Stroker Plates

[Ohio HD]

I learned something new yesterday. George Bryce has been posting the steps he's taking in building his latest M8. He had custom pistons made for NO2, so he had them made taller in the ring land area, a thicker top ring, and a thicker oil ring. So that put the piston out the top of the cylinder by maybe 0.040" or so. He had Cometic supply 0.020" spacers to use with their 0.010" to 0.020" standard SLS base gaskets. That way he can get his needed 0.050" to 0.060" lift he needs.

I knew that Competic has steel stock up to 0.140" thick. But It never occurred to me they could or would make spacer plates. Just something to keep in the mind if ever needed. The photo is from George's post.

[kd]

George's success comes from his ability to think outside the box and KISS (keep it simple).  Some of us always knew what Cometic would or could do as long as they had the stock and the pattern.  They have been saying and doing it all along.  George simply knew where the problem was in the piston, what had to happen to compensate, looked at what was available, chose to use 2 different size base gaskets plus a spacer wafer and voila.  As you have pointed out, you can do a mock=up and figure out the dimension you need to compensate for and call Cometic.  You won't even have to use off the shelf base gaskets because as they say, they will make them from what ever dimensional stock they have.  Off the shelf is nice though for quick and easy access.   

[Ohio HD]

George is just one of the many guys that knows more than I do. I listen to what I'm told, and then weigh my situation as to if it's the best solution for this instance. I always like to share when I learn something that probably isn't general knowledge. 

He's one of the many that has many years of build and design experience. I need a neighbor like that.   

[Ohio HD]

I don't know this for a fact, but I just suspect it. I had Cometic make some SLS 4.125 bore base gaskets for TC. They used a steel shim of 0.022" and two 0.004" rubberized gasket material to make 0.030" SLS base gaskets. As I said, I suspect that thicker than that and you would have trouble getting the embossed gasket to crush correctly. And I imagine that also is what drove George/Cometic to the spacer route.

[tdrglide]

Also aluminum 6061 up to .625 thk. Keep in mind there is a manufacturer's mill tolerance on thickness +/- that is beyond cometic's control. Aluminum base gasket/spacers I ordered 0.063 were 0.061. Definitely not the end of the world.
Had to wait for them to waterjet cut them. I'd bet if you could send them a cad file like Solidworks or Autocad they'd make any shape you want.

[jsachs1]

I built several 3/4" stroke Evos, in the early 90's, using sportster 1200" pistons, thick base gaskets, stock 1340 big twin cylinders, and .060" head gaskets. Works out to be 92". They all made over 105 h.p., with no issues. I still run 1 in my 1995 FLHR. Great stock looking sleeper combo.  
FWIW, when height is added to the engine, you might find you need a wider intake manifold, or T-body.
John

[SP33DY]

I built several 3/4" stroke Evos, in the early 90's, using sportster 1200" pistons, thick base gaskets, stock 1340 big twin cylinders, and .060" head gaskets. Works out to be 92". They all made over 105 h.p., with no issues. I still run 1 in my 1995 FLHR. Great stock looking sleeper combo.  
FWIW, when height is added to the engine, you might find you need a wider intake manifold, or T-body.
John

When I did a lot of Ironhead, Shovelhead and Evo strokers I used the S&S 53-0201 measuring kit to order oversize (wider) manifolds. It was pretty handy. I don't know if they still offer those wider manifolds. It was a lot easier than welding them up and trimming them to fit.

[hrdtail78]

For my 128 TC with custom design 15:1 Diamond pistons.  .060 and sourced through Cometic. You cannot see attachments on this board.

[Ohio HD]

Jason, I'm not surprised that guys like you know these things. As you do it for a living. I need you for a neighbor!   

I suspect that Cometic has a laser in house. Those cuts on your plates look really clean.