Advice..130TC cams on a RWD engine.

[csi2000s]

I purchased a set of Abarth 130TC cams on an internet auction site and they have been modified to suit RWD Fiats. The distributor drive on the exhaust cam has been machined off and a oil gallery has been drilled to feed the rear of the cam. Does this proceedure work or have I wasted my money? I also have purchased NOS Abarth valves.

My car is a RHD 1974 Fiat 124 Spider with a 2 litre engine equipped with twin 40mm side draught webers and high compression Mahle pistons.The head currently on the car is from a UK specification 1980 131 Superbrava.

I would like to prepare a new head with the Abarth cams and valves to replace the one already fitted on the car.
Is there anything I need to know such as rejetting the webers etc?

Thanks
Angelo

[Guy Croft]

The cam oil mod is absolutely correct. In this setup the cams do need that bleed hole which is absent on the 130TC setup which has an alloy housing for the end-drive distributor. Those cams are good for a fast-road motor, you will keep the lovely standard torque curve and get about 120bhp if stock.

As for carb setp please list the following sizes and I will advise:
1. Choke (eg: 32mm)
2. Main jet
3. Emulsion tube
4. Air corrector
5. Pump jet
6. Idle jet

You should test the pump jet function by fillling the float chamber and operating the throttle. The float level should also be checked and frankly if the carbs are not new you should get a pair of overhaul kits and give them a thorough 'going-over'.
Best use a Facet Interrupter fuel pump mounted in the back of the car (pushing not pulling the fuel) and make sure you don't have more than 3.5-4psi pressure at the carbs with the engine 'off'.

G

[nabihelosta]

Hello Guy

I use that same camshaft setup in my car, but I wasn't aware of drilling a hole in the intake cam.

The engine has been running for 7k kms now with no problems at all. What kind of damage may I encounter if that hole isn't there?

Is it absolutely worth pulling it out again and drilling it?

Thank you.
Nabih

[Guy Croft]

It might be worth taking a look! Dunno!

As we all know here for every thing that I say (do this/that..) there will be an owner who has done something, er, 'different' and not encountered any particular problems.

I try to give what one might describe as 'sound technical advice' - which I did in this case (because that was the practice with the cams by Fiat), but I have not explored the limits of doing things 'the wrong way' to see what happens,

if you follow my drift..

G

[nabihelosta]

Well yes you are right on this one.

At 10k kms, I will be re-checking my valve clearances, so it will be a good opportunity to look down there.
And in both ways, I'm probably going to take those cam towers off to change their gaskets. I spotted a minor leak on them last day.

Just one more thing, I saw you were advicing a Facet fuel pump, which we use widely on carburetted BMWs here. As I am a very busy/lazy one, I'm letting my Facet pump hanging there on the shelf, with no time to install it. What am I loosing on performance without this pump? (I'm on OE mechanical fuel pump).

Thank you for being interested Guy!

Nabih

[csi2000s]

Thanks for the information Guy.

The work on the head will start during the Australian winter along with a few other things I have planned for the car. I'll post the jet sizes then. Have a happy new year!

Best Regards
Angelo

[MinorTC]

Nabih,

I tried a Facet solid-state electronic pump, mounted at the rear near the fuel tank on my 2-litre standard Fiat twin cam, and while it worked well enough, it was noisy and could be prone to overfuelling it at lower revs. You could sometimes be driving along OK, have to slow down for a junction or traffic and the engine would stall due to flooding.

I reverted back to the standard mechanical block-mounted pump and it runs better.

Bear in mind though, that in my application, I just have fuel flow to the carb and no return fuel line (yet), so that may have something to do with it.

[nabihelosta]

Bear in mind though, that in my application, I just have fuel flow to the carb and no return fuel line (yet), so that may have something to do with it.

You pointed out to the problem yourself. Yes Facet fuel pumps can use return lines too. Plus you should manage the pressure they are delivering. Anywhere more than 4 psi and you have a serious problem.

When used in a carburetted BMW 2002Ti, (runs on Weber 40 or 45 DCOE), we generally connect the fuel return line, but restrict it by a "jet" of 1mm. This is useful too to keep pressure as low as possible, without compromising the huge flow those pumps can deliver.

Anyway my question was: When using the Facet pump, did the car pull stronger on high revs? Did it rev higher? Does the mechanical pump have a flow limit at a certain RPM and cause fuel starvation or going low in the bowl?

Thank you for your interest :-)

[MinorTC]

I don't have any prior experience of Fiat twin-cams, nor Facet fuel pumps for that matter, so bear with me as I'm still learning. I only fitted the Facet because I was having difficulty getting the engine to start and run properly with the mechanical pump. In the end, this turned out to be an incorrectly routed (by the previous owner) hose that was connected from the carb's fuel return outlet directly into the base of the inlet manifold; it should instead have been routed from the bottom of the air cleaner housing (breather hose); so as the fuel pump delivered the fuel, half of it was being shot straight into the inlet manifold, bypassing the carb altogether, making it run extremely rich!

Having discovered this and refitted the hose properly, I only briefly ran it with a Facet, and found it to work OK for normal driving, however, in my application, it would cause flooding and when the second choke kicked in as you were going along a dual carriageway at say 60mph, the engine would 'back up', i.e., hit a flat spot, backfire, then clear itself and carry on as normal, then some time later it would happen again.

I rebuilt the carb with a service kit, but it would still do this. I even swapped the carb, a Weber 34ADF54/250 for a 34ADF15/250 (similar but without the anti-stall valve) and still it does this, even with the stock mechanical pump! So, I'm assuming this is all down to the lack of a fuel return line causing it to over-fuel under certain conditions. I hope to rectify this soon - return line hose is on order...

I would suggest that the stock mechanical pump is fine for any standard engine but if you're fitting a pair of Weber DCOEs then you'll probably need a Facet. Bear in mind they are rather noisy in operation (I had mine mounted on the rubber insulating posts supplied with it, underneath the car at the back, yet it was still very audible in the cabin), so that's something to consider for a road car if you want refinement. I didn't notice it to pull stronger or rev higher with the Facet than it does with the mechanical pump - both about the same.

[Urbancamo]

I personally have very good experience on German HÜCO fuel pumps. They are very quiet and reliable. I'm always used fuel pressure regulator with these. Fuel pressure 0.18 - 0.2 bar max no matter what the carb is. And no return line for sure.

Never had a single issue with one or two carbs!

[nabihelosta]

It may be interesting to ask some folks here that own a Strada/Ritmo 130TC, what kind/make of fuel pump is it originally equipped with?
I heard it is an electric fuel pump, but have no experience on it, neither on its location (in-tank, in-line, pusher, puller...)
Since the car is factory ran on dual Webers or Solexes, one could assume Fiat used the optimal pump for this application.

Any 130TC owner willing to help here please?

Thank you in advance.

[Biancorally]

Hi Nabih,
here are the 130TC technical data of the electric fuel pump:

150 liter / hour
0.15 to 0.4 bar at 12 volts
the system includes a pressure regulator which is located just before the carburetor and a return line.
The pump is located outside the fuel tank.

I hope this can help, Nabih.


Regards

Daniel

[nabihelosta]

Many thanks to you Daniel. Indeed, this information was very useful. I bet this must be the best setup for a mildly tuned 2L engine running on 40 IDFs.

The Bosch 012 pump can be sourced from any Bosch dealer, or Fiat spare parts shop. But regarding the regulator, can you post a picture of it? Any idea about its make, model, or availability? Can it be sourced new or used?

Thank you for your time Daniel, I appreciate your help.

Nabih

[Biancorally]

Nabih,
here the pressure regulator, (below).
I never had a problem with this set up.
I do not know where you could still find this regulator.
One more precision, the return line is 6mm, carburetor line 8mm

Regards

Daniel

[nabihelosta]

After some intensive research on the net, I think the device shown here is more of a "one way check valve" than a regulator.
It used to be OE on all carburetted Fiats, even the ones equipped with a mechanical fuel pump. Their main job is to avoid fuel syphoning back into the tank.
But due to time failure, and them being unavailable, they were just discarded from the car by common mechanics.

Could be a kind of pressure regulator too. I have never seen one, I'm just telling you what I found, so I could probably be wrong here.

Thank you for your kind attention.

Nabih