howell v4 piston ring gap dowel diameter

[mic]

hi
making rings for jerry howells V4
made the mandrel for heat treating piston rings and found that
gap dowel diameter wrong or mandrel diameter incorrect ???
rings are made to spec ie .875 x .799 x .038, but when fitting onto mandrel the dowel spreads ring diameter too large for the
mandrel dia of .827 as stated on sheet 50 of the construction notes. have some purchased rings of .875 and they have a dowel gap of .131 as per jerrys specs
if i use .875 x 3.1416 = 2.7489 + .131 = 2.8799 devided by 3.1416 = .9166 OD and same again for ID i get .8406 this is .013 larger than the .827 jerry quotes. will try using the .840 ID. can any one enlighten me if am correct or on the wrong path

mic

 

[jwcnc1911]

I have not built this engine yet but here's what my constructoin notes as of 2006 say:

Sheet 50 - CAUTION • Make the pistons and rods as near the drawings as possible so you can balance the engine by facing the
crank cheeks. It is generally agreed that aluminum alloy 2024-T351 is the best readily available bar stock for model engine pistons, although a great majority of model engines are running just fine with 6061•T6 pistons. Turn the pistons and cut the two top ring grooves ONLY for now. Use a collet to hold the pistons to cut the oil ring groove and oil escape groove AFTER the wrist pin hole Is drilled and reamed to prevent the hole from leading off.

Piston Rings - I make my own piston rings using the "Trimble" method which was published in Strictly I.C. Magazine Vol. 2, issues
#7, #8, & #9 in 1998. The back issues are still available as of 2006.
E-mail: [email protected] I have made rings for many engines using this method and it produces very good rings. Ring specifications for this engine (.875" bore) using this method are:
Wall Thickness = .038", Ring ID "' .799", Gap Dowel Diameter =
.131", Mandrel Diameter = .827" and Mandrel to Dowel Center
Spacing = .436". It is advised that the anealing temperature be reduced to around 950 degrees. F. as per the web site article
below. If you have not made piston rings before, don't be
intimidated. Also, there is other information on making rings on my web site at: www.jerry-howellfPistonRings.html There is a Ring Thinning Holder and a Piston Installer tool on Sheet 64.

Debolt Machine sells nice .875" diameter cast iron piston rings. E-mail: [email protected] Phone: 740-454-8082

My connecting rods are the high strength 7075-T6 aluminum alloy. Considering the robustness of the rods, 6061-TS alloy would probably be perfectly satisfactory.

 

[mic]

thanks jw

have just finished new mandral at .840 with .131 gap and will heat treat the rings now. will update later on compression etc

mic