Compression plates/stuffer plates

[Emerica1975]

I’d like to learn about stuffer plates. I’ve read a few comments in this site about them and heard them mentioned a few times in various articles I’ve read. But I’m hoping someone could help steer me into n the right direction so I could learn how to make and install them in a 165 engine. The most I’ve seen them talked about for Hummer engines is in the article about Jack Cantrell and the Sandiego hop up method.

[billc]

maybe we should have a sticky for hop up subjects and info ?

[Mutt]

they are just a disc that fits in between the flywheels. It takes up volumne in the crankcase thereby up'ing the compression. I just installed one in a 165 motor yesterday

[Emerica1975]

Since I’ve never done it before or seen one in the live it’s hard to envision how to secure the plate. Would it be possible to get a few pictures and measurements of the plate before install and in the case?

[Mutt]

here is a picture of the stuffer plates. The one on the left for the 175cc, the one on the right for 125/165cc motors

stuffer plates.jpeg (137.94 KiB) Viewed 25223 times

[billc]

when stuffing the crankcase is it nescessary to also bump the compression in the combustion chamber ?

[Emerica1975]

Thanks for the pictures. Are they aluminum? How are they secured inside the crankcase. How thick should they be? And do you have a suggestion on how to layout a pattern to the correct shape. Sorry for all the questions and I understand if it’s all trade secrets but I gotta try?

[Mutt]

No, you can stuff the crankcase without messing with the combustion chamber. But why? Upping the compression in the head makes more power.

[Mutt]

Thanks for the pictures. Are they aluminum? How are they secured inside the crankcase. How thick should they be? And do you have a suggestion on how to layout a pattern to the correct shape. Sorry for all the questions and I understand if it’s all trade secrets but I gotta try?

Yes, aluminum for lightweight and no rust. >.290" to .305" thick depending on how close your flywheels are to each over after truing. It all varies, if you are using flyhweels that use a straight crank pin. Not so much if ya have the early or the later crank pin with shoulders It's not a trade secret. You have the cases where you can get the dimensions. Machine you an aluminum ring that is the diameter of the recess in your left case half. (5.525" if I remember correctly.) I.d. of the ring will be about 3.875" for the 175 motors, and another .062 less for the i125/165 flywheels. Once you have that done, you'll need to machine a lip on the outside diameter of the plate. It wont be centered. The lip (approx. .055" thick, measure your own case recess) leaving .002" less for clearance) will fit into the recess in your case and the plate will be centered in each case half. Once that is done, lay the stuff in the case recess and mark the mouth of the cases onto the ring and cut that much away, for the rod to clear. Once ya get that far, let me know and I'll type how to locate and pin the plate into the case

[Emerica1975]

Thanks Mutt! I’m gonna start next week on it.