RB270 Project

[Solid Air]

First step of RB270 project complete with the barrel now stripped of nikasil and ready to be fitted with a cast iron sleeve. My mate Viv is taking care of making a packer plate for the base of the barrel and the necessary extra meat and cooling fins added to the top. The original exhaust port will be bridged and then the small exhaust ports will be opened up into the main port on each side. All based on a CasaCase with 70 x 120 crank.

[Covboy]

What case is that mark ? Casa ?

What clutch & gearbox are you planning to use ?

[Solid Air]

Yes it is a CasaCase Steve, clutch is a Casa powermaster and gearbox AF 5 speed.

[dickie]

Clever stuff. So, where is the 70/120 crank from?

I'm guessing with such a long stroke that you're looking for low to mid range performance mostly?

[Solid Air]

The crank is from Casa Performance Dickie and yes we're planning for the power to be exactly that. Using an Ex-Box ST, hoping we're for peak power to be between 6 and 7k making a easy, smooth and torquey ride.

[Adam_Winstone]

Nice project.

[Knowledge]

Hi Mark. I will be following this one.

If the original RB was intended to run a 58mm stroke then the measurement from the bottom of the transfers to the top of the barrel would be 58mm. If you up the stroke to 70mm, how will you increase the distance from base of the transfers to the top of the barrel to 70mm?

(I know how I would do it, but let’s see what you plan to do)

Martin

[Solid Air]

Hi Martin, while up at the racing and in Viv's workshop, we were looking at what we are working with and have had a slight change of plan.

Piston wise, we may use a TS250 piston which is slighter longer than a standard TS1 or RB. This should negate the need for lifting the lower edge of the exhaust port and a base packer plate.

At the top of the barrel, Viv will make an ali collar that will be welded to the barrel, machined to accept the cast iron sleeve and then fitted with some extra cooling fins. It is being done this way, collar separately from fins, due to the space needed for the welding equipment.

Whilst it is a RB barrel, it will not necessarily use the same port layout once it is sleeved and Viv has tinkered with it.

How does that sound?

[Knowledge]

Perfect. Go for it.

Let me know if you need any help. I know an excellent ali welder at Ipswich if you are looking for one (probably not)

[Solid Air]

Thanks Martin, I appreciate that. Luckily, just around the corner from Viv's workshop is someone that can do both the welding and the sleeve

[ULC Soulagent]

Certainly looks good from what I seen from it yesterday

[Nigel. S]

How smooth will that crank be? (in terms I understand )

[Solid Air]

Silky smooth I'm hoping Nigel

[Knowledge]

It is likely to be a rather long engine. My engine is only 62mm stroke and the barrel is pretty long already.

Will your even-longer engine fit? You might consider making a new head cowling out of two standard cowlings. Make sure you get the hole for the plug in the best location, cos I didn’t.

(I’m not being negative here, just making sure you have thought of stuff, which probably sounds rather patronising. Sorry. I’ll get my coat)

[Adam_Winstone]

My 290 72 x 72 Mugello just fits but I did have to push the legshields as far forward as they would go, which then allows the rear runners to align forward too.

[Solid Air]

It's definitely going to be a long engine Martin, but will have to wait until it goes into a frame to see what we're dealing with.

Not showing off, but I have a Mammoth head and cylinder cowl to go with it

[Norrie Bodge]

What port timings are you aiming for on this setup??

I did a TS240 last year - 62x70
Welded an added 8mm extra fin onto the donor cylinder
before sending it off too get steel linered, so too keep the port timings down

[Knowledge]

And I guess you need a piston which is at leat 71mm tall.....

So may questions for you, you massive cranker

[Solid Air]

After a period of inactivity for one reason or another, work has restarted on the RB270 project and machining the top and bottom additions for the barrel, not by me I hasten to add though.... what are friends for?

Norrie, apologies for not responding sooner, not sure what happened there.

Timings will be:

Exhaust 175
Transfer 125
Boost 130
Inlet 360





bb image

[Norrie Bodge]

Some great work goin on there mate

Timings will be:

Exhaust 175
Transfer 125
Boost 130
Inlet 360

About where I setup mine .. that’ll be a great ride