Small Fan Housing & Magneti Marelli Distributor Reproduction

[stretch]

All of a sudden i get a liitle stirring in my groin area. Beautiful.

Now where did i put my penny bottle

[PhilipB]

Does the finished article use points or does it have modern internals?

[911hillclimber]

Great example of engineering and faith in making a good batch with the assumption they will all sell, but keeping the cost down.

I guess Mike means getting the engine as a whole to tune together all the parts of a twin spark system.

Nice effort by all.

[Darren65]

[Mike]

What I mean is that there is a world of difference between producing nice shiny copies of racing parts, and then getting them to perform as the originals.

I'm sure the vast majority here would be more than happy to have a 'bling' twin dizzy in their engine bay and it will work fine, but if you are trying to extract
the very last hp out of your motor using this dizzy, like we were with the Martini RSR, then it's a very different matter.

We ended up having to throw away the internals and start again with very specialist expert help, it took 18 months and thousands of pounds to get it to work
how we wanted it to. The very last degrees of advance required to run the motor at high rpm are incredibly hard to find, and when you're operating at such
high speeds the tolerances required on machined parts, bob weights and throwout springs are crucial.

Also a little concerned about the dyno testing previously mentioned here, I think Darren is confusing a distributor tester with a dyno, again a world of
difference between bench testing just the dizzy and then running it up in the real world environment of an engine dyno.

But obviously I'm talking about racing which is what this part was originally designed for, as any racer knows it's the last 20-30hp which makes the
difference from being at the front to running midfield. Btw, be very careful with your cap and rotor arm choice, be aware of vibration which will destroy
them in no time.

[Darren65]

Does the finished article use points or does it have modern internals?

Hi Philip,

Ben offers a choice of a fully authentic dizzy that's correct in every detail, one with Bosch type internals or just the case for you to install your own.....if you follow Mike's advice you'd probably choose the latter!

[stretch]

I thought we were running twin plug because we are trying to avoid detonation due to the high CR of our engine builds. Yes, a 10 HP gain is a bonus but i I don't think we have much choice with the CR above 10.

Don't think many DDK cars would require a shiny dizzy due to detonation.

[Darren65]

I'm sure the vast majority here would be more than happy to have a 'bling' twin dizzy in their engine bay and it will work fine

....not really Mike, I'm sure the vast majority here, like me, would want the parts they fit to theirs cars to work exactly as intended!

I've no wish to fan the flames of any issue people might have with Ben, not for DDK imo and he can fight his own battles....and nor do I 'big up' Ben to get up anybody's nose, but for the record....

....I don't post this stuff to curry favour....I've never been asked to promote anyone and I don't get paid....every part I've acquired from Ben I've paid for in full; it's hard to negotiate with someone that point blank refuses to join in!...

.....I post this stuff purely because I'm fascinated by the process, I'm in awe of the quality, detail and dedication that goes into the items that Ben produces and figure others might be interested too?

Mike's right to question anything technical I say because I know diddly squat!......but what I do know is that the experienced Porsche engineers I've asked to look over Ben's products have been blown away by the quality and detail of his work, I know the Honda Touring Car team are pretty happy with Ben's work as they were with the 'World's Fastest Lawnmower' that he built and I know that Ben's products are used by racers and have helped win events.

My 2.5 engine build will incorporate Ben's High Butterflies, Small Fan Housing, Racing Oil Filter Housing and of course, his Magneti Marelli Twin Spark Dizzy......Ben's products are allowing me to build a pretty authentic ST motor that'll be indistinguishable from the real thing, something I'd have never have been able to do/afford without Ben. Obviously I'm pretty chuffed he does what he does! .....

....and the engine has to work because it's going to get used hard and used often!.....over the coming weeks as my engine gets put together I'll be able to comment first hand how effective my racing parts are and one things for sure, I'll post details in full.....

.....good or bad!

Cheers,

[hot66]

I thought we were running twin plug because we are trying to avoid detonation due to the high CR of our engine builds. Yes, a 10 HP gain is a bonus but i I don't think we have much choice with the CR above 10.

Don't think many DDK cars would require a shiny dizzy due to detonation.

I know there is never one single answer as every engien spec / build can differ , but I've been reliably informed by 3 engine builders that you can run run 10.3 CR on single plug with S cams .... although piston design will also have a bearing on this . Twin plug allows more ignition advance which is where the extra hp comes from ( I think ..... these days I forget more than I remember )

[fetuhoe]

Original 2.0 litre 906 engines with large domed pistons suffer significantly from plug shrouding as the piston effectively cuts the combustion chamber into two sections and combustion tends to be limited to only one of the sections.

As compression ratio increases this effect gets worse and worse and there is little gain in horsepower at the expense of mid band performance.

This is not really a detonation issue just a problem with incomplete combustion where it counts.

As you can see from looking at the 1965-66 lower cam box covers there was always a plan to run Twin Plugs but this was, I believe, dropped at the last minute.

Twin plugging these early engines has a huge impact when high compression and race cams are concerned.

The later engines with revised valve angles and shallower combustion chambers also respond quite well but with less relative gain than the early motors.

Setting up an original spec S121A is a nightmare as they have a triangular 'cam' and 4 sets of contact breakers with 2 x condensers.



Base casting



Completed Unit



With 4 sets of breakers installed


Trying to get them right without setting them on a distributor tester is virtually impossible.

Fortunately we have a Sun 504 if decent condition




The S121B is easier as this model a hexagonal cam and two sets of contact breakers which is more similar to the Maserati 3500GT and some of the V6 Ferraris.

The 3.0 RSR had a Bosch Dizzy with a magnetic reluctor and is much easier to use.

There is a potential clearance issue with the S121A and this concerns the angle of the distributor mounting in the crankcase.

The body of the S121A can touch the part of the crankcase that aligns the fan housing and this part of the case is the same regardless of fan housing size so a small fan housing doesn't solve this issue.

The 901/20 engines used in the 906 and the 911R had the hole that accepts the distributor shaft machined at a slightly different angle to the standard engine to provide clearance between the body of the dizzy and this part of the casing.

As we can't modify cases in this area we have modified the base casting we have used and added some length to raise the body slightly further out from the engine and increase the clearance in this way.

This S121B and the Bosch Dizzy are not affected by this issue.

[stretch]

Are you selling these now Chris ? What are the internals, and what is your price.? I tried a PM but it floated into thin air.!

[Mike]

I've no wish to fan the flames of any issue people might have with Ben, not for DDK imo

Darren, if you read my posts I've been very careful not to make any personal comments on Ben, in fact I'm the first to compliment
him on his foundry castings which I'm happy to have helped him set up a few years ago. I'm just pointing out a few technical issues
with the dizzy you're talking about, just to help anyone who might be thinking of going racing with it.

So don't quite understand your comment above, it's not for DDK so why on earth do you mention it?

[markm]

Would it be rude to ask how much this was Darren?

[Darren65]

I've no wish to fan the flames of any issue people might have with Ben, not for DDK imo

Darren, if you read my posts I've been very careful not to make any personal comments....

....and if you read my posts Mike neither have I?

I've acknowledged a number of times that I'm aware of a few people that have had issues with Ben in the past as he can be hard work to deal with and was simply stating that I'm not just posting to blow his trumpet.

I took your posts as a slight on the integrity of my build and that maybe I'm happy to accept 'bling' over substance.......definitely not the case. I expect every part I use to perform equally as well as originals.

I also highlighted that you're right to question anything technical I comment on.......in that respect I'm simply not qualified and only quote what I've been told, often incorrectly!

However I will be able to comment first hand on how well my dizzy performs very soon.

Cheers,

[Darren65]

Would it be rude to ask how much this was Darren?

A few different options Mark so prices vary. Not cheap but much less than you'd expect and imo excellent value.

Not really for me to post, give Ben a call if you're interested.

Cheers,