Edelbrock Carb Help
 

I got a question for you guys anyone good with tuning a carburetor?

I need some help for sure. :lol: alright so I know I'm going from manual choke to electric so a few things are different but I know I don't have to pump the gas anymore or most of the time.

When it cranks up the idle shoots up to about 1,500rpm I usually let it sit there a couple of seconds and then tap the gas and it will idle down to around 500-750rpm, and I guess sometimes because it hasn't warmed up fully sometimes it'll die. Also if I let it just idle there for a little while say 5-7 minutes then I kill it, try to crank it back over it's like it doesn't fire right away but when it starts it's on all 8, is that just a way the electric choke works or do I need to do some tweaking? It runs and performs waaaay better just trying to start understanding it a little better.

Re: Edelbrock Carb Help
 

Mine did the same thing. One thing that I did notice on the old build was that one of my throttle return springs had fallen off, so I was only running on one spring. The accelerator would basically be on the floor and I'd either have to pull it back up with my toe or a quick tromp on the pedal to get it back to idle. Also, the throttle cable was a little sticky due to the PO twisting it to get it back on the linkage, so the cable was a little bit bigger (kind of like untwisting a rope, if that makes sense). I know there are two screws on the throttle linkage, one for idle and one for high idle, I had to bring up the idle. I'd check these few things first.

When I rebuilt mine last week, I put everything back exactly the way it was except hooking up the second spring and the straightening the cable back out and the it was sooo much better at idle. As far as the choke, you can loosen the three screws and rotate the choke to lean/richen the mix. Maybe it's too rich? I'm new to these carbs to, so I'd be interested in any other ideas.

Re: Edelbrock Carb Help
 

Yeah that's my belief is that it's getting too much fuel especially with a harder crank. I went and bought new return springs and everything. I even had to buy a shorter cable due to fact the old one was too long and needed one shorter cause it was so tight. It's still a tight but it's not where I have to mash it I do have to put a little effort into it.

I'm not too sure I want to mess with the choke just yet but I have a feeling that, that might solve the issue overall cause I know from a cold start it's going to take a little ump to get it going but from a warm start should crank and I'm thinking either it's not getting enough to make it an easy start or it's getting to much for a hard start.

Hopefully we can get our answer I know there's knowledge on here if I figure it out on my own I'll let you know.

Re: Edelbrock Carb Help
 

With the engine cold, and on a cool day (not freezing cold)---The fall days are the best for this. With the air cleaner off of the carb, loosen the three screws on the choke housing and turn it back and forth, while doing this watch the choke butterflies and see what would make them start to move off of full open position. This should be close to where the choke should set itself and close for a cold start. Set the screws and work from there. When the choke is set, there is an idle screw on the drivers side of the carb (under the throttle shaft) adjust it to the RPM that you want the truck to run when it is cold. The adjustments from there can be made in small increments until you are happy. You do not want the choke plates to stay closed for a long time, that is where you get the rich smell from.

Re: Edelbrock Carb Help
 

Okay could that also be part of the problem of after letting it run for a good amount of time if the choke isn't open all the way cause the a harder warm start?

Re: Edelbrock Carb Help
 

Excuse me for butting in, but my Edelbrock Carb (size Unknown) Is doing the same thing I think, plus every time I shut off my truck it smells like a gas station just poured gas all over my truck. I can't find any leaks either, so Is that the choke closing after I turn off the key and draining fuel into the carb.?

Re: Edelbrock Carb Help
 

Sounds like you've got two issues just as piecesparts says. Too much choke and too high of a on-choke idle. You may also want to use a vacuum gauge to set the off-choke mixture to ensure warm idle fuel (with no choke) is correct.

Re: Edelbrock Carb Help
 

No fuel should drain from the carb at any time. If it does, you have a stuck float and/or leaks (internal leaks are harder to spot). The choke is only a metal flap that closes to restrict air going into the engine, it will not act on the fuel directly speaking.

Re: Edelbrock Carb Help
 

Well I just figured out an issue that I did that might fix all of my problems, I didn't put the right hose on the right vacuum so could that be causing issues?

Because my distributor vacuum isn;t connected to the right port, and my manifold vacuum isn't in the right port either, could that solve all my issues?

Along with the choke issue.

Re: Edelbrock Carb Help
 

:agree:

Mine was flooding bad last week, and I ended up rebuilding the carb. It was ~$45 for the kit, and had it off, repaired, and back on in an hour or two.

Shark:
As far as vacuum lines, what do you have/how are they hooked up? Here is what mine looks like:

http://i234.photobucket.com/albums/e...psf0cc9433.jpg

Passenger side goes to the distributor, driver side goes up to the deal above and to the left of the brake booster. Center goes over to the driver side valve cover, and the back orifice connects to the brake booster.

Since the rebuild mine runs better than it ever has!

Re: Edelbrock Carb Help
 

Yeah I think I have my manifold vacuum connected to the timed vacuum port and the manifold vacuum port blocked off. So I pretty much just have it all switched up. When I started watching more youtube videos today from Edelbrock and the more I watched the more I realized I was missing something. :lol:

Re: Edelbrock Carb Help
 

You do not have to connect the manifold vacuum to the ports on the carb to get vacuum to the distributor. The carb is the source of the vacuum to the dizzy, through orifices built into the carb body. You just have to pick either the timed port or the open port as to how fast you get vacuum to the dizzy dash pot. The adjustment of the idle screws using a vacuum gauge is the most efficient way of setting the fuel mixtures. When you connect the gauge, all you have to do is connect it to the intake manifold at a vacuum source and adjust the screws to get the right idle mixture and speed settings. My truck is connected to the open port and not the timed port due to my setup on my distributor springs and weights. If you are mostly stock, then the timed port is what you want. Cap off theother port if you are not using it for something.

The Edelbrock and the Carter AFB model carbs are EXACTLY the same carbs, with the same parts, just using different part numbers to make it look like they built them in different factories. Parts from one brand works in the other. They are built by a company called Magnetti-Marelli.

Set the idle first with the vacuum gauge and then wait for a cool evening or morning to get the choke spring to cool and set the choke plate for actuation when you push the throttle pedal down one time. Make sure that your electrical wire to the choke is on a ignition triggered power source, so that it starts to heat the choke spring when you turn the key on.

I set my idle speed, when it is on the choke about 1200 RPM and that is when it is on the high cam point of the choke rod cam. (the cam is on the driver's side of the carb down low and the idle speed screw sets against it) That way if it is not too cold, then it hits and idles at an RPM just a little lower than that.

If you have run your engine for a good amount of time and the electric wire to the carb is on at all times while the ignition is on, then the choke should be open. After you turn it off, it will take a while to start to go in the closed direction as the spring inside cools. If you do not push on the throttle or move the throttle in any way, after you turn the engine off, the choke plate will stay open due to the set screw sitting against the cam lobe on the side of the carb. When you push the throttle back, then the spring will snap the choke plate towards the closed direction.

Re: Edelbrock Carb Help
 

Good info Frank, I probably need to tune mine a little better following your instructions above, mine seems awfully rich at idle. Thanks for taking the time to spell that out for us!

Re: Edelbrock Carb Help
 

Okay thanks pieceparts!

Well upon further and further reading and watching of youtube it seems to actually all be in the timing, being that I was basing it off the original way doesn't always work correctly so I'm going to be search either tonight or tomorrow whenever I have free time. I'm going to see about setting the timing to the correct timing.

The only bad thing about trying to do it on a cool morning is with Texas weather that's so unpredictable so it'll hard to be do it on a cool morning or evening.

Thank you everyone for all the help and advice you've given me I greatly appreciate it.

Re: Edelbrock Carb Help
 

If you are not using the thicker insulator between the carb and the manifold, I have hear that will give you the hard starting issues when it is hot. WE did a couple trucks down here and they were fine until you tried to restart it hot. Once we put in the thicker isolator, problem went away.

Re: Edelbrock Carb Help
 

Thanks Palf70Step going to have to keep that in mind incase it continues once I get the timing set correctly.

Re: Edelbrock Carb Help
 

So the truck is running beautifully and better than EVER!!! The PO apparently had no idea what they were doing it was ridiculous they were 1 tooth counterclockwise off and they were running at least 20 degrees advance is what we guess they also had scratched into the balancer what they thought might have been the correct line, so that's solved so the truck just loves sitting at 0 tdc so that's what we're going to stay with tomorrow if I can I'll get some test runs in

Re: Edelbrock Carb Help
 

I have the same carb as you (1406), How hard is it to rebuild? I'm a novice but I'm willing to try. I also need to do something about oil leaking out of the Intake Manifold bolts, They loosen up all the time which lets oil seep out onto the aluminum intake not bad but it looks like a mess all the time. So when I remove the Carb I would like to fix that at the same time. Is that Hard?

Re: Edelbrock Carb Help
 

I bought my carb brand new so no rebuild kit necessary but I would think a rebuild kit just follow the instructions ans use the recommended tools and you'll be fine. Concerning your issue with oil can you tell where it's coming from? My only real suggestion I can give you is replace your gaskets and use a sealer for the intake manifold and use cork gaskets for the valve covers if you swap those out too but that's the best advice I can give you.

Hops it helps

Re: Edelbrock Carb Help
 

Don't know if that question was for me, but It wasn't very difficult at all to rebuild. The rebuild kit was around ~$45 at O'Reilly's and had full instructions on tear down and rebuild.

As far as being a novice, don't worry about that. I had never rebuilt a carb before either, and I felt this was pretty easy. I did have my iPhone right there during tear down so I took lots of pictures to reference when putting back together if needed. For the fuel mixture screws: before removing them, actually count the number of turns to tighten them until snug, then remove then. When you reinstall them, tighten till snug, then back them off the same number of turns.

Re: Edelbrock Carb Help
 

You got it set at 0*!!
Good indication your balancer has slipped or you set your timing with the advance hooked up.
Find true tdc #1 and see where your timing marks line up.

Re: Edelbrock Carb Help
 

You will want the timing advanced to more than "0". Something ain't right there.

Re: Edelbrock Carb Help
 

We also made sure that we had the advance unhooked and plugged to try and get the best accurate reading possible.

We tried going to 8 degrees and the truck just wouldn't have it, it was too much advance for it that it wanted to die.

it's not sitting at 0 tdc I wrote that wrong it's sitting at 0 degrees btdc I'm sorry i just saw my error in my writing.

Re: Edelbrock Carb Help
 

Guess what!!
0* tdc or 0* btdc is still zero.
Which way did you turn the dizzy to advance it. More timing at idle won't kill it. Retarded timing will.

Re: Edelbrock Carb Help
 

Oh okay, I didn't know that.

I was counterclockwise for the timing, but when we tried to get to 8 it just wasn't running right it was running rough, when we went to 0 it was running smooth as could be.

I'm unsure if it does or doesn't have a cam in it, if the cam is timed could that cause some issues with it as well?

Re: Edelbrock Carb Help
 

THe only thing for you to do is verify true tdc on #1. Buy or make a piston stop. Confirm or remark your balancer to your timing tab.
You can make one from an old sparkplug like in this link.
http://www.corvetteactioncenter.com/...ing-383-a.html

Re: Edelbrock Carb Help
 

being as I've never seen that before how does that work? If I made a pit stop how would I use it?

Re: Edelbrock Carb Help
 

Simple process!
Pull #1 plug, stick your finger or thumb in the hole and bump the motor over till air is pushing your finger out. You're close to tdc then.
Disconnect the neg post on the battery. You don't want anyone to crank the motor.
Put your tranny in neutral if an automatic. If a standard have someone hold the clutch pedal to the floor. Makes it easier to turn the motor by hand.
REmove all the plugs.
Insert the piston stop. Make sure it reaches about 3/4 inch past the end of the plug threads.
Hand crank the motor till the piston stop makes contact with the top of the piston.
Put a mark on your balancer at the zero mark on your timing tab. A dab of white paint works well.
Now hand crank it all the way the other way until the piston hits the stop. Again put a mark on the balancer. Now you'll have 2 marks on the balancer. At the point exactly betwwen them will be tdc #1 at the zero mark on your tab. Mark it really well. It will be permanent. Use a hacksaw blade to cut a small groove in the balancer.

Re: Edelbrock Carb Help
 

Okay thanks man!

Re: Edelbrock Carb Help
 

Okay so need help once again under an attempt at hard acceleration it kind of bogs and wants to die then seems to do a backfire through the carb any suggestion?

Re: Edelbrock Carb Help
 

See post 26 and 28.
Your timing is wacky.
FIX IT!!!
Or enjoy a crappy running motor till the end of time!

Re: Edelbrock Carb Help
 

Get the timing straightened out and then troubleshoot the carb for any further issues.

Re: Edelbrock Carb Help
 

Okay fellas thanks for the help! I'll have to work on it tomorrow bug I'll get it fixed.

Re: Edelbrock Carb Help
 

A couple of things worry me here.

First, we have a previous owner who modified the engine enough that they marked their own timing mark on the balancer. Something inside the engine isn't stock. Cam most likely has been changed and is either running advanced, retarded, or simply 180 degrees out from the balancer.

EDIT: This part removed. I just reread geezer#99, he's dead on with the piston stop for the timing mark.

Re: Edelbrock Carb Help
 

Truthfully that is a concern for me as well. What the PO told me when we bought the truck was they did a rebuild on it, didn't say how much of an rebuild they did just said they rebuilt it. I have just always assumed it was gaskets.

They showed me the original cam that was in the truck and said they just went and got a replacement because it wore a lobe off, how's that possible?

Whenever we found the mark on the balancer my first thought was actually if the timing on the truck is completely off 10:1 odds the cam isn't timed correctly either.

Now I really want your guys opinion here, I was already planning to overhaul this motor and build it CORRECTLY where I knew all the pistons were done right etc etc. since I'm having this issue with the motor kind of seems like I might as well tear into now and get it done right what do you guys think?

Re: Edelbrock Carb Help
 

It's definitely possible, my '79 GMC that I had in high school wore THREE lobes down, the tallest of the three was .030 from being perfectly round. My uncle helped me put a new cam in, and he said it was common back then because of the metal that was used.

If it were me, I think at this point I would tear it down and rebuild it. You will fix this issue and more than likely another will pop up, kind of like a doctor treating the symptom and not the true cause. At least if you rebuild it, you will absolutely know that all is right inside the block.

Re: Edelbrock Carb Help
 

Oh okay thanks for letting me know that.

Yeah that's what I had the feeling of doing because when you put it back together you'll know all is well and know that it's done right and truth be told of course there's been minor issues to be done, I rather do it right the first time then have to redo it again. Looks like I need to start doing some saving. :lol:

Re: Edelbrock Carb Help
 

I have found the real problem with the timing checked everything and made sure the truck was on TDC and well it was as perfect as can be, so it has to be in the timing chain, so $100 later I have ordered a new timing chain and gear set and balancer on the way from summit, so looks like I know what I'll be doing this weekend.

Re: Edelbrock Carb Help
 

So, did you buy or make a piston stop?

Re: Edelbrock Carb Help
 

Actually what we used was a like a BIC pen and we verified it was close as possible to TDC