340 Chugging instead of Reving
- Thread starter 1969GTS340
- Start date
-
should run longer then 10 seconds on the bowls if you are@3k when you kill the pump unless its dumping gas in the motor imo
check float height again
And you’ve removed the air cleaner, got it running and brought up the rpm’s to the trouble range and eyeballed as best possible that there’s no excessive fuel dribbling, bubbling out dumping etc from the bowl vents, or etc?
Yes. But I'm currently not running an air cleaner. I fired it up, reached inside the car to shut off the fuel pump, it only ran for 10 seconds as I gave it some throttle, I could see the initial spray of fuel when I hit the linkage, but I didn't see any other signs in those brief seconds. I don't have any help here to turn the pump off when it's in the trouble range.
10 or so seconds is about right without pressure from the pump.
Carnut68
Well-Known Member
This. The PV gasket will cause this.
Just for the heck of doing it, start it up and cut the lights out and look closely at the the plug wire connections on both ends for sparks to ground on the plug side or arcing between cylinders at the distributor. Costs nothing and only takes a minute.
It will be Tuesday before I'm in the shop again. Thanks guys for the continued suggestions. I'll get to them all until this is resolved.
Thanks for the suggestion RRR,
With the lights off in the shop, there was no sign of arching anywhere under the hood. The coil is mounted inside the car, I checked there and where the coil wire connects to the moroso bulkhead feed though. Pitch black.
Another test tonight, I pulled one spark plug wire at a time, running on the remaining seven. No change at all.
Your referring to PV as Power Valve?
Well that's good......and bad I guess. lol At least you've eliminated that.
I'm uploading a video of the car running. It starts instantly and idles. It's hard to hear in the video, but towards the end it shows how much throttle I'm adding before it begins popping out the headers.
Last edited:
Inertia
Well-Known Member
Are you actually test driving the vehicle, or just revving it up in your driveway with no load ?
Reving in the shop mostly. I did take it for a mile ride down our road and back and it acted the same way. Videos attached.
Last edited:
512Stroker
We are all here because we are not all there.
What is your fuel pressure when it popping?
5.5 lbs currently. I've slowly adjusted fron 5 to 7 and tested the throttle every half pound with no change.
It strictly a drag car but I still may have a chance to take it to the track on a test and tune night.
The jets are currently 72. It was a size I chose to start with. The plugs read that it's running rich. Black and wet. When I removed all the plugs during a compression test, fuel sprayed out of the plug holes the first few cranks. I brought the rpms up to the break up point and shut off the fuel pump. It popped until it ran out of fuel.
Rat Bastid
Dunamis Metron
That carb is black. That’s a reversion issue. Did you degree the cam? I had to ask but that’s bad.
Also, if it has so much fuel going through the engine that it blows out of the plug holes, you need to get some fuel out of it pronto. You’re killing the rings.
A 72 jet doesn’t sound outrageous but it’s getting fuel somewhere.
I can’t hear what you’re hearing but being pig rich will make them pop and bang and miss.
The carb was loaned to me to see if the problem would go away. It came to me black.
I did degree the cam but it was 1* off so I decided not to order a keyway, just break it in dot to dot and get some track time to dial everything in at another time.
I agree on getting the fuel out. I only run a few minute test or two then remove the plugs, air it out for a few days and lightly lube before trying another test.
-
