Engine carb questions (Edelbrock 800 cfm

[Fourateecid]

Hello I used to be on the old caddy board, but like this way better now seeing it. Ok my problem is I have a 472 bored 30 over has 260 miles on it since build. The truck has sat in garage for 4 months. I go to fire it up the dang thing wont idle now! I took carb apart found accel pump on the edelbrock to have a gasket blown out. I replaced that and upgraded the springs for the metering rods to silver springs. Carb is a 800 CFM EPS edelbrock carb. Bolted it on today truck fired right up but I had to give it gas. The thing runs fine above 1900 rpm, once I hit 1900 rpm it goes dead and burps acouple times. Now wtf is wrong with it, could it be the metering rods? I am just confused how sitting 4 months could do this to a carb thats 2 years old. Heck I got all the old treated gas out of system and has new 93 octane. I donno just bout ready to invest into a demon carb. Thanx for reading. Dan

[Modly]

I'm quite satisfied with my Demon, though they do require some learning curve to tune them.

I've never really been a fan of Edelbrock carbs honestly, and I pulled the one that was on the car when I got it off, and replaced it with a Demon.

[Terrible One]

Not sure about the problem, but that sure is a nice looking engine bay. My friend replaced his Old Holley with a Demon and boy was it a mad difference once he finally got it tuned right.

[Dale]

Very nice looking. I'm working on a '66 C-10 with a 500. Would you have any more pics? I'll try and get some of my project up. It's coming along slow but I have had a blast working on it.

[shakedog]

Your Edelbrock carburetor is based on a Carter AFB. I would first do a Google search for "carter afb troubleshooting" or "edelbrock troubleshooting" for whichever carb # you have. You might want to be prepared with a couple of cans of carb cleaner beforehand (i like berrymans B12 chemtool). I'm not really well versed on AFBs, but I dont think they have any vacuum diaphram power valves in them like holleys do that can blow out when you have a backfire.The power valve on a holley gives a fuel enrichment below a certian vacuum (which the demon is based on). I do know this, I would learn all you can about your Edelbrock and keep using it before trying another carb that may not mount up to your manifold. My experience with Holleys has been that while they are easier to tune, they are not as good as the Carter for every day street driving. Heres another thought, you run fine @ 1900 rpm but not below that, so the problem has already shown itself to be in the primary metering circuit or or a related circuit. Ya dig?? Did you turn in the air/idle screws all the way until they bottomed out and scar them up?? If so the shavings off of the screws can find their way into where theyre not supposed to be (like clogging up a tiny jet or metering passage?) Good Luck ~SHAKEDOG~

[shakedog]

http://www.edelbrock.com/automotive/eps_sect1.html#metering

[Fourateecid]

Shake dog I pulled it apart today and blew all the circuts out with compressed air/ used carb cleaner than blew em again. I pulled the idling circut out and blew them out as well no dirt or shavings where found. The weird thing this truck ran perfect than sat those 4 months. After that I had this problem, I had this carb tuned and running like a top and the screws werent screwed all the way in. I double checked that, I donno ive seen the inside of that carb enough that its in my dreams lol.. Well shake thank you for your advice I donno where to go next.. Kinda lose your confidence in yourself and in the carb when weird stuff like this happens. It acts like it runs out of gas and trys to rekick when it goes dead right at 1900 rpm.. I even have the fuel floats adjusted so make sure I have enough fuel... Dan


As for the demon owners what carb cfm are you running?
Engine spec is 472 bored 30 over with a comp magnum cam
224 intake 224 exhaust at .050 Max lift .516 on 1.7 shaft rockers..

Hey Dale e-mail me at [email protected] I got some pictures of my on goin project. Dan

[Modly]

I'm using a Road Demon 725. I had to lean it way out though, so I'm assuming a 625 would probably power it just as well. Though, I guess it's always better to have more power on tap, if needed, than to get something that doesn't give enough..

[Andy V]

when you say you "upgraded" to silver springs, what springs were you running before?

Changing springs is used to tune when the metering rod enrichment occurs, based on the vacuum drop of your cam/engine combo. If it was running like a top before, you need to put those old springs back in before doing much else.
What rod/jet combo you using?

When you say it's falling off at 1900rpm, does it run ok up to 1900, or it runs ok above 1900 and won't run below it ?

I've ran the Edelbrock's on my caddy and had pretty good success. If you're is relatively new there's no need to buy a Demon.

[Fourateecid]

Ok reason i put the silver springs in was remembering back hearing how well these engines perform better to that upgrade on the carb. It had the orange springs.. Ok here is what I do to start it,

Step one: Hit gas 2 times crank it over it burps and trys to start
Step 2: put foot to floor it fires right up, i run it to 2500 and hold it there.
Step3: run to 3 grand time to time no burping popping nothing it runs really smooth.
Step 4: slowly brings it down to 2 grand, and still sounds good
Step 5: hits 1900 acts like loss of fuel tach goes dead engine burps 2 times after tryin to refire on its on.

That is what im dealing with ive had this whole carb apart 3 times now carb cleaned, compressed air ect... I even adjusted the floats to get as much fuel I can in the bowls seeing as it acts like fuel starvation.
This thing ran perfect b4 could have been a tick richer, but I dont see how 4 months non run time did this to a carb thats 2 years old. The idling circut tubes are clear along with every other tube in carb. I really wish I could get this carb to run again. Hell this hurts my ego lol cant get the easiest carb setup to work right again. Dan

[shakedog]

Hey dan.
I would do what Andy says and put the orange spring back. It sounds like you have a problem BELOW 1900 rpm. The spring you changed was in the primary metering rods, right? And you still have a normal mixture at higher rpm. :wink: Couldnt hurt to try.
~SHAKEDOG~

[shakedog]

Looks like the plain (silver) spring needs 8 inches of vacuum and the orange spring needs 5. I think we're on to something here.
"Metering Rod and Step-Up Spring changes can typically be made in less than five minutes and without removing the carburetor. First, loosen the Step-Up Piston Cover Screws (See pg. 30) and twist the Step-Up Piston Cover Plates to the side. The Metering Rods and Step-Up Springs can now be removed and replaced if necessary. Be sure to replace the Step-Up Piston Cover Plate and tighten the Step-Up Piston Cover Screw when finished." Thats from the link I posted above......Let Us peel!!!!!

[Terrible One]

Sounds like it to me. If you don't still have the orange springs, get some more! That is a big difference there between vacuum needs.

[Andy V]

First steps I'd do:

1) replace the orange springs back in. These are the stock calibration.
make sure the metering rods aren't bent or boogered up. Make sure the rod moves up/down in the jet freely before you tighten the hold down plate back on the airhorn.

2) recheck your float settings. with airhorn upside down, should be 7/16" between the float end and gasket surface. Right side up should be 1 1/4" these are important.

3) recheck the idle mixture screws. Gently turn all the way in (bottomed) and then give 2 turns out on each screw for a baseline setting.

It kind of sounds to me like it is flooding out at low rpm's. Like the power circuit is not being shut off and it's not going back to the idle circuit. If the metering rods aren't sucking down into the jet this would happen. Also a stuck float or needle/seat will flood it out. If the needle/seat wasn't right I would think you would have gas coming out all over though.

let us know how you make out

[Fourateecid]

Ok will throw the orange springs back in I got the ones from carb and new orange ones with the setup up kit. Just wanted to know which ones would give me the best. Will check 4th time for the 7/16th setting. Seems to be that everytime i check. Heck I wish it was different lol, than that means I found the prob. Will bottom the screws out, and turn them out like u said. Will do this Saturday when I got time. Damn work takes too much time up lol. Dan

[SMITH29]

Hello I used to be on the old caddy board, but like this way better now seeing it. Ok my problem is I have a 472 bored 30 over has 260 miles on it since build. The truck has sat in garage for 4 months. I go to fire it up the dang thing wont idle now! I took carb apart found accel pump on the edelbrock to have a gasket blown out. I replaced that and upgraded the springs for the metering rods to silver springs. Carb is a 800 CFM EPS edelbrock carb. Bolted it on today truck fired right up but I had to give it gas. The thing runs fine above 1900 rpm, once I hit 1900 rpm it goes dead and burps acouple times. Now * is wrong with it, could it be the metering rods? I am just confused how sitting 4 months could do this to a carb thats 2 years old. Heck I got all the old treated gas out of system and has new 93 octane. I donno just bout ready to invest into a demon carb. Thanx for reading. Dan

xxxx
Sounds like vacuum leak.
You have to have a lot of air going thru the venturis to keep it lit and when you start to close down the carb the vacuum leak leans out the mixture too much and she shuts down.

29

[Haunted Ken]

I have an old AFB on my poncho mill and I discovered that the rods and springs make a HUGE difference- put the old ones back in and then if you want to tune it, get a edelbrock strip kit and change them one at a time, one size at a time. Take note of how the thing runs and then try one size in the opposite direction of the original and take it for test drive and note the changes, working back and forth until optimum tune is found.

Nice thing about the AFBs, is that you can change the rods and springs just by removing the little access plates on top--- at least on mine you can. Beats messing around with a holley, IMO.... :?

H Ken

[shakedog]

Yup. Fourateecid probably has it fixed by now and is out doing smokey burnouts! Beats messing around with a Holley for sure.......

[Fourateecid]

Wish I was doing burnouts lol. Sorry for long time for new response. Ok I did what was posted earlier screw in the screws till they bottom out than out 2 full turns. Than put the new orange springs in, checked my plugs it is not leaning out. The plugs where black, so she is way rich ok clean plugs check gaps 40 thou seeing I got the DUI HEI distributor on it. Ok go to crank it up trys to fire had to floor it and fired right up. Ran at 2500 rpm till it hit 180 on water temp. Let it down easy got to 2000 didn't go dead. I was like woohooo, than got to 1700 I'm like damn maybe its fixed. Than hit 1600 SPLAT dead, followed by a few burps. Soooo now I sit here pulling whats left of my hair out. Funny thing this thing spits fire through the carb, maybe cause I have to floor it to start it. One thing I noticed when I pulled the old orange ones out few weeks back they where burnt... Could the seats be FUBAR? The metering rods seem to be ok, and seat good.. I checked for vac leaks rubbing my hand around back of intake, around heads ect... before it got hot. Didn't feel any sucking sensation. I donno I dont wanna give up on this carb but man that 850 electric choke Speed Demon carb for 400 dollars is looking tempting. :roll:

[DV8]

I just went through something quite similar with my edlebrock - check out your floats to be sure they haven't been swallowing any fuel!

Mine had partially filled themselves through a small (very small) pinhole - I drilled it out, soldered it shut, and went home and ordered a new pair. Problem solved.

My carb had about 100,000 miles on it, so that's not too bad for original floats....

DV8