OPS .40 cylinder head

[timothy johnson]

Yes mine came with aluminum .016 shim. Sounds like something is up with your bore!! also remeasured the bore and .866 is more like it. Sorry.

 

[Terry Keeley]

I wasnt thinking when i said id get a measure on the rod. The engine is all buttoned up, besides the head. Im not taking it back apart, I hate cleaning loctite out of screw holes so i guess well never know. I did measure the bore though, it is .863; also, at TDC, the piston is .154 below deck, Terry, do you have one of these engines that you could compare with?

I ran the 45's back about 30 years ago, lol.

I remembered I had a book of old specs and the 45 had a 22mm (0.866") bore and 19.75mm (0.778") stroke, sounds like either the 40 and 45 had the same bore or the 45 piston/liner drops in and that's what you got.

Does your motor say "40" on the case? Can you measure the stroke?

 

[MarkKing]

I ran the 45's back about 30 years ago, lol.

I remembered I had a book of old specs and the 45 had a 22mm (0.866") bore and 19.75mm (0.778") stroke, sounds like either the 40 and 45 had the same bore or the 45 piston/liner drops in and that's what you got.

Does your motor say "40" on the case? Can you measure the stroke?

The engine casing has “40” cast into the side of it. From what Timothy said about his .45, id say ive got a .40 with a .45 piston and liner in it!

 

[MarkKing]

I

I ran the 45's back about 30 years ago, lol.

I remembered I had a book of old specs and the 45 had a 22mm (0.866") bore and 19.75mm (0.778") stroke, sounds like either the 40 and 45 had the same bore or the 45 piston/liner drops in and that's what you got.

Does your motor say "40" on the case? Can you measure the stroke?

I could measure the stroke, but that would mean tearing the motor back down, I dont want to do that I suppose i could zero an indicator out on the top of the piston and turn it over once, but knowing the stroke really isnt going to help me any. Im just gonna solve my head clearance issue, and run it.

 

[Richard Hartley]

If i remember correctly the original OPS 45 had 40 on the case.

 

[Terry Keeley]

I could measure the stroke, but that would mean tearing the motor back down, I dont want to do that I suppose i could zero an indicator out on the top of the piston and turn it over once, but knowing the stroke really isnt going to help me any. Im just gonna solve my head clearance issue, and run it.

Pretty easy to get the stroke as you mentioned, that might solve the mystery of why the head is loose and hits ATDC.

Maybe you got a 40 head in a 45 motor?

 

[MarkKing]

Pretty easy to get the stroke as you mentioned, that might solve the mystery of why the head is loose and hits ATDC.

Maybe you got a 40 head in a 45 motor?

Possibly

 

[MarkKing]

UPDATE
Made major headway with the cylinder head for this little engine this morning; it should work! Chamber volume is right at .4 cc and squish will be .011 with a .020 shim. I have yet to tap the hole for the glow plug, tap should be in before the end of the week. Im still hunting for shims, if anyone has a few, i will buy them from you! I really dont want to have to make them

 

[timothy johnson]

Very nice !!

 

[brad nichols]

Looks good!

Brad

 

[MarkKing]

Thanks guys. Its coming together slowly. Should be able to run it by early next week

 

[Terry Keeley]

UPDATE
Made major headway with the cylinder head for this little engine this morning; it should work! Chamber volume is right at .4 cc and squish will be .011 with a .020 shim. I have yet to tap the hole for the glow plug, tap should be in before the end of the week. Im still hunting for shims, if anyone has a few, i will buy them from you! I really dont want to have to make them

What did you make it with?

 

[MarkKing]

What did you make it with?

I work in a machine shop. All the lathe work was done on a msc engine lathe. Drilled the bolt holes and glow plug hole, and Interpolated the combustion chamber with ball endmill on a kondia mill fitted with a SWI CNC kit.

 

[MarkKing]

Well been awhile since ive given an update on this little engine. Progress halted with deer season, but my season came to an abrupt end so back to it! I sourced another exhaust pipe, I think it will work well, time will tell. Turned a short header for it, hopefully the divergent taper doesnt mess with exhaust pulses too much. Also made a flange to secure header in the coupler; all im waiting on now is the spring for header, and fuel to get to the lhs, and ill run it a bit to make sure all is well.

 

[Steve White]

I work in a machine shop. All the lathe work was done on a msc engine lathe. Drilled the bolt holes and glow plug hole, and Interpolated the combustion chamber with ball endmill on a kondia mill fitted with a SWI CNC kit.

Looks real nice. Been years since making any heads for this guy - back then I did all the work on a Unimat and ground the tools for shaping. Also, what is the thread for a standard glow plug?

0.008"-0.0010" is the ball park for a .40-.45.

Thx.

 

[ids987]

Going back to head shins, I’ve had success with a compass cutter and copper foil. It’s a bit painstaking, but managed to make quite a number of head shins that way.

 

[tom galdys]

Would you like a new head button? I have many, send me your address and I'll get them out right away. Tom Galdys

 

[bermudadude]

Okay, ill see if i can buy some shims before doing all that Ive already replaced the crank bearings, and the liner/piston and rod are all new. Thanks
-Mark

hmmm simple one-- where did u get the rod? are u sure its a .40 and not the newer or present day .45 rod ? for that matter idk if they will fit but is the piston/liner the right one? the pin boss would be a different hight

 

[ian thompson]

Making head shims is really easy if you have access to a lathe..

 

[Gary Lauer]

For some reason the link wont open. Do you punch the holes then turn the outside on s mandrel?