The V8 Owners Forum -

Did the 4.6 Rover EFI V8 have pistons with valve cutouts as standard??

Is it possible to fit pistons without valve cutouts to the 4.6?

i think the 4.6 is like the other rv8 varients,
they all came without cutouts,

the cuts outs were only added for the use of high lift cams,

If you engine is a recon then it is possible that the pistons have been fly cut.

I have recently built a 4.6 from a brand new short engine supplied by a company called Power Train Products. They did cut the pistons as they were supplying short engines to Morgan and a few other low volume car builders. (When I say brand new it is a 97 block and pistons that has been under someones bench for 11 years!)

Pete

Thanks Pete and Tony
That seems to be the case with this one.
Not having had a 4.6 before I assumed the cutouts were normal.
On my old 3500 I used the Blower cam and comp gaskets and had no clearance issues. I'm going to put some stock items back in soon and see if I get any problems with the valves hitting the pistons.
Now I just have to check the bores to see if they are oversized.

I've just measured my bores as best I can with my digital vernier and I get a fairly constant 94.02 to 93.98 so I'm guessing this is the standard bore size as the +20 bore seems to be 94.5mm according to the RS book.

I only have the vernier so I cant be that sure.
Would the +20 thou pistons be bigger than the stock ones?
The info in the RS book states bore size only and not piston size.

Does the +20 thou piston set just include +20 rings I wonder?
I'll give John at RS a ring tomorrow, but its normally quicker to ask on here.

Thanks
Perry

pistons are +20 too. Undersized pistons by 20 thou would make a seriously loud noise shortly before probably destroying themselves.

Just done a few bores with a spring divider then checked the divider with a vernier. All four are 94mm +/- 0.1 mm so I guess its stock and not +20 eh?

RS only do +20 stuff so I'll check the guys you lot use next week for a set of stock pistons and rings.