murrayarnold Posted August 30, 2020 Report Share Posted August 30, 2020 Hi guys. My 6 is running tripple webbers and full stainless race pipe. When ever I let of the gas the cars popping and banging. Sounds great, but is this a sign that somethings needing adjusted. Thanks Quote Link to post Share on other sites
mtrehy Posted August 30, 2020 Report Share Posted August 30, 2020 did it always do it or recently started doing it? Quote Link to post Share on other sites
murrayarnold Posted August 31, 2020 Author Report Share Posted August 31, 2020 I didn't do this in the past. Not that I recall. Its very pronounce. I'm wondering if its a timing issue. Quote Link to post Share on other sites
Mike C Posted August 31, 2020 Report Share Posted August 31, 2020 1 hour ago, murrayarnold said: I didn't do this in the past. Not that I recall. Its very pronounce. I'm wondering if its a timing issue. Might be right. Ignition timing is easy enough to check. There's always the possibility it's the valve timing or a burnt exhaust valve. Quote Link to post Share on other sites
elclem1 Posted August 31, 2020 Report Share Posted August 31, 2020 I had this problem - distributor cap was faulty and was arching across inside. Quote Link to post Share on other sites
mtrehy Posted August 31, 2020 Report Share Posted August 31, 2020 7 hours ago, murrayarnold said: I didn't do this in the past. Not that I recall. Its very pronounce. I'm wondering if its a timing issue. check exhaust manifold / gaskets for air leak Quote Link to post Share on other sites
ntc Posted August 31, 2020 Report Share Posted August 31, 2020 22 hours ago, murrayarnold said: Hi guys. My 6 is running tripple webbers and full stainless race pipe. When ever I let of the gas the cars popping and banging. Sounds great, but is this a sign that somethings needing adjusted. Thanks Have you set the misabs correct Quote Link to post Share on other sites
murrayarnold Posted August 31, 2020 Author Report Share Posted August 31, 2020 The what. Ive no idea what that is. Quote Link to post Share on other sites
stuart Posted August 31, 2020 Report Share Posted August 31, 2020 2 minutes ago, murrayarnold said: The what. Ive no idea what that is. These are what Neil means https://weber-carbs.co.uk/shop/product/misab-plates-weber-dellorto-carbs/ Stuart. Quote Link to post Share on other sites
murrayarnold Posted August 31, 2020 Author Report Share Posted August 31, 2020 Ah ha. The shock absorber washers. Everything is brand new. The complete internals and all manifold fittings. I very carefully installed everything myself. If there was a leak the engine wouldn't idle and the carbs wouldn't tune. I used a colour tune on every piston. And ballanced them. They idle perfectly with no spitting or popping. Quote Link to post Share on other sites
ntc Posted August 31, 2020 Report Share Posted August 31, 2020 You are wrong every time you use the throttle the carbs move, the spacing needs to be correct. Quote Link to post Share on other sites
murrayarnold Posted August 31, 2020 Author Report Share Posted August 31, 2020 I know. Thackery washers are installed correctly. I actually installed my first DCOEs 30 years ago. I do know how to install them. I am.very wrong. Ha. Really. Like someone said, and I am leaning that way, its a timing issue. Quote Link to post Share on other sites
DRD Posted September 1, 2020 Report Share Posted September 1, 2020 On 8/30/2020 at 5:34 PM, murrayarnold said: Hi guys. My 6 is running tripple webbers and full stainless race pipe. When ever I let of the gas the cars popping and banging. Sounds great, but is this a sign that somethings needing adjusted. Thanks My everyday car does this as standard! It seems the engine map deliberately squirts a little bit of fuel in on the over-run to generate what are termed 'burbles' to make the engine sound sporty. Quote Link to post Share on other sites
Richard71 Posted September 1, 2020 Report Share Posted September 1, 2020 19 minutes ago, DRD said: My everyday car does this as standard! It seems the engine map deliberately squirts a little bit of fuel in on the over-run to generate what are termed 'burbles' to make the engine sound sporty. My Pi car does exactly the same thing. This feature was tuned-in deliberately by Revington TR. Their mechanic advised me that by the time I drive home (500 miles later) I find I don't like it, then I should ring him and he'll instruct me on how to re-tune......over a year later and he hasn't heard from me. Richard. Quote Link to post Share on other sites
Steves_TR6 Posted September 1, 2020 Report Share Posted September 1, 2020 27 minutes ago, Richard71 said: My Pi car does exactly the same thing. This feature was tuned-in deliberately by Revington TR. Their mechanic advised me that by the time I drive home (500 miles later) I find I don't like it, then I should ring him and he'll instruct me on how to re-tune......over a year later and he hasn't heard from me. Richard. Mine too! Quote Link to post Share on other sites
c.hydes Posted September 1, 2020 Report Share Posted September 1, 2020 1 hour ago, Richard71 said: My Pi car does exactly the same thing. This feature was tuned-in deliberately by Revington TR. Their mechanic advised me that by the time I drive home (500 miles later) I find I don't like it, then I should ring him and he'll instruct me on how to re-tune......over a year later and he hasn't heard from me. Richard. Hey this sounds good. My PI used to do this slightly on overrun, especially on hard acceleration, so whats the secret to getting it back play with the MU adjustments? But which one, dont want to mess it up or take it too far out? Regards, Colin. Quote Link to post Share on other sites
Tom Fremont Posted September 1, 2020 Report Share Posted September 1, 2020 My TR250 driver with CP cam and triple DCOEs doesn't fart or burble on overrun at all, let alone pop and bang - never did, and likewise with a Kent TH2 cam ( 295 deg. duration ) before that. I've only driven (1) P.I. TR6 and rode in another courtesy Racetorations; both guilty of farting and burbling on overrun. Do all of them do this? Weber jets mix air with the fuel before entering the inlet tract, so even with throttles completely closed some air gets in. As for Murray's issue, my guess is timing too. Tom Quote Link to post Share on other sites
murrayarnold Posted September 1, 2020 Author Report Share Posted September 1, 2020 Hi Tom. Yep I think so. Strange its never been like this before. But the car drives OK. No pinking etc. But maybe it should run better. Its a black art all this isn't it. Quote Link to post Share on other sites
Richard71 Posted September 1, 2020 Report Share Posted September 1, 2020 1 hour ago, c.hydes said: Hey this sounds good. My PI used to do this slightly on overrun, especially on hard acceleration, so whats the secret to getting it back play with the MU adjustments? But which one, dont want to mess it up or take it too far out? Regards, Colin. Yes Colin, MU adjustment required, but don't ask me how. I see you're not a million miles away from Revington TR, why not pay them a visit? Richard. Quote Link to post Share on other sites
DRD Posted September 1, 2020 Report Share Posted September 1, 2020 4 hours ago, Richard71 said: My Pi car does exactly the same thing. This feature was tuned-in deliberately by Revington TR. Their mechanic advised me that by the time I drive home (500 miles later) I find I don't like it, then I should ring him and he'll instruct me on how to re-tune......over a year later and he hasn't heard from me. Richard. I like it but at a relatively low level. Some cars make ridiculous bangs which just annoys everyone else! Quote Link to post Share on other sites
JohnC Posted September 6, 2020 Report Share Posted September 6, 2020 @Colin - if everything else is set up correctly, then screwing *out* the A3 adjustment screw (try 1/2 turn for starters) will lean out the minimum fuel setting, which results in popping and banging on over-run. If everything else is *not* set up correctly then it may not. Alternatively, sacrifice a chicken (pref, a Silkie as they are good layers if you chicken(!) out) and cry "please make my car bang" while running around naked outside your next group meeting venue... Cheers, John Quote Link to post Share on other sites
John L Posted September 6, 2020 Report Share Posted September 6, 2020 I thought that screwing the A3 out should lean the fuel out on overrun and actually stop it banging, there should be hardly any fuel on the overrun? John Quote Link to post Share on other sites
c.hydes Posted September 6, 2020 Report Share Posted September 6, 2020 4 hours ago, JohnC said: @Colin - if everything else is set up correctly, then screwing *out* the A3 adjustment screw (try 1/2 turn for starters) will lean out the minimum fuel setting, which results in popping and banging on over-run. If everything else is *not* set up correctly then it may not. Alternatively, sacrifice a chicken (pref, a Silkie as they are good layers if you chicken(!) out) and cry "please make my car bang" while running around naked outside your next group meeting venue... Cheers, John Very good John, my "spindly legs", would match a chicken. Think I`ll leave it well alone for now, but thanks for the info, at least I now know which adjuster on MU is for leaner or richer. Colin. Quote Link to post Share on other sites
JohnC Posted September 7, 2020 Report Share Posted September 7, 2020 Hi Colin, The A3 screw is the minimum fuel stop. It has no effect other than to determine how much fuel is delivered at high vacuum (i.e., over-run), limiting how lean the mixture can get. @John L- If the mixture is too lean you get popping & banging. Counter-intuitive, but I understand it's because an over-lean mixture doesn't fully combust and so you get unburnt fuel which then ignites in the exhaust. John Quote Link to post Share on other sites
John L Posted September 7, 2020 Report Share Posted September 7, 2020 @JohnC If you set it with no fuel at high vacuum there will be no popping and banging, nothing to burn. John Quote Link to post Share on other sites
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