Chevy 305 piston ?
- Thread starter 67 Falcon
- Start date
The small end of the rod has to be enlarged to .927" to fit the Chevy pin. The block has to be bored to 3.736". And you need to check your deck height carefullly as the 305 piston can have a compression height of between 1.540 to 1.560" (.040-.060" taller than the 200/250 piston).
That's the standard bore for a 305.
MandarinaRacing
Famous Member
the Autozoo online catalog lists Badger pistons for $13.99 each or a set of 8 for $62.
The big obstacle is the 1.560" CD.
The big obstacle is the 1.560" CD.
MandarinaRacing
Famous Member
I think these ( L2486F ) are forged. Forgot to mention that. BTW How bad is this Compression Height issue. How much would is "stick out" on a stock deck height????
Alex
Alex
You're aboslutely correct. I meant to point out that the Badgers were cast to show the price difference. 
The CD problem depends on the piston. The 1.560" distance is for a stock piston. But a new piston may actually be 1.540". It's common practice to "destroke" a piston to account for milling the deck.
At 1.540" with a stock deck, the piston sticks up past the block .040". If you mill the deck (and you should) it will be sticking up higher. to make it fit properly you should chuck it into a lathe and take a few thou off the top. .050" off of a stock piston should pose no problem, but does add to the cost of retrofitting these things.
In my opinion it's not really worth it unless you need a forged or hypereutectic piston.
The CD problem depends on the piston. The 1.560" distance is for a stock piston. But a new piston may actually be 1.540". It's common practice to "destroke" a piston to account for milling the deck.
At 1.540" with a stock deck, the piston sticks up past the block .040". If you mill the deck (and you should) it will be sticking up higher. to make it fit properly you should chuck it into a lathe and take a few thou off the top. .050" off of a stock piston should pose no problem, but does add to the cost of retrofitting these things.
In my opinion it's not really worth it unless you need a forged or hypereutectic piston.
To resolve the deck height problem, you can also offset turn the con rod crank journals. If the journal needs a .010 cleanup, offset it .030 to pull the piston down .020. The journal gets turned .010 on one side and .030 on the other side.
For what it's worth, my 200ci pistons stick out of the bore .006". I wanted to experiment with options to take up some of the extra squench created by composite gaskets. It hasn't broken yet - about 4000 miles.
Off-set grinding the crank rod journals also works in reverse. You can either raise or lower the piston.
Ain't it fun???
Good Luck
For what it's worth, my 200ci pistons stick out of the bore .006". I wanted to experiment with options to take up some of the extra squench created by composite gaskets. It hasn't broken yet - about 4000 miles.
Off-set grinding the crank rod journals also works in reverse. You can either raise or lower the piston.
Ain't it fun???
Good Luck
