The Stovebolt Site Forums The Shop Area Engine Shop inline 6 engine specs

And when you bore it .100" over you get 260.6, or 261.

Does anyone consider quench when doing all this cam swap, stroke stuff? im curious how many Strokers and cammed rides are actually hindred by the mods.

These aren't really "quench" motors, with the stock setup leaving the piston ~0.050" in the hole and using .050" head gaskets. But with the right setup you can improve things considerably. Yes, that is a factor.

I only bringt it up because you normally bore and stroke for more performance. Seems like quite a few project motors turn in to more of a boat anchor. I would tinker with rocker ratios to get a better valve sequence before I invested in another head but that's just my cheap side typing. Decreeing a cam shaft is a big bonus also.

Doing race engine stuff on a stovebolt is putting lipstick on a pig. The stroker 261 gains 30 cubic inches, and maybe a little more compression pressure for more torque. That's going to give it a measureable performance increase in torque alone. Getting ridiculous about volumetric efficiency, which the stovebolt engine cannot improve much due to its basic design, is a total waste of time and effort. Cam degreeing just checks the accuracy of the cam grinder's effort, unless you're tweaking the timing for extra straightaway speed or holeshot off the turn on a round track engine by advancing/retarding the cam.
Jerry

Thanks Lincoln, that clarifies it. But the same basic principals apply I think. If I were to make the effort of boring a block and machining to accept a different crank I would make every effort to get stuff right. Maybe I'm a lil overkill.. I'm not trying to start an argument with anyone, I only had some questions is all.

It's easy to fall into the trap of applying modern engine theory to what's essentially a glorified tractor engine. These old boat anchors were designed to chug along at a pretty sedate RPM range and haul a load of hay, grain, or horse manure where it needed to go to keep the family farm in business. They did their job well, and also helped win WW II by hauling GI's and their supplies around in some pretty hostile places. I'm reminded of a saying I've heard in the pits for over 50 years- - - -"Horsepower is nice to brag about, but torque wins races!"
Jerry

The biggest limitation in the Stovebolt is still the cylinder head. Its marginal in breathing and performance even for supporting 235 cubic inches. So adding more cubes often shows little gain in performance compared to other engines with the same mods for the costs involved. As HotRod Lincoln said, it's basically a tractor engine by design. The GMC cylinder head being very similar however, lacks the shortcomings the Stovebolt has, and makes its design more responsive to modern technology and techniques.

That's funny. When I dropped my 235 block and head off at the machine shop, the guy charged with cleaning the engine before it goes off to the machine shop, asked me, "What's that, a tractor engine?" I looked at it from his perspective, and told him that I see why he would think that.
Carl

Several years ago, I reworked a cylinder head for an Oliver 6 cylinder tractor. The intake valve stems were worn out, and the guides were all egg-shaped. Oliver parts were obsolete and unavailable. I substituted Chevy 6 cylinder intake valves and guides, which were a drop-in swap, the only difference was the diameter of the valve stems. I believe the Oliver stems were 3/8", and the Chevy was 11/32". The OD and length of the guides were exactly the same.
Jerry

Torque does win races, I make 680 lb/ft at 2800-6800. Does me no good in a truck on street tires though. Are there aftermarket pistons for these boat anchors? Has to be someway to add some get up and go to them. What's the avg compression? 8.5:1?

The bored and stroked 261 might get up a little over 9:1 with an 848 head and flattop pistons. Have you looked inside a stovebolt combustion chamber lately? The recess for the exhaust valve could hold a little people's convention with some room left over. Why would you want more than 9:1 at the very maximum? Unless we're considering camshaft duration somewhere in the 290 degree range, there's no need for actual compression ratios over 9- - - -all it does is promotes massive detonation. The only reason for compression ratios in the 11-12 ballpark is to get the actual compression pressure back to where it once was when the intake valve actually closed near the bottom of the compression stroke. Getting the compression way up there without a corresponding increase in cam duration is a fool's mission. Stovebolt heads don't breathe well enough to benefit from long-duration cams, so why bother?
Jerry

figured as much. I know zero about the original equipment the old rides came with. Would a tighter lsa on the cam help at all? I'm also well aware of the limits of today's fuel on a 9.5:1 and higher engine.

No reason to stay that way. There's a lot of information out there for someone willing to dig it out and spend a little time learning. it's pretty informative, learning just how much common sense and ingeneuity went into designing the older engines, and how well they have performed over the years with supposedly primitive manufacturing methods and engineering.
Jerry

"Common sense and ingenuity that went into designing these old Stovebolt" engines. i.e. "tractor" engines.

My old 216 impressed me this past weekend. We hit freezing and of course I had left the 49 sitting out overnight in it.
1 pump of the throttle, full choke and my handy hand-throttle fast idle device set and that old 216 fired right up without hesitation. It turned over pretty slow but fired within a couple turns of the starter. It then did it's 50 mile run, loaded down part of the way, without incident. Did I mention it's still 6v?
These old powerplants have done their thing from deserts to icecaps and all points inbetween.

I thought long and hard about repowering the 49 and I decided to stay close to period correct and am building a slightly modified 54 235 to eventually replace that 216. I could have easily went SBC, got more power and done it cheaper. But I enjoy driving it so much that 300hp seemed like too much overkill (did I really say that) for a country road & occasional interstate runner. If it does ever get shown, it'll be driven there
So a slightly hopped up 235 is in the works.
Keep exploring and releasing the info boys. These old tractor engines can always breath alittle better and provide alittle more grunt.....

Dave