Backfire when lifting off (rover v8)

Ignition timing. Particularly the auto advance. and check the vacuum tube to the distributor, the little plastic ends are prone to leaking when they get old.

HTH

Steve

Oh yeah, forgot about that. How easy is this to do with one pair of hands, zero knowledge and a timing light?

The vac tube to the dizzy is ok (no leaks when I suck on it) - I replaced it last summer when I found the old one had deteriorated as you describe.

Cheers,

Neither of which will make the slightest difference to the acceleration.

Popping suggests exhaust leaks somewhere. You need the extra air to burn the fuel in the exhaust.

Assuming the Holley is correctly jetted try a bit more ignition advance. My EFI is running at 2 degrees more than standard - seems to be something to do with unleaded. I use Super, of course.

Righto - I use super as well (Tesco's 99, usually) so I will look to the timing. Can it be satisfacorily set in a home garage with one person with a timing light/strobe gun? I've got the Haynes SD1 3500 BoL - are there any deviations from the procedures in there that I need to bear in mind?

Cheers,

How old is this rover V8? Has it got (gulp) points? if so, first check the points gap, if the gap has closed up, usually through wear on the heel which touches the rotor shaft, this will affect the timing and may well be all you need to fix. Steve

Yes it's a one man job. Slackening the clamp bolt can be the most difficult part. ;-)

Don't slacken it completely - keep a bit of friction so it doesn't lose its setting.

Make sure you get the idle below the start of advance. 600 rpm if you can.

I tap the distributor round with a hammer handle on the vac unit.

84 vintage, according to the invoice for the original conversion (from Ian Lines in weston super mare)

It has electronic ignition - a toothed wheel in the dizzy activates a light sensor which acts in place of the points. This outputs to a black box, which outputs to the coil.

(Sparks are OK on all cylenders)

Cheers,

Good! I had previously found the timing marks on the crankcase and had the idea I needed to adjust summat down there, while lying on my back under the car.... Unpleasant idea.

Due to the layout of the TR7 engine bay, the radiator top hose passes tight up to the back of the dizzy - it interferes with gettting to the rear clip holding the cap on (The clip nearest the centre of the engine)

- might that be obscuring anything useful?

I will have a look this evening, as SWMBO is out :->

Cheers,

That's not a standard Rover distributor of '84 - they use variable reluctance sensing.

Sounds like a Luminition conversion of a points one - not that there's anything wrong with that.

If the distributor matches the engine it sounds like a pre SD1 unit from before the mid '70s.

There's normally a pointer mounted above the crank pulley on the timing cover on the oil pump side which can be viewed from above. With the scale engraved on the crank pulley.

It's not crossfiring is it? Rover V8's can be very fussy about the exact routing of the plug leads. Try and make sure they're not touching each other anywhere, it's awkward to do but can make a big difference. Everything else seems to be covered, although exhaust popping is often an airleak somewhere in the exhaust.

Exhaust leak, letting air in, allowing combustion.

Well that was a right bugger to sort out.

Timing was fine. One garage was baffled. AA geezer was baffled. Second garage did a lot of tests, replaced manifold gaskets, rebuilt carb (again) and then....

... it was the effing rotor arm leaking current down the dizzy. There are no trace lines on it, and it's shiny-brand-new, so everyone assumed it was OK. I bought it when the trouble started in december (yes yes, I know - but I moved house and got married in between, so the poor old TR has been neglected :-< ) and have done about fifty (unreliable) miles on it.

I'm kicking myself, for two reasons - a) I should have suspected a dodgy new component as I have been trained that way, and b) I've had two similar situations where changing the arm cured problems. I also had one fall to bits inside the dizzy - the rivet holding the brass arm in fell out.

I'm assuming that they're just badly made - does anyone know of good ones? I had Intermotor bits on before, and the mechanic has put a Lucas item on. They look identical right down to the moulding lines though, so we're assuming they come from the same factory (probably in China).

Cheers,