Manifold or tappets?

[izthewiz]

My Chimp has had the precats removed according to the previous owner, and I've read somewhere that some side effects of this are noises that mimic those of tappets or a cracked/leaking manifold, which I can hear, but not identify.

Is there an easy/cheap way to ascertain the exact source of the noise?

I await the bestowal of the collective PH wisdom....

[Belle427]

I would say it does not mimic them to be honest but manifold gaskets are very common to fail.
A pita to do but maybe something to think about if just as a maintenance job.
Tricky to pin down, the old tissue paper trick may help holding it in various places to see if it blows around.

[TarquinMX5]

I can't say that I've heard that 'mimic' view before. Presumably no obvious marks on the manifold to indicate leaking exhaust gas?

[izthewiz]

I've got a sinking feeling that it's going to be the tappets. Manifolds seem pretty leak-free as far as I can tell, at welds and joints.

Any other suggestions as to what it could be, or how to check?

If it is tappets, what are my options?

Thanks.

Iz

[Belle427]

May be worth pulling the rocker covers just to check the pads are all still on the rocker tips.
What grade of oil do you use and when was it changed last?

[izthewiz]

That's a good shout, Belle. If it's the tappets, I'll do some cam measuring with a DTI and decide what to replace.

20W50 Valvoline VR1 according to the receipts folder, shortly before I bought it. The noise is there on startup, but quickly disappears, only to then be audible when warm at around 1800rpm.

I've had it since Christmas (best present to myself ever) and I'm planning to do a full fluids service in the next few weeks just to know absolutely what its status is. I've used VR1 in other RV8 cars and it's been fine.

Having spoken to Jools, he remembers mapping it after an Emerald K6 installation and being particularly impressed at 268bhp. It's a 400 allegedly, standard TVR cam but with some head work by a previous owner, and Jools thought there might be some additional mods beyond that, given the curves it produced. I haven't contacted the owner/modifier yet though (long list of other things to do). More puzzles to solve...

[Belle427]

That's a good healthy number for a lightly tuned 400 with some nice heads etc.
Some cars can be a bit noisier than others with certain cams, would be interested to know what was done to the top end.