RV8 4.6 piston question

mgbv8 · Post by **mgbv8** » Tue May 06, 2008 7:57 pm

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?

Post by **Coops** » Tue May 06, 2008 8:48 pm

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,

sidecar · Post by **sidecar** » Tue May 06, 2008 8:57 pm

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

mgbv8 · Post by **mgbv8** » Thu May 08, 2008 2:49 pm

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.

mgbv8 · Post by **mgbv8** » Thu May 08, 2008 7:30 pm

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

Post by **katanaman** » Thu May 08, 2008 8:24 pm

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

mgbv8 · Post by **mgbv8** » Sat May 10, 2008 7:02 pm

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.