John, how much displacement are you getting out of those motors.  Maybe my math is faulty, but it seems like you are boring the 292 blocks .080 thousandths.  Is that correct?   Thanks

Jan  Urbanczyk  Major USMC Ret.

                                                                 Bowie Maryland

John, my wife pointed out my mistake in math.  I never was very good at it.  She pointed out that it should be .060 over 292 and net about 317 cubic inches. 

Jan  Urbanczyk  Major USMC Ret.

                                                                 Bowie Maryland

Cactus:

You are correct, I'm boring 292s .080 over.  With the stock stroke 312 crank, I get 317 cubic inches.

John

John - "The Hoosier Hurricane"

So a near stock block 292 or even a 40 over 272 might be just as good with the blower? I've always been a bigger is better kind of guy when it comes to engines. Chuck

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Someone mentioned a C2AE block.  Does having that block change the allowable bore?

Jan  Urbanczyk  Major USMC Ret.

                                                                 Bowie Maryland

Re: C2AE block, the one I looked at had tilted cylinders, visible through the freeze plug under the starter. I've heard that it sonic tests thinner than 50's blocks, too. I think that was on Mummert's site.

Best regards,



Paul Menten

Meridian, Idaho

Thank you.  I did find that info on Mummerts site.  I might have to back up and regroup on my plans. 

Jan  Urbanczyk  Major USMC Ret.

                                                                 Bowie Maryland

Jan, I've been scrounging late 50's blocks. One of my ECZ-C 312 blocks has the tilted cylinder (it's already at .060 over), but the other looks good (standard bore. Go figure). I still have to pull the freeze plugs on a B9 block to see what it looks like, and I have a line on an EDB-E truck block that I should follow up on. I also have a 1956 EDB-A engine, but it's almost ready to install and I'm loath to pull the fresh freeze plugs out.



I think the other choice would be the ECZ-A 292.



I looked at the price of sonic testers today. $800? I might spring for one, a birthday present to myself

Best regards,



Paul Menten

Meridian, Idaho

Chuck.

         I would doubt that adding cubic inches would make horsepower as fast as adding boost. Here's the deal, lets assume that your 312 is 100% efficient at max hp. It would make 312 ft lbs at that point. (theoretical, won't happen unless you're Wally or Ted Eaton). If you could add a blower that blew 7.35 lbs and consumed zero hp to do it, you would now have an engine that acted like a 312 x 1.5 or 468 cubic inches. Kick that to 9 lbs and it's now a 502. This all assumes the heads can carry that much air, the blower doesn't take any horsepower away and the heat of compression in the blower doesn't thin the air out (it does). But you get the point, you can't make a 312 that big with boring and stroking. Best to make the walls stiff, the rings seal, and the heads flow all they can. Then run a cam with limited overlap so the blower stuffs the cylinder, and does not blow half of the charge out the exhaust pipes. Retard the timing, run 106 octane, and keep the carb a little rich, Make sure you have fuel pressure and Moon Shadow will destroy tires and the '56 rear end.  

Frank/Rebop

Bristol, In ( by Elkhart) 

Chuck.  As John and Frank brought up, stick with the thicker wall scenario versus going "as big as possible" in the blown application.  Cylinder wall flex ends up being a player when adding a supercharger to the mix.  Although adding some block fill can alleviate some of the flex, just keeping the cylinders walls thicker is the best insurance.  When initially sonic checking Randy's C2 block it was good for being bored 0.110" over if being normally aspirated but because of the blown nature, I just cut that value in half and kept the finished bore size to 3.800".  Here's the sonic check results of Randy's block after final boring.

These are all the minimum values when sweeping the sonic check probe the length of the cylinder wall.

After sonic checking a variety of Y block castings, there is no set rule for one block casting number being better than another.  I've now seen 272's that would bore out to 312 plus while others are iffy at 0.060" over.  The C2 blocks seem to be the most predictable but core shift is still an issue thus forcing offset boring if going for the larger bore sizes.  Sonic checking is a prerequisite if wanting to be sure of what you have.

Lorena, Texas (South of Waco)