Surging problem

[jj9879]

I've been having a problem on and off where my car will start to surge on and off when I floor it. Also every once and awhile when I hit the gas hard from a dead stop the car will just die on me. Its not a constant problem, but is obviously pretty annoying. I'm just wondering what could be causing this. People around my area have said way too many things for me to start narrowing it down without replacing a jillion parts.

Here's my setup
1970 Barracuda
383 4-barrell(stock carb)
3 speed auto slapstick
K&N intake
New 2.5in dual exhaust
Everything else pretty stock but restored

Thanks for any help in advance.

[DartMan360]

Here is what i would check out first
1. Carb. Is eveything all right and adjusted ok
2. Fuel pump. is it supplying enought fuel to the motor at all times?
3. Fuel filter. Is it clean? this is something alot of people over look.

I would think that it is something to do with ur fuel system.

[SpeedSleaze]

Sound's like you've got a bog. Usually that means you're lean. Like Dartman said, check fuel supply side of things, make sure there's enough juice.
The idle mix might be lean. The accelerator pump might be worn. Timing could be retarded. But if it comes and goes...
How high do you get standing behind the car while it's idling? I mean, how Rich does it smell? How many unburned hydrocarbons are there, in parts per million? Just kidding. Wipe a finger in that new 2.5 exhaust- is it real black and thick? If yes, you might be "loaded up." That same carbon is coating your plugs and making them harder to fire. When you take it out on the freeway and open it up, it tends to clean out the excess. And then it responds to punching it. Ever see the pro's (door slammers)? Just before they stage, they'll rev it up in neutral a few times to blow out the system.
If you've got a Carter carb, it's probably an AVS-Air Valve Secondary. The spring controls how quickly it opens. Too quick and you bog. But I don't think I'd wish the chore of adjusting the preload on anyone. It's a real bitch without the tool. One of the mags (HPM?) had a do it yourself tool section not too long ago that had one of those tools home-made. But the air valve wouldn't cause an intermittent prob as you describe. So I'd leave that for now.
When I grenaded the 383 in the RR and dropped a 440 in, it was a dog. It had a brand new Mallory Unilight Distrubtor. I'd put 2 light springs in the 383's distributor. (Directions: "Use 1 spring for street and race 4 speeds, and both springs for race auto." I used 2 on a stock 383 with headers and a 780 Holley. It was fast.) So I took the springs out of the 383's distributor & put them in the Mallory. They were shorter than the Mallory's, so I just unwound a coil to get the length right. It woke up that 440 big time.
Point is, you have to accelerate the motor before you can accelerate the car. So make sure the timing's right. The best way would be with a timing tape on the balancer and check for total advance (w/ vacuum advance disconnected and plugged. It's the only thing I use golf tees for (or fore).) The timing tape, back in the day, was like $5.00, real cheap. Just make sure there's no oil on the balancer or the tape won't stick.
Your compression ratio's probably up there- MP says it gets higher as the carbon builds on the piston and chamber- and that's gonna limit the amount of advance you can run. I like more initial timing (10-12 or as much as you can get away with) and they say total 35-36 degrees. But you might ping, depending on CR and gas quality. I think stock has too much mechanical advance- that little bit of twist of the rotor. You may have to take the distributor to a shop that curves distributors to dial it in.
Do you know if you've got the Hemi converter? Hold the brake and bring up the throttle in drive (for JUST A SEC) and watch the tach, if you got one. The rpm, beyond which the motor won't go, is an approximation of your stall. (You got good brakes right?) Make sure the road is clear ahead of you. (I hate body work). You could use a "Tune-up" type Tach if you don't have one in the dash.
Damn. Did it again. I need an editor!
`69 Road Runners were factory equipped with smokin' tires!

[JCFcuda]

I think dartman right the fuel is not getting to where it needs to go.

[concord997]

Just my 2 cents - - - - - - -

Check the power valve for sticking, or a vacuum leak.



Don - 51 Plymouth Fastback Road Runner