3.9 timing

bones · Post by **bones** » Wed May 06, 2009 7:17 am

ive done more checking today ,and this is how goes, 1000rpm 10 deg, at 1250rpm its 14 deg at 1300 its 16 deg, it seems to cut in quick, At what rpm should it cut in ,advice needed again, where would i be without this forum, (o yeah fishing)

rich Ok edit time, ive stripped the dizzy ,first thing noticed rotor has been cutting through the green wire ,and only had about 4 strands connected, and the 2nd thing is the bob weights 1 can be moved about 3/16 and all it does is pull the spring down it doesnt stretch it ,bob needs to be moved right to the side before the spring starts to stretch . Is it supposed to slide up and down ?? ,the other bob spring doesnt .This is the first time ive looked inside the dizzy and not sure about the springs and bobs ,Advice as always is needed

rich

sidecar · Post by **sidecar** » Wed May 06, 2009 9:43 am

bones wrote:ive done more checking today ,and this is how goes, 1000rpm 10 deg, at 1250rpm its 14 deg at 1300 its 16 deg, it seems to cut in quick, At what rpm should it cut in and has anyone got the rpm and deg aswell please,also ive got my old pertronix dizzy aswell with 2 wires black and red where would they go ,im using a hyfire cd ignition box and ballast resister, as i might see about trying this dizzy instead of the mallory ,advice needed again, where would i be without this forum, (o yeah fishing) rich

If you run without the vac you can have the mechanical advance come in very hard and quick. I've ran my setup with two soft springs, all the advance was in by 2200 RPM and the car drove fine. (A did replace one of the springs so its all in at 2700 now)

If I was you I'd run a bit more static advance, 12-14 at 1000 RPM, it wants to be all in around 2700-3000 RPM. The total wants to be around 34 for a 3.9 lump. You will find that you tickover goes up as you wind in a bit more static, you can just run it back to 800 or whatever you run with the idle screw.

I can't help with the other stuff, sorry!

sidecar · Post by **sidecar** » Wed May 06, 2009 10:35 am

bones wrote:ive done more checking today ,and this is how goes, 1000rpm 10 deg, at 1250rpm its 14 deg at 1300 its 16 deg, it seems to cut in quick, At what rpm should it cut in ,advice needed again, where would i be without this forum, (o yeah fishing) rich Ok edit time, ive stripped the dizzy ,first thing noticed rotor has been cutting through the green wire ,and only had about 4 strands connected, and the 2nd thing is the bob weights 1 can be moved about 3/16 and all it does is pull the spring down it doesnt stretch it ,bob needs to be moved right to the side before the spring starts to stretch . Is it supposed to slide up and down ?? ,the other bob spring doesnt .This is the first time ive looked inside the dizzy and not sure about the springs and bobs ,Advice as always is needed rich

You need to check that when you move the bob weights that this movement does translate into a rotation movement of the shaft that the trigger (star wheel) is fitted to. (Maybe about 10 degrees of rotation). If it does then at least that part of the mechanism is working. As to the springs, quite often they are knackered and stretched, one one dizzy that I worked on they were virtually rusted away. When you move one bob the other should move anyway if the system is working properly.

Personally I'd change them using ones out of the kit that RealSteel flog if you have a standard Lucas type of dizzy. If you have a Mallory then you may have to get Mallory springs.
I do not run one of my springs slack but I've read that this can be done to create a two-part advance curve. (You really are after the last BHP if you are doing this sort of stuff

).

You need to get all this sorted out otherwise you will never get the ignition to work properly. I suspect that there are many, many RV8 lumps being driven around with loads of BHP that is locked up inside badly setup dizzies!

Where abouts do you live? Remind me, what dizzy do you have?...Edit, Essex! Bit far away, I live in Surrey. Another edit...Unlite, I don't really know anything about them, hopefully someone will!

Pete

bones · Post by **bones** » Wed May 06, 2009 10:53 am

Im in nth essex, 1 of the bobs wrattles and has got about an 1/8" play in it, the other is smooth to operate and is close to the centre. Its not so much that i want every last bit of bhp ,just to run right is fine with me, The cut wire will be re-done and heat shrinked, but these bobs confuse me, as i dont know if they are ok or not, the dizzy is a mallory

rich

sidecar · Post by **sidecar** » Wed May 06, 2009 11:58 am

bones wrote:Im in nth essex, 1 of the bobs wrattles and has got about an 1/8" play in it, the other is smooth to operate and is close to the centre. Its not so much that i want every last bit of bhp ,just to run right is fine with me, The cut wire will be re-done and heat shrinked, but these bobs confuse me, as i dont know if they are ok or not, the dizzy is a mallory rich

From your description I'd say that there is a problem with the loose bob weight, I think that you will have to take the thing apart carefully (take some pictures so thatyou know how it went together).

Hopefully you will suss out what's wrong.

Cheers,

Pete

bones · Post by **bones** » Sat May 09, 2009 7:27 am

Just a quick ???, with a mallory unilite dizzy, how much play should there be in the rotor, mine can move about 1/4",but it does spring back, is this right.

rich

CastleMGBV8 · Post by **CastleMGBV8** » Sat May 09, 2009 8:54 am

Rich,

Is this a new or wel used Mallory?

Mallory distributors are apparently notorious for having poor quality advance springs which soften very quickly allowing the advance to come in very quickly.

The 1/4" play is ok it's the shaft turning against the advance mechanism.

From what you said earlier it doesn't look too far out, if you rev the engine to 3000RPM can you read an advance figure. if so and its no more than 34 deg, rev the engine to 3500RPM and check there is no further advance if that is the case it's ok.

If you get more than 34 deg of total advance then you may have to back off the initial slightly to bring the total advance back to where you want it.

This may bring the initial down too far and you will need to consider getting a recurve kit.

If the total advance is coming in too early say below 2700RPM then you will need to replace the advance springs.

I would strongly recommend running without vacuum advance unless you know it's restricted to no more then 5 deg of aditional advance.

Interesting thread on Mallory dizzys from the Brish V8 Forum.

http://forum.britishv8.org/read.php?6,5627

Just re-read this thread and it states the the Unilite has 24 deg of mechanical advance so you may have to restrict your initial advance to 10 deg.

Distributors horrible fiiddly little bas....ds

I'm fiddling with my carb later to try and get that almost right!

You still hoping to get to N/Weald tomorrow?

Just found this which may help.

http://www.loco4fomoco.com/MalloryAdvanceCurveKit.pdf

Kevin.

bones · Post by **bones** » Sat May 09, 2009 12:24 pm

Not hoping to be at nth weald ,but i will be there, timing will be done today, and hope it will run ok, if not ive got another dizzy with my old pertonix ignitor in it,And thanks for the advice and help all, Are you still going tomorrow Kevin. and is an pertronix ignitor classed as a magnetic or electric, i am taking both dizzy tomorrow as the timing doesnt seem to stay on 10 it jumps about

rich

bones · Post by **bones** » Sat May 09, 2009 9:51 pm

Well had a mare of an afternoon, the dizzy clip decided to pop off with the engine running ,dizzy bounced up and rotor snapped off the carbon spring tip, on the unilite, tried another dizzy and no joy. So bodged up the unilite and it works so , as someone says on here, its only a bodge if it doesnt work

rich

bones · Post by **bones** » Mon May 11, 2009 8:14 pm

Ok more ignition stuff, ive got a mallory c4 promaster coil fitted inside the car near the hyfire away from engine heat ,is it ok to have it that far away from the dizzy,?

bones · Post by **bones** » Thu May 21, 2009 10:29 am

. this is how far bob comes out before any resistance by the spring[/img]

bones · Post by **bones** » Sat May 23, 2009 12:48 pm

i got a vacuum kit today ,and im being lazy but what springs should i use toget advance all in by 2800rpm, and di i need to use the plastic red key thing??

rich

sidecar · Post by **sidecar** » Sat May 23, 2009 1:48 pm

bones wrote:i got a vacuum kit today ,and im being lazy but what springs should i use toget advance all in by 2800rpm, and di i need to use the plastic red key thing?? rich

I don't know about your dizzy but if you go for the settings that I've suggested with regards to the static and the all in (Including the RPM that its all in by) then you will give issues if you run with a vac system.

CastleMGBV8 · Post by **CastleMGBV8** » Sat May 23, 2009 1:50 pm

Rich,

Did you mean vacuum kit or do you mean mechanical advance kit?
don't know what the red key thingy is unless the Mallory has adjustment for the mechanical and or the vacuum advance.

Should be some instruction that will advise which colour springs to use for the desired mechanical advance curve.

Kevin.

bones · Post by **bones** » Sat May 23, 2009 2:23 pm

Sorry my fault, mechanical advance kit , just wondered what colour springs to use, the red plastic keys are for the bottom plate adjustments,they have retarding degree numbers on them??

rich