Fiat 130TC misfire problem

[Guy Croft]

Should be OK on standard rated for the motor, NGK BP6ES from memory.

Good photo of ex header when you get a moment please, just want to be sure.

GC

[sumplug]

Way forward i think with this once plugs etc are changed is a rolling road session or emission test. I think its a case of out of tune carbs, and solex ones with the additional airbleed screws on top of carbs need delicate tuning.
I presume there are no leaks around the manifold causing a lean mixture? Maybe a cam timing problem?

Andy.

[Guy Croft]

Dunno Andy, open the throttle sharply the whole motor 'bogs' down. That's not easy to trace beyond pump jets and ex back-pressure.

Everyone loves to help, but

Ideas only from those with actaul & DIRECT fault-finding experience of this fault on this one from here on in please.


GC

[leifa]

Should be OK on standard rated for the motor, NGK BP6ES from memory.

Good photo of ex header when you get a moment please, just want to be sure.

GC

I'm sorry about the delayed answer, but I've been busy for a period. I finally got time to play around with the carburators. The problem is almost gone if I reduce the stroke of the accellerator pump. I've reduced the stroke about 3 mm. According to the factory manual of the Ritmo 130 TC should this reduce the amount of fuel when I apply throttle. I suppose I have to put in smaller pump jets. The ones supplied with the engine from factory are 0,45 mm. Any suggestions about size?

I've attached a photo of the headers to this post.[/img]

[130tc]

Hello, All

I just picked up my 130TC today. It now runs perfectly.
About 4 weeks ago I changed carbs to 45 Dellorto DHLA.
After that change the car would stutter on light acceleration.
I¢ž¢m running:

Standard Digiplex (I did replace vac line)
Standard Extractors
Standard Dellorto trumpets

The only change I made was the carbs.
So I sent my car out to get the carbs tuned, I drove it home tonight the car now drives better and a lot smoother than the Solex.
I have not talked to Barry yet but when I do in the next day or two I¢ž¢ll post the jetting settings and what he did to resolve.

Hope this will help

Stephen

[leifa]

I'm sorry about the delayed answer, but I've been busy for a period. I finally got time to play around with the carburators. The problem is almost gone if I reduce the stroke of the accellerator pump. I've reduced the stroke about 3 mm. According to the factory manual of the Ritmo 130 TC should this reduce the amount of fuel when I apply throttle. I suppose I have to put in smaller pump jets. The ones supplied with the engine from factory are 0,45 mm. Any suggestions about size?

I've attached a photo of the headers to this post.[/img]

Time for an update and a small question. After having spooken to the guy that dynoed the car some 15 years ago (Tore ’‹Å“stli at TK ’‹Å“konomitrimming in Norway) i found out that the engine runs to fat at the medium range but he had to do it like this to avoid that it got to lean the upper end. He had problems getting chockes and jets. Thanks to this forum I got in touch with "Abarthnorway - Remi L" and he supplied me with a set of 36 mm chockes. What a difference! No problems with hesitation and stuttering around 3.500 rpm any more. My only concern now is if the engine runs to lean at the top end. I've done a test. Running the engine at full trottle around 6.000 rpm for about 5-10 secs. and then switch off ignition and clutching out the engine. I've attached a photo of the spark plug at #3 after this test. Does this look OK?

Quting from an earlier post about the setup: Ritmo/Strada 130 TC engine in a 131. Has Kent FT11 camshafts and IRESA 4-1 header. Carburators Solex C 40 ADDHE 27 which are the ones delivered when the engine was new. The carbs are like this: Venturi 32 mm, Aux Venturi type 4,8, Main jet up from stock 145 to 150, Air bleed jet down from stock 190 to 170, Emulsion tube A04. Fuel pump is Facet red top and stock Ritmo pressure regulator. Ingniton is stock Digiplex from Ritmo 130TC.

[Guy Croft]

Leifa, hi

that is a very good try, especially that it's in English, but I need a much better quality plug photo to be certain, looks like pale brown insulator and grey out region, which would be OK if I'm right about the colours.

Regarding jetting and carbs, I'm lost, sorry.

Please just write the summary like this, I am confused with all the references to previous posts:

- the engine is: (state spec)

- jetting was: (jets, chokes, carb type)
'this setup caused misfiring etc..'

- now: (jets, chokes, carb type)
and then - state the improvement gained.

Thanks,

GC

[Guy Croft]

Here's a very good link to plug colours, posted by Richard Ridge at http://www.mirafiori.com

http://www.dansmc.com/Spark_Plugs/Spark ... talog.html