[Healeys] exhaust popping

[Derek Job]

The popping on overrun, as explained by Bob, is due to excess fuel burning
in the exhaust pipe. This is very common on cars with higher performance
engines, particularly hotter cams. My cam is 300 degree duration which
means big overlaps between intake and exhaust valves. When you suddenly
come off the throttle, excess fuel goes straight out of the exhaust ports,
then ignites on the hot exhaust. My car does this all the time. Its the
same reason that you see flames coming from some high performance race
cars. We even had some flames at last weeks Big Healey Invitational race at
Castle Coombe.

On Fri, Oct 10, 2014 at 7:17 PM, Len and/or Marge Hartnett <
thehartnetts at earthlink.net> wrote:

> When I acquired my BJ8 back in 1970, a previous owner, there were two, had
> removed the two resonators across the rear of the car.  The backfiring on
> deceleration was quite annoying to my copilot/navigator especially when
> descending hills in a lower gear.  I wasn't that fond of it either.  I
> reinstalled resonators and the popping went away.  No other changes were
> made as far as I can recall.  She and I were quite content going down hill
> after that (in the Healey, not the marriage).
>
> (The Other) Len
> Fairfield, CA, USA
> 1967 AH 3000 MkIII, HBJ8L39031
> ***199,380 miles (recalculated 10/06/2014)***
>
>
> ----- Original Message ----- From: "Bob Spidell" <bspidell at comcast.net>
> To: "Oudesluys" <coudesluijs at chello.nl>; <healeys at autox.team.net>
> Sent: Friday, October 10, 2014 6:10 AM
> Subject: Re: [Healeys] exhaust popping
>
>
>  >
>> ...............At times, my BJ8 has not popped on decel/downhill/etc.
>> with different exhaust systems.  Don't know why, I've kept pretty much the
>> jet/mixture setting as long as I've had the car (31 years)............. >
>> Bob
>>
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