('85 ram 150, 318 engine, Holley 2-BBl carb)

Does this carb have a power valve in it?

Would a ruptured power valve make the engine hesitate/bog/lurch/sometimes die?

If by power valve you mean accelerator pump then yes.

A bad one would cause trouble.

On the Holley IIRC they are on the lower side of the bowl, and towards the front. Held in by a small cover with 4 screws.

Hmmmmm......I don't see a power valve in this diagram...do you?


http://www.carburetorfactory.com/expvw16.html

30/31 I believe

30, 31, 32 spring, plunger, and rod would be the accelerator pump components.

Looks like that one is mounted from the top, similar to the Carter/Eddy carbs.

32 gasket

yep.

A power valve and an accelerator pump are two dofferent things. The acc. pump gives the carb. it's initial squirt. While the power valve is in the metering block of the carb.

and IIRC those 2 bbls dont have metering blocks to put a power valve in to..The 2300 Holley 2 bbls like the 6 pack center carb has a power valve..

Malebovineexcrement!

There is a power valve, it just doesn't LOOK like a traditional Holley 4-barrel power valve. #25 and 26 are, IMHO.

R.

This is from a 79 FSM. I had trouble with the vacuum down piston coming loose, so I had to restake it. Seemed to solve the problem.

Thanks to rustbuckett's pic, it looks like # 25 is the power valve?

I'm guessing the power valve is either stuck/worn out/ruptured?

Here are the symptoms (also mentioned in another thread):

runs fine when cold/warming up.

When operating temperature is reached, there is a severe bog/hesitation/lag immediately after throttle tip in, when stepping on gas pedal. If you push farther down on the gas pedal quickly enough the engine will start running with a huge lurch forward.

It will pull away initally from a stop sign/ resting stop fine, then bog down at appx 900 rpm. Usually it will die, restarts immediately.

We have replaced:

accelerator pump
spark plugs/wires
dist cap/rotor
fuel filter
fuel pump
ignition module
coil
ballast resistor
pcv valve
egr valve vaccum line pulled/plugged
vaccum line to canister on heat riser pulled/plugged
distributor advance vaccum line pulled/plugged

timing verifed as to factory specs

carburator misture/idle adjusted numerous times.

timing verified

IMHO,that is a power piston. it does the transition from idle circut to power/cruz mode.

goes up with less vac to raise the needles out of the jet to flow more fuel. goes down under high vac to lower needles in the jets to restrict fuel flow to the idle circut.

power valve will have a rubber diaphram(sp?) that will ruptur and dump fuel all of the time makeing for a rich idle and slugish throttle responce from a rich idle to a rich power/cruz mode.

power valve should only open under low vac rating to allow more fule to flow at a power mode/WOT.

the bore for the power piston carbons up and causees it to stick sometimes in the up or down to cause drivabilty problems like you discribe.

like the other poster mentioned,it may have a retainer poped loose and would need to be restaked to hold the piston in the bore corectly and right hight on needles/jets.

I have to restake the retainer on the power piston on my 40 yr old q-jet now and then.