Another twin spark 105 conversion

[Colin Byrne]

hi guys
Just started building up a twin spark engine for my road 105, decided i didn't like the idea of having two dizzy's so managed to get a nissan twin spark cap and rotor to fit the originally dizzy body, talking to the guys that have already done the conversion the dizzy on the cam gets very close to the radiator so this should solve that problem. I'll keep posting pics as the project progresses
cheers

[Stuart Thomson]

Hey Col,

Can you make me one too?  I already have the top bits from a Nissan.

Cheers
Stuart

[Paul Gulliver]

Thats not a distributor its the size of a Christmas tree

[Colin Byrne]

Hi Guys, few more pictures of the engine, still not finished yet, build going a bit slower than planned due to some confusing with valve guide and seal sizes!
I've added a return fuel line and installed the pictured fuel pump/surge tank assembly under the back seats
Couple of little mods on the engine
-   105 water pump with mechanical tacho drive
-   Thermostat from a Lada should allow the use of standard 105 radiator hoses
-   Air bleed screw added to back of inlet manifold to allow use of 105 non-pressurised radiator overflow
-   Nissan Twin Spark Dizzy cap and rotor fitted to allow removal of Cam Driven dizzy

And if your looking for new rubber connectors for the inlet manifold Bunnings has a standard pluming fitting that does a great job

Also I've realized I'm missing the support arm for the inlet manifold (I'm assuming there is supposed to be an arm from the bottom of the manifold to the engine mount), anyone got one or know where I can get one? And does the original tube that goes from the black canister to the cam cover have an S in it or is it just straight, as I don't seem to have one of those either

Cheers

[cjheath]

Hey Colin, thanks for the update!

I'm in the process of getting my 1750 twin-spark back on the road again and need to to the same thing with the fuel pump under the seats. The old tank got damaged in the prang and I wasn't happy with the retro-fitted in-tank pump anyhow.

Can you tell me what you used and show a picture of how it's mounted?

[Colin Byrne]

I used a facet type low pressure pump to feed the surge tank and the FI pump is a Bosch replacement for the original 75 Fuel Pump (Bosch Part No. 0 580 464 070) It is supposed to be an intank pump but I've ran them externally before without a problem.  The unit is mounted under the drivers side rear passenger seat, it required moving the brake lines around a little but, I'll see if I can get a photo tonight

[MD]

Colin,

I take it that you are intending to use the original Motronic ECU ?

Unless you need the extra grooves in the front pulley for other services, you may consider reducing the mass of the original one and have it's balance checked prior to fitment.(see photos)

An upgrade to that is a proper harmonic balancer with an aftermarket trigger wheel to protect the crankshaft.

[Colin Byrne]

Hi Md
Yea planning on using the original Motronic ECU at the moment, but with plans to upgrade in the future.  Also started looking at the possibility of swapping the AFM to MAF sensor using a micro controller to modify the output signals.

I did think about turning down the pulley, but I want to look at running AC in the future so I didn't do it, if I can get my hands on a spare pulley I'll defiantly go down that path

[MD]

Very well. The only other suggestion I can help with is to advise that the TS pulley has a tendency to crack along the keyway. This is possibly due to its long extension to provide for triple pulleys.

Suggest a crack test before fitting and score a spare one for sure.

Best of luck with the conversion. Should be a very nice package with that early torque.

[cjheath]

The unit is mounted under the drivers side rear passenger seat, it required moving the brake lines around a little but, I'll see if I can get a photo tonight

The reason I'm interested is because I'm concerned about clearance. Fuel pumps are one thing you don't want hitting the ground!

[Colin Byrne]

Fuel pumps are one thing you don't want hitting the ground!

very true, the entire assembely is higher off the ground than the rear passanger footwell, so it is nicley protected.

[njh1964]

I've added a return fuel line and installed the pictured fuel pump/surge tank assembly under the back seats

And if your looking for new rubber connectors for the inlet manifold Bunnings has a standard pluming fitting that does a great job

Hi Colin,

I really like what you've done with the fuel pump/surge tank assembly. I'm also in the process of a Twin Spark conversion, and I came to the same conclusion regarding the necessity for a surge tank. Can you please provide additional photos of your assembly, from other angles, and could you also let me know the model number for the high volume/low pressure lift pump that you've used? Did you make or buy the surge tank itself?

As for the rubber inlet manifold connectors, are you confident the Bunnings plumbing fittings will handle any engine heat issues? I realise we're talking the cooler side of the engine, but I'm guessing it still gets rather warm around the inlet manifold. I was thinking about high temperature silicon tubing to replace my standard rubber inlet manifold connectors.

In answer to your later question regarding the oil vapour trap, the hose from the black canister to the outlet on the side of the valve cover is an "s" shaped black rubber hose

Regards,


Nick

[Colin Byrne]

hi Nick, yea i reckon a  surge tank is required, i fabricated this one up using some SSteel tube.  The low pressure pump is just one of these
http://cgi.ebay.com.au/Electric-Fuel-Pump-12-volt-Solid-State-3-4-5psi-120LPH_W0QQitemZ400100273010QQcmdZViewItemQQptZAU_Car_Parts_Accessories?hash=item5d27d5ab72.  I've only got these two other photo's, I'm away for work at the moment when i get home i'll take a photo of the installation under the seat.

are you confident the Bunnings plumbing fittings will handle any engine heat issues?

Yea the rubber has got a working range up to 120 deg i think so should be fine.  Would have been nice to get some of the original ones but haven't been able to find any.

[116gtv]

Colin,

nice work on the conversion!

Can i ask you - does having the surge tank set-up mean no need for an in-tank pump? Or were you worried about fuel starvation in a 105 tank? Reason for asking is that I'm working out what to do for my alfetta GT track car conversion..

thanks!

[Colin Byrne]

Hi Martin
   Yea the 105 fuel tank is pretty basic, which is fine with carbies as the float bowl acts as a bit of surge tank, but would cause issues without a proper surge tank with FI I would think.  Also I didn't want to modify the actual tank as good 2L 105 tanks are getting harder to get!
   Should get the head back soon, and once I have that it should be game on!