I'm working overtime to find new issues it seems. I was suspicious of high fuel pressure as I wasn't able to lean out the carb with rod changes in cruise mode. I don't have any other evidence that this is the problem as plugs look ok. I rigged up a temp fuel pressure gauge and got 7.5 psi. Edelbrock states 5.5-6 psi so it is a bit high...no idea if this would be problematic. I got a few options 1) bolt on my spare 30 year old fuel pump (output pressure unknown) and see what happens 2) install a Holley regulator ($100 plus hoses and fittings ) and try and figure out where to mount it while keeping the engine bay looking stock 3) pay $$$ ($320 up here!) and buy a 6 psi Edelbrock carb 4) follow @Bewy advice and lower the float level to 9/16" (found a 2 year old thread on this). I thought the issue was with the needle and seat? Anybody had a problem similar to this?
Edelbrock AVS fuel pressure / Carter M6866 7.5 psi pump
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Icetech
Well-Known Member
My first step would be the old fuel pump and test pressure, it it's 6 or below see if the issue goes away.. that's free and i like free... I use the carter M60514 and it comes in right at 6psi.. i don't trust it at all and i carry a second one in the trunk but so far it's fine (first one made crazy noises and was dropping pressure, it's my spare in the trunk.. it's replacement has been silent and perfect)
The M60514 looks exactly the same.. pressure might be the difference...
I just looked at carters spec sheets and the 60514 is max pressure 7.5 and the 6866 is 7... i came in at 6, so no idea.
Icetech
Well-Known Member
the newer pumps are just crap... i am kicking myself for throwing away my 62 pump.. didn't know there were rebuild kits and didn't know how bad new pumps are.. even the $200 edelbrock pumps have issues
Plymouth 65
I'll be in the shop
Running a fuel pressure regulator is always a good idea. Maybe you can locate it where it's not in plain sight. 65
Sounds like a lot of guesswork to me.. Why spend any money until it is fully diagnosed? Problem may not be fuel at all.
It doesn't respond to carb tuning changes during high vacuum driving / cruising and I know the pressure is too high so it does need to be resolved.
I have found 4 psi is about max for the Carter/Edelbrock AFB/AVS.
I should rephrase,4psi is where I set the regulator for both street and drag cars using the AFB/AVS.
Worked for me !
I picked up a regulator today at the place that sold me the carb. He said the Edelbrock carbs were very sensitive to fuel pressure.
Edelbrock clearly says 5.5 to 6 PSI and you are over that range. That would be the first thing I would correct. Have you thought about running a return line? That would likely drop the pressure right on Edelbrock's recommended range.
Geez I knew somebody would point that out
I had no idea stock pumps put out too much pressure. So much for keeping the engine bay stock looking.
They certainly can. It's like everything else nowadays regarding parts. Nothing is consistent and not all new parts are "good". An unfortunate reality.Geez I knew somebody would point that out
bee1971
Well-Known Member
I have run Factory Carter AVS , Carter Competition Series , Edelbrock 1407 Edelbrock AVS Thunder and now Edelbrock AVS2 with 7PSI from a mechanical fuel pump through a factory 5/16 fuel line with no return for decades and have never had a flooding issue , idle issue , hard starting issue , tuning issue other then the door stop 1407 - Run numerous float levels , up to .110 Needle and Seats
Since when did 7PSI become an issue with an Edelbrock Carb ?
Since when did 7PSI become an issue with an Edelbrock Carb ?
I saw a stock Car Quest pump put out close to 10.Geez I knew somebody would point that out
5# or less for a AFB Tech will recommend 4.5-5.5. Use a regulator if you are having issues.
Post #13 nailed it.
The fuel inlet of Carter & Edel carbs are IDENTICAL. Same n/seat, same float [ although Carter did use different shaped floats in some models ]. The parts can be swapped between brands. Here is the chart AGAIN. If you have 7 psi, that is FINE, & I would reset the floats to 1/2".
You maybe mistaking cruise mode for idle mode [ running rich ]. Depending on a variety of factors, the idle cct provides fuel up to about 60 mph. So changing jets & rods will do NOTHING.
[1] idle vacuum?
[2] idle rpm & timing at idle
[3] how much transfer slot is showing the blades at idle
[4] does removing & plugging the PCV change anything
[5] how rough is the idle
The fuel inlet of Carter & Edel carbs are IDENTICAL. Same n/seat, same float [ although Carter did use different shaped floats in some models ]. The parts can be swapped between brands. Here is the chart AGAIN. If you have 7 psi, that is FINE, & I would reset the floats to 1/2".
You maybe mistaking cruise mode for idle mode [ running rich ]. Depending on a variety of factors, the idle cct provides fuel up to about 60 mph. So changing jets & rods will do NOTHING.
[1] idle vacuum?
[2] idle rpm & timing at idle
[3] how much transfer slot is showing the blades at idle
[4] does removing & plugging the PCV change anything
[5] how rough is the idle
Icetech
Well-Known Member
thanks for posting that, i'm buying a avs2 800 in the next week or 2 and am going to take it apart before using it just to make sure everything is ok, that will be handy
It starts (cold) and runs and drives fine...idles fine at 700 rpm and no part throttle hesitation. If I didn't have an AFR meter I wouldn't know the difference driving around town and freeway. I haven't got into WOT analysis. Getting part throttle AFRs out of the 12s and into the mid 13s is an issue. I'll find out today if I was barking up the wrong tree with the fuel pressure.
The choke housing / upper gasket is very fragile and ripped the first time I took the top off. Its very thin through the middle where the carb stud goes. I bought a pack of 5 yesterday. The tuning kit is essential with any carb IMHO (add $100) although you could run it out of the box and see if you get lucky.thanks for posting that, i'm buying a avs2 800 in the next week or 2 and am going to take it apart before using it just to make sure everything is ok, that will be handy
Icetech
Well-Known Member
yeah, i'm going to get the tuning kit... i have a street demon right now and the tuning kit is $130 for 4 rods and a few jets.. it's insane compared to even the eddy kit. I have already read too many stories bout guys never getting them to work right so i'm just gonna cut losses.. always had good luck with avses
Was hoping to find a used avs2 but none near me cheap.. meh.. they aren't that expensive anyway.
P.S. one weird thing bout the street demon is how hard the secondaries are to open.. really have to stand on the pedal.. i don't recall avs's being that bad
stock float height is 7/16" so something is different between these carbs. The blades are barely open (3/16" idle adjusting screw sticking out) and the mixture screws seem to like it at 1 turn out.
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Lots of people have pressure problems with Edelbtock and Carter carburetors, so it is a problem. Sometimes we forget there are other variables. Altitude, % of ethanol in the fuel not to mention misadjust or defective carburetors. There IS something to this because it is pretty wide spread. Not to mention Edelbrock clearly states the fuel pressure range for these carburetors.
I got the fuel pressure reduced to 5.5 psi. It was still 12.7 AFE at cruise (I call it heavy cruise - approx 3000 rpm I have no tach). There is no combo of jets/rods to lean cruise further so I put in a rod that was supposed to lean the power mode (bigger diameter). It did lean 3000 rpm cruise to mid 13s which makes no sense as at idle the piston is down so it should stay in down in cruise mode and be running off of the larger diameter rod. Lower rpm cruising (2000 rpm?) is still around 12.5 but will never drive in that range much. Idle AFR is high 13s. I can live with this set-up although I might try a different spring to see what happens. I still don't like the idle speed rising when the engine gets hot, hard hot starting and I don't like how hot the fuel filter gets which makes me wonder if that is causing some of the issues. I'm going to replumb it. It’s a long winter here so I've got lots of time.
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A smaller diameter rod is going rich.I got the fuel pressure reduced to 5.5 psi. It was still 12.7 AFE at cruise (I call it heavy cruise - approx 3000 rpm I have no tach). There is no combo of jets/rods to lean cruise further so I put in a rod that was supposed to lean the power mode (small diameter). It did lean 3000 rpm cruise to mid 13s which makes no sense as at idle the piston is down so it should stay in down in cruise mode and be running off of the larger diameter rod. Lower rpm cruising (2000 rpm?) is still around 12.5 but will never drive in that range much. Idle AFR is high 13s. I can live with this set-up although I might try a different spring to see what happens. I still don't like the idle speed rising when the engine gets hot, hard hot starting and I don't like how hot the fuel filter gets which makes me wonder if that is causing some of the issues. I'm going to replumb it. Its a long winter here so I've got lots of time.
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