226 common stroke numbers

A person who's never built a big engine can speculate things to death as Butch does. When you hard block a engine the piston manufacturer will tell you to open the piston to wall clearance up .Most of the time it opens up double of what a machinist is use to going by the dimensions provided on the manufacturer box piston are supplied in .

Edited by mgburchard - 11 Jan 2017 at 8:45pm

HudCo wrote: so how many cubes , or bore on a 226 when it has to be poured solid ?    thanks hud

A good thing to remember when modifying engines for performance is that few questions such as those have a definitive answer. When I built custom rifles I was often asked "how far can I push speed before I get in trouble?" and my answer was always the same. Add powder one tenth of a grain at the time until it blows and then back off a couple. The smart knew what I was saying, the dumb would ask how the heck can that work???
Same thing applies to building a hi-perf engine, if you run into an "expert" who claims different be careful about what you take as gospel from him.  Marty (WI50) has always been good about pointing out power vs longevity and I am sure he willc hime in with an answer you can take to the bank.
 Some here boast about how big they build  and might say "X" sleeve thickness is it,,,yet at the same time they sit on the sidelines among piles of busted up parts. The big gun mentioned earlier that won a class at Tunica is currently not running. How thin were his sleeves/ maybe the so-called expert will clue us in but what I know about the Allis block I would have to say DAMN thin. It was obviously hard blocked BUT hard block has it limitations too. Did his oil ring collapse or did his tin foil sleeves fail? I have my guess but that is all it is based upon experience with other engines that had very thin sleeves and hard blocked to back them up. Fact is you cant run tin foil for sleeve material and depend on hard block to save your dreams from destruction on past the test stand.  If you are doing nothing but pulling then hard block has many pluses but also carries some baggage that cannot be ignored, Marty also has made mention of that.


Edited by Butch(OH) - 16 Dec 2016 at 9:20am

so how many cubes , or bore on a 226 when it has to be poured solid ? and what about the head would some areas make for more porting ? bigger?    thanks hud

mgburchard wrote: If it's to far just go to Maryland

The general layout of the United States is  now included on the rather large list of things in life that escape you,  LOL

Marty Tunica must b the only place Panky and friends pull at.lol. Never been there but I wander what is so hard about pulling at Tunica. If it wasn't so far I would take my big cubes and have some fun with them.

HudCo wrote: do these big c.i. engines have the water jacket  poured full of cement ?

Typically they are filled with a hardblock, moroso filler etc.  All those are grout based and hard on tooling should you have to machine into it in the future.

I use a product called Rokblok (spelling I'm not sure on)  but it's available from Competition Products in Oshkosh Wi.  It's fiber based, use water and mix up to a pancake batter consistancy, it hardens in 15 minutes or so and is full cured in 24 hrs.  I'll plug the holes in the top of the block and I have a little plate with a air fitting so I hook on the water pump port, I'll put 5-10PSi air in when I fill to force it anywhere things could leak and I pound the block with a dead blow hammer for a bit also.

HudCo wrote: do these big c.i. engines have the water jacket  poured full of cement ?

Not cement as in Portland cement but they use various hardening materials in the blocks. Advantages are they can use very thin sleeves, it seals thing up and keeps the water separated from the oil and it also stiffens the entire block.

do these big c.i. engines have the water jacket  poured full of cement ?

To answer the original posters question, 4.5 is stock.  A common stroke would be 4.75" if using a Chrystler rod or 4.8 if using the Buda rod without welding a crankshaft.

But if welding then the 5.5 fits nice with Chrystler or Farmall rods, there's common pistons heights that work well.  Or if going with billet rods then 6" fits easy with room to spare, 6.25 needs just a little touch up on the block oil pan rail.

On any engine, I tell people to measure the crankshaft to camshaft centerline distance.  Lets just say it's 5" on an engine.  Now we have 5" to work with, we could have a camshaft minimum shaft diameter of say 1", and lets say 2" on a crankpin.  We have to leave just say .4'' clearance to fit a rod cap (thickness of cap at minimum point where it will intersect the camshaft, just say .300" for example), bearing shell thickness (.062 typically)  and clearance to swing.

Taking the centerline distances and the above sizes we have half crankpin diameter, 1" plus half camshaft diameter, .5" and the .400" for clearance and we have a total of 1.9" for our parts.  Take the 5" distance of centerlines and subtract 1.9" we have 3.1" of crankshaft offset, or double that for the stroke length so 6.2" stroke will fit easily.  But with my numbers above I would only have .038" of clearance and we need more than that for an engine to run, things flex.    Now we have to look at the orientation of the camshaft and how the block is cast and what will fit or distances to those items from crankshaft centerline.

The 201 and 226 AC blocks have a 5.25" camshaft to crankshaft centerline distance.  With the above numbers, we could go to 3.45" offset or 6.7" stroke and clear without butchering parts to bad, maintain a 2" crankpin and rod cap with decent strength and not have to butcher the camshaft.

Now we can see what rod cap angle we need to make the rod swing past the camshaft, if it is in the way, or if it's something in the block or how it is built. 

A flat spot on a camshaft or a flat spot on the rod cap will allow for more clearance, or a larger crankpin, larger rod or longer stroke depending on the application.  Hence, shrinking the rod, the crankpin or the cam allows for longer stroke or more clearance, but what's going to last and what isn't?  It's not rocket science, just basic math and geometry.

Somewhere I had pictures of a simple tool I made to simulate different stroke lengths and parts.  I simply turned a slug to fit the main bearing bore and put a 3/4" hole in the center through it, one to fit the rod bore for the rod in question and put a hole in the center tapped for a 3/8" bolt.  A piece of 3/4 shaft with the end tapped for a 3/8" bolt.  Now a series of arms or flat pieces of steel with a hole in each end and the center to center distance of that hole to simulate the crankshaft offset or (1/2 stroke length).  Now I have a tool to use for various engines, rod and stroke combinations to mock up and do a quick check of what fits, how a cap needs to be orientated if making a billet rod, where to position bolts or what to clearance off a rod, block, cam, etc.  I can do this before starting a project so I don't have suprises when done and can clearance an engine without having to assemble and disassemble the nice (and heavy) parts.



Edited by wi50 - 13 Dec 2016 at 1:10pm

Marty I think it still got by birdsong does he still use you or has he given up loosing all the time and switched builders

Good to see he's finally getting the decimal point in the right place after years of tape measure follies.

Probably scuffed the skirt a little and anothe .002 out of liner will clear an it up if it did scuff . He flat schooled the allis Chalmers guys at tunica like he normally does

Oil rings typically don't get a ring end gap as large as the first or second ring so when the piston to wall clearance isn't enough for a dry block and everything grows the oil ring butts and fails or collapses

O.P.S. Heads wrote: So as Shawn from Pa. said, it didn't hold up. It needs to be taken apart and repaired. Please explain how an oil ring collapses from an improper hone job?

It ran at tunica but think it collapsed a oil ring but that's just a hone issue hone another .002 out of it for dry block and that will stop