Still hesitating

-
R

R3N0

Well-Known Member
Joined
Apr 25, 2022
Messages
115
Reaction score
52
Location
Lockhart Tx.
So the motor is still hesitating off idle. My timing is 14* idling at 600rpm. When I put it in gear idle drops just 100 rpm. I have no vacuum leaks, i pulled all vacuum assisted instruments off the intake tee. Checked the brake booster it's working well, and is brand new. If I let off the main idle screw the motor dies if I turn, I turn it in rpms go up as expected. I've changed to all 3 pump shot holes, and my secondary idle screws work as long as the main idle screw isnt too far in or out. If I go too out they dont work and too far in and the carb starts acting like it's getting more fuel... no sure how to describe it only to say it seems the screws are working in reverse at that point. I'm starting to wonder if my idle circuit is effed. Any thoughts?
 
You need to do us a favor and include all the details of what this is with your posts. It's hard to keep up with what everyone has when there are many people asking for help.
 
“The motor” Doesn’t help us much. Details please.

why is the idle speed so low?
 
Last edited:
LA360 bored .030 KB hyperueretic pistons
Comp cam XE256H w/ springs , hydraulic lifters,
308 swirlport heads ported and polished
Melling valves 2.02 int 1.96 ext
Edelbrock air gap intake
Edelbrock 1406 carburetor
Hooker headers w/ independent exhaust
MSD coil
Summit racing HEI capped distributor w/ 20* mechanical advance
Intial timing 14* all in at 34* (vacuum advance is available but not currently used) both blue springs in use
360-380 HP
4.10 gearing and 35" tires
 
Just stopped by a tuner shop in town, told me that I'm running way to lean and that my initial is way to low for an engine that is running 350+ hp. But they also want me to spend 350 bucks for them to run diagnostics and possibly more depending on what needs to be fixed
 
My apologies, I'll make sure next time to include relevant info, or try to anyways
RustyRatRod said:
You need to do us a favor and include all the details of what this is with your posts. It's hard to keep up with what everyone has when there are many people asking for help.
Click to expand...
 
Is this the same one from a couple weeks back where the fella was having a hard time understanding timing?

What color are your spark plugs after you run for a bit?
 
jos51700 said:
Is this the same one from a couple weeks back where the fella was having a hard time understanding timing?

What color are your spark plugs after you run for a bit?
Click to expand...
Yes it's me, my spark plugs are a light tan

20221023_135016.jpg
 
If I run the largest jet I have .101 and the smallest rods I have .037 that would give me the most fuel I can consume with this carburetor. Not sure this is a good idea... but worth a try.
 
So I guess I can call it fixed:
Tried every jet and rod combo that edelbrock suggests for the 1406... non worked. Decided to try the .101 jet and my smallest rod .037 and viola!
Conclusion: I need a bigger carb... this little guy just isnt doing it. I'm assuming this is as big as this carb can go... maybe the AVS 2 ( being a 750) will work better. Thanks to everyone who has helped me along this journey of headache and pain. Yall rock!
Edit: apparently the .101 & .037 setting is a 1405 setup.
 
R3N0 said:
So I guess I can call it fixed:
Tried every jet and rod combo that edelbrock suggests for the 1406... non worked. Decided to try the .101 jet and my smallest rod .037 and viola!
Conclusion: I need a bigger carb... this little guy just isnt doing it. I'm assuming this is as big as this carb can go... maybe the AVS 2 ( being a 750) will work better. Thanks to everyone who has helped me along this journey of headache and pain. Yall rock!
Edit: apparently the .101 & .037 setting is a 1405 setup.
Click to expand...
A bigger carb is NOT necessarily the answer to your situation. A bigger carb does NOT mean more fuel. Bigger jets and smaller rods do. If that carb can't be jetted to make your combo run, I suspect there's another issue.

Others will have other opinions, and I'm certainly no expert on which carb is best for you, but remember, large carbs aren't the best for street use.




And as I read your post, you ran the largest jet smallest rod you have available, and "viola!"

If you have "viola!", why do you need to change the carb? What's the symptom you're still trying to cure but that you still have "Viola!"?
 
No need for a bigger carb. It is well matched to the rest of the combo.

Glad it is working for you.
 
R3N0 said:
Just stopped by a tuner shop in town, told me that I'm running way to lean and that my initial is way to low for an engine that is running 350+ hp. But they also want me to spend 350 bucks for them to run diagnostics and possibly more depending on what needs to be fixed
Click to expand...
Screw that
 
jos51700 said:
A bigger carb is NOT necessarily the answer to your situation. A bigger carb does NOT mean more fuel. Bigger jets and smaller rods do. If that carb can't be jetted to make your combo run, I suspect there's another issue.

Others will have other opinions, and I'm certainly no expert on which carb is best for you, but remember, large carbs aren't the best for street use.




And as I read your post, you ran the largest jet smallest rod you have available, and "viola!"

If you have "viola!", why do you need to change the carb? What's the symptom you're still trying to cure but that you still have "Viola!"?
Click to expand...
I guess I just figured that if this is the biggest I can go on this carb, then a slightly larger carb would allow me more "play" as it were. Truck stills a bit sluggish, but I think that may have more to do with how I have the TV cable set... there is still a good 1/4 inch of "play" / run when the throttle is at WOT. But I feel like if I pull more TV cable then my start off of idle will be drastically changed... and I've already turned the line pressure up 1 1/2 turns. Also I know for a fact this is the wrong cable as it came off an A500, and this is an A518 46RH. I may just split the difference in the cable and see how it acts.
 
R3N0 said:
I guess I just figured that if this is the biggest I can go on this carb, then a slightly larger carb would allow me more "play" as it were. Truck stills a bit sluggish, but I think that may have more to do with how I have the TV cable set... there is still a good 1/4 inch of "play" / run when the throttle is at WOT. But I feel like if I pull more TV cable then my start off of idle will be drastically changed... and I've already turned the line pressure up 1 1/2 turns. Also I know for a fact this is the wrong cable as it came off an A500, and this is an A518 46RH. I may just split the difference in the cable and see how it acts.
Click to expand...
I HIGHLY doubt you're using all that carb has to offer.
 
Try turning the idle rpm up a little, maybe 700-750. Do this and try driving. Better, worse, no change?

After that, try opening up the idle mixtrure screws a 1/8-1/4 turn on each side and see if that helps the stumble. Fatten up the idle a smidge. If 1/4 turn helps, open it another 1/8 turn. It may want to run a little richer at idle. Ede's aren't as easy to tune on the accelerator pump as holleys.
 
Last edited:
If the truck is a little sluggish [ post #15 ].......
It might well be just the engine size & heavy load, something you just have to live with. It is what it is.
The worst thing you could do would be to install a bigger carb on a sluggish engine....
 
Bewy said:
If the truck is a little sluggish [ post #15 ].......
It might well be just the engine size & heavy load, something you just have to live with. It is what it is.
The worst thing you could do would be to install a bigger carb on a sluggish engine....
Click to expand...
I'm going to try adjusting the mix a little. I got rid of the hesitation, it's a bit sluggish on the top end, I know this cam says it makes power from 1000rpm to 5000rpm but I dont get anywhere near 5000rpm. Getting it to 2500 rpm is a challenge... but maybe not a problem as I'm doing 70mph at 1800 rpm. I'm thinking that maybe now would be a good time to hook up the vacuum assist and get a bit more timing on the low end. Also if I put a heavier spring in the distributor will that allow the rpms to climb higher? Does it allow for more pickup ? Also looking at limiting the all in timing as its 20*... this would allow me to put more timing into inital while still holding it at 36* just some thoughts and questions I have. Thanks for all the info yall.
 
R3N0 said:
I'm going to try adjusting the mix a little. I got rid of the hesitation, it's a bit sluggish on the top end, I know this cam says it makes power from 1000rpm to 5000rpm but I dont get anywhere near 5000rpm. Getting it to 2500 rpm is a challenge... but maybe not a problem as I'm doing 70mph at 1800 rpm. I'm thinking that maybe now would be a good time to hook up the vacuum assist and get a bit more timing on the low end. Also if I put a heavier spring in the distributor will that allow the rpms to climb higher? Does it allow for more pickup ? Also looking at limiting the all in timing as its 20*... this would allow me to put more timing into inital while still holding it at 36* just some thoughts and questions I have. Thanks for all the info yall.
Click to expand...

CHANGE ONE THING AT A TIME AND GET BACK TO US before YOU CHANGE ANYTHING ELSE.

Can we get an ADHD specialist assigned to technical questions? JFC....

Tuning is not a one n done "ideal setting" thing. You might dial in some more timing, and then discover it'll take more or less fuel. Then when you get your fuel perfect, see if it'll take more or less timing. Then after all that gets figured out, you start looking at what you need from it.

Maybe you have a bad combo like a torque converter for a semi truck combined with an intake for a jet airliner.
Pick ONE THING, and work on that. Once you get to a certain point, leave that thing alone and go to the next.
a GOOD tuner looks like they're diddling all the knobs at once, but they're not, they're going through a process and they know what they're looking for so as soon as they get it, they move on.

dial in your carb, leave timing out of it for now. Later, you can switch but you're just chasing your tail when you mix it all up.
 
Last edited:
Okay, so TV cable moved back a little : started hard shifting, also shifting way to high a RPM. Moved it back.
Added alittle to the idle screw : starts much better. But still cant find any top end power. Gonna leave it where it's at.
Could I possibly be giving it too much fuel? Would this cause a loss of power on the top end?
 
It would be veeeery unlikely that you have an excessively rich top end mixture that is making the engine sluggish.
Have you checked with your foot on the acc pedal to see if the carb is going to WOT? Might need an assistant to check. You would not be the first to find otherwise!!
 
R3N0 said:
So I guess I can call it fixed:
Tried every jet and rod combo that edelbrock suggests for the 1406... non worked. Decided to try the .101 jet and my smallest rod .037 and viola!
Conclusion: I need a bigger carb... this little guy just isnt doing it. I'm assuming this is as big as this carb can go... maybe the AVS 2 ( being a 750) will work better. Thanks to everyone who has helped me along this journey of headache and pain. Yall rock!
Edit: apparently the .101 & .037 setting is a 1405 setup.
Click to expand...
Keep in mind the 1406 is NOT a performance carburetor. It is essentially for use as a stock replacement. They're very lean. The 1405 as you've alluded to is the performance version and much richer, so that's probably why you had to richen the 1406 up a good bit.
 
You must log in or register to reply here.
-

Back
Top