Ozdat Home Feature Cars Ozdat Classifieds Event Calander Links Trade Link Tech Resource Merchandise Donate Web Mail
It is currently Fri Mar 29, 2024 5:48 am

All times are UTC+11:00




Post new topic  Reply to topic  [ 21 posts ]  Go to page « 1 2
Author Message
PostPosted: Wed Nov 14, 2012 12:06 am 
Offline
User avatar

Joined: Fri Apr 18, 2008 11:51 pm
Posts: 284
Location: Melbourne Eastern
Something that may help- vacuum advance needs to be hooked up to a vacuum port on the carby that leads to a hole in the throat beside the throttle butterfly in closed position. The idea is you get no vacuum when the throttle is closed, good vacuum when the throttle is slightly open (the vacuum is caused by air rushing past the hole in the carb throat) but very little at wide open throttle. This advances the timing under light throttle "cruise" conditions and improves throttle response. Vacuum advance is not needed at idle or WOT.


Remember that adding boost means you need a stronger spark and a healthy SII dissy will be better than a standard points dissy unless you spend up on an ignition amplifier (eg MSD).

Yes, you can use a vacuum advance/boost retard module on a SII dissy and it'll work fine. Mine does. It has no centrifugal advance. I can't help with settings since I'm running 7:1 compression, big cam and straight LPG, so the settings I use won't be right for you.

Because the SII dissy is a Bosch it's easier to use a Bosch module (Cordia one may not be) and I think there was a Magna which had one which looks good or you could go through a Bosch catalog. Getting the right amount of advance & retard is still critical and experimenting can be hazardous to your engine's health. Too little advance is safer than too much.


Good luck!


Top
   
PostPosted: Wed Nov 14, 2012 6:55 pm 
Offline
User avatar

Joined: Fri Dec 12, 2008 1:32 am
Posts: 34
180BSSSt wrote:
Something that may help- vacuum advance needs to be hooked up to a vacuum port on the carby that leads to a hole in the throat beside the throttle butterfly in closed position. The idea is you get no vacuum when the throttle is closed, good vacuum when the throttle is slightly open (the vacuum is caused by air rushing past the hole in the carb throat) but very little at wide open throttle. This advances the timing under light throttle "cruise" conditions and improves throttle response. Vacuum advance is not needed at idle or WOT.


Remember that adding boost means you need a stronger spark and a healthy SII dissy will be better than a standard points dissy unless you spend up on an ignition amplifier (eg MSD).

Yes, you can use a vacuum advance/boost retard module on a SII dissy and it'll work fine. Mine does. It has no centrifugal advance. I can't help with settings since I'm running 7:1 compression, big cam and straight LPG, so the settings I use won't be right for you.

Because the SII dissy is a Bosch it's easier to use a Bosch module (Cordia one may not be) and I think there was a Magna which had one which looks good or you could go through a Bosch catalog. Getting the right amount of advance & retard is still critical and experimenting can be hazardous to your engine's health. Too little advance is safer than too much.


Good luck!
Thanks for the input :thumbsup:

Ok that's handy to know about how the vac point on the carb works. I will use the vac point on the carb for the twin point set up,
But plum it into the manifold for the dual reference diaphragm.

Will the twin point be fine for 9psi? I didn't think it would be a problem at those levels.

Is there an easy off the shelf dual reference diaphragm to fit to the SII dizzy? If so anyone know any more details like part numbers or model car they are fitted to?

I could probably do some playing around with the Cordia diaphragm and work out the advance amount and at what pressure it happens, I hope. And by using the Cordia ignition unit (E101) and knock sensor on theses when the knock sensor detects a knock the E101 will retard timing an additional 8 degrees of timing.

_________________
=============DATSUN 1600, NOT JUST TRANSPORT FOR YOUR GRAND MA================


Top
   
PostPosted: Thu Nov 15, 2012 12:10 am 
Offline
User avatar

Joined: Fri Apr 18, 2008 11:51 pm
Posts: 284
Location: Melbourne Eastern
You're right about plumbing the twin point distributor. I haven't used one on a turbo car so I can't comment about how much boost to run but they're a fairly crude way of retarding the timing. You get to a certain boost and wham, it retards the timing. It's unlikely to be spot on for most situations, let alone all of them.

Plumb the vac advance side of the diaphram to the carb and the boost retard side to the inlet manifold.
I know there are Bosch bits that work (or can be made to work) but I don't know part numbers. Jerry at Ignition Torque built mine.

If you're capable of making the Cordia bits work with a knock sensor, etc, you are probably better building a Megasquirt and running four Chev LS2 coils with a crank trigger (As a bonus you can use it to drive fuel injection or even water injection when you get around to it). That's what I'm up to at the moment. Let me know if you want a trigger wheel that bolts on to a L-Series (I can get more laser cut) plus a bracket and VR type sensor.

Cheers!


Top
   
PostPosted: Thu Nov 15, 2012 9:28 pm 
Offline
User avatar

Joined: Fri Dec 12, 2008 1:32 am
Posts: 34
Mite be a good idea. what is the rough cost of a system with the mega squirt and what are the benefits?

_________________
=============DATSUN 1600, NOT JUST TRANSPORT FOR YOUR GRAND MA================


Top
   
PostPosted: Fri Nov 16, 2012 2:43 am 
Offline

Joined: Tue Feb 10, 2004 9:17 am
Posts: 807
Location: Covington,Wa USA
man I got a stack of these dual point dizzys.
In the US its relayed(by the radiator) thru the 3rd gear switch on the trans.
also theres a switch on firewall for the Full trottle.
95% of the people yank these out(goes to the dump) and go EI matcbox setup.


Top
   
PostPosted: Sat Nov 17, 2012 11:02 pm 
Offline
User avatar

Joined: Fri Apr 18, 2008 11:51 pm
Posts: 284
Location: Melbourne Eastern
Using a programable EFI computer to control the timing gives you complete adjustability and fine control (so you can tailor the ignition for best power & driveability) plus being able to use hardware that will give you a great spark. There is no need to regularly adjust the system or replace bits as it wears (like you do with points). The benefits are better power, driveability, reliability, economy and easier starting.

Using a crank trigger ignition removes the mechanical distributor drive components from the ignition system and improves the timing accuracy (Nice if you ever use high revs and/or boost).

As I said, if you use a programable EFI computer you can also use it to drive fuel injection or even water injection. I don't know what your current inlet manifold setup is but replacing it or converting it so you can run injectors will yield big improvements in power, driveability, reliability, economy and easier starting and will allow you to use an intercooler so you can safely use more boost and get even more power (which is why you're turbocharging in the first place, right?). Water injection can be great too, but I don't want to be typing all night so I'll leave that for now.

The downside of programable EFI is cost and complexity, especially on a car that didn't have it stock.

Since you seem to have the confidence to tackle a Cordia ignition unit & knock sensor transplant you might find assembling a Megasquirt (http://www.megasquirt.info/ ) to be a cheap way to get an excellent EFI computer. I don't know what the current pricing is and it depends what version and specification you want but we're talking in hundreds, not thousands. I'm using one with 4 LS2 Chev coils (EBay, about $140 landed here), a knock sensor (from the wrecker) and I've just made the crank trigger components.

The fuel side requires at least one EFI fuel pump (plus wiring, a relay & I recommend an LPG safety switch) and a filter, possibly a swirl pot, definitely new rubber fuel lines, a fuel rail and regulator, a return line and injectors. Price depends on what bits you choose, new or second hand and how much you do yourself. Or you might consider going straight LPG and the government'll kick in $1500 bucks (I think that's still current) to help with the conversion. There's carb and injection options there, too depending what you want to spend (but blow-through carb is the cheapest that allows you to run an intercooler).

And you'll want an intercooler.

Whatever you choose, allow money and time for tuning. This is critical! I'd expect LPG carb to be cheapest to tune, followed by EFI and then suck through petrol carby with custom distributor based on the amount of time and fiddling required.

I wish there was an easy "rough cost" I could give you but it all depends on what parts you choose and how much you do yourself. Some research will be needed to find the right answer for you.

Enjoy!


Top
   
Display posts from previous:  Sort by  
Post new topic  Reply to topic  [ 21 posts ]  Go to page « 1 2

All times are UTC+11:00


Who is online

Users browsing this forum: No registered users and 3 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to: 

Powered by phpBB® Forum Software © phpBB Limited