Stovebolt.com Forums The Shop Area The HiPo Shop "Baby Chicken" 261 stroker pistons- - - - -

As in "CHEEP- - - - -CHEEP- - - - -CHEEP!" A standard bore piston that fits a Buick 231 V6 is .050" bigger than a 261 piston, the wrist pin is just a few thousandths of an inch bigger, and the compression height works well with the 3/8" stroker crankshaft I'm contemplating running on 235 and 261 engines. It's also got a dish in the top that will allow a higher than standard lift on the intake valves, and/or a milled cylinder head. The 235's can run pistons for a Ford 223 inline six with minimal machining. 235's become 270's, and the 261's approach 300 cubic inches, depending on the oversize used. Ebay is loaded with brand new 231 pistons for under $100.00 a set!
Jerry

Jerry, just asking, but are you going to build a motor using one or the other or both of those pistions? The reason I ask is that for quite a few years I was told that with minimal machining you could install GMC 302 truck rods in a 261. It turns out while that statement was true, it was only sort of true. In fact, if you asked all the folks who were expousing this statement whether they had ever build a 261 with GMC rods, none had ever done so. I actually built one. Yes, you can machine the sides of rods down to 261 size, and rebuild the rods to fit a 261, but then comes the rest. No off the shelf pistons so to compensate for the longer GMC rod length and altered compression height so you need custom pistons, the GMC rod bearings have to be narrowed because they interfere with the235/261 rod journal filets which requires a lathe and a homemde tool, the cam has to be relived between the lobes on the flats to clear the rod bolts. I learned those things during the build. It was time consuming.

I have one more bare 261 block, a pair of spare 235 blocks, and a couple of spare 235 cranks. If you are building a stroker motor using these off the shelf pistons, I think I will wait to see how the build progresses, then use these blocks and then engage in outright flattery, adulation and then theft and follow on your coat tails. Truth be told, I would rather not reinvent the wheel if you are headed in that direction. My youngest son has been my right hand man for all things old cars and trucks for quite a few years now, since he was a teenager. A stroker 261/235 would be a good project for he and I to do together.

Yes, I have both 235 and 261 blocks available, and several crankshafts to work with. Both engines will run the same crank- - - -offset ground to have a 4 3/8" stroke, and using connecting rods for a Nissan 2.4 liter 4 cylinder. The rods are narrower than stovebolt rods, so spacers around the wrist pins will be needed to center the rod on the crankshaft journal. I'm also experimenting with putting a bushing in the big end of a stock stovebolt rod to adapt it to the Nissan bearing. Once I have a block and crankshaft set up, then I'll start tinkering with rod length and piston compression height to get the pistons close to the top of the block. The Buick piston tops have a circular dish almost 1/4" deep, so some tinkering with compression height can be done without compromising the strength of the piston crown in case the piston sticks out of the top of the block a little. Ford 223 pistons are 3 5/8" flat tops, and have a lower compression height than stovebolt pistons to compensate for the longer stroke.

You're welcome to copy all my designs- - - -just give a little credit to who dreamed up the whole Rube Goldberg idea- - - -whether ir works or not! I'm currently working on putting a pressure lubed crankshaft and rods into spray-oiler engines, 216's and 235's. That should work to salvage some of those spray-oiler "boat anchors". The big sticking point on those engines is main bearings- - - -they're as scarce as hens' teeth! I might need to work on a way to use my line bore machine to narrow the thrust face on the spray-oiler blocks to accept the narrower 235 thrust bearings.
Jerry

I just bought a set of hypereutectic cast pistons for the 231 Buick engine- - - -.020" oversize which will be .070 over in the 261 block. I have a 261 block that's 40 over right now, so with the Buick pistons and 3/8" extra stroke, it should come out very close to 300 cubic inches (296). I've also got a set of H beam Nissan rods that are rated for 600+ HP. Now- - - - -if I can get those roller valve lifters and rocker arms to work with an 848 cylinder head, things might get "interrrrrressssting!"

BTW, shipping included, the cost of the pistons came out to the princely sum of $14.00 each! Unsold inventory from a parts store that went belly-up! Ebay to the rescue!
Jerry

Jerry I’m looking forward to seeing and hearing the engine run once you get it all wrapped up and into a truck. I would assume a You Tube video will be in the works.

I'm daydreaming about setting up a demonstration engine with my dyno attached, put it on a small trailer, and making the rounds of a few car shows with it. A mockup engine turned by an electric motor, with a clear plastic valve cover and pushrod cover to show off the unique valve system would be an "extra added attraction"!
Jerry

Jerry, I know it would be a big hassle but, get a GoPro and record each step with narration of what you’re doing. Post the videos to YouTube. Only so many years left, buddy!

Good idea, Martin- - - -being the youngest and healthiest member of my household has me balancing caregiver duties with shop time. Right now, the shop is playing a pretty discordant second fiddle!
Jerry

Just throwing ideas out there. If you have a Technical School or even a High School close by that is offering a film/video class you might talk with the instructor about making it an ongoing class project. Could bring in a few $ for their program and you to. Might even lead to someone wanting to do an apprenticeship since you have a teaching background. I can see an Oscar in your future!

Those programs are just about ancient history. The state trade school program in the town 20 miles west of us used to have an auto mechanics program- - - - -I know, because I was the instructor. They closed it down in 1990, and laid me off. The construction trades class, welding, and machine shop programs also went away. Now the school doesn't do much of any kind of education that doesn't involve kids sitting around and punching a keyboard all day. After I retired from running an very successful high school shop in Nashville (which also got cancelled) I volunteered to help out (free) at the high school auto shop program my grandson was attending- - - - -"No, thanks!" They never got back to me!
Jerry