OPS ? need info

[jim kapanowski]

Have two OPS engines i picked up, unfortunately the engine size is not on the sides i think there 65-67 can anyone tell me thanks

 

[JRXHydros]

Back in the day,I remember they had a gold cooling fin head with a lower silver cooling ring which was the .65... I seen all OPS engines run Fast back in the day,even seen the winning giant twin win at Indy Unlimited with OPS 60s,man that twin rigger was very powerful. Have Fun!

 

[Timbo Whalen]

Have two OPS engines i picked up, unfortunately the engine size is not on the sides i think there 65-67 can anyone tell me thanks

Jim, looks to be an older OPS 65...maybe pull the cap and button and measure bore and stroke.

Later model 67/80's had a finned cap.

 

[JRXHydros]

Yes they had finned red heads,but if your tired of them red heads...you can get a finned blue head

 

[MarkDanielsSr]

Those cases are from the .65 motors, yes, they had gold air cooled head caps. The 67 motors lost the cooling ring and went to a red finned water cooled head. If you run both, it is actually too much cooling. The 65 and the 67 p/s are interchangeable in the cases. The small all in one head button and cooling cap shown were on needle bearing rod motors, that top is also interchangeable as is the needle bearing rod, crank, and needles provided you have all the parts. I have cut the cooling rings off of several old cases I had in the drawer, still obvious what it was but not a bad look. I have a pair like that with 67 p/s and needle bearing rods in a twin hydro. Another with standard rod and 67 p/s in a mono. The biggest difference I have found is in the cranks, original early 65 cranks did not have the extra plug and were subject to vibration at upper RPM. The 67 motors were all balanced and I feel much more confident turning them up after some normal mods.

 

[MarkDanielsSr]

Looking back at your pictures, the OS 7F carb is an improvement in flow, The bore is a little bigger. If you are going to do any extensive mods, make some metal shims and bolt an OS drum intake on with the 9B bolt on carb and hold on tight.

 

[jim kapanowski]

there is a blue cap in the box ??

Those cases are from the .65 motors, yes, they had gold air cooled head caps. The 67 motors lost the cooling ring and went to a red finned water cooled head. If you run both, it is actually too much cooling. The 65 and the 67 p/s are interchangeable in the cases. The small all in one head button and cooling cap shown were on needle bearing rod motors, that top is also interchangeable as is the needle bearing rod, crank, and needles provided you have all the parts. I have cut the cooling rings off of several old cases I had in the drawer, still obvious what it was but not a bad look. I have a pair like that with 67 p/s and needle bearing rods in a twin hydro. Another with standard rod and 67 p/s in a mono. The biggest difference I have found is in the cranks, original early 65 cranks did not have the extra plug and were subject to vibration at upper RPM. The 67 motors were all balanced and I feel much more confident turning them up after some normal mods.

i am going to open it up later Mark do you have a good spare crank i need one

 

[MarkDanielsSr]

I will have to look, I have many OPS motors and more completely disassembled for parts. I will message you this week.

 

[jim kapanowski]

I will have to look, I have many OPS motors and more completely disassembled for parts. I will message you this week.

cool i will message you later one motor has the mallory slug one doesn't so I'm thinking one is a 65 one 67 if i read the responses correct

 

[MarkDanielsSr]

Not a good indicator. the cranks are interchangeable, so are the 65 and 67 p/s. Those are over 30 years old, could be any combination, put a mic on it.

 

[RobBinnie]

Jim
The alloy head is a home made mod
probably to add extra water cooling
A ops 65 gold head has water around the allow ring only and has a no water finned head on top of a small head button
Apart from the water cooled band this is the difference in the casing and finned top more or less the same engine as a OPS 67
A later OPS 67 red top has water on top of a bigger head button insert only
OPS 67 slightly bigger bore but the sleeve fits the OPS 65 but head button needs to be redone to suit bigger bore
Hope this helps