The Stovebolt Site Forums The Shop Area Engine Shop 261 Pistons

I'm having trouble finding Pistons for this motor at a reasonable price does any one know if there's any that'll interchange with it ? I think a 265 has the same bore but I don't know if the pin is the same size I need help thank you

What's your idea of a "reasonable" price? There are several of them available on Ebay right now, new .040 and .060 oversize, for $27.50 each.
Jerry

That's reasonable I need 6 of them plus the rings, most sets I've seen for a 261 start at about 300

It's surprising how much new or reconditioned stovebolt engine stuff ends up on Ebay. I shop for bargains there frequently, particularly when someone doesn't really know what their stuff is worth.
Jerry

Egge caries 261 pistons.

Cheap cheap is not always the best way to go . I take quality at a higher price than cheap low quaility.And if you know exactly what you want then you look for the best price. Have fun!

If the 265 is the same, summit has sets of 8 for under $200. With free shipping.

Hollow65,

The 261 and 265 pistons are different part numbers. The diameters are the same, but the rings are different. Maybe the wrist pins are also different?

Bummer, it would be nice to get some decent compression out of the inline 6's. Sounds like a lot of work, but might be worth swapping rods and all of it has to come apart anyway.

What do you consider to be "decent compression", and why would it be necessary on an inline six designed to produce mainly low-RPM torque? 265 pistons have the wrong compression height, and the wrist pin is much larger than the ones the 235/261 engines have. The bore size is the only similarity.
Jerry

I've read that the inliners only had about 7:1. Another 2.5 points has to help something, no? I don't know the cc on the head, but that is really low compression imo. I was just curious if there was anyway to slap some better slugs in one of these engines? Didn't mean to flip the apple cart.

The 1959 235 truck engine compression specification was 8.25:1; the 261 was 8.00:1

Good luck getting 9.5:1

Mill the head?

The intake valve/piston clearance is pretty close unless the valves are recessed the same depth as the milling cut, further compromising breathing. Flycutting the piston might be a possibility if someone just has to see lots of PSI on the compression gauge for some unfathomable reason. It's really not necessary on a stovebolt, and will probably cause destructive detonation due to the shape of the combustion chamber.

Let me respectfully suggest that you actually look at a stovebolt cylinder head sometime before continuing to propose unnecessary modifications.
Jerry

I had the head milled .060" on my stock 302 GMC, made a significant difference, shimmed the rockers like amount.

The GMC and Stovebolt have much different combustion chamber designs than one another, and what works on one head doesn't cross over and apply to the Stovebolt. Cutting the Stovebolt head excessively requires sinking the intake valve by the same amount of the decking and really kills the airflow, negating any gains that might have come from the decking to begin with.

235 L6 pin: .865"
261 L6 pin: .927"
265 SBC pin: .927"
GMC & BBC pin: .990"

The V8 pistons are wayyy too short, big compression loss and no quench.

Shimming the rocker shaft up after milling keeps the pushrod angle correct (if it was correct before), but unless the intake seat is sunk the rocker geo to the stem will be wrong.