Carb fuel filters

I'm with Rick on this one. The check valve allows fuel to enter the carb,
and prevents back flow. Of no issue, really, because Quadrajet carbs on
Olds engines with active exhaust crossovers will boil off todays fuel in
the float chamber upon shut down. That, except for the amount that doesn't
leak out the bottom through the leaky BB shot plugs, in the bottom of the
float chamber. California equipped coaches have another (2) charcoal
canister plumbed into the Carb bowl vent to reclaim this venting. Lots more
hoses for little gain.
Jim Hupy
Salem, Or
78 GMC Royale 403 (49 state emissions equipped)

> I think the idea behind the check valve is to keep the carb from draining
> back into the tank when the engine is off. I just can't imagine that it's
> needed in our application--doesn't the mechanical pump already have a check
> valve?
>
> I've bypassed both the carb filter and the mechanical pump, but I have an
> electric pump that gets fuel to the carb when the ignition is on.
>
> Rick "wondering if the change was driven by another application" Denney
>
> On Sun, Dec 17, 2017 at 1:06 PM Scott Nutter

>
> > Still waiting for a answer on check valve/flapper vs non check
> > valve/flapper carb filters on the advantages. Or maybe I missed it in a
> > post?
> > Thanks, Scott.
> > --
> > Scott Nutter
> > 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21
> final
> > drive, Quad bags, tankless water heater, everything Lenzi.
> > Houston, Texas
> >
> > _______________________________________________
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> >
> --
> Rick Denney
> 73 x-Glacier 230 "Jaws"
> Off-list email to rick at rickdenney dot com
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> GMCnet mailing list
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>
 
I also believe it was an anti-drainback check valve. All I know is GM changed to that style on ALL GM vehicles,
in 1976, not just on the GMC. To my know ledge they never went back and suggested that earlier vehicles be
changed to the new style / part number.

It is your choice. Use which ever one that you want. I looked up the spec on that filter and it is 20 micron.

I do not have a recommendation. Thousands of GM vehicles have been using both styles for years and years.
I do not remember which style I put in mine. I just wanted to explain the two different part numbers out there.

Ken B

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Thanks Rick, James, and Ken.
I think I'll go with the non flapper valve filter. I buy in bulk from Amazon, and didn't want to get stuck with the wrong one.
Scott.
--
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi.
Houston, Texas
 
I thought the check valve was for a roll over scenario to ensure that fuel
does not siphon out. I could be wrong.

We all have old chevy mechanics in the family... My father restores
corvettes for the past 40 years and was quick to advise removal of the
check valve as they have been known to fail. All hearsay as far as I know.

> Thanks Rick, James, and Ken.
> I think I'll go with the non flapper valve filter. I buy in bulk from
> Amazon, and didn't want to get stuck with the wrong one.
> Scott.
> --
> Scott Nutter
> 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final
> drive, Quad bags, tankless water heater, everything Lenzi.
> Houston, Texas
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
If you have a rollover you’ve got a lot more to worry about that a tiny amount of fuel from the carb. And where would that fuel go? Back into the fuel line I imagine.

Emery Stora

>
> I thought the check valve was for a roll over scenario to ensure that fuel
> does not siphon out. I could be wrong.
>
> We all have old chevy mechanics in the family... My father restores
> corvettes for the past 40 years and was quick to advise removal of the
> check valve as they have been known to fail. All hearsay as far as I know.
>
>
>

>>
>> Thanks Rick, James, and Ken.
>> I think I'll go with the non flapper valve filter. I buy in bulk from
>> Amazon, and didn't want to get stuck with the wrong one.
>> Scott.
>> --
>> Scott Nutter
>> 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final
>> drive, Quad bags, tankless water heater, everything Lenzi.
>> Houston, Texas
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Scott,

The filter that is in the rubber line that connects the steel line to the fuel pump inlet in Double Trouble is the same one that has
been there for YEARS! I've been taking it out, blowing through it, noting that it is free flowing; put it back in.

Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808

-----Original Message-----
From: Gmclist [mailto:gmclist-bounces] On Behalf Of Scott Nutter
Sent: Monday, December 18, 2017 8:39 AM
To: gmclist
Subject: Re: [GMCnet] Carb fuel filters

Thanks Rick, James, and Ken.
I think I'll go with the non flapper valve filter. I buy in bulk from Amazon, and didn't want to get stuck with the wrong one.
Scott.
 
Thanks Rob,
I can appreciate that.
But if I'm going to pull out the old filter I might as well replace it with a new one. They are cheep enough in bulk from Amazon.
I fave a few here for you.
Scott
--
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi.
Houston, Texas
 
Ken B,
The part numbers on Amazon for the Wix are 33048, and 33052. Just Incase.....
Scott.
--
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi.
Houston, Texas
 
> Ken B,
> The part numbers on Amazon for the Wix are 33048, and 33052. Just Incase.....
> Scott.

WHOA!!! I screwed up in the original posting. I'll go back and correct
that in the original posting. Emailers will not see it because they do not
see corrections or updates. There is nothing I can do for them.

Thanks again for the correction.

Ken B.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana