3.5 smoke/idle issue

[Burtie2904]

Hi All,
My 3.5 V8 recently went for a service and an MOT, it had its throttle cable replaced and thats about it.
It now wont idle like it used to, idle is very inconsistent, i keep adjusting the idle rpm screw and it then will be fine for a bit but then will either be idling too high or idle to low and begin to stall the next time it gets started up. I have noticed the idle falls a lot if i have the electric fans on (drawing currents and reducing spark) but even without that it changed from 400 ish and stalling, to 800 from hour to hour. The next symptom is when accelerating/after you floor it or get going from idle it puffs out a noticable amount of black ish smoke (running too rich?), smokes when increasing throttle, not when at throttle. Also not sure if i just hadnt noticed it before but it seems new, when the air filter is off you can hear a hissing like sound which seems to be fuel related (rises with throttle position before revs rise), that might just be normal but i dont remember it from before.
Also its a 1988 3.5 with stock twin SUs.
And ideas appreciated.

 

[norseman]

I've owned four RV8's but they've all been efi so I'll leave it to others to advise you.
The only re-assurance I can give is that the hissing sound is perfectly normal with SU / Stromberg carbs, in fact when balancing these by 'ear' it's the marginal changes in sound that the tuner listens for.

 

[Burtie2904]

I've owned four RV8's but they've all been efi so I'll leave it to others to advise you.
The only re-assurance I can give is that the hissing sound is perfectly normal with SU / Stromberg carbs, in fact when balancing these by 'ear' it's the marginal changes in sound that the tuner listens for.

Thanks, I thought it was fine, just hadn't noticed it before. Next time i see go to my local mechanic ill see what he thinks. It definitely seems to be as if its excess fuel and it is most noticeable from accelerating from a low throttle position/ low rpm range.

 

[FFG]

What colour are the spark plugs? Whip one out to get a good idea if its running rich. Also the AFM's tend to give up, run rich splutter then dies over a few miles so it may be that - replaced a few on the TVR. Does it kick out a load of carbon every now and again?

 

[Burtie2904]

What colour are the spark plugs? Whip one out to get a good idea if its running rich. Also the AFM's tend to give up, run rich splutter then dies over a few miles so it may be that - replaced a few on the TVR. Does it kick out a load of carbon every now and again?

Yeah ill have a look when this rain stops. It just seems to dump unburnt fuel under throttle, so yes, certain loads and rpms tend to give a nice big puff out the back. Also Im relatively new to the rover V8, what do you mean by the AFM, I assume Air flow meter and i dont quite get what u mean by that in relation to the SU carbs.

 

[FFG]

Sorry, didn't read the SU part of the post so ignore any reference to air flow meters. Have you check the routing of the new cable to see if its catching and has a smooth routing?

 

[Burtie2904]

Sorry, didn't read the SU part of the post so ignore any reference to air flow meters. Have you check the routing of the new cable to see if its catching and has a smooth routing?

Yep that was a problem about a week ago, but now its all fine. Thanks though.