Popping Exhaust

[Mike G 0]

Hi guys

A while ago, I inserted a topic on this subject and received a bunch of replies which was all very helpful. The likely cause of the noisy 'popping & gurgling' on the overun (downhill with foot off accelerator pedal) I concluded was the silencer, i.e. the packing had blown out! Custom Chrome have checked over the silencer and reckon that it has the same amount as when new. They might try to squeeze some more in, but they suggested I look at the fuel side of things.

 

My engine is a 1600cc Pinto, only done 5,000 miles since recon, has a recon 28/30 Weber carb, manual choke, and no obvious gas leaks. I believe all tappet clearances are correct. Big puzzle as to why the problem reared its ugly head over last 500 miles or so. Perfectly OK before that.

 

Anybody got any fresh ideas?

Cheers

Mike G

[paul091085 0]

why would you want to get rid of that sound?!

[Swan Jnr 5]

my 2b does the same thing. when it was on a rolling road in blackpool the technicians there told me that it could be due to the differences from a standard sierra exhaust compared to the rh, especially the length, (less than half the length) they also said that there was nothing wrong with it, and no reason to do anything about it.

They took it as a sign that everything was pretty much as they'd expect with engine/exhaust set up. (This was echoed by the figures and tests etc)

[alan rowe 0]

you should hear mine on overrun - pops and bangs - sounds brilliant

 

A

[paul091085 0]

i was quite dissapointed as ive changed my engine over and it hardly does it anymore

[BigLee 68]

Yoo want to hear mine. I scare dogs and old ladies - until I get around to fitting 2 new silencers I've got. 110 db each side! My timing and fuel is pretty much spot on. It doesn't do it much when cold only when hot.

 

I wouldn't worry about it

[STEVE OXON 0]

when my 2 litre 2b was rolling roaded i was told the shape of the exhaust all 90 degree bends and unequal lengths of pipes and poor design of 4 into 1 in too short a length was the basic problem with it popping etc.

just have to get used to it

steve

[Mike G 0]

Thanks Guys

 

It's all a bit of a puzzle! When I replaced the beancan that RH supplied, that rattled with loose baffles and sounded fairly naff, the Custom Chrome one was a real treat, nice sound when accelerating and a constant subdued roar on the overrun. Then after more than 2,000 miles of use, not sure if the regular noise got any louder but on the overrun it gradually got more unacceptable with the popping and gurgling. Driving downhill with very slight pressure on accelerator pedal mostly stopped this, but meant that I ended up going too fast at the bottom!

 

The engine runs a treat, and once the carb is full (drains back during non-use), it re-starts instantly every time - hot or cold, and tickover is reliable and even at about 1000rpm. Fuel consumption is worse than our 2 tin-tops, but then 19 year old technology and aero-dynamics of a brick probably account for most of this. With a 5-speed gearbox, it accelerates up to about 60mph fairly quickly, but after that it tails off, and the typical top speed is probably 75mph @ about 3500 rpm. Can't guarantee the speedo or rev-counter's accuracy, although I suspect the gearing is fairly low.

 

I suppose to improve performance and mpg I could take it to a Rolling Road outfit, who might re-jet it and improve the carb side of things. But this will possibly still not effect a cure, and answer the question as to what happened to cause the change of exhaust overrun 'noise' in the first place?

 

All answers on a postcard to........................

 

 

Cheers

Mike G

[peter2b2002 262]

my old rh twin pipe used to pop and bang on overvrun all the time, now i have a nice 4-2-1 all 4 pipes are the same and the 2 pipe bit are the same length, but i still get the odd pop and bang, i think it has some thing to do with back pressure, the engine is a 2ltr efi, the silencer is a cherry bomb muff diver(no snigles)

pete2b

[john 5]

I think the popping is a good feature, but if you want to reduce it, I always understood it to be a sign of weak mixture, I can tune it out a bit with the mixture screws on my 38dgas.

[Tim Norman 272]

The V8 does it and I make sure it does it especially under bridges a in tunnels. WHAT A FANTASTIC NOISE. I just need the flames out the side now.

[salty_monk 1]

and a trunk monkey..... (both SA anti theft devices...)

 

Dan

[elwe 0]

The V8 does it and I make sure it does it especially under bridges a in tunnels. WHAT A FANTASTIC NOISE. I just need the flames out the side now.

 

Put a switch on the dash to cut the spark. When I had a rotor arm go I got 2 foot flames out of the exhaust as I rolled to a halt.

[yob 0]

Had Mr home tune out to mine found tiny crack in inlet manifold gasget.Ok to have a bit of backfire but down hill it was deaf un ing.

[vacinc 1]

dont no if this will help, cut my box open to repack it, nothing in side (as normal) it was poping and fart"in

and backfireing, as they all do. repacked it, nearly two full bags of that fibreglass stuff, ( still picking bits of it out of my hands 2 weeks later. take note, were gloves next time) well put all back together, its not so much queiter, more of a deeper ( must say sporter note, very impressed) but no fart"in ,pop"in, backfireing at all

( "o" i do miss it so ) but i find the deeper note, wich is nice, gives me a sore head, so what you want backfireing or a sore head, i no wich one i"d take ps, need ear plugs now