The art of good comedy

[martynharrison]

I've just been out on the drive to adjust my timing. The big book of rover v8 maintenance told me what to do, so I used the starter motor to jiggle the engine around to TDC where the garish blue paint on the pulley had been scraped off to show the marks and then took the top off the dizzy.

 

Unfortunately, the picture in the book was quite different because S&S changed my wiring to electronic ignition and I've got a sort of slotted black disc and a (opto electric?) sensor sitting across it.

 

First question, how do I set the timing with this? The engine was at TDC but the slots looked much of a muchness and there was no obvious way to add or remove degrees. Probably an S&S answer on that one as they know what it has got.

 

As a second stab, I don't mind doing it by feel, if it is done by twisting the dizzy like it was back in the days of the Reciprocating Steam Engine I last did this on, in 1846 as I recall. What should it sound like? How to tell when it has gone too far either side, at tickover?

 

Second question, I tried sucking on the vacuum advance tube which I pulled out of the carb, there was a sort of "glocking" sound like a diaphram with a leak, but nothing was moving around the pin that goes from the vacuum pump thing into the underside of what would be the condensor plate. Having done this before long ago, I was expecting the whole plate to move round a few degrees depending on how hard I sucked on the tube. Do I still need a vacuum advance? If so, does it normally move in these circumstances or does it need much more vacuum than I was achieving to shift it?

 

Wasn't a dead loss, I changed the cap and leads, found a very loose spark plug all oiled up, and the car seems a bit smoother, probably that missing cylinder.

[rayjones]

Martyn,

 

My 2 litre has a similar set up, from S&S, I just used an old strobe light I'd had in the garage from 1848 I think. Was last used on a newish triumph spit I had once, still worked though, as you suggest, you just twist the dizzy until the now fairly stationary timing mark moves to the right place at tickover, then you can watch it advance as you rev up!

[malcolm]

It's funny this should come up.  I just adjusted mine (V8) using the basic static method described in the Autodata Rover SD1 book.  So today I got out my trusty timing strobe gun, which I'm used successfully on a few 2L cars.

 

According to the timing gun I'm way way off.  Right off the scale in fact - maybe as much as 30 degrees before TDC.  Static timing days 6ish degrees before.  So is it broken, or do you need a different one for a V8?

 

I'm fairly sure it is set-up properly, there's not much you can do wrong  :laugh:

 

Malcolm.

[rayjones]

Maybe there is a "wasted spark" on the V8 engine that is upsetting the strobe gun? ie one on the non firing stroke as well! Correct me if I am wrong, I'm trying to get my head round this, not knowing the Rover V8 but a four cylinder dizzy runs at half the engine revs I think, which makes it possible to get the Dizzy 180 degrees out, as there are only two sparks per engine rev, but four leads from the dizzy. does the V8 dizzy run at engine revs, with four spark take off points, from the cap, with two leads on each "spark point" so that you get a spare spark on the non compression stroke. Malcom's timing must be OK as the car is obviously running normally. As a point of interest, when I fitted my electronic ignition system, I did have to move the distributer quite a fair bit to get the timing back to where it should be, but as my engine runs fine, it's got to be OK.

[malcolm]

You've exceeded my understanding Ray.  There are 8 contacts in the dizzy but I'm not sure at what speed it runs?  I'm loathe to move the timing round to the point indicated by the 'gun' as it's running fine now!

 

Malcolm.

[Cinnobar]

Ray, No wasted spark on a V8 standard ignition just with 8 lobes not 4. Dizzy runs off the cam same as any other 4 stroke of the period. If its 180 out it bangs and pops same as any other engine.  Wasted spark is 2 strokes and very modern EDIS type ignition which is only on very late GEMS RV8s

 

Malc, couple of thoughts, firstly if your pulley is anything like mine the TDC marks will be out mine were about 8 degrees and mine is the original pulley for the engine, I've heard others talk about being 30 deg out!!!!! Is this the same pulley that rattled loose a few years ago? That could have B^***d the keyway which won't help. Mine has accurate TDC & 10 deg BTDC mark and mine runs about 12 DEg at idle with Vac connected or 10-11 with no vac. What dizzy you running? Best way to check is to loosen dizzy and whilst engine is running move back and forwards to get peak revs, then retard a little. Test drive, if it pinks under load then it needs retarding a little more. This gets around the dodgy marks issue, which makes timing lights ineffective. If you ever have the heads off then mark an ACCURATE TDC mark, which is straightforward even without a Dial gauge. Let me know if you want to know how to do it.

 

Jim

[Guest ajttriumph]

srobe is the way to go with engine warm and idling the desirable amount of advance will depend upon engine tune and fuel.

 

Often on a performance engine vacuum advance will be disabled, with the mechanical advance or the electronics doing things for you.

 

Best to get someone to show you how to do the timing, you will only need to be shown once.

 

BE EXTERMELY CAREFUL about how much advance you dial in as it can cause severe engine damage.

[Cinnobar]

AJTTriumph, thats great if he has accurate timing marks I suspect he hasn't hence my comment about doing it by ear.

The Rover is not anything like as sensitive to ignition timing as some, probably due to the decent combustion chamber shape & alloy heads, it helps that you generally don't use huge amount of revs on a 7 V8 anyway, but yes over advance will cause detonantion and damage.

 

Jim

[malcolm]

Thanks Jim.  All a bit of a problem really.  If the pulley is way out then goodness only knows what it's actually set to.  A bit of experementing next weekend I think.  On the plus point the car is running nicely now - responsive and no sign of 'pinking' so it can't be *that* far out?

 

Malcolm.

[andrewt]

You should be able to establish TDC via a spark plug hole and a long probe on a clock gauge. Having a vacuum advance is an advantage on a road engine as it vastly improves tractability at low revs and part throttle, but is of little advantage on a high revving performance engine where off cam tractability is not an issue. As a general guide with a road type cam you do not want more than around 34 deg advance at any time or head gasket failure looms. Also although the V8 will run with the timing out, it is as sensitive as any other engine if looking for optimum performance & economy.

With the optical type ignition, then it is a case of getting the timing close then cranking the engine over whilst moving the distributor 'til it will start. Once it is warmed up  a bit, then time it by ear as above, then use a timing light to optimise it. (using your verified TDC marks). My preference is for a timing light with advance built in so you use the TDC marks only but these are harder to find or borrow. Get it right & the engine will feel better than ever!

Reasonable rates for homers if you bring your car to Aberdeen or pay my expenses to come to you!

 

Cheers

Andy

[malcolm]

Interesting stuff.  I've now taken the view that (since the TDC and before/after marks are meaningless on my set-up) it is best to play it by ear.  It's paid dividends too.  After some adjustment and a few test runs everything is as it should be.  It seems the timing was too far advanced, but now I have a good pickup from low revs, an excellent free run up to 5,500 and no 'suspicious' noises.

 

:cool:

 

Malcolm.