Technical Backfiring Again

[FR85]

Hi All,

I'm back.....firing again!

500 with a 650 engine, accelerate at all while in neutral and it'll put put put through the exhaust and then die. The dying is a new symptom!

Last year I went through all this, timing, changed exhaust, did valve gaps, new ignition system, did timing again and bought a peach of a carb from Toshi and all was going well.
Towards the end of the summer on its final run the valve cover gasket cracked, oil all over the place so it's been parked up. Last week, new gasket, fresh fuel, charged the battery and brought it for a spin and I thought this things going better then it ever did and then tonight we went back 12-18 months.

Other than starting the whole process of last year again has anyone any suggestions?

The one part of the entire system I don't like are the plug leads I got from FD Ricambi last year, they feel very soft, always have and I dont think they are the best quality but I can't blame them as they're do their job.

Also in that time, a brilliant Irish Fiat guy passed away, Stewart Walsh, he was brilliant to bounce ideas off and get suggestions from, he always was generous with his time and knowledge and he got me through the worst of it along with Toshi's carb and help so a key ingredient is unfortunately gone.

Thanks all!

Gavin

 

[the hobbler]

Hi All,

I'm back.....firing again!

500 with a 650 engine, accelerate at all while in neutral and it'll put put put through the exhaust and then die. The dying is a new symptom!

Last year I went through all this, timing, changed exhaust, did valve gaps, new ignition system, did timing again and bought a peach of a carb from Toshi and all was going well.
Towards the end of the summer on its final run the valve cover gasket cracked, oil all over the place so it's been parked up. Last week, new gasket, fresh fuel, charged the battery and brought it for a spin and I thought this things going better then it ever did and then tonight we went back 12-18 months.

Other than starting the whole process of last year again has anyone any suggestions?

The one part of the entire system I don't like are the plug leads I got from FD Ricambi last year, they feel very soft, always have and I dont think they are the best quality but I can't blame them as they're do their job.

Also in that time, a brilliant Irish Fiat guy passed away, Stewart Walsh, he was brilliant to bounce ideas off and get suggestions from, he always was generous with his time and knowledge and he got me through the worst of it along with Toshi's carb and help so a key ingredient is unfortunately gone.

Thanks all!

Gavin

A couple of reasons for back-firing are (a) the timing is wrong and, (b) the valve settings have closed up (probably the exhaust). It might be worthwhile re-checking both these things. Have you got 'points' ignition or, 'electronic' ignition. Electronic ignition is (in) famous for causing the ignition timing to go all wrong as it dies. I suffered this, badly, after a very successful TO my destination and then a horrendous trip back---the back-firing was so bad that the engine was holding back. Electronic ignition systems, irrelevant of cost, ALL suffer the same problem--they wilt (spelt D.I.E.) when exposed continually to more than 100C---and the "cooling" air coming from the engine, and blowing over the distributor, can often exceed 100C. In the light of my experience I devised and fitted an "air-barrier" inside the thermostat housing---touch wood, I haven't experienced a repeat of the problem for some time. If you would like a copy of the article that I wrote for the club magazine (Fiat 500 Enthusiasts Club) and some pictures of the barrier, feel free to contact me direct-- [email protected]

 

[timmycm850]

I would check and blow out the idle jet in the carb. They easily block with debris.

Tim

 

[FR85]

Hi Hobbler,

I'm still on points, it had an electronic ignition but that went.

I think a day is going to have to be dedicated to going through the lot again.

Thanking you!

 

[FR85]

Tim,

I'll be going through the lot again, just surprised how 6 days between drives and everything can change!

Cheers,

Gav