The V8 Owners Forum -

hi there i have bought a uprated distributor, il attach link to the item i have bought.
http://www.ebay.co.uk/itm/120717865699? ... 1439.l2649

it has a vacuum on do i need to remove the vaccuum, or not. if i do what do i need to do to the timing etc any help much appricated.

What is the application?, i.e. what engine / vehicle?

I hope that's the right coil - I've only ever seen Bosch coils for those ignition amplifier type distributors.

Chris.

its a 3.9 range rover 35D 500 edel borck

guys could really use some imput can i remove the vacuum or shall i jsut leave it? need to no as im drag racing in 2 weeks thanks

v8mini1 wrote:guys could really use some imput can i remove the vacuum or shall i jsut leave it? need to no as im drag racing in 2 weeks thanks

Here's some stuff that i wrote ages ago...

http://how-to-build-a-pilgrim-sumo.wiki ... by-members

Here's some stuff on the carb...

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

Basically my humble opinion is that the vac system does not suit the carb in question but you also need to do some work on the dizzy if you want to get the best out of this setup.

Sidecar, those articles are very interesting.

On the carb; when used on a lightweight vehicle, the secondary circuit can be altered to come in sooner by lightening the vacuum operated bob weights.

Any thoughts on this ?

Denis247 wrote:
On the carb; when used on a lightweight vehicle, the secondary circuit can be altered to come in sooner by lightening the vacuum operated bob weights.
Your thoughts ?

Yep that's what I did by drilling 7.5mm holes in the weights. I actually drilled 10mm holes but the valve opened too quickly which caused a bog. I back filled the holes with solder and re-drilled them.

The thunder series carb has an adjustable valve but the hole drilling works very well, it's just a bit more fiddly!

sidecar wrote:

Denis247 wrote:
On the carb; when used on a lightweight vehicle, the secondary circuit can be altered to come in sooner by lightening the vacuum operated bob weights.
Your thoughts ?

Yep that's what I did by drilling 7.5mm holes in the weights. I actually drilled 10mm holes but the valve opened too quickly which caused a bog. I back filled the holes with solder and re-drilled them.

The thunder series carb has an adjustable valve but the hole drilling works very well, it's just a bit more fiddly!

I though it was only me who did this as I haven't found it referred to anywhere. It's a bit like weaker springs in the SU carb damper, gets the carb open sooner. It must be balanced with the other specs of the car, but generally a lighter car can take advantage of this whereas a heavier one may 'bog'. Personally I prefer a mechanical linkage..memories of the old Webber 28/36 DCD I guess.

Denis247 wrote:

sidecar wrote:

Denis247 wrote:
On the carb; when used on a lightweight vehicle, the secondary circuit can be altered to come in sooner by lightening the vacuum operated bob weights.
Your thoughts ?

Yep that's what I did by drilling 7.5mm holes in the weights. I actually drilled 10mm holes but the valve opened too quickly which caused a bog. I back filled the holes with solder and re-drilled them.

The thunder series carb has an adjustable valve but the hole drilling works very well, it's just a bit more fiddly!

I though it was only me who did this as I haven't found it referred to anywhere. It's a bit like weaker springs in the SU carb damper, gets the carb open sooner. It must be balanced with the other specs of the car, but generally a lighter car can take advantage of this whereas a heavier one may 'bog'. Personally I prefer a mechanical linkage..memories of the old Webber 28/36 DCD I guess.

LOL, I thought that I came up with the idea!

Muscle manta then loaned me a book on Eddy carbs and it mentioned grinding some metal off the weights in order to lighten them.

I was both pi55ed off and quite chuffed at the same time to read about this in the book!

When I had a 3.5 lump I tried removing the valve completely....it was interesting to say the least, even at 3000 RPM you could kill the motor stone dead just by booting the throttle, the motor would only fire back up as you took your foot off the throttle.

I guess the effect depends on exactly where you drilled the holes but just out of interest what size holes did you go for?

sidecar wrote:

Denis247 wrote:

sidecar wrote:
Yep that's what I did by drilling 7.5mm holes in the weights. I actually drilled 10mm holes but the valve opened too quickly which caused a bog. I back filled the holes with solder and re-drilled them.

The thunder series carb has an adjustable valve but the hole drilling works very well, it's just a bit more fiddly!

I though it was only me who did this as I haven't found it referred to anywhere. It's a bit like weaker springs in the SU carb damper, gets the carb open sooner. It must be balanced with the other specs of the car, but generally a lighter car can take advantage of this whereas a heavier one may 'bog'. Personally I prefer a mechanical linkage..memories of the old Webber 28/36 DCD I guess.

LOL, I thought that I came up with the idea!

Muscle manta then loaned me a book on Eddy carbs and it mentioned grinding some metal off the weights in order to lighten them.

I was both pi55ed off and quite chuffed at the same time to read about this in the book!

When I had a 3.5 lump I tried removing the valve completely....it was interesting to say the least, even at 3000 RPM you could kill the motor stone dead just by booting the throttle, the motor would only fire back up as you took your foot off the throttle.

I guess the effect depends on exactly where you drilled the holes but just out of interest what size holes did you go for?

7mm, drilled quite close to the edge for maximum effect.

Other settings I use are: Primary jets 80, secondary 110 with 62/52 needles.

Found via MUCH trial and error, even going to 65/52 needles made it hunt on mid/high throttle. Carb fed with Facet Red Top, no pressure regulator needed as some is already lost in the 5/16" pipe run from the boot.

Car weighs 1200Kg and Engine is 4.6 with 216 cam, modded big-valve heads, but a very restrictive block-hugger exhaust manifold. Std distributor with vacuum, with points but using transistor assist. (I've seen too many cars incapacitated on the road when their electronic pointless system failed.) I do use heavy duty points though for their anti-bounce value (and the electronics has some anti-bounce also).
But your article about modding the distributor has given me renewed interest in sorting out my ignition. Be interested in your views on this
http://www.ebay.co.uk/itm/V8-Rover-Luca ... 1c0fecc140
(With suitable coil of course)

Denis247 wrote:
Found via MUCH trial and error, even going to 65/52 needles made it hunt on mid/high throttle. Carb fed with Facet Red Top, no pressure regulator needed as some is already lost in the 5/16" pipe run from the boot.

Car weighs 1200Kg and Engine is 4.6 with 216 cam, modded big-valve heads, but a very restrictive block-hugger exhaust manifold. Std distributor with vacuum, with points but using transistor assist. (I've seen too many cars incapacitated on the road when their electronic pointless system failed.) I do use heavy duty points though for their anti-bounce value (and the electronics has some anti-bounce also).
But your article about modding the distributor has given me renewed interest in sorting out my ignition. Be interested in your views on this
http://www.ebay.co.uk/itm/V8-Rover-Luca ... 1c0fecc140
(With suitable coil of course)

Hi Denis,

Your setup sounds interesting. I've fed your carb setup into my spreadsheet, it is 19% leaner than the base setup on cruise and 21% leaner than the base setup on acceleration. The WOT is alot richer due to your huge 110 secondary jets!

My setup is quite different, it is 86 primaries, 69-52 rods. My secondaries are 80 at the moment, it does run well with 77 secondaries. My AFR figures are 14.5:1 on cruise, 12.5:1 during acceleration and around 12.5 -13:1 at WOT. The rods are home made, I made a set of 70-52 rods, the car was undriveable even though the rod was only 1 thou thicker than the 69 rods. My setup is 16.9% leaner than base on cruise and 0% leaner than base on acceleration. All this goes to show that no two engines are the same which is why I have changed my tune somewhat...I don't like giving out carb setups anymore! I run an Edelbrock electric pump with no regulator (around 6 PSI, I think).

My 4.6 lump is in a Cobra replica which is around 1000kg. It has stage III V8Dev heads, skimmed to give 10:1 CR. I run a Piper 285 cam driven by a Piper duplex chain. I run standard lifters, adjustable pushrods set to 20 thou pre-load. I run an Eddy manifold port matched to the heads. The headers are home made, around 30 inches long, 1 +3/4 diameter. They lead to large side pipes which shoot out flames on overrun!

I was running the ignition setup that I linked to but since then I've gone to something that you won’t like if you are into points! I now run a programmable MSD along with Magnecor leads, I made a new base plate for my dizzy and mounted an MSD pickup to it which is triggered by the standard Lucas 'spike wheel'. The bob weights are locked up as the curve is fully programmable from the MSD. I was not expecting much difference in performance, I went to MSD because I now run NOS and the MSD has a NOS ignition retard function but I must say that there was quite a big difference in performance even without the NOS. I was quite shocked and pleased! The engine was dyno’d at 285 BHP at the fly with the old ignition, I’ve tweaked the carb and fitted the MSD since then, I’m hoping that it will make 300 BHP.(The NOS adds another 85 BHP) My MSD allows me to run about 6 degrees timing from 0-600 RPM, it then holds at 16 degrees from 600 to 1000 RPM. I get a good tickover with this setting, the 6 degrees at very low RPM gives the starter motor an easy time. My all in is 28 degrees at 2700 RPM. When the NOS is running it knocks off 3 degrees. I still don’t run a vac system but Muscle Manta now runs the same setup as me with a vac system. I can not run the MSD vac system as my cruise vacuum is exactly the same figure as the idle vacuum. (The ported take off is no use either!) Mr Muscles car can do 27 MPG which he is pleased about!

The ebay link to the replacement for points that you posted up looks OK but it is hard to say how good it is without some technical info. What KV does it knock out and how many milli-joules can it supply,not to mention what the RPM limit is. I would say that I would not be surprised if your points setup is costing you power, There just is not enough time to saturate the coil fully on a V8 with points. Having said that you have fitted some electronics to your system so that will help but I bet you still have timing scatter.

I’m very wary of after market rotor arms since I had issues with a few, I think that the rotor misalignment issue was not helping them either.

Cheers,

Pete

Thanks for the info Sidecar.

One fine day I'll try your primary/rod combination. Marvelous what a difference 1 tho can make eh. Didn't find the secondary made much difference in wot performance over 89, so I'll probably go back to these next time I get a mo. Forgot to mention I also use a (modded) lowrider restrictive aircleaner for hood clearance reasons.

I know my ignition is lacking, and I'll get around to trying a decent electronic setup soon. But I will keep a set of points in the boot in case!. I've looked at the programmable ones and those seem the way to go, but thought I'd try just what a difference a cheaper setup would give. But the system in the link I gave shows the complete unit!, I thought it only showed the pick-up.., so all the electronics are in that little housing. Not very promising, it's probably just an electronic points substitute, so your comments re not saturating the coil would still apply.

I used to run a 1293 mini-cooper S with 649 (full race) cam (1960's) that revved to 7500 on a points distributor, and then even built my own capacitive-discharge system for that to see what difference it made. Not sure about Joules, but it put out a 400v spike from a big capacitor. Slightly disappointingly, it only seemed to make pick up smoother, no more power. But that was 4 cylinders, and this is 8, the points are closed for only half the time relatively, so I would expect more gains here.

Sometimes I think I'm having just too much fun.

It does sound like you are having fun!

You won't be able to use my jet and rod combo unless you make a set of rods (A huge pain in the ass) but you could try 83 primaries, 65-47 rods. That would be 15.9% leaner than base on cruise and only 0.2% leaner than base on acceleration. If your motor will run with a leaner cruise setup than mine then there is no reason not to stick with it to be honest. I did find that if I leaned the acceleration off it did not pull as well. I made a set of 69-54 rods, they were no good!

I reckon your headers will be at least one good reason why your setup differs to mine. I run a 14x3 inch Holley cotton filter, it runs a drop base but the filter lid is still at least 2" from the top of the carb. Oh I've cut the choke tower off the top of the carb as I don't use the choke.

sidecar wrote:My AFR figures are 14.5:1 on cruise, 12.5:1 during acceleration and around 12.5 -13:1 at WOT.

Pete, I did a lot of work on my Rover engine with regards to power and afr targets (easier with megasquirt) and found the best for my engine was 14:1 at idle, 15.5:1 at cruise, 13.5:1 on acceleration and 13.1:1 at WOT. I know we had similar engine outputs albeit with different induction and wondered whether you had tried the above figures and what your opinions were? Just for everyone else's info Pete is on carbs and I had tb injection.

Cobratone wrote:

sidecar wrote:My AFR figures are 14.5:1 on cruise, 12.5:1 during acceleration and around 12.5 -13:1 at WOT.

Pete, I did a lot of work on my Rover engine with regards to power and afr targets (easier with megasquirt) and found the best for my engine was 14:1 at idle, 15.5:1 at cruise, 13.5:1 on acceleration and 13.1:1 at WOT. I know we had similar engine outputs albeit with different induction and wondered whether you had tried the above figures and what your opinions were? Just for everyone else's info Pete is on carbs and I had tb injection.

That's very similar to what I've ended up with. But my engine is an otherwise standard Vitesse unit.