[Healeys] Another backfiring question

[John Spaur]

I use a Uni-Sync too but I also used a hose when I recently installed new HS4 tricarbs. The hose works well too but it does not give you an indication of air volume, just equal noise.

 

John

 

From: Healeys [mailto:healeys-bounces at autox.team.net] On Behalf Of Bob Spidell
Sent: Friday, January 29, 2021 8:18 AM
To: healeys at autox.team.net
Subject: Re: [Healeys] Another backfiring question

 

I dunno if it can cause high RPM backfiring (I think it could), but the airflow on all (2-3) carbs has to be the same--or, at least, very close--at all throttle positions. This has to be checked off-idle, obviously, but if it's good at, say, 2,500RPM it should be good at all speeds; if not, you have to disconnect the throttle connect shaft to set them. I suppose a crack Brit-car mechanic can test with the recommended 'hose-in-the-ear' technique--my ear hose is collecting dust somewhere--but I use a Uni-Syn.

To paraphrase the TV commercial we've all (probably) seen a thousand times: "If you don't have a carburettor synchronizer, get one."

Bob

On 1/29/2021 6:13 AM, healeyguy--- via Healeys wrote:

Len and Listers

Pushing the pin up to lift the piston is the start of the "test the mixture setting" exercise. You begin the push, ever so slightly,  and listen to the idling engine. The idle goes up.  What do you do next? You continue to raise the pin  to see what happens. If the idle continues to rise you know you are in a rich condition. If the idle stops going up and starts to drop off the mixture is pretty close. If the idle does not increase from the start you usually assume you are in a lean condition.  This gets the carb mixture close at idle which in theory means the carb is going to operate throughout the RPM range.  

 

There is one other assumption here, that being that the carbs is in the same condition as new mounted on an engine operating as new. That is when allot of other stuff comes into play.  The carb float bowl items, needle/seat and float level  must be set correctly. Float must not be leaking thus making it sink. Carb must have the correct main needle and jet and they have to be installed and adjusted correctly. Flutter at high RPM may indicate that the piston spring in the suction chamber is weak or the incorrect spring installed. Ignition timing and condition and setting of ignition points.

The list goes on and on......

P



-----Original Message-----
From: Leonard Berkowitz  <mailto:DrBerkowitz at hotmail.com> <DrBerkowitz at hotmail.com>
Subject: [Healeys] Another backfiring question

Hi all

 

Just finished repairing and reinstalling the carburetors on my BJ7. I thought I had everything adjusted properly. According to my Haynes Manuel the engine speed should increase slightly when you lift the piston a very small amount. Mine does that.  My dwell angle is where it needs to be and the car starts and idles nicely. Also sounds beautiful when I punch the accelerator linkages. The problem is that when I get it up to 60-70 mph I get what sounds like backfiring into my carburetors. Also sounds like it doesn’t have a whole lot left in the tank, so to speak. Does that sound like I am running too rich or too lean? 

 

Len Berkowitz 

 

 

 

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