The V8 Owners Forum -

Is it always the same 2 plugs that die?

If so that should narrow down where to look.

Could it also be the spark is not good to these 2 cylinders - dizzy not central to cap etc.? Perhaps managing to leak down / jump across to another spark wire - space wores differently.

If the 2 cylinders that die are on a single carb - swap this with another carb and see if the flooding follows tha carb ir stays on original cylinders
Could be too much fuel pressure on this carb - due to routing of pipework.

IAn

(Out of interest the CO at idle is 3.8% but the hydrocarbons are 5000!!!!! 500 would be nice.)


Does 3.8%CO( which i think translates to 13.0 afr) at idle sound OK? whats he meaning with the hydrocarbons

Steve

idle best at 13.5 afr = 2.6 co and 0.92 on lambda

full throttle should be 13.0 afr 0.88 lambda =3.8 co

From my understanding high hydrocarbon reading is due to unburnt fuel - i.e not incomplete combustion - that results in a high CO - but not being burnt at all.

CO is formed when there is not enough O2 present to complete the combustion process - Too much fuel

Sounds to me it's burning rich and at the same time some are not burning at all.

Weaken the mixture and check the ignition/plugs - Makes me wonder about the places you are taking this to if the carb mountings have not been noticed before and why the current one did not offer solution to the way its running.

I would start with a new set of plugs a thorough check of the ignition system and a full check on the idle balance of the carbs / float bowl heights and see where I was before anything else.

Andrew

Looks they have got some results, hopfully QUOTE from email;
Co at idle is 3.9 with Hc 2500 . any lower on the Co and the popping starts again. This is a feature of your cam.
5.0 Co through the range and 6.0 when gunning it with Hc never more than 300

So maybe the best i can expect with the webers/engine spec

I am pretty sure that wont get you through an MOT test though as its still far too high

Andrew

Why re the MOT?

The emissions are based on the age of car or engine whichever is the older

TR7 - probably pre1975

Visual smoke test only - leave the fags at home and it passes

Ian

Its just had its MOTC last week saying that Andrew it wont have to do the ammisions bit on the mot with it been a older car, it wont be doing its bit for the enviroment though

Maybe still not perfect but much better then it was, without looking at the last rolling road print out the afr's were dipping into the 10's mid range

Looking at How to power tune Rover V8 Engines by Des Hammill, he reckons the ideal is; idle afr 13.5;1 (2.6%co) accelerating from a standstill using max throttle;12.5;1 afr (5.0%co) so not a million mls out, just thinking though that them figures are prob possible with fuel injection but not with four big old fasioned webers
As mentioned Idle is ; 3.9co (13.0 afr) full throttle 6.0co (12.2 afr)then 5.0co through the range (12.5 afr)

As I read it as an '82 TR7 or bigger than a 3.5 which makes it newer than 1980 then I figured this would apply.

First used between Aug 1975 & July 1986 CO max 4.5%, HC max 1200ppm

Andrew

Darkspeed wrote:As I read it as an '82 TR7 or bigger than a 3.5 which makes it newer than 1980 then I figured this would apply.

First used between Aug 1975 & July 1986 CO max 4.5%, HC max 1200ppm

Andrew

You might be right Andrew Saying that they have never bothered testing the TR in the eight years iv owned the car, maybe they just dont bother with the older stuff as much

Its back the starting prob seems to have gone, dont know if its the change from NGK 7's to 6's or there playing around with the jets?

Only prob seems to be the idle, they have set it around 5-600rpm (on idle it sound c--p) its always been around the 900=1000rpm mark, i noticed after a run last night the oil light just flicked on a few times on idle, took it up to 900/1000 rpm and the oil pressure was up to 15+psi with no oil light, so the question is what is the normal idle for a RV8 with stage heads and cam etc?

Steve

To be honnest, as slow as it will idle at a stable speed without hunting and with enough oil pressure that the oil light stays out (cam and bearings are safe and it isn't washing the bores as the mixture goes momenterily rich). Usually 650 to 900 revs depending on cam.
Mike

OK it seems to be starting OK, BUT i took it for a good run the other day (Around 60 mls) which it ended up using about £35 worth of fuel i worked that out about 10mpg taking it really easy
What i did notice though on the AFR gauge (which mabe isnt accurate, but gives some idea) idle still seems a bit on the rich side. But say when holding it at 60ish with hardly no throttle the afr gauge is in the low 10's give it a touch more throttle and they are up into the mid 12's low 13's, seems fine on full throttle through the range.
Any ideas lads, Its like having the fuelling back to front take it steady with hardly no throttle and its drinking fuel, give it a bit more and its OK

What is it with these tuners they are great at talking but just dont seem to be able to get it right

Just about had enough with the carbs now after 2 years of trying to get the right, ime sure its done more mile on the rollers then me driving it

It does seem really close to been right though? its just the richness on very light throttle/cruise/

HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Drop down a jet size on the idle jets as these control the idle and progression circuits which you are indicating are very rich.

What size are the jets on the idle circuit?

Andrew