Excessive Popping on Slow Deceleration

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sixpipe98
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Excessive Popping on Slow Deceleration

Post by sixpipe98 »

So I've had a go at tuning my weber carbs quite a few times now and feel like I'm getting ok at it. I use the procedure outlined in 101 projects and seem to get a nice strong idle. On that note, it does seem a little high up at 1000 rpm. This is with the idle adjustment screws at the front of the carbs all the way out such that the throttle is completely closed and none of the air bypass screws excessively screwed out. Anyway, when I then go for a drive, there is in my opinion excessive popping on deceleration, especially when slowly going down through the revs with no braking and closed throttle. This is fixed by richening all the idle mixture screws about 1/4 to 1/2 turn out. This of course does then mean that it doesn't idle as well. The car is a '73 T with E cams and S pistons/barrels. The exhaust is a bit ridiculous (see attached) so perhaps it's a bit too free flowing and that has something to do with it? Would be keen to hear your thoughts. cheers, Sam.
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exhaust2.jpg
210bhp
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Re: Excessive Popping on Slow Deceleration

Post by 210bhp »

Popping and banging on the overrun is usually unburnt fuel igniting in the hot exhaust (and you look to have plenty of it).

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Mike
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sixpipe98
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Re: Excessive Popping on Slow Deceleration

Post by sixpipe98 »

I guess the main question here is whether it is bad for the car or not? If not, the sound doesn’t bother me too much.
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Nige
Nurse, I think I need some assistance
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Re: Excessive Popping on Slow Deceleration

Post by Nige »

Maybe try bunging some of the outlets/tips on the exhaust, maybe leave two open and see if that makes any difference?

That might help to show if just an exhaust issue.

Top marks for the most crazy exhaust though. 8)
sixpipe98
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Re: Excessive Popping on Slow Deceleration

Post by sixpipe98 »

Ok will give that a go thanks. It does drone a bit but sounds incredible past 4000 rpm.
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