lucas Dissy

[RCCob]

Hi every one, I was checking my dissy over the other day after I developed a slight misfire, I found that one of the springs on the advance weights was stretched and loose, the other one was tight and still springing back ok. I dont know much this would effect the timing curve? Question is, is this supposed to be like this? if not should I replace the springs? and where do I get them from? I understand there is different stiffness of springs available, So which should I buy?

any help appreciated Russ

[Sidecarbod]

Originally Posted by RCCob

Hi every one, I was checking my dissy over the other day after I developed a slight misfire, I found that one of the springs on the advance weights was stretched and loose, the other one was tight and still springing back ok. I dont know much this would effect the timing curve? Question is, is this supposed to be like this? if not should I replace the springs? and where do I get them from? I understand there is different stiffness of springs available, So which should I buy?

any help appreciated Russ

Hi Russ,

I presume that its a Rover dizzy that you are talking about.

I did a lot of experimenting with my dizzy on my 3.5 lump (now 4.6 ).

You will be getting too much advance too early with your setup which could cause problems unless the slack was compensated for when the timing was first setup by retarding the dizzy.

Real Steel sell a kit for 10 quid that has several springs in it. I found that two of the silver springs will give you full advance at 3k RPM which is just right. (One silver spring and one gun metal spring will do the same at 3500RPM).

Whilst you've got your dizzy off you can check out what the total advance is by fixing a 360 degree protractor on the end. (You get one from WH Smiths). It is easier to check when no springs are fitted.

Hold the dizzy in a vice and setup a pointer to the protractor then work the advance mechanism. Whatever the number is needs to be doubled for crank degrees. The reason that this is important is that you want to be running your 3.5 lump at 36 degrees total advance, any less than this and you will be losing BHP. (Don't go more than 38 )

If for example your dizzy measures 12 degrees then that is 24 at the crank. You will then want to set the static at 36-24= 12. The standard damper marking don’t go past 10 from memory but I made a load more at the static range then even more at the max advance range.

6-8 degrees static is often quoted as the static for one of these lumps but this gives bad low end BHP and bad top end! Rover were just playing safe due to wallies loading up the engine instead of changing down and/or poor fuel.

Up to 14 static is fine and infact 14 is good!

I modified my dizzy so that I could restrict the total advance to allow me to run 14 static.

I did loads of mods to my 3.5 lump to get more BHP but the only one that made me go "hey I can feel a difference" was setting the timing as described above. (Even fitting stage III heads was only just noticeable)

The extra advance makes the 3.5 pull a lot better from low RPM, I'd guess at 30 BHP more between 2-3.5k RPM. (Seat of the pants dyno!) It’s the cheapest 30 BHP you’ll ever get assuming that it was set at 6-8.

Regards,

Pete

[westborne]

Pete - tried to track you down at Godders on Wed but you seem to be amongst the chaos of moving offices.

looking at your recent posts - you are in danger of becoming a bit of an anorack !!!

(Mind you a knowledgeable one !)

[Sidecarbod]

Originally Posted by westborne

Pete - tried to track you down at Godders on Wed but you seem to be amongst the chaos of moving offices.

looking at your recent posts - you are in danger of becoming a bit of an anorack !!!

(Mind you a knowledgeable one !)

Hi Chris,

I doubt that you'd have spotted me from Godalming, I'm in Las Vegas!

Coming back today though and going straight into the garage to fire up the V8!

Anorack hey.....I guess I find cobs and V8's more interesting than IT....don't tell my boss though!

Catch tou next time you visit.

Pete

[RCCob]

Originally Posted by Sidecarbod

Hi Russ,

I presume that its a Rover dizzy that you are talking about.

I did a lot of experimenting with my dizzy on my 3.5 lump (now 4.6 ).

You will be getting too much advance too early with your setup which could cause problems unless the slack was compensated for when the timing was first setup by retarding the dizzy.

Real Steel sell a kit for 10 quid that has several springs in it. I found that two of the silver springs will give you full advance at 3k RPM which is just right. (One silver spring and one gun metal spring will do the same at 3500RPM).

Whilst you've got your dizzy off you can check out what the total advance is by fixing a 360 degree protractor on the end. (You get one from WH Smiths). It is easier to check when no springs are fitted.

Hold the dizzy in a vice and setup a pointer to the protractor then work the advance mechanism. Whatever the number is needs to be doubled for crank degrees. The reason that this is important is that you want to be running your 3.5 lump at 36 degrees total advance, any less than this and you will be losing BHP. (Don't go more than 38 )

If for example your dizzy measures 12 degrees then that is 24 at the crank. You will then want to set the static at 36-24= 12. The standard damper marking don’t go past 10 from memory but I made a load more at the static range then even more at the max advance range.

6-8 degrees static is often quoted as the static for one of these lumps but this gives bad low end BHP and bad top end! Rover were just playing safe due to wallies loading up the engine instead of changing down and/or poor fuel.

Up to 14 static is fine and infact 14 is good!

I modified my dizzy so that I could restrict the total advance to allow me to run 14 static.

I did loads of mods to my 3.5 lump to get more BHP but the only one that made me go "hey I can feel a difference" was setting the timing as described above. (Even fitting stage III heads was only just noticeable)

The extra advance makes the 3.5 pull a lot better from low RPM, I'd guess at 30 BHP more between 2-3.5k RPM. (Seat of the pants dyno!) It’s the cheapest 30 BHP you’ll ever get assuming that it was set at 6-8.

Regards,

Pete

Hi Pete, thanks for the reply and yes it is RV8 3.5. I don't have dissy off but I did have it to bits, that when I noticed the spring on the weights at the moment we have a silver on and a loose fitting gun metal one. dose this would mean I get full advance at about 3500-rpm? How did you mod your dissy to get the extra advance needed?

Regards Russ

[Sidecarbod]

Originally Posted by RCCob

Hi Pete, thanks for the reply and yes it is RV8 3.5. I don't have dissy off but I did have it to bits, that when I noticed the spring on the weights at the moment we have a silver on and a loose fitting gun metal one. dose this would mean I get full advance at about 3500-rpm? How did you mod your dissy to get the extra advance needed?

Regards Russ

Hi Russ,

Even though your springs are the same colours that I described I doubt very much that they are from the Real Steel kit. Infact the Real Steel springs do not go slack even when the dizzy is in its rest position. (Unless they've been stretched?). For 10 quid I'd just get a kit then you can be pretty sure that your dizzy is advancing at the same as mine.

You may not need to increase the advance, you may need to decrease it, this is why you need to measure how much advance it is giving you. There is a number stamped on the advance mechanism but I'd still check it with a protractor. Taking the dizzy off is not a big deal, you just need to make a note of where the rotor arm is pointing AND mark the dizzy housing against the timing over (Make the mark where the dizzy body goes into the timing cover). You might need to knock up a tool to move the oil pump drive to aid refitting the dizzy. A piece of steel tube worked into a rectangular hole works fine.

If the total advance needs restricting this can be done by making thin sleeves out of brass or steel tube that slide over the spring peg that acts as the stopper. If more advance is required you can use a dremel to grind the part of the mechanism that hits the peg. To do this you will need to knock out the roll pin that attaches the drive gear at the bottom of the dizzy. When refitting this gear try test fitting it on the shaft both ways as you will find that the holes for the pin line up better one way then the other way. If you don't do this and just hammer the pin back in you can crack the gear. (I did this and had to by a new one!).

The dizzy does need to come off the engine to do this work so some people might not bother! If you want the best out of your engine you have to put the effort in! The timing always needs resetting after taking the dizzy off no matter how well you line the marks up, I always find that it is a couple of degrees off!

Pete

[RCCob]

Hi Pete looks like new springs then thanks for the help by the way you have PM. regards Russ

[Sidecarbod]

Originally Posted by RCCob

Hi Pete looks like new springs then thanks for the help by the way you have PM. regards Russ

No problem, so do you!