Mixture/timing???

[TVRIK]

Gentlemen.. Whilst having the beast in for a change of gearbox,
I asked for the mixture and timing yo be set, unfortunately he hasn't been able to do it as it drifts back out however he sets it. The oil pressure seems quite high but lowers at higher revs.
Not sure that has anything to do with it.
Any ideas?? Oil pump? Filter??

Hopin one of the wedge Gods can help! :/

[marcus1875]

Probably not got anything to do with it but my oil pressure fluctuated from 3 when driving to under 1 when idling.
i changed the oil and filter and it is a steady 3 now. no movement at all.
dont see how that would effect the trouble you have tho.
marcus

[mrzigazaga]

Hi mate..I wish i could be of more help but im sure high oil pressure is not a good thing and can cause damage to an engine pretty quick..Could be a sticking oil pressure relief valve??..Not 100% im affraid..Sorry...Ziga

[TVRIK]

Cheers guys.. I always though it was low pressure that was a big problem!
Gonna Get a new filter anyway, just to see if that effects anything, as they cost next to nothing.
Gonna have to go back in as well, making a right racket!
Don't think they have the manifold gaskets on right, sounds blood awful.

[ralph350i]

TVRIK said:

Cheers guys.. I always though it was low pressure that was a big problem!
Gonna Get a new filter anyway, just to see if that effects anything, as they cost next to nothing.
Gonna have to go back in as well, making a right racket!
Don't think they have the manifold gaskets on right, sounds blood awful.

Hi Rik
The manifolds are a right beast to get right mate, they probably gave up trying to do up the hard to reach bolts, and in regards to your oil pressure, what's it reading at idle mate? the dizzy and oil pump are connected, so this could be why the timing is playing up? but I can see how unless your oil pump is seizing up, worth checking mate, good luck

[TVRIK]

ralph350i said:

Hi Rik
The manifolds are a right beast to get right mate, they probably gave up trying to do up the hard to reach bolts, and in regards to your oil pressure, what's it reading at idle mate? the dizzy and oil pump are connected, so this could be why the timing is playing up? but I can see how unless your oil pump is seizing up, worth checking mate, good luck

Hi Ralph, well it's starts out about 3 on idle, but gradually creeps up to 5 but when you rev the engine it drops,
That seems all backwards to me?
What's the oil pump like to fit, never done one?

Cheers Ralph.

Rik

[wild rover]

Wondering whether the sender unit for the gauge has an intermittent fault or a sticking relief valve at the oil pump. I would agree with changing the filter first.

[TVRIK]

wild rover said:

Wondering whether the sender unit for the gauge has an intermittent fault or a sticking relief valve at the oil pump. I would agree with changing the filter first.

Yeah Ziga has said something similar, gonna put new filter on, don't expect it to fix the problem but be interesting to see if anything changes!

[Wedg1e]

TVRIK said:

What's the oil pump like to fit, never done one?

The oil pump on the RV8 isn't a unit as such; it's formed as a couple of chambers in the engine front cover into which the gears fit, followed by a cover plate.
Usually the casing gets scored causing loss of sealing of the gears and LOW pressure, so I wouldn't worry that the pump is dying - if it is, it's not a five minute fix.

Sticking relief valve again often causes low rather than high pressure (though it could do either); there's a modified valve piston (the 'tadpole') that generally cures it. I fitted one to my car and in 12 years it's never had oil pressure problems that weren't caused by cornering too hard

[adam quantrill]

What is drifting? The mixture, or the timing, or both?

I wonder if the timing problem is related to the oil pressure problem because they are both driven off the camshaft on the same cog, upwards goes to the dizzy and downwards to the oil pump.

If the timing is drifting then make sure the vacuum is disconnected and plugged and the idle revs are steady of else you're on a losing battle.
If you still can't get it to settle (it should go back after blipping the throttle) then maybe the advance weights are sticking inside the dizzy? You should get a smoot advance as you increase the revs and go smoothly back down to 6deg BTDC as you reduce them again.

[V8 Fettler]

Start with the easy things first. When was the oil and filter last changed? What condition is the oil in? Then fit a mechanical pressure gauge to eliminate possible issues with existing pressure sensor and existing electrical gauge.