little backfiring

[Darren]

Hey guys I just install a new electronic ignition (proform)
In my 68 383 Cuda 4 speed. Everything went well. I set initial timming at about 12 deg and took for ride and when I stomped the gas the first couple of times I heard a little pop (backfire ) then after a while it stopped. Any ideas? PS I heard the same noise the last ride when running points ing.
Next on my list is to rebuild the 4426 carter. Thanks

 

[slowdown]

Hey guys I just install a new electronic ignition (proform)
In my 68 383 Cuda 4 speed. Everything went well. I set initial timming at about 12 deg and took for ride and when I stomped the gas the first couple of times I heard a little pop (backfire ) then after a while it stopped. Any ideas? PS I heard the same noise the last ride when running points ing.
Next on my list is to rebuild the 4426 carter. Thanks

Popping through exhaust I believe has to do with carb-fuel. Mine popped through exh an fouled plugs, did u look at your plugs? Pop through carb I think has to do with timing.

 

[nm9stheham]

Just a possibility for an exhaust backfire..... an erratic ignition switch or ignition connection can do this. The ignition will cut out for a moment, unburned fuel will build up in the exhaust, and can be lit off when the engine refires. Tends to only happen with an open throttle.

 

[mguner]

May still need more initial timing. Unless you have degreed your balancer there is bound to be a little error from the factory. Under load is when your secondary ignition is stressed the most and most common for a backfire. I would also check resistance on your plug wires. Most resistor core wires will still show something in the 20K range. Any thing over that or open circuit is suspect.

 

[TrailBeast]

Start with the carb paying special attention to the accelerator pump.

A good clue is if it only does it BEFORE the engine is warmed up all the way.

 

[mguner]

Start with the carb paying special attention to the accelerator pump.

A good clue is if it only does it BEFORE the engine is warmed up all the way.

Excellent point. With the air cleaner off look and see if you are getting a squirt when you start to open the throttle. You may need to move your pump rod to the hole closest to the pivot.

 

[Darren]

Thanks for the tips guys.. my first thought was oh no maybe I wiped a ex cam lobe. But when it stopped after the car was warmed up I started looking else where. The plugs are 1 year old, and wires, coil and electronic ignition where installed yesterday. But like I said I heard the popping last week with all the old parts so that's why I am thinking carb.

 

[RustyRatRod]

Get the timing right FIRST before anything else. Doesn't have enough initial timing, IMO.

 

[Darren]

Get the timing right FIRST before anything else. Doesn't have enough initial timing, IMO.

So if I am at 12 deg now at idle, maybe bring up to 15 -17?
When setting initial timming can I leave the vac adv hose connected? Thanks

 

[mguner]

So if I am at 12 deg now at idle, maybe bring up to 15 -17?
When setting initial timming can I leave the vac adv hose connected? Thanks

I would not have vacuum connected. If you are running manifold vacuum to advance you will get a wrong reading and if your idle is cranked up to compensate for a cam your "ported" vacuum may be applying as well.

 

[FJ5]

Vacuum advance disconnected with port on carb where vacuum advance attaches plugged.

 

[Darren]

Will give it a shot.. thanks boys

 

[Darren]

Ok so I reset the initial timming to 18 deg. And took it for a ride, no more poping or little backfiring. With no pinging. but one thing a noticed after I did my timming I plugged a vacuum gauge and at 800 rpm i have no vacuum but when I bring the idle up to 1000 I get about 6 inch.
Gauge could be Incorrect too. Any thoughts

 

[mguner]

You are checking vacuum on the "ported" nipple. That one has an opening above the throttle plate at idle and is exposed at part throttle. You need to try a different port for manifold vacuum.

 

[Darren]

You are checking vacuum on the "ported" nipple. That one has an opening above the throttle plate at idle and is exposed at part throttle. You need to try a different port for manifold vacuum.

Checking here that's where my vacuum advance is plugged in..