The compression height is 1.975, the stock rods are 6.600 inches, the stock stroke is 3.900 inches, and the production deck height is 10.57 inches.
That adds up to pistons that are 0.045 in the hole, but JMS decked the block 0.005, so the real-world number is a poor 0.040 below the deck.
On our test engine, the compression represents what you’ll get from a stock ’71 to ’76 junkyard 455 or what is running in your Buick right now.
The Speed-Pro L2353F pistons start life with 27.8cc dishes, then add another 3 to 4 cc for the custom valve notches, bringing the total to about 32 cc.
Sadly, the state of gearhead living has changed drastically over the last five years, and even here in So Cal, the Buick 455 engine donors just aren’t in the ‘yards or on the streets like they used to be.
The lobe-separation angle is 112 degrees, and valve lift is 0.459/0.470 inch using stock replacement shaft-style rocker arms (Sealed Power PN R857) with a 1.55:1 ratio.
Using what is perhaps the smallest cam seen in CC this decade, we ran four intakes across the 455: an Edelbrock Performer, an Edelbrock B4B, a TA Performance SP1, and a TA Performance SPX.
The ’75 to ’76 castings have factory 78cc chambers and are never used by TA.
The ’70 heads are 68 cc, and the ’71 to ’74 units have 71cc chambers that are milled to 69 to 70 cc during the rebuild process.