Jarvis and CW dizzy in an SC, plus carb questions.

[Mark Henry]

I'm getting everything together for my 914 3.0 build, I'm going to be running 3.0, twinplug, with 9.7+:1 CR, RSR style mahle pistons, 120/104 WEBcams (like GE60).
This is my engine, I bought Shaun's project from him a few years ago.
http://forums.pelicanparts.com/911-engine-rebuilding-forum/500127-classic-3-0-motor-build-2.html

Although I'm most likely going to do a ITB fuel injection eventually, right now I have 40 Webers. I figure it might be easier to break in the engine on the carbs and also they would be worth more to sell later if they are a known good running set.

Figuring on getting 34mm venturi's and my research says to start at
160 Main Jets
55 Idle Jets
F3 Emulsion Tubes
160 Air Correctors - Main circuit
100 air correctors - Progression Circuit

Does this sound about right?
I'd rather start a hair small as I have a jet reamer set and a wideband.

Right now they have 28mm venturi's
125 Main Jets
55 Idle Jets
F26 Emulsion Tubes
180 Air Correctors - Main circuit

I'm not sure what this is? "air correctors - Progression Circuit"

Now for the second set of questions.

I can get a good deal on a Jarvis twin plug dizzy, does anyone have experience with this dizzy and is it a good unit? I can't find much info on it, I think it's the one Patrick sells.

Also it's a CW dizzy and a 3.0SC is CCW. can I just take the drive gear from a 2.0-2.7 crank and put it on the SC crank or is there more to it?

Thanks Mark

[Flat6pac]

When you change the drive on the crank, you also need to go to the 3 prong CD and 2.7 distributor. The early 3.0 used a 2.7 crank and rods, 76/77 distributor with the points.
Bruce

[toddu]

I realize you said you can get a good deal, but have you looked at the JB unit? Have you thought about how you will control spark, etc?

Going down this road myself currently.

Todd

[Mark Henry]

If I did this I'd be using the Jarvis Tech dizzy and MSD. Sorry if I wasn't clear on that.

A search takes me to this site JB Racing - Porsche Engine Components
Is Jarvis Tech and JB racing the same thing? Or at least the same distributor?

This is the CW dizzy in question.
It was originally in a carerra case and has very little time before the seller went full crankfire FI

[Mark Henry]

Originally Posted by toddu

I realize you said you can get a good deal, but have you looked at the JB unit? Have you thought about how you will control spark, etc?

Going down this road myself currently.

Todd

See the above post I think it could be the same unit but I don't know for sure. I think it has a mag igniter and adjustable mechanical advance. One post I found mentions it has GM HEI internals.

I was going to go the mega jolt jr or programable FI route but this came along.

Nice thing is I will have this in my hands before I commit to it, I do have dibs pending research and inspection.

[Mark Henry]

Doesn't really look like the JB unit.

[toddu]

Originally Posted by Mark Henry

Doesn't really look like the JB unit.

Yeah, not the same thing. I didn't realize you already had the unit and MSD. Thought you had a line on a good deal.

Todd

[Mark Henry]

Originally Posted by toddu

Yeah, not the same thing. I didn't realize you already had the unit and MSD. Thought you had a line on a good deal.

Todd

I don't have the Jarvis yet, it's just I can get it for a good deal (not a steal) and hold it in my hands before I pull the trigger.

I have one MSD box and 1 coil, I've already twin plugged my heads, I have one set of magnacors and I have the 40 webers.
I wasn't going to go this route but I already have this stuff and now this possible deal on the dizzy.

Just I can't find out much about it....other than it has an fugly rotor

[Mark Henry]

Does anyone know which distributor drive gear to get to change a 3.0 SC engine to clockwise?
Will a 2.7 gear work? Or do I need the gear from a 3.2?

This Jarvis I have is clockwise, engine is apart, the engine is custom and carbed so it's never going back to CIS, in fact if I'm not happy with the carb/dizzy set-up it will go programmable FI/ITB with crankfire.
Yes I did a search, I did read Wayne's book, no real info on doing this other than there are 3 types of gear....I've seen some conflicting info out there...hoping someone has done this.







.

[LJ851]

The gear you need to change is on the crank and requires engine disassembly.

[Mark Henry]

Yes ....I realize this, the engine is apart.

I'm just wondering if I can use the 2.7 drive gear that I have (on another crank), or do I need to buy a different gear (3.2?) for my 3.0 crank to make the drive CW?

Wayne's book makes mention of 3 gear types with no other info or specs.

[LJ851]

^ I'm sorry, i missed that your engine was apart.


I'm not sure about the 2.7 gear, the folks i've seen do it use the 3.2/turbo gear.

[Mark Henry]

So that's 1 for the 3.2 gear ...dang over $100... I have a wole box of the "VW" gears

[Flat6pac]

Any of the clockwise gears work at least from 72 on
Bruce

[Eagledriver]

That set-up for the carbs sounds way to rich. I have PMO's with 36mm venturies, 150 mains and 200 air correction jets. I don't remember the emulsion tubes, so I don't know if that will make much difference. My experience is that you can't get the carbs right without either a dyno test session or an installed WB Oxygen sensor. I did the oxygen sensor and I wish I'd done it right away. Solved all my tuning problems.

-Andy

[Mark Henry]

Originally Posted by Eagledriver

That set-up for the carbs sounds way to rich. I have PMO's with 36mm venturies, 150 mains and 200 air correction jets. I don't remember the emulsion tubes, so I don't know if that will make much difference. My experience is that you can't get the carbs right without either a dyno test session or an installed WB Oxygen sensor. I did the oxygen sensor and I wish I'd done it right away. Solved all my tuning problems.

-Andy

I do have an wideband, I'm going to get the emulsion tubes and I have a jet reamer set, I'll make my own jets.

Debating on 34 or 36mm ventuies.

[Matt Monson]

I sold the Jarvis distributor for several years when it was first released. There were some teething pains trying to get it to work right in FIA cars that required stock Bosch cd boxes. But it was really straight forward and reliable on msd controlled vehicles.

Regards

Matt

[Mark Henry]

Thanks Matt, good to know.