Twin Spark Conversion

[LeMans_GTV]

Probably been done 100 times but I was wondering if anyone has any examples of a full conversion to a EFI Twin Spark setup? Lets assume I source parts and get a shop to assemble.

Plan is looking like next year I will be selling my daily, and I was thinking of maybe putting that money into my GTV instead of buying some other 4 pot run about.

Or...I suck it up and drive a carby car daily, I was just thinking of the convenience of EFI in a daily situation.

Option C is to buy a 147 GTA and then just delay the slow restoration of my 105 a little longer.

Anyone been through a similar situation?

[cjheath]

Yaaarh, me hearties.  Hugh Harrison did my original conversion, but Mauceri added a proper air box, adapted from one of the Alfa 33 models, during a major repair (car was hit in the rear while stationary). Summary of the modifications:

• entire TS engine bay wiring loom fitted, with the ECU high in passenger footwell under the carpet. Relays beside the battery.
• Small washer bottle under the overflow bottle, filled through a 12mm PVC tube (re-routed dash light switch to activate pump)
• coils and AFM bolted to side wall
• right-angle plug leads for top distributor
• original fuel pump fitted low on the front of the tank (must bend fuel gauge aside to ensure pickup from the central swirl pot in the tank)
• bracket to mount bicycle brake cable between throttle level and pulley
• small clearance problem with throttle pulley and bonnet required bending bonnet frame slightly - no idea how Hugh achieved this without visible damage!
• drive shaft requires small amount of machining(/drilling?) to mate with the 1750 gearbox
• thermatic fan (this is much older and now needs a modern temperature switch)
• electric tach motor fitted ($$) inside the old mechanical unit since the TS lacks the drive point (though an old water pump could be fitted instead)
• air cleaner as mentioned - back case needed hacking to step around the chassis rail

Some folk modify a Nissan 8-way distributor down low and cap off the top one, but though tidy it isn't necessary.

Some move the battery to the boot to make more room. Not sure what it buys you though, it's the other side where space is really tight.

You might want to investigate a better way to get clearance for the throttle pulley.

https://www.flickr.com/photos/70954832@N00/5268489964/in/photostream/

EDIT: One more item I forgot: The headers attach to the head at a different angle. I'm not sure how that was handled, but I think that just the ends got replaced.

[LaStregaNera]

Or...I suck it up and drive a carby car daily, I was just thinking of the convenience of EFI in a daily situation.

There's not really any significant "convenience" from the EFI motor over a well setup/maintained carb setup. Even the coldest of cold Brisbane mornings (Bwahahahahah) the GTV starts no problem and idles/drives fine after maybe a minute's warmup.

[cjheath]

There's not really any significant "convenience" from the EFI motor over a well setup/maintained carb setup. Even the coldest of cold Brisbane mornings (Bwahahahahah) the GTV starts no problem and idles/drives fine after maybe a minute's warmup.

Hard to agree with this one, though the 1750 I had (still have, of course, but in storage) was very nice. The TS starts every time on the fourth rotation, hot or cold, summer or winter (Melbourne), needs no choke, runs smoother (never splutters), has a wider power band due to the variable inlet valve, and more power in standard form. No questions about using it with modern fuel either, though the lack of lead is not thought to cause any problems in the older engines.

[AikenDrum105]

Couple of other goodies

* 2L 105 flywheel or aftermarket Alloy unit from PACE and other vendors.  Stock 2L steel ones are very heavy - they can be lightened a lot without making them fragile.  If yours is an early cable clutch car you can buy flywheels / clutches to suit that will fit the TS engine - or convert to a later hydraulic clutch.  Similar pennies involved in parts or labour there  - now that stronger aftermarket cable clutch units are available - usually easier to keep the cable unit.

* 105 Fuel tank sender modified with return fuel fitting and a return fuel line under the car

* 105 tanks don't have much of a swirl pot in the bottom - you might need a separate swirl pot fitted if doing heavy cornering to prevent the EFI pump gasping air at low fuel levels.

* to use the cable tacho - along with the 105 water pump you also need a timing gear fitted with the helical drive on the nose.  That's a head, sump and timing cover off job to replace.  You *could* drill the end of the timing gear shaft in-situ as the helical gears are a separate piece to press in ...   by the time you mess about making a jig to hold the drill straight and then ream it you might as well pull the head or mod the tacho
** 105 timing gears need to be modified to fit in the TS timing case, the shaft is too long and the gears spaced too far apart - quick job with a lathe and a press

* 105 sump and oil pump.

* if your twinspark crankshaft doesn't have the spigot bushing hole for the nose of gearbox input shaft to fit into the crank - you'll have to have it machined - can be done in-situ with a jig - but often better to pull the crank and have it done in a lathe (you can also use a 2L nord crank instead if you have one handy) 
** you may as well chuck new crank and rod bearings in if it's apart  - the slippery slope starts here
*** if you have the crank out - you have the front cover and probably the head off too  - getting very slippery...

Finding a TS engine with the crank spigot bushing hole already machined becomes a big win

* spot on with the different header angle - PACE makes a nice TS to 105 header set as do AH. 

* Thermostat - A TS one will work fine - test it if it's s/h (they have a rubbery sealing ring inside that distorts and jams them open.   There are some nice inline ones available from AH  (but this does away with the bypass circuit which is a nice to have for engine longevity)

Depending on budget - you might prefer to buy a well worn unit and rebuild it with all the options to make a nice bespoke conversion  - or save some pennies by finding a good used unit with the spigot bush hole already there and convert around it.   They area  strong unit and there are many conversions done on 150k+ engines which run beautifully, don't smoke and are also raced. 

* If you find a used one with a blown head gasket - be warned the TS heads can be a nightmare to get off - the studs cement themselves into the head and it can take lots of time and special jigs to get them off - adds a bit of cost if your mechanic has to stuff around with it for a couple of weeks getting the head off

Very satisfying project though    don't be daunted !     It's a natural evolution after all    

Cheers,

[tjb0274]

There seem to be a lot of 105 TS conversions around these days. Also quite a few Alfetta GTVs at track days.

I just had a TS put in my track car and it's great, but I wouldn't knock a properly maintained nord engine - I used to use a 1750GTV all year round as daily driver, and I even drove my Ricciardi (with 1750 motor) to work through a Melbourne winter one year. Never had a problem with starting.

If you're going to do it, probably a good idea to talk to a local specialist who's done a few. In Melbourne I know Monza (who did mine) have done a ton, but I'm sure Mauceri and Maranello have as well.

It's really about the packaging - making sure everything's mounted in a logical location with minimal changes to the original car.

[Evan Bottcher]

And I've got the perfect basis for a conversion! 

http://www.alfaclubvic.org.au/forum/index.php/topic,13071.0.html

[Divano Veloce]

Awesome conversion info! Kinda glad i bought one already done! Mine has the stock motronic which I like

you will probably want an lsd too (if you dont already have one).

[LaStregaNera]

Hard to agree with this one, though the 1750 I had (still have, of course, but in storage) was very nice. The TS starts every time on the fourth rotation, hot or cold, summer or winter (Melbourne), needs no choke, runs smoother (never splutters), has a wider power band due to the variable inlet valve, and more power in standard form. No questions about using it with modern fuel either, though the lack of lead is not thought to cause any problems in the older engines.

If you were using the choke, that's probably your problem. No-one *ever* uses the choke on weber fed alfas - it's an excellent way to flood the motor and foul the plugs.
I start mine, let it warm for a moment while checking my tyre pressures (porous wheels - 2 hold pressure, 1 drops 2 psi/day, the other drops 4 psi/day), then never have to worry about it miss-behaving. It never gets cold enough in Brisbane to be an issue. In Adelaide I occasionally had to use the hand throttle for the first couple of minutes to hold idle.
Certainly if convenience is your only concern, converting to twin spark is alot of time and money for not a huge return.

[cjheath]

If you were using the choke, that's probably your problem.

Every engine and climate is a little different. In seven years daily driving I learned my situation and car very well, and though I never had trouble, but it was never as easy as it is now.

[AikenDrum105]

>> is alot of time and money for not a huge return.

Except when you factor in how *AWESOME* it is. 



I used to use the choke on my 1750.  Also the 2L nord with Dellortos (the choke on them makes a racket though - boy)  Melbourne.  Winter.  Damp.  Cold.  Works as advertised - it's variable - not an on-off system.  A little asphyxiophilia goes a long way.

Just convert to Electronic ignition.   The motronic one comes with fuel injection, steeper intake angle, flat top pistons and two spark plugs per cylinder.

[Divano Veloce]

A motronic TS is very fuel efficient. I get 7.5-8.5 L/100kms in the Berlina. My 1750 GTV was 12-13L/100kms. It will also tolerate lower octane fuel if all leads and plugs are working. It might not pay for itself but it will be cheaper to run.

[LeMans_GTV]

Wow awesome replies guys.

Im not rushed yet but didnt want to leave the homework to the last minute. Electronic ignition conversion is an interesting medium...Ill have to check that out now too.

The conversion isnt quite as straight forward as I was hoping, unless thats just some major detail that you guys have given (which is brilliant...thankyou)