The Stovebolt Site Forums The Shop Area The HiPo Shop Stroker crankshaft headed for the machine shop- - - -

I've been in the process of scavenging parts and pieces from a 1954/55 235 engine that had a catastrophic failure of the water jacket- - - -totally unsalvageable, and ended up with a very good condition crankshaft- - - -standard diameter, even. It's headed for the local machine shop I've been doing business with for 40+ years to have the stroke changed and the rod journal diameter altered to run big block Chevy H-beam connecting rods. With .040 oversize pistons for a Ford 292 V8 and a 4" stroke crankshaft, I'll end up with 274 cubic inches from a 261 block I've had stashed away for a while. I've also got a pretty heavily milled 848 cylinder head that should bring the compression up to about 9:1. With the Melling CCS-1 version of the 261 camshaft and a little valve work and pocket porting of the head, it should be a pretty good performer.
Jerry

One of the cylinder head mods is going to be an upgrade to 1.6" stainless steel exhaust valves that are normally used on hotrod small block Chevy V8 engines. Thats almost 1/8" bigger than the original stovebolt valves, and with the increased exhaust duration of the CCS-1 cam, there should be much better exhaust scavenging, which improves volumetric efficiency.
Jerry

FWIW I've found that the exhaust temperature under load once my 261 gets "up on the cam" 2700RPM and up) to be pretty high. I attribute that to early opening exhaust valve. On motorcycle engines I'm familiar with that contributes to more exhaust noise too. On my truck it pretty much burned the guts out of a FlowMaster muffler. The 848 head that came with the 261 from a bondyard in Wis. had valve rotators on it. I used my recently rebuilt head without the rotators but now I wish I'd made the swap. My Ispro pyrometer indicates 1200 to 1350 deg. F under load -- for hours on end.

I'll most likely use rotators on the exhaust, along with a timing gear that has been opened up slightly to be a snug slip fit, so I can tinker with the cam timing with offset Woodruff keys during dyno runs. I'll do a little modifying to the gear so it can be attached with a flat head Allen bolt and a thick flat washer, instead of a press fit. Advancing the cam produces more low end torque (what I'm building for) while retarding it makes more top end HP. The restrictive manifolds and ports of the 848 head makes that a lost cause because of poor volumetric efficiency at high RPM.
Jerry