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Which Carburetor Fuel Filter 'Rochester 4 Barrel'?
Owner's manual states to use AC Delco GF471F. Unknown if the carburetor fuel filter has a 'check valve'. Cannot readily acquire that information at the moment. Quadrajet.com lists two applicable filters: 1.) 2253 Without Check Valve and 2.) 2253 with Check Valve. I've always replaced the Carburetor fuel filter and never paid any attention as to the properties. This is what a PC has done to me.
* From Rochester or Quadrajet.com:
Stock replacement paper fuel filter element is located in carburetors fuel inlet housing. Built in check valve prevents fuel from draining back out of carburetor when engine is turned off.
Note:
Check valve filters do offer more restriction to high RPM fuel flow than non-check valve filters. For performance applications we recommend 2253 (No Check Valve Filter) or if you really want the check valve with higher fuel flow, you can pull out the check valve from the filter end and carefully pull bottom end of spring out of check valve and snipe a few coils off end of spring, then push end of spring back into the valve.
Vehicle: 1986 Oldsmobile Cutlass Supreme Brougham 307 C.I. Vin Y > Rochester 4 Barrel
A.) Should I use the filter with or without check valve?
B.) The Fram CG3389 has no mention as to whether a 'check valve' is part of the fuel filter. Again, cannot acquire the information at the moment.
Enclosed are some pictures. Any and all information relating to the above is most appreciated.
x2 What olds 307 and 403 stated. I just recently went through this as a matter of fact. I replaced the fuel filter when I purchased the vehicle last year - not knowing there was any difference. Then, about 2 months ago I rebuilt my Quad 4 bbl w/ a kit I purchased from Cliff Rugels. No biggie, the kit was fine, contained all the right stuff, etc. I noticed the kit contained a different fuel filter than the one I replaced. Cliff's filter did not contain the check valve - which at the time I did the rebuild I still didn't know what that little rubber valve thing was for. I thought to myself though, well, it's probably newer than the one I put in a year ago, so I'll go w/ the one in the kit. And, sure enough. When I start the vehicle first thing in the morning, when choke is engaged, it fires up in 3 seconds - no pumping required. But, the big issue is every start throughout the day when there is no choke being applied. That little check valve does keep the fuel from returning and keeps the fuel in the carburetor. I have to crank the engine longer to get fuel flow back into the carburetor without that little bitty check valve in the fuel filter. It's been a couple weeks now and it's annoying me so I'm going to grab another filter with the check valve in it. Lesson learned for me.
Buy the filter with the check valve. If you want to experiment, just pull the valve out of the filter, and shazzam, you've got a no-check-valve filter to try.
x2 What olds 307 and 403 stated. I just recently went through this as a matter of fact. I replaced the fuel filter when I purchased the vehicle last year - not knowing there was any difference. Then, about 2 months ago I rebuilt my Quad 4 bbl w/ a kit I purchased from Cliff Rugels. No biggie, the kit was fine, contained all the right stuff, etc. I noticed the kit contained a different fuel filter than the one I replaced. Cliff's filter did not contain the check valve - which at the time I did the rebuild I still didn't know what that little rubber valve thing was for. I thought to myself though, well, it's probably newer than the one I put in a year ago, so I'll go w/ the one in the kit. And, sure enough. When I start the vehicle first thing in the morning, when choke is engaged, it fires up in 3 seconds - no pumping required. But, the big issue is every start throughout the day when there is no choke being applied. That little check valve does keep the fuel from returning and keeps the fuel in the carburetor. I have to crank the engine longer to get fuel flow back into the carburetor without that little bitty check valve in the fuel filter. It's been a couple weeks now and it's annoying me so I'm going to grab another filter with the check valve in it. Lesson learned for me.
* Thanks very much. So, is the check valve that 'rubber' insert at the carb end? I will certainly take your advice. Really never paid any attention to a fuel filter before until I started researching filters. Every part seems hard to find or come by as the car gets older, even a small part.
Buy the filter with the check valve. If you want to experiment, just pull the valve out of the filter, and shazzam, you've got a no-check-valve filter to try.
* Thanks, much appreciated. No experimentation planned, just replace what was previously there. I've replaced the fuel filter prior and never really noticed any detriment to the fuel filter. Is there any benefit for replacing the fuel filter? The filter has not been changed in about 10 years or more and the car runs fine. As a preventative measure, should I just switch it out or let it sit?
As stated parts are getting harder to find...buy a couple of quality check valve filters and keep on hand. Completely agree with using OE style check valve filters. That carb should use the nylon seal on the end of the inlet nut, get a couple extra of those also.
About not changing the filter now, if the mileage is under about 10-15k in that time I wouldn't be concerned. It's a balance between changing it often and disturbing the inlet threads on the carb.
As stated parts are getting harder to find...buy a couple of quality check valve filters and keep on hand. Completely agree with using OE style check valve filters. That carb should use the nylon seal on the end of the inlet nut, get a couple extra of those also.
About not changing the filter now, if the mileage is under about 10-15k in that time I wouldn't be concerned. It's a balance between changing it often and disturbing the inlet threads on the carb.
Good luck!!!
* Thanks very much. Certainly, disturbing the inlet threads are a concern of some. However, the threads on my inlet are excellent; very careful with them all the time. The fuel line is treated in the same manner. Preventative maintenance has always been something I've set in place. I believe that the filter was not changed for over ten years, maybe 30,000 miles in that time. Upon removal, I noticed some areas of dirt clogging the channels, maybe two: dark lines. I tried to capture with a camera but it was somewhat difficult. * Those 'nylon' seals I've been searching for. Where can I find them, as well as the spring? I did not even remove the spring, as being left in the inlet with the nylon gasket. I've never replaced the nylon gasket (seal) in 33 years, as well as the spring.
* Seems to be a touch smoother, and seems to have slightly better response. The four barrel certainly kicks in in overdrive. Thanks very much for the input you provided.
I was told the check valve was to keep carb from dumping out say in a roll over. It was a late 70’s change It goes at the fuel line end.
* Common sense where the the Check Valve end goes. The statement you make could possibly be factual. However, I've never heard of that, "the check valve was to keep carb from dumping out say in a roll over". Thanks very much.
The springs & the two sizes of gaskets are available on the link of your first post. Go to the URL link, click on the Spring link &/or the gasket links.
The springs & the two sizes of gaskets are available on the link of your first post. Go to the URL link, click on the Spring link &/or the gasket links.
I was told the check valve was to keep carb from dumping out say in a roll over. It was a late 70’s change It goes at the fuel line end.
The check valve prevents fuel flow from the carb back towards the fuel pump, but freely allows fuel to flow from the fuel pump to the carb, It would not stop fuel from flowing through the system from the pump to the carb in a rollover (or any other) situation.
For higher horse applications I toss the check valve. It causes fuel starvation at the upper end. I know this first hand. I fought nose over for a few years. Once I yanked the ck valve, nose over fuel starvation GONE.
Could be why Cliff uses the checkless.
Any time after the initial start in the morning I tap the key and it starts like an injected car. It can sit for a week with the same results (if the choke is set).
I prefer the non-instant startup for the first start after its been sitting for a month. Prevents dry starts. I let the engine crank 10-15 secs until I see oil 40 psi. Push the gas once fires right up.
Just one man's opinion.
For higher horse applications I toss the check valve. It causes fuel starvation at the upper end. I know this first hand. I fought nose over for a few years. Once I yanked the ck valve, nose over fuel starvation GONE.
Could be why Cliff uses the checkless.
Any time after the initial start in the morning I tap the key and it starts like an injected car. It can sit for a week with the same results (if the choke is set).
I prefer the non-instant startup for the first start after its been sitting for a month. Prevents dry starts. I let the engine crank 10-15 secs until I see oil 40 psi. Push the gas once fires right up.
Just one man's opinion.
I'm glad you posted this. I had the same experience over the years (70s to 90s) with Hi-Po applications but thought since the original poster had a stock G-body the performance issues didn't apply. It's good to get the information out there for others, though.
I'm glad you posted this. I had the same experience over the years (70s to 90s) with Hi-Po applications but thought since the original poster had a stock G-body the performance issues didn't apply. It's good to get the information out there for others, though.
* You are correct, it does not apply to my motor (7A Cylinder heads, swirl port heads- (1.30 x 1.30). It is a low compression motor, no need to run open. Love those rollers though, more so than flat tappets.
Last edited by synoptic12; June 23rd, 2019 at 09:59 PM.
This is simply a thread update for posters who need to determine the correct orientation of the fuel-filter & spring on the Rochester Quadrajet 4MC. This information is taken from the 1971 CSM. It would appear to me, based upon the image contained w/in the 1971 CSM for the Rochester Quadrajet Model 4MC, the check-valve orientation is depicted on the left-hand side of the fuel filter image. Again, it appears that way to me. This is the orientation of the fuel filter I employ w/ the check valve. Regardless if there is or there is not a check-valve in this image, the correct orientation of the spring and fuel filter remains the same as depicted in the image.
Appears the check-valve is oriented to the left in the image. Appears the check-valve is oriented to the left in the image.
Don't remove the check valve. It provides two very important functions:
1) It prevents drainback of fuel from the carb bowl.
2) More importantly, it is designed to prevent fuel leakage in case of a roll over accident.
Read this on is on another forum, that’s what my mechanic said about the check valve. Roll over.
2) More importantly, it is designed to prevent fuel leakage in case of a roll over accident.
Read this on is on another forum, that’s what my mechanic said about the check valve. Roll over.
Please explain how that would work. What fuel would be prevented from leaking, and from where?
Here's how I see it:
The check valve prevents fuel from flowing from the carb back towards the fuel pump.
So in a rollover, fuel could not flow from the carb back towards the fuel pump.
But the two ounces of fuel in the float bowl could drain out of the vent in the air horn.
Any fuel coming from the fuel pump would flow freely through the filter/check valve towards the carb, then drain out the air horn vent.
So again, how does that check valve prevent fuel leakage in a rollover? I just don't see it.
June 22nd, 2019, 10:07 PM
Which Carburetor Fuel Filter 'Rochester 4 Barrel'?
