Another Carburetor question

jbschneeweis

jbschneeweis

Well Known Member
I know this has been asked many times, but here goes again. I am having problems with my Edelbrock AVS Thunder series 1803 carbs. My Edelbrock carbs are gong bad again, this is the 2nd set. My Edelbrock's started messing up again & overload at idle & can't seem to clear them out without revving to 3000 + rpms. Also car doesn't want to idle. This happened a few years ago with the cards & we couldn't figure it out so we just replaced them & everything was ok for one season but now they are doing the same thing. The fuel pressure is set at the recommendation & I have the orange springs on the metering rods. I have run the car about 11 runs & on the return on the last run it lost power & started doing this again. We are checking everything else but it really seems like it is loading up & seems okay if you rev it up to clean it out but it won't idle. If I need to replace the carbs any suggestions, don't want the same thing to happen again, Thanks.

Joel
 
MRHP

MRHP

 
Supporting Member 1
Fuel pressure needs to be 5-5.5 max I have found. Also verify float settings. I run my floats a touch low. Other than that I have never had any issues with mine. Maybe some trash in the needle and seat.
 
4

427John

Well Known Member
AFB type carbs are a little harder to adjust fuel bowl level but easier to verify actual level,just shut it off when it is acting up and pull the tops off the fuel bowl level is there for you to see along with any floats that may be sinking.That will tell you right off if thats the cause of your idle issues,once you have verified that then its just a matter of determining if the problem is sinking floats,trash in the needle and seats,or excessive fuel pressure.It doesn't take much excess level to cause idle issues.
 
jbschneeweis

jbschneeweis

Well Known Member
Thanks. We have checked all the basic stuff to ensure that nothing had happened to the engine during the races when the carbs seemed to have the problem. All engine stuff checked out okay. Still doesn't want to idle & has backfired through the carbs. Going to check the electronics & distributor tomorrow, think that might be it instead of the carbs. We will see what happens with that before digging into the carbs. Thanks again.

Joel
 
Jim Sullivan

Jim Sullivan

Well Known Member
Supporting Member 10
jbschneeweis said:
Thanks. We have checked all the basic stuff to ensure that nothing had happened to the engine during the races when the carbs seemed to have the problem. All engine stuff checked out okay. Still doesn't want to idle & has backfired through the carbs. Going to check the electronics & distributor tomorrow, think that might be it instead of the carbs. We will see what happens with that before digging into the carbs. Thanks again.

Joel
Click to expand...
Joel, you probably have electronic ignition of some sort, but I'm just remembering several years ago I had an issue with a bad condenser on my Mallory dual point distributor that caused a poor or no idle and hard starting when hot. I can't remember if there was any back firing.
 
skipxt4

skipxt4

Well Seasoned Member
Supporting Member 18
I remember, back in the 60's, my 64 started backfiring occasionally.:rolleyesChanged plugs, wires Dist. Cap. points etc. Didn't really cure the problem.:dunno Found out a while later, a few cam lobes were going south.:eek3
 
425/409ER

425/409ER

Well Known Member
I am not sure with what goes on with the Eddy carbs either. I had a 1405 that I super tuned and that 600 on my 350 was better than any small carb I have ever used, but after sitting out the winter (fuel bowls drained too) the next spring it ran like crap on the primary side so I gave up on it and I put a Holley 750 VS street HP carb on the car. Once it's warm the car idles and run great. We had some of the same issues you did when we ran a dual quad setup on the SB. There were times when it ran good and then it would idle like crap, that was with the Eddy 500's. I am real hesitant to put the dual quads on the 409 but I have 2 300hp 327 Carters to use, one is brand new. I will wait until after the big car show to change them, but ya I feel you pain with the Eddy stuff, I have had some bad experiences with Edelbrock in the past. Their reps at the car shows hate me.
 
jbschneeweis

jbschneeweis

Well Known Member
Well we got it running. The major problem was electronic, a problem with the distributor & pickup. New cap, rotor & wires. Runs better but still has a load up problem at idle. We will be going over the carbs next week(guy who does my work is racing this weekend). We will check float levels, fuel pressure, jetting & metering rods. I am currently using the orange springs for the metering rods. We are thinking of changing those to a lighter spring(any suggestions?). I usually don't drive the car on the street. Mostly drag racing but it loads up sitting in the staging lanes & have to clear it out before it will run. The person who works on the car wants me to switch to a single 4 barrel, believes my problems would go away & times would be better & more consistent. I'm kind of old school & really like the 2 x 4 setup. Thanks for all your help & any additional suggestions would be appreciated.

Joel
 
blkblk63ss

blkblk63ss

Well Seasoned Member
Supporting Member 5
You can loosen the screws on metering rod covers while it is running and see if the rods are all the way down . At idle should be down if vacuum is good . Spring rate important also .When you accelerate they will pop up. Push down on them at idle to see if that is your problem and are indeed all the way down and see if it improves idle. If that's ok then further carb teardown required. A little trash can mess up needle and seat, see if bowls have trash in them. Leaky floats, improper setting on float . Leaking gasket under carbs. Also make sure the back barrels are fully seated at idle on both carburetors. I never liked dual 4's ,double trouble, three duce's, triple trouble. My opinion and sticking to it!!!!:D
 
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D

Don Jacks

Well Seasoned Member
Supporting Member 3
There are kits out now that let you convert to throttle body efi,then you wouldn't have to constantly putting up with this :furious
 
dm62409

dm62409

Well Known Member
Supporting Member 12
As blkblk63ss has said , check for trash in the needle & seats, and proper float levels, test metering rods running as he said. My guess is if you have a bigger cam than stock, you will have less vacuum at idle to hold down the metering rods. So installing a little lighter spring should help keep the rods seated at idle. I think the yellow spring is the next lighter one from the orange. Don't give up on your 2x4s.
 
La Hot Rods

La Hot Rods

Well Seasoned Member
Supporting Member 15
When you get it set and idling well at home, when you go to a track away from home I always have to re adjust for idle for the change in weather/ climate. This will help for loading up problems at different track.
 
jbschneeweis

jbschneeweis

Well Known Member
Well I believe we got the problem solved. The magnetic pickup in the distributor was bad. Replaced it and everything seems ok. Replaced the spark plug wires, distributor cap & rotor. Went through the carbs & checked the floats, etc. replaced the orange springs with the yellow ones & put in larger metering rods for the SLC area. Cars seems to be running good & now idles. Going to Woodburn this weekend for their Oldies Event, hopefully it will run good. Will put in smaller metering rods for sea level racing & hope for the best. Last time at Woodburn was not good. Will meet up with Paul & a few other 409's for a great weekend. If everything goes okay will see you all in Earlville in about 3 weeks. Take care.

Joel
 
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