lifter preload

[rv8500]

Hi, can anyone help me? I am a new owner of a 5ltr chimaera with a few problems. What should the preload be set too? Is it .020" - .060" as in a normal rover v8. Mine appears to be .100" (must be too much) Also my car is a 97 but my cylinder heads and rockers are all dated 94, is this normal or has my car its heads changed? Thanks

[rv8500]

I havn't had the heads skimmed, but they might have been done before I bought it. The engine has been to bits before, because the inlet gasket was covered in black sealer and that can't be original I'm using a composit gasket from tvr gear. The cars only done 18500 miles so it can't be too bad! (I hope) Thanks

[rv8500]

Oh no, thanks for the reply but I thought the bigger the shim under the rocker pedestal the less the preload. I've taken the cylinder head off the drivers side today and valves 4 and 6 havn't been closing properly, I'm guessing this is my problem. If the heads dated 94 it must have been changed at some time, so could be a miss-match of bits.

[rv8500]

Yep, the date on the heads (both of them) is 94, also on the rockers. They are tvr spec with 42.8mm inlets and really well ported and polished. The exhaust valves on 4 and 6 have black soot on the seating face ( I had low compresion on those two cylinders only when warm) The bores look imaculate tho.

[rv8500]

I just did a static compression test with a not very good tester, but when it was hot I got 15 psi The good valves were reading about 125 psi, which isnt great either but my guage might not be too acurate. The car did run well tho, just had a bit rough idle and a miss fire upto 2000 rpm then was fine. I'm sure its had work done but not had its pre load set holding these two valves slightly open (they gave a good seal when the rockers were removed) so it cant have run properly for a long time.