Carb will not adjust

[aa-1159]

73 Duster 360
Have tried 2 different Carburetors and neither one will adjust, can turn screws all the way in one at a time and nothing changes
First Carburetor brand new brawler, second one Proform, 650's, double pump, fuel pressure 6lbs
410hp. Need a little help
No vacuum leaks

 

[Dana67Dart]

I know you say you don't have a vacuumed leak but your symptoms screen vacuum leak.

Might be inside the manifold to the oil gallery

Remove the PVC valve and plug the hole. Check the oil filler and see if the block gets pressurized or pulls a vacuum

 

[Dana67Dart]

Just thought of another thing. Maybe your throttle blades are open too much and you are not using the idle cir at all.

 

[dano]

Just thought of another thing. Maybe your throttle blades are open too much and you are not using the idle cir at all.

^This. What cam, initial timing and total timing and when? Are you using a vacuum gauge? If so what are you getting for vacuum idle?

 

[Inertia]

Reading part of this should cover everything,.
Cheers

Initial timing

While trying to rectify a hard start(Eddy 9266 ordered) I figured I would check initial timing and proceed from there. With vac advance disconnected, I plugged the vacuum line to carb. 700 RPM in park and 30* initial. Seems like a lot? Verified TDC with piston stop. Set #1 firing at 10* BTDC...

www.forabodiesonly.com

 

[AJ/FormS]

With the engine Off;
Check to make sure the oil level in the CC is below the crank, and
Defeat the Vacuum advance system, and
make sure your PCV system is plumbed to underneath the Primary throttle valves, and is functioning correctly, and
if you have power brakes, Clamp the line shut; and
Make sure the secondaries are closed up tight, and
reset the mixture screws to 1 turn out, then;

Start the engine and;
Back the Ignition timing up to 10*,
while keeping the rpm around 750/800.Then
make sure the WET fuel level in the carb is correct and is stable, and then
look down the bores of the primaries while the engine is running to make sure the boosters are not dripping fuel.
If you now still have problems;
Check the HOT valve lash; or if hydros,
Go check for a ruptured power valve, if good, then
go look for a vacuum leak, again,
including into the valley.
If no leaks found, consider the cam-timing.

Now you can begin your tuning routine.
Happy Hunting

 

[RustyRatRod]

A ruptured power valve will affect nothing at idle. Nothing. It's on the power circuit. It's easy to see on a Holley cutaway diagram. In order for the power valve to introduce fuel to the engine, the throttle blades must be open to pull fuel out of the boosters. No air flow over the boosters and the power valve can be removed and thrown on the ground and the engine runs fine.

 

[AJ/FormS]

Rusty said;
"In order for the power valve to introduce fuel to the engine, the throttle blades must be open to pull fuel out of the boosters."
AJ says;
Oh good then we can just skip looking for a flooding condition, and don't have to go down that rabbit hole..

 

[Bewy]

360 wit 410 hp. Going to be a sizable cam to get 410. Post #3 nailed it. Check how much transfer slot is exposed on the pri bores at idle. I will bet it is more than 0.060"...& that would be the problem.
Engine would need a LOT of timing at idle, likely 25-45*. That will close the pri t/blades.

Read the Man Vac Experiment under 'General Discussion'.

 

[RustyRatRod]

Rusty said;
"In order for the power valve to introduce fuel to the engine, the throttle blades must be open to pull fuel out of the boosters."
AJ says;
Oh good then we can just skip looking for a flooding condition, and don't have to go down that rabbit hole..

Hardly. We can eliminate the power valve making the engine run rich at idle, smart butt.