1997 Volvo 4.3 gs No Powervalve??

[czimpel]

Does anyone know why the carburator on the 4.3gs does not use a powervalve? The engine number is 4.3PLKD. I'm working on trying to solve a very fuel thirsty motor, and wondering if not having a powervalve could be a reason for more fuel consumption.

Thanks, Cory

 

[Don S]

Re: 1997 Volvo 4.3 gs No Powervalve??

Yes, it has (or should have) a power valve. Here is a picture of the valve and gasket circled and where it goes.
If missing or damaged, it could cause high fuel consumption.

 

[Fun Times]

Re: 1997 Volvo 4.3 gs No Powervalve??

More then most of the volvos engines run a power valve size 2.5

 

[cr2k]

Re: 1997 Volvo 4.3 gs No Powervalve??

Holley carb shown. If you engine backfires you most likely damaged the power valve.

Holley power valves come in many settings.

the number indicates the in. of vac. at which it will open.

usually you would set and tune engine and put a vacuum gauge on it and see what the vac. is at idle. say it is 10 in. then you would want a power valve that opens slightly lower like 9.5. Or see what the vac. drops to on acceleration and go a little lower.

If you can find a high altitude valve with the right setting it will last a lot longer as they are shielded.

 

[cr2k]

Re: 1997 Volvo 4.3 gs No Powervalve??

Oh yea, A blown power valve dumps raw gas in to the engine causing higher fuel consumption.

 

[Maclin]

Re: 1997 Volvo 4.3 gs No Powervalve??

No power valve or a ruptured one makes it flood after shutdown also, and almost impossible to start after that. They will not hardly idle at all either, way way too rich, it is like trying to run as someone pours gas down the carb. With no powervalve screwed in or a ruptured one the engine would have to be at WOT before it could be able to even try to take in all the extra fuel. Do you have symptoms like that?

Does your carb's metering plate just have the threaded hole for the power valve with nothing threaded into it? Or is there just the depression for the valve with no threads? Not all Holley metering plates have power valve provisioning, some carbs have a secondary metering plate with no powervalve plumbing and just use bigger jets. Or is "something" screwed into the power valve spot? They also make a power valve plug or dummy power valve, it is used so you can use a plumbed metering plate for a non-valve situation and it is almost never used in the primary metering bank.

 

[czimpel]

Re: 1997 Volvo 4.3 gs No Powervalve??

There is a powervalve plumbed into the metering plate, but there is a dummy plug in the opening. I know that this is the way the 4.3gs was configured due to it saying so in my selco manual. What I'm wondering is why is the 4.3gs the only model to not run a powervalve?

Thanks, Cory

 

[Maclin]

Re: 1997 Volvo 4.3 gs No Powervalve??

The jets will be larger size, and it probably has the 50cc accelerator pump chamber as well. At cruise a non-power valve setup has the potential to use more fuel than the power valve setup due to the larger jets. But if an engine is always under load and the power valve does not close then that setup can use more fuel. Automotive apps can save fuel with the power valve setup over the larger jetting. Boats have different fuel curves and that was Holley's way of meeting the spec Volvo supplied.

They used the plug to "convert" a primary metering block to one without a powervalve. This way they would get the idle and accelerator pump circuits of the primary block and not have to have 1 more type of block to make.

Yours is immune to the backfire-killing-the-powervalve problem though, the dummy valve will never blow out and start dumping the fuel from the bowl directly into the intake!

 

[Maclin]

Re: 1997 Volvo 4.3 gs No Powervalve??

You can convert back to the power valve setup, the jets would need to be smaller to work in conjunction with the power valve. Most Holley boat carbs use a 2.5 or 3.5 valve, while stock for automotive out of the box is more like a 6.5 or 8.5. The rating is how much vacuum in HG it takes to keep it closed.

On yours I would leave it at OEM specs, there is engineering behind that configuration.