Rover V8 timing set all in @ 35 degrees but idle is now 20!!

smash · Post by **smash** » Sat Mar 24, 2012 9:55 am

Title says it all really - before I set timing I checked TDC and found it was not where the fly said it was only about 4deg out tho. So I remarked TDC - disconnected vac and set all in timing at 35 deg.

Then I checked idle timing which was showing something like 20!!

Lucas single points 35 dizzy running powerspark Aldon igniter type electronic ignition. The engine is P6 9.25cr running stock (as far as I know...) bar offy mani and Edelweiss 500cfm drowner(!)

Should I be worried? Should I throw my dizzy away?! Or should I just drive it like I stole it!

Grateful for pearls of wisdom...

jan_rrc39v8 · Post by **jan_rrc39v8** » Sun Mar 25, 2012 10:04 am

i would probably start by checking/cleaning/lubricating the mechanical advance mechanism inside the dizzy and also check if the vacume advance actuator is still working correctly.

then i would also check if the crank pully is still showing correct timing marks (set nr 1 cil at TDC by feeling for compression through the plug hole)
if the TDC mark does not line up with actual TDC of the nr1 piston the crank pully (vibration damper) is probably fubar.

also check for any leaks in the intake side because these effect vacume which in turn effects vacume ignition advance.

smash · Post by **smash** » Mon Mar 26, 2012 12:11 pm

Little confused here - all the timings I did were with vac disconnected so having no effect. Should max be done with vac?

All I can say is car is going very well at mo

DEVONMAN · Post by **DEVONMAN** » Mon Mar 26, 2012 12:46 pm

smash wrote:Little confused here - all the timings I did were with vac disconnected so having no effect. Should max be done with vac?

All I can say is car is going very well at mo

Yes, timing should be done with the vac disconnected.

Back when Rover produced the p6, it is unlikely that they aimed at 35 degrees all in for the engine timing. Although this figure is now often found to give good performance for a 3.5 RV8 it is pushing the limit and makes no allowance for bad fuel and driving styles/conditions. So the dissy advance curve was amended accordingly and many advance settings will be found inside the Lucas dizzys.
It's possible to find dizzys with say max advance of 9, 11, 13 degrees total advance which effectively gives 18, 22 and 26 degrees engine advance on top of the initial idle setting.

With a 20 degree initial idle setting you may be risking damage when the vacuum advance comes into effect at say light to medium throttle particularily if the carb is not the original factory type. Some aftermarket carbs give massive ported vacuum.
Even at high rev full load conditions the vacuum advance can become effective and give too much advance.

Unless you are going to check all the various conditions, I consider an initial advance of between 12-15 degrees to be a sensible compromise. If your top end performance noticably falls off using this setting , then you will need to play around with the dizzy to get the all in timing back up to 35 degrees.

Denis

PS. On the lower baseplate/weights within the dizzy you will find a number stamped which indicated how many degrees the dizzy is meant to advance.

sidecar · Post by **sidecar** » Mon Mar 26, 2012 12:55 pm

For what its worth here is my 2 pence worth...

http://how-to-build-a-pilgrim-sumo.wiki ... by-members (The bit on dizzies after the gumph on braided hoses)

To sum up what I wrote in the link above I'd run 14 at idle, 36 all in at 2700-3000 RPM and don't use the vac system at all. (Before anyone kicks off it just does not work well with the Eddy 500 carb)

The OP referred to the Eddy as a 'drowner'....it is on the standard jetting when fitted to a 3.5 engine. Run it like this for 5k miles and you won't have any bores or rings left! (bore wash)

smash · Post by **smash** » Tue Mar 27, 2012 12:24 pm

Thanks for replies - I will check baseplate and also read link. I appreciate and take on board all advice.

Yeah sorry, I called it a drowner purely a bit tongue in cheek as 500cfm seems a bit big. The jetting/rods are as per Rpi recmds for 3.5 Rover.

I am currently using the timed vac port on the Edelbrock.

sidecar · Post by **sidecar** » Tue Mar 27, 2012 4:01 pm

smash wrote:
The jetting/rods are as per Rpi recomends for 3.5 Rover.

I am currently using the timed vac port on the Edelbrock.

RPI's setup.....oh dear!

Sorry mate but RPI's settings in my experience are totally rubbish! (Mind you they never seem to use the same settings twice). The carb itself is OK for a 3.5 despite what the on-line CFM calculators might say.

Have a read of my article with regards to the timed port.

Might be teaching you to suck eggs here but here is some gumph on the carb, its under the stuff on fuel pumps...

http://how-to-build-a-pilgrim-sumo.wiki ... ing-system

smash · Post by **smash** » Tue Mar 27, 2012 5:11 pm

What would you recommend as starting point for the Eddy 500 on 3.5 stocker?

My rods are 6252 @mo. *edit* it's on silver springs at mo and not the orange

I know I should do the Innovate wideband AFR (had one on my cob and dialed that in really well with that even got Stoic happily at idle) - just this thing's a cheap toy and I know how easily I can get carried away!!

Again appreciate all help.

sidecar · Post by **sidecar** » Tue Mar 27, 2012 5:31 pm

smash wrote:What would you recommend as starting point for the Eddy 500 on 3.5 stocker?

My rods are 6252 @mo. *edit* it's on silver springs at mo and not the orange

I know I should do the Innovate wideband AFR (had one on my cob and dialed that in really well with that even got Stoic happily at idle) - just this thing's a cheap toy and I know how easily I can get carried away!!

Again appreciate all help.

Those rods are standard, I bet the jets are 83 or even 80's. If you let me know I'll compare your setup to what I reckon will be OK for your engine which is...

86 primaries, 67-55 rods, silver springs, secondaries probably around 86.

With regards to the springs you need to be careful, the orange paint falls off them, they then look silver!

Please bear in mind that it is hard to jet a carb over the web but trust me, RPI's setup is usually rubbish!

Cheers,

Pete

smash · Post by **smash** » Tue Mar 27, 2012 9:41 pm

Defo silvers I've got - not a hint of orange and tightness of coil is a bit different. I know what your saying about baseline setup - I did dial in my last edelbrock on a 302 pretty well but I had an Innovate Wideband AFR and once you disconnect the secondaries and lock them shut, primary set-up is easy, then reconnect secondaries and finish the job. I just don't really want to spend out on another Innovate and pull the pipe to weld the bung etc. as this car is supposed to be just a cheap toy. I guess I could just get it on the rollers - ATSpeed in Rayleigh is my local but no experience. And tbh, an innovate is probably cheaper! I will persevere - what's the worst that can happen (don't answer that!)

I will pull the carb apart and see what we have and report back - cheers again.

Boosted LS1 · Post by **Boosted LS1** » Tue Mar 27, 2012 10:04 pm

Static should be up to 10 degrees. At 14 degrees or more the car will wheelspin off the line like a scalded cat. Tiz good fun when you get the sharp response. Any more then that and you'll get starter motor kickback, never seen a car go backwards though but it could happen I guess, lol. Centrifugal advance could be another 18 degrees, ie 28 total advance under WOT. Add in some extra for cruise, high vac conditions but back off if the engine pinks. Just food for thought.

sidecar · Post by **sidecar** » Wed Mar 28, 2012 4:45 am

Boosted LS1 wrote:Static should be up to 10 degrees. At 14 degrees or more the car will wheelspin off the line like a scalded cat. Tiz good fun when you get the sharp response. Any more then that and you'll get starter motor kickback, never seen a car go backwards though but it could happen I guess, lol. Centrifugal advance could be another 18 degrees, ie 28 total advance under WOT. Add in some extra for cruise, high vac conditions but back off if the engine pinks. Just food for thought.

If that car wheel spins off the line due to the fact that the engine is making good power then you could always back off the throttle!

My starter motor can cope with more than 14 degrees advance, the idle timing should be set to what the engine wants by careful testing, really if the starter motor can not cope then it is a poor compromise if you have to then back off the timing.

28 degrees total is fine for a 4.6 lump but the 3.5 lump needs more advance than that.

The Lucas vac system does not work well with the Eddy 500 carb, it can be made to work if the mechanical advance and static are all compromised but then the WOT performance will suffer.

According to Des Hammill JE Developments do not run with the vac system and do run the timing figures that I've quoted.

sidecar · Post by **sidecar** » Wed Mar 28, 2012 5:02 am

smash wrote:Defo silvers I've got - not a hint of orange and tightness of coil is a bit different. I know what your saying about baseline setup - I did dial in my last edelbrock on a 302 pretty well but I had an Innovate Wideband AFR and once you disconnect the secondaries and lock them shut, primary set-up is easy, then reconnect secondaries and finish the job. I just don't really want to spend out on another Innovate and pull the pipe to weld the bung etc. as this car is supposed to be just a cheap toy. I guess I could just get it on the rollers - ATSpeed in Rayleigh is my local but no experience. And tbh, an innovate is probably cheaper! I will persevere - what's the worst that can happen (don't answer that!)

I will pull the carb apart and see what we have and report back - cheers again.

Sounds like you know what you are doing with the carb.

I also tried setting one up by disconnecting the secondaries it works OK but you can force the carb into a situation that it would not normally be in which is the primaries fully open and the secondaries not open at all. Normally the secondaries start to open before the primaries are fully open.

I found that using a vac gauge connected to the non-timed port was a good way to setup the acceleration circuit, basically open the throttle enough to get the car to accelerate hard enough to require the richer mixture. (in other words the engine is being put under load). Make a note of the vac reading then make sure that you have fitted piston springs which will have the rods in the up position at that vac level.

I guess the problem is that in order for the car to accelerate hard enough to warrant the mixture to be richened up then some heavy cars might require the secondaries to be open to a small degree, the problem is that the only way to set the AFR at this point is via the thin part of the rods, using the secondary jets to make the change would be bad, they can really only be used for the WOT setting.

My mates Cobra with a 427 lump in it has the opposite problem, even when the car is accelerating hard the vacuum under the carb is still high so the rods are still in 'lean mode' even though we have fitted the purple springs. I'm going to make some spacers that we can push inside the pistons that lift the rods so that they do lift even with around 10 inches showing on the vac gauge. (We can test this by running the engine with the piston covers sort of half fitted so that we can see if they are up or down). I know that his carb is not too small because the vac does drop to 1.5 at WOT.

An LC1 is a good way to go, I'd lend you mine but you live too far away!

I have a mate who has an LC1 that he never uses, I'll ask him if he wants to part with it.

Regards,

Pete

DaveEFI · Post by **DaveEFI** » Wed Mar 28, 2012 7:59 am

sidecar wrote:
My starter motor can cope with more than 14 degrees advance, the idle timing should be set to what the engine wants by careful testing, really if the starter motor can not cope then it is a poor compromise if you have to then back off the timing.

Of course with mapped ignition, you can have a separate setting for cranking versus idle - something not really practical with a mechanical system.

sidecar · Post by **sidecar** » Wed Mar 28, 2012 8:53 am

DaveEFI wrote: Of course with mapped ignition, you can have a separate setting for cranking versus idle - something not really practical with a mechanical system.

Very true!

That's what I've done with my programable MSD, below 500 RPM my timing is around 8 degrees from memory, from 500-700 RPM it then advances up to 16 degrees and it remains at this to 1000 RPM so basically my idle timing is 16 degrees at 800 RPM (I may push this to 18 as Muscle Manta runs the same setup and his engine seemed to like 18 degrees). Before I went to this system my starter motor would cope with 14-16 degrees even though my lump is a 10:1 CR 4.6. I know that some Rover starter motors are not as good as others so a compromise may have to be set. I still run a dizzy but it's 'locked out'.

The idle timing does depend on several things, not least the cam but usually with a bit of fiddling you can find the sweet spot which is always more than what Rover specified!

AJMHO!