . . or other dumb stuff - because they have no flathead experience or knowledge.
Think about these things and check with your machine shop . . . before they potentially do "bad things" to your engine (not even knowing they're doing them).
B&S
They should have the correct guide-bore pilots (made specifically for a flathead) and not just use a standard OHV pilot inside a flathead valve guide. Do they have the correct pilots?
Do they also understand that the valves on the Driver's side of the flathead are about .043 or so higher (as compared to the deck) as compared to the passenger side? The valves are all the same length, but the relationship to the deck is different due to the crankshaft being offset. I've seen shops do things like try to deck the block to make "both sides the same", sink the valve seats on one side . . . or other dumb stuff - because they have no flathead experience or knowledge.
Think about these things and check with your machine shop . . . before they potentially do "bad things" to your engine (not even knowing they're doing them).
B&S