hey guys like the title says the engine sputters like its flooding when i mash the pedal at speeds of 35mph up to around 70mph. The timing is set to 15 degrees advance and appears to be advancing correctly at higher rpm. The car sat for several years before i bought it now ive been driving it regularly for about 6 months. Does anybody have a good approach to narrow down the problem? thank you guys in advance

 

Sputtering could just easily be caused by lack of fuel, as easily as too much fuel. In fact, its far more likely to be caused by fuel starvation. I had the exact same problem and it was fuel starvation. This can be caused by a clogged in-line fuel filter, sediment in the tank or even possibly the carb.

What happens is the carb bowls will fill up and everything will be fine, as long as you're foot is out of it, but once you mash the gas and haul ***, the demand exceeds the supply and the carb bowls drain dry and suddenly, the motor is sputtering, because it doesn't have the fuel it needs. Then you get out of it, cruise a bit, the demand is not as high, the fuel bowls fill up and everything seems fine.

What I did, was to temporarily hook up a fuel pressure gauge, right in front of the windshield, taped to the bottom with duct tape and watched the fuel pressure as I drove around. No problem cruising around. 5-6 pounds is what most engines need and it was having no problem. Then I punched it on a long straight away and watched the fuel pressure go to zero! That told me, what was happening, right off the bat.

I then found out, by looking in the tank, that the mesh sock for the gas tank sender, had totally rotted away, letting in tons of sediment to the fuel filter and it clogged the in line fuel filter. And there was plenty more sediment in the tank to cause even more clogs down the line. Ended up having to drop the tank, replace the sender and it came with a fresh mesh sock and also the fuel filter. Have had zero problems since. I also took a permanent marker and wrote the date on the new in-line fuel filter, so I'd have an idea later on, when I changed it. Hope this helps.

 

That is very helpful thank you f22

 

Spark plugs?

 

The entire ignition system has less than 1000 miles. Pretty much the first thing I did was replace the coil, cap, rotor, wires and plugs. The plugs are still in good shape, I just had them all out when I put the headers on. I checked the fuel filter that's on the carb, is there another one underneath the car somewhere?

 

if you have a Holley you could check the fuel bowl levels, it could be to too high. Go on YouTube and watch how to adjust floats leves. Make sure you have a flat area a firetiguisher.

 

It just has the stock qjet on it

 

Has the carb been rebuilt recently?

 

I can't say for sure but my instinct is that it has not. I'm pretty sure it set in a shop for around 10 years before I bought it

 

If the fuel pressure is good under load I would suspect that carb needs a good rebuild. I just had mine done by Lars and it runs MUCH better.

 

I still say, that before you do anything, you should know what's going on with the fuel pressure. You can find in-line fuel pressure gauges, that you can easily hook up with a length of fuel line to the bottom of your windshield. Then, you could move on to the other solutions suggested.

 

I will try that first so I will be able to make an informed decision. If the pressure is good I have had my eye on a new edelbrock 650

 

Another thing to consider is, since it is a Quadrajet, the secondary air valve spring may not be properly adjusted and the sputter is really a bog?

 

It really seems like it's an issue when the other 2 barrels open up. I even get what sounds like a backfiring noise at the carb when i open it up and it's not under load, but carburetors but these 4 barrels still baffle me

 

Do a general tune up first-points, plugs, capacitor, wires. Then turn to the carb.

 

He already did that

 

But was it done properly, and does the distributor need a rebuild?

 

I would say it's time to send it to Lars. While you're at it, send that distributor as well.

 

Sounds to me like the Secondary wind-up spring needs adjusting. Lars wrote a paper on how to adjust it.

 

Thanks, I will check that out