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Posted by: 415PB Feb 4 2004, 06:48 PM

I got off from work early today and thought I would finish up my alluminum sunvisor mounts, I was wrong. I picked up an extra decel valve and decided to open it up. I plugged mine because It was all jacked up. I know most dont use their decel valve anymore, but thought if nobody had opened one up and posted it here before, this might help the ones that still have them.


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Posted by: 415PB Feb 4 2004, 06:49 PM

In pieces:


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Posted by: 415PB Feb 4 2004, 06:49 PM

Diaphram was in good shape considering it is 30 years old.


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Posted by: 415PB Feb 4 2004, 06:50 PM

Top portion with the adjustment tube


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Posted by: 415PB Feb 4 2004, 06:51 PM

and back together again after a really good cleaning, some crimping and JB Weld.


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Posted by: Brad Roberts Feb 4 2004, 06:56 PM

See how far you can throw it.

Just kidding. Interesting that they used a diaphram almost identical to a carb accelerator pump diaphram.


B

Posted by: 415PB Feb 4 2004, 06:58 PM

I almost did Brad. Figured I didn't need the damn thing, why not screw it all up by taking it apart.

Posted by: ! Feb 4 2004, 06:59 PM

Yah,.....give it the "float test"......

Posted by: busaslidr Feb 4 2004, 10:07 PM

Why would one want to remove the decel valve, for what purpose???

Posted by: swood Feb 4 2004, 10:30 PM

Is that an early decel valve? Mine on the '75 was more of a flattish disk kinda thing.

Posted by: 72914S Feb 5 2004, 11:22 AM

Decel valve? I thought that was for fuel pressure, at least thats where I adjusted mine.

Posted by: Dave_Darling Feb 5 2004, 11:49 AM

That is a decel valve, the FPR is similar. The 1.8 FPR has three fittings on it (fuel in, fuel out, manifold vacuum) and is not adjustable; the 1.7 and 2.0 FPR has two fittings (fuel in, fuel out) and is adjustable. The adjustment on the DV looks like the one on the FPR, but the fitting is much bigger on the FPR.

The 1.8s (except possibly some very early ones) had the flat disk skaped DV. The one shown here is a 1.7 or 2.0 one. (Or maybe that early 1.8.) The DV got hard to find a while back, so it is possible that the 1.8 one was retrofitted to other systems. I think the 1.8 version was still available for a good while longer because of its use in the Bus engines.

--DD

Posted by: busaslidr Feb 6 2004, 12:27 PM

So what does a decel valve do??

Posted by: ! Feb 6 2004, 12:47 PM

Keeps the throttle from slapping shut too fast, leaving unburned fuel in the system....aka "smog shit"....

Posted by: swood Feb 6 2004, 06:49 PM

So is it better to have than not have?

Posted by: airsix Feb 6 2004, 07:17 PM

It momentarily bleeds air into the intake when you snap the throttle shut. This reduces emissions but also makes the rpm's fall SLOWLY when you close the throttle. The only benefit to drivability is it keeps the rpms from dipping below idle speed when you snap the throttle shut quickly. The downside is this makes shifting slower, and adds more work/wear to the tranny syncros (IMHO).

Some take their decel valve off and throw them away. Personally I think that's the wrong approach. You should take it off and hit it with the biggest hammer you can find. Then throw it away.

-Ben M.

Posted by: swood Feb 6 2004, 07:34 PM

Well put!