OPS 1.27 build

[dwilfong]

Here is the beginning of my OPS 1.27 build up.

This is a OPS .90 eng with a new OPS 1.20 P/L fitted in the case.

Also a VAC .91 rod installed with no modification to the VAC .91 rod or the OPS1.20 piston.

The R/S ratio came in at 1.47 a little lower than I would like. But this will be a grunt eng not a rever.

There needs to be some jocking around to the liner hight and digging in the case to make it all come together.

Looks like the final # will be 135 transfers on the lowest point and any ex I wish.

Thanks again to Steve wood for the great job fitting the P/L to the case.

Thanks Steve.

 

[dwilfong]

Yes the piston is a nice fully machined cast piston. very light.

Will see if it stays together with a 40% nitro load.

The dang thing is 1.257" It is BIG!!!!!!!!!!!!!!!!

Biggest ABC set up I have seen.

Now this will be a sledge hammer.

I am going to take what I learned from the VAC 1.05 build and balance this eng.

Also use the full complement ceramic bearing for the crank.

The bearing are testing very good in my 1.01 no failures so far with many gallons thew the eng.

 

[charles siler]

Verry cool are you going to inlarge the exaust port and can a black head be fitted for one of thoughs monsters . Is the rod shorter than the original ops 90 rods and have you seen a new style knife edge ops 90 rod same with the new pistons and liners are extreamly diferent from the old ones. Any thrust spacers on the rod looks like alot of space . Sooper idea cant wait to see the results

later Charlie

 

[dwilfong]

The black head jug dose not have the meat with all those fins to open up the ports.

I will have a 189 ex timing after I make the move. This will give me a good starting point.

I will cut some ears on the ex port.

I have a black head also that I used to study for this build.

The VAC .91 rod is shorter but no modifications are needed to do this build.

The space is where the rear disk drive fits.

The piston pin size is the same on the OPS 1.20 as the VAC .91 rod and the bottom end of the VAC .91 rod is the same as the OPS .90

I will give up some R/S ratio but the steel rod more than makes up for any losses. The short rod will also move the toque curve lower in the RPM range.

Don't think I will have to spin this monster up to make power. 24000RPM should do it.

This will go in a 47" Cal Craft mono for testing.

Now getting the right prop is an other story.

 

[wayne middlemiss]

The black head jug dose not have the meat with all those fins to open up the ports.

I will have a 189 ex timing after I make the move. This will give me a good starting point.

I will cut some ears on the ex port.

I have a black head also that I used to study for this build.

The VAC .91 rod is shorter but no modifications are needed to do this build.

The space is where the rear disk drive fits.

The piston pin size is the same on the OPS 1.20 as the VAC .91 rod and the bottom end of the VAC .91 rod is the same as the OPS .90

I will give up some R/S ratio but the steel rod more than makes up for any losses. The short rod will also move the toque curve lower in the RPM range.

Don't think I will have to spin this monster up to make power. 24000RPM should do it.

This will go in a 47" Cal Craft mono for testing.

Now getting the right prop is an other story.

nice info David , like the idea of the vac rods

 

[Ray Sametz]

Nice project, with a 4 piece case make sure the crank is true 90* to cylinder. If your use the disk rotor check the clearance. Old school OPS 90 runner......==={}

 

[ALLAN YUEN]

Wow Look big bore piston :blink: tell me measure ?

 

[dwilfong]

Wow Look big bore piston :blink: tell me measure ?

1.257"

will make the eng 20.8cc

 

[charles siler]

When are you going to test it. And are you going to do a video.

 

[dwilfong]

When are you going to test it. And are you going to do a video.

Looks like every thing is on hold for now.

I have sold my house and will be in a rental for a few till the new one is built.