Twin Spark options

[rafael]

I have been reading all the TS threads I have found on alfabb.

Basically there are two ways forward:

with motronic fuel injection:
Required: complete engine with wiring & bosch computer, special exhaust manifold, oil sump, flywheel, crankshaft with additional hole.

Pros: Better drivability for road use, and fuel consumption.
Cons: more modifications on older cars (changing wiring, adding return fuel line). Electrically more challenging.

with carbs
Required: engine, special exhaust manifold, manifold for carbs, modified distributor with nissan top, oil sump, flywheel, crankshaft with additional hole.

Pros: better for racing, no electrical changes in older cars. Easier to return to original nord engine.
Cons: worse drivability for road use.

The carb option uses in most cases 45 webers in combination with ported head, high CR pistons, and more aggressive camshafts.

My questions:
1) Did I miss something above?

2) Can you reuse the nord water pump to avoid converting the tach to a electronical tach?

3) What if you go for a TS engine with 40 carbs, and you leave the engine as is (no porting, stock cams and pistons). Is there any advantage in this as compared to a stock nord engine?

[Capp]

rafael-- I can answer your question about the Nord water pump: you must make a small modification to the intermediate timing gear to utilize that pump on the TS front engine cover. Look here for details and specifications of this mod.: info@autocomponenti.com. It basically involves pressing apart the intermediate gear and removing some thickness of material and reassembly.
There may be other, simpler ways around this issue but this is how I did it.
It is really very easy to add the wiring of the factory harness and it's hardware to older cars-- no permanent modification is needed. The motronic harness is basically a separate stand-alone electrical system which only needs +12v, some common grounds (earth), and a switched wire from the ignition. I re-terminated one wire on the rear of the fuse block to cause the fuel pump to be controlled by the Motronic relay pack as opposed to the ignition key. I didn't cut a single wire or modify ANY electrical connectors but made up adapter wires/terminals so the process is easily reversed. For me, one of the hardest jobs was routing the harness in a tidy manner throughout the underhood area.
Admittedly the other tasks such as plumbing are easier on a U.S. version Spica-equipped car because it already has a fuel return line routed to a good fuel filter and a fuel pump of the correct pressure. IMHO unless you are modifying for racing or high performance I'll bet you would spend as much or more time (money?) making a carbed version run equally well as the original Motronic system. YMMV of course, and it depends on the "look" you are after.

[rafael]

Capp, what do you mean with; pls clarify:
"IMHO unless you are modifying for racing or high performance I'll bet you would spend as much or more time (money?) making a carbed version run equally well as the original Motronic system. YMMV of course, and it depends on the "look" you are after."

[crashmctavish]

more modifications on older cars (changing wiring, adding return fuel line). Electrically more challenging.
The wiring is easy use the entire TS underbonnet harness and relay block, seriously its not very hard at all.

[rafael]

Do you need a different petrol tank to acomodate the fuel return line?

[crashmctavish]

No the gti pump & level gauge has the return line built in. It is noisey when below 50% level, later cars have sound deadening mouldings around the pump.. The return line route is the same as the original & there is a spare hole in the body near the tank to pass it through. Just do it its pretty easy stuff.

[Capp]

rafael-- Indeed, my previous statement was not clear. If you are preparing your TS conversion for road use or the occasional track day and are trying to decide whether to use carbs OR original injection/ignition then my opinion is that you will probably get there quicker and cheaper using the factory Motronic system. I'm assuming this is for a 105 or 116 series car, right? Others on this forum have told of the need to spend money and tuning time for a programmable ignition system to fully realize the potential of the TS if used w/ carbs which will need to be tuned also. I can understand doing this if you like the period correct look of an ALFA w/ carbs on the side-- it is certainly a cleaner, more aesthetically pleasing option. I'm also assuming that you are not intending to use the car in vintage racing (old-timers) events, in which case the TS engine is surely not legal.

[rafael]

Hello crashmctavish,

Thanks for your explanation. However, I do not understand what you mean. Can you pls post a picture (or a link) of the gti pump & level gauge to clarify?

Capp: thanks; now I understand

[crashmctavish]

Try looking in a manual Im a bit busy to be taking pics & stripping out fuel tanks at the moment. Motronic for the road is ideal

[Alfajay]

Rafael had asked: "What if you go for a TS engine with 40 carbs, and you leave the engine as is (no porting, stock cams and pistons). Is there any advantage in this as compared to a stock nord engine?"

Why would you go with 40mm carbs? As I understand it, the manifolds for the TS engines are sized for 45's. Also, a bit of research on the web indicates that new 45 DCOE's sell for the same price as new 40's (see redlineweber.com).

I like Rafael's last question, an am disappointed that no one has touched it. I think he's asking: All things being equal, how much "better" is a TS as compared to a Nord? That is, if both engines have the same carburation, both have unported heads, both have stock cams, etc., what difference would you feel in your butt?

Of course, things never are totally equivalent. Any TS --> 105 chassis conversion is going to involve tube headers, while a truly stock Nord setup would use cast iron. As I noted above, you're probably going to be running 45mm Webers on the TS vs 40's on the Nord. The characteristics of the stock camshafts no doubt differ between the two engines (and what year/model Nord "stock" camshaft are we talking?).

Still, all this does beg the question: After you've spent the time and $ to do a TS conversion, what are the benefits? I'm not expressing skepticism, just re-asking Rafael's question.

[iachella]

If all else is equal, then the question can be re-phrased as this: Is there a benefit from better intake and exhaust port geometry from the TS compared to the Nord, is there a benefit of better combustion chamber design, is there a benefit from two sources of ignition? The answer is of course, YES.

[69alfa]

When I got my 69 spider it had the 1300 motor that it came with and as far as I can tell it was in good shape. It leaked some oil but ran strong for what is was. I was going to do all the things you can to a 1300 to make the car faster then I read Jim Kartalamakis book and the light bulb went on.By the way the new one has lot's more TS info but I am sure we all have it right? http://www.alfabb.com/bb/forums/engi...-new-book.html
Found two Twin sparks put one in ,and had no luck with the new Weber 45 carbs. So I got a pair of 40's set up for a nord conversion and wow the power was great . Drove from Toronto to New Hampshire for the Alfa convention less than a week after getting to new motor in and it ran great, strong from the bottom to the top.
When I got back I found I had too much fuel pressure .The 40's would take it but the 45's have bigger inlets and would not so I was getting way to much fuel . Fixed that dumb mistake and put back the 45's . Oh my the car leaped forward it was like I had been pulling an anchor.
I would say I started at 80 to 90 hp then 130 hp and now 150hp give or take.( ***Numbers for comparison only.*** As Neil Young said " Numbers add up to nothing")
All that being said I have lost the love I once had for carburetors. This winter I am converting to throttle bodies and a computer. I have never got the Weber setup quite right. The motor goes like hell but only runs smoothly with very rich jets.

[180OUT]

Quote:

I like Rafael's last question, an am disappointed that no one has touched it. I think he's asking: All things being equal, how much "better" is a TS as compared to a Nord? That is, if both engines have the same carburation, both have unported heads, both have stock cams, etc., what difference would you feel in your butt?

[rafael]

Jim and David: thanks for the info.

Another question from my side: how do you see from the outside if the crankshaft has the additional hole or not? Apparently TS engines were made without and with the hole in the crankshaft.

[180OUT]

Quote:

Jim and David: thanks for the info. Another question from my side: how do you see from the outside if the crankshaft has the additional hole or not? Apparently TS engines were made without and with the hole in the crankshaft.