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SC12 Questions
https://www.ausmini.com/forums/viewtopic.php?f=5&t=88583		 Page 1 of 2
Author:  notabmw1 [ Wed Feb 11, 2015 7:28 am ]
Post subject:  SC12 Questions
Hello Gents, had a few questions as I am about to embark on the SC12 kit install on my stock 1098 clubby estate.

1. I have an older MSD Boost Timing master that works with a distributor (I have electronic distributor w/ vac advance). Can I still use the vacuum advance on the distributor? I assume I can send signal to the MSD BTM via the output for boost gauge and just put a T in the line. The vacuum lines on the supercharger to carb, would I still connect vac from carb to distributor. What would be the advantages vs just capping the distributor? Eventually I will be going megajolt, but not until 2015/2016 winter.

2. Kit I purchased used only has 12lb pulley that came from a 1275. I assume this is gonna be way too much for a stock 1098. I will try and contact Ben on getting a stock 6lb pulley.

This is the Mini it's going on, I am very excited to get some more bananas out of it.

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I managed to get a very very low mileage SC12 unit, 45k original miles. This was before I "cleaned" up my engine bay.

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As it sits now...
Author:  simon k [ Wed Feb 11, 2015 9:47 pm ]
Post subject:  Re: SC12 Questions
notabmw1 wrote:
1. I have an older MSD Boost Timing master that works with a distributor (I have electronic distributor w/ vac advance). Can I still use the vacuum advance on the distributor? I assume I can send signal to the MSD BTM via the output for boost gauge and just put a T in the line. The vacuum lines on the supercharger to carb, would I still connect vac from carb to distributor. What would be the advantages vs just capping the distributor? Eventually I will be going megajolt, but not until 2015/2016 winter.


Don't put the boost into the vacuum line on the carb, that'd mean you're leaking boost back into the carb.

I don't quite get what the MSD does in terms of retarding the ignition while on boost, but vacuum advance is still relevant so I'd say leave it connected - EXCEPT if you get a backfire through the manifold (it happens...) then it'll go into your vacuum advance and likely kill it

notabmw1 wrote:

This is the Mini it's going on, I am very excited to get some more bananas out of it.

Image


nice :)
Author:  notabmw1 [ Wed Feb 11, 2015 11:59 pm ]
Post subject:  Re: SC12 Questions
Attached is the instructions for the BTM, this was a universal one made back in the day, it's no longer made. All the new units I understand have to work with a add on ignition box, the old style can work with a distributor/coil setup.

I never have run a boosted application before, I am just confused as to whether or not to run advance on the distributor, as this unit will retard X amount dependent on boost.
Author:  simon k [ Thu Feb 12, 2015 3:53 pm ]
Post subject:  Re: SC12 Questions
Well vacuum advance does just that, it advances the timing when there is vacuum in the manifold. Vacuum is the opposite to boost. Vacuum advance and boost retard are mutually exclusive by definition. If your MSD is seeing boost and retarding the ignition, then the vacuum advance can not be doing anything

Vacuum advance is an economy device, if there is vacuum in the manifold then the engine is not under significant load and it can handle more spark advance, which basically lets the engine produce more power for a given amount of fuel, so you can run a leaner mixture at low load

So, what I said is true, you can run both, but a backfire might kill your vacuum advance*. BUT you now that you know a bit more about what vacuum advance does, you might decide you don't need it anyway because you're putting a supercharger on, why would fuel economy come into the picture, right?

*because it's a diaphragm inside and a big pressure wave could blow it to pieces
Author:  notabmw1 [ Fri Feb 13, 2015 3:30 am ]
Post subject:  Re: SC12 Questions
Right, I think I understand. So I will just leave the vacuum disconnected/plugged and set it statically. Then the msd unit will work it's magic to retard it under boost. I believe kit should be showing up next few days. I'm having Ben send me a 6 psi pulley, which he thinks will equate to 9 or 10psi on a 1098. Should be interesting. Hopefully I can get away with running 93 octane, the msd BTM, and that's it... enjoy this spring/summer/fall then do megajolt if there is room for improvement.
Author:  simon k [ Fri Feb 13, 2015 3:33 pm ]
Post subject:  Re: SC12 Questions
notabmw1 wrote:
Hopefully I can get away with running 93 octane


erk.... I don't think it'll be at all happy on that
Author:  Morris 1100 [ Fri Feb 13, 2015 4:44 pm ]
Post subject:  Re: SC12 Questions
Don't forget they measure octane differently over there. (must be the smaller gallons thing!)
Author:  timmy201 [ Fri Feb 13, 2015 9:32 pm ]
Post subject:  Re: SC12 Questions
The US use AKI as their octane number.. 93 AKI is the same as our 98 RON
http://en.m.wikipedia.org/wiki/Octane_rating#Examples
Author:  notabmw1 [ Wed Feb 18, 2015 8:21 am ]
Post subject:  Re: SC12 Questions
Well the kit showed up from UK yesterday, so while it was snowing I figured I would pop it on another Mini I had in the garage to mock it up. I ordered a new pulley from Ben last week so should have that soon.

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Author:  notabmw1 [ Fri Feb 20, 2015 4:44 am ]
Post subject:  Re: SC12 Questions
Had time to get it mocked up, working on tappet covers right now to add breathers and waiting on new gaskets. Also waiting for some other odds and ends.

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MSD Boost Timing Master

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Author:  notabmw1 [ Tue Feb 24, 2015 12:02 am ]
Post subject:  Re: SC12 Questions
I was working on the smaller details while waiting on some parts (tappet covers to mod, 10psi crank pulley, catch can, boost gauge, and speakers). So I fabbed up this 1/2" heater hose line to bring the return line to the other side so it is clear of the supercharger. I think it turned out good. Just waiting on 1/2" bulk head plate to run heater hoses through.

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Painted green. Thinking about putting some crinkle black on the supercharger, we will see.
Author:  MINI66 [ Tue Mar 03, 2015 2:46 pm ]
Post subject:  Re: SC12 Questions
Hi there

Looking good mate.
I run the same MSD boost retard module that you have.
Vac advance disconnected. Nissan Pulsar distributor.
Pointless to leave vac advance on as the module is trying to retard at the same time?
Retard is dialed in to start at 5psi on mine. Depending on the quality/octane of fuel, on my current tune, I only set it at about 0.5deg retard per pound of boost over 5psi. (I assume it has the on dash dial to change retard on the fly like mine)
Mine is a homemade SC kit (similar design to Ben's) about 10psi max boost.

cheers
Rick
Author:  notabmw1 [ Thu Mar 05, 2015 1:30 am ]
Post subject:  Re: SC12 Questions
Rick,

I recieved my new crank pulley. So I got everything disassembled to pop that on, also working on fabbing a new tappet cover breather to a catch can. I can run 93 Octane (USA), always have. The MSD box I do have is probably the same model, it does have a knob on the bottom of the box for start, and a knob for in the car. I will run it this way this spring/summer/fall. I am hoping that I will be happy with it, and maybe next winter revisit whether to go megajolt and a water/meth setup. I am running out of time though. I need to have the car up and running in less than 2 weeks so I can move it out of the garage and make way for the Morris Minor and start building my new garage.
Author:  MINI66 [ Thu Mar 05, 2015 10:58 am ]
Post subject:  Re: SC12 Questions
I would stick with the MSD unit. I did look at the Megajolt / Megasquirt option myself but back then you needed a reluctor wheel and crank sensor setup and with the thick SC pulley there, there is bugger all room left. Unless you are running a high compression ratio, I wouldn't think that you would need water/meth injection. The SC12's run out of puff/efficiency at about 14psi. My CR is 8.4:1 dish top pistons and on Aus 98 octane and a rich tune (around 11.5:1) and if I turn the MSD retard down to zero I only get slight detonation at 10psi(my max)

Also, I have all of my SC breathers hooked up together. When I vent them to the vac advance port on the carb for some reason it leans off/ changes my tune considerably.

Hope this helps
Cheers
Rick
Author:  clr60 [ Fri Mar 06, 2015 1:28 am ]
Post subject:  Re: SC12 Questions
This is a bit off the original thread, it looks like you are running 7 inch rims, what tyre size are you running

Regards
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