RB's are all slotted screws, just a few use cap head. Mostly japanese engine use cap head screws, that I have noticed.

James, get better screw drivers and you won't mess up the screw heads so badly.

I have 40 different screwdrivers Tony and I even went as far as finding the perfect fit and then grinding down the edges so the driver fits into the holes in the cooling head. The design of the screws are just so bad that the driver slips loose before I can apply any torque. The P5 has a large O-ring type squish band under the head button that gets torn up fast and needs to be replaced and my engine needs a new front bearing. FYI the Werks head screws fit perfect and they are 3mm cap head hex so they will be very difficult to strip out if anyone is interested.

RB's are made by novarossi, at least the good ones...


those hafta be 3.5mm thread with 3mm head correct?

Correct, as far as I know, the Nova's use slotted screws,

How is the O-ring getting torn up so quickly? If its squished down, nothing is moving to tear it up. The 21-4 has the same type of O-ring thing.

As soon as you tighten it down it gets chewed up. It's not a good fit into the button and the button tears it up when you tighten the bolts

I have not measured them yet. They are slightly shorter but I think they will work fine.

The newer RBs with the Low profile head ( LG ) uses shorter head screws, the LG head is made with 2 cooling fins sitting lower over the engine case. If the head screws are shorter, its easier to strip out the threads on ths engine case if they are to short

I also just used screws off a old dead engine I had. The head screws were two threads shorter but that shouldn't matter. Idk what nova was thinking, let's put a shallow slot flat blade screw for the head bolts. Much easier to torque with the allen heads.

http://www.amainhobbies.com/product_...si-Engine-Head

This Hudy screwdriver is made for the Nova's, it fits into the head PERFECT and I have never had a issue

i disagree, as soon as you start to wear the allen head out, good luck getting it out of the case. I use a nice stanley screwdriver with the tip dremeled just a touch to fit in the head a little better and havent had an issue and i take my engines apart regularly

Flathead screws: reasoning , harder to apply too much torque that will warp the block
James : if you are tearing up the oring its because your shimming is lower than novarossi recommended .65mm is the very lowest i will shim a novarossi , .60mm is ok but ......

Just leave the oring out , wont harm anything

However Neal sends em out is how its shimmed..I will measure when I get back home..The flathead screw now makes sense But I still hate them..I have never in my life heard of anyone warping their blocks with metric hex head cooling head screws but I guess anything is possible.....

I agree with James hex hex way better screws with slots equals problems. I don't run the oring on my cre P5 -head button