BrainDrainin

I have a stock sbc in my c3 with a weiland intake and edelbrock 1405 carb. My issue is a idle of 1000rpms with my idle screw not touch anything (backed all the way out). fast idle cam is not interfering choke is disconected with plate open. I have sprayed carb cleaner all around and I can not find a noticeable rise in idle or smoothing. Iv plugged all ports and disconnected brake booster for testing. I can check initial timing but total advance timing was set to 34• mech advance, usually just let initial fall where it does after but I'd guess around 12•. New plugs, wires and dist. Car revs fine, pops out of the open headers slightly at around 2000rpms/ mid throttle. Here's what leads me to think it's carb... when I close the choke it dies.... wouldn't a vacuum leak make it stay running. Idle mixture screw change the idke but make it run rough if to tight and if out rises the idle more. I start at two full turns out... Any ideas? Thank you for taking the time to read my long winded post.

Hammerhead Fred

You'll get better feedback if you include year model.
Type ignition; elec or points

TOM B1

A few things to check.
Is it getting to much fuel at idle, maybe a metering rod is sticking, when idling the rods are fully in there seats, if sticking up just a bit then you have a high idle, Ethanol does this a lot.
Are the secondary throttle plates open a little.

Vacuum leaks:
Spray slowly around the carb base and then at the vacuum ports on the carb. then the manifold to head joints. then spray the manifold end seals in the front and rear.
If nothing is found then plug all vacuum ports on carb and manifold. , this is the best way because vetts have vacuum for just about everything, or
Check that the vacuum advance pod on the distributor is not leaking, this is a very common leak. also check that this line is to a ported vacuum at the carb.
If you have a automatic check the vacuum line to the trany, another common leak.
Check the power brake booster for leaks, if you push on the brake peddle and the engine revs up or down then you have a leak or plug it and see if the idle returns to normal.

The13Bats

I had a lot of issues with the edelbrock carb i ran on both my 383 the 454, it seems all webers are extra bad about trash and funk in them, im glad its too small, good excuse to buy a holley 3310 or a modern ripped clone of it,

But the edelbrock isnt a bad carb at all,
while there are different things that could be giving you those issues if it were me i would rebuild that carb, i got where i could rebuild mine super fast, might be some trash in something my veedub trike did that and a carb rebuild fixed it right up...

BrainDrainin

The year is 75, has a stock 350, 4spd, HEI. i put a new short block in last year and it has always idled a little high. The manifold that came with the old motor was an offy that was alumi welded twice ( by PO) and still leaking some coolant. It was idling 800rpms with screw all the way out. I replaced the manifold thinking leak somewhere and it was beat, gasket material on both sides of the intake gasket and front and year rubber gasket. Iv sprayed all those spots with carb cleaner but will try again to see if I missed something. Last week I soacked the carb disassembled l and rebuilt it, now idling is 1000rpms no less. I cleaned both metering rods and even took them back out again made sure the spring up and Down smooth. opened the top half to see if any floats were stuck or height was messed up when it was reassemble. Put all back together, no change...

BrainDrainin

If there was a good vacuum leak, would closing the choke plate be able to still stall the car? Iv also adjusted my butterflies twice, they don't hang up and are as sealed as possible. When I push the secondary with a screw driver while running it feels seated well and has no effect. iv disconected all the vacuum hoses for now so I can isolate the source or sources?? All plugged with good caps

Jebbysan

Not if the leak is coming from the bottom of the intake at the heads......you also would get no change in idle from spraying.....

First, pull the carb and make sure the primary plates are closed and sealed when released......
Next....reseal the intake.....I do a lot of them in my shop for a multitude of reasons....one to clean the intake and detail, two to block the heat riser....and three to make sure it is sealed. I always use ARP stainless intake bolts as well (they look better longer, and the 12 pt is much easier to wrench in tight places).

Jebby

BrainDrainin

Thank you for all the feedback and help! Is the stock felpro intake ok for aftermarket intake? All the holes were the same and lined up fine. Iv done the intake twice now, second time I made sure to permatex both side of the gasket. Do you think it would be helpful to spray wd-40 or carb cleaner into the valve cover? I haven't tried that yet because I wasn't sure about carb clean on my rockers and springs? Thanks again all the advice almost immediately after posting! What a great community

BrainDrainin

i made sure bitterflies close completely and throttle cable is not holding anything up, makes no difference connected or not.

Im thinking your dead on and I have a leak. Would you recommend trying to spray carb cleaner or wd into valve covers?

Jebbysan

Use a 1204 Fel Pro gasket.
Do not spray anything into the engine......
Just reseal it......I can do one in about 1 1/2 hours. Then you know it is done.....you will see oil witness marks where oil is trying to get into the ports and even oil in the ports....if it is leaking.

Jebby

BrainDrainin

understood, your right it doesn't take long and is worth it to be sure. Just for curiosity Il check what model gasket I used before. Thanks for all the help and tips Jebby

whats a good product to remove gaskets. I usually use a 3m plastic brush for my mini angle grinder but it's to aggressive for aluminum intakes, works great on the heads.

BrainDrainin

I should say gasket material actually, more the rtv sealant that's left from removing the gasket

Jebbysan

Use the white Roloc bristle.....it was designed for aluminum...more specifically for Dodge Neon 100% failure rate head gasket repair!
Yes...3M developed it for Chrysler in 2000!

Jebby

BrainDrainin

Jebby your a cool cat😎, thanks for the help. I have the yellow Roloc. Guessing the white is softer, Il let you know how I make out.

RATT7

I had a similar problem with my edelbrock, I checked everything possible and in the end, I removed the idle mixture screws, sprayed carb cleaner down the mixture screw hole and then applied some compressed air to blow out the idle circuit. This worked and the carb was able to idle fine with the idle mixture screws turned out about 1.5 turns.

BrainDrainin

il give it a shot, when I rebuilt the carb I had the screws out but never shot compressed air into there. Il give it a shot

TOM B1

I would not use the rubber or cork manifold end seals.
I wish they would not supply them with a kit as they always leak.
Just put down a 1/4 inch bead across the whole lip up into the gasket tab, let it dry 20 minutes then apply a very thin bead to the lips of the manifold and assemble immediately.

BLUE1972

If you can use a straight edge on the manifold and head to see if there is any dip or bump.

BrainDrainin

iv been told that before and I think it's time to stop being thick headed and listen to more experienced folks

-sinner-

Someone above said it, but I'll second it: these Edelbrock carbs are prone to getting trash in the lines and doing funky things. I used canned air and other methods to clear one on my 72 C10 Chevy truck that I ran out of gas. I rebuilt the carb (super easy, they are very simple) and still ran wonky. It took compressed air from the big compressor at around 80 psi to clear the carb. Once I did that, it ran perfectly. Take out one mixture screw at a time, pull the metering rod and spring on that side, and blow it out really well. Do it a few times. Disconnect your fuel line in and blow air in from there as well. Put the mix screw back in, turn it all the way down until it bottoms out lightly, then back it out about one-and-a-half turns. Put the metering rod/spring assembly back in and lock the plate down. Do the same to the other side, and remember to come at it from the mixture screw's location AND the fuel inlet at the back. It really took a lot more pressure than I thought was even safe for the carb. Put it all back together and prime it with a little fuel, then give it a shot.

The Edelbrock was new to me, but I was impressed with how simple it was, and how it ran pretty damn well straight out of the box. I had resisted doing much to it because I didn't want to spend two hours with a vacuum gauge and a timing light dialing the carb back in after a rebuild. It was a real shock when I just screwed the two mix screws in and backed them out the same amount, then fired it right up and it ran very well. I tried adjusting mix/idle some more, but it was optimized at the settings I dialed in with the car turned off! I might even replace the Holley on my 454 in the 69 Vette with one, the next time the carb needs service.

G'luck!