Ok, my friend and I have been trying for several days to get the stumble out of the carb in his Roadster. Its a Edelbrock 1406 model. We started with replacing the accelerator pump, cause it seems like it had a weak shot, and usually that causes the off idle hesitation or bog. No dice. So we bumped the timing to 36 overall, put the accel pump in the bottom slot (biggest shot), richened up the primary/secondary one step each (95 jet w 1437 rod in front, and 98 jet in back) and this thing just hesitates and stumbles coming off a stop like crazy....If he stands on it, there is a momentary bog then its burning rubber. I dont get it....fixin to sell him a Holley outta my spare parts. Proverbial small block, 9.5cr, 280 dur. 480 lift cam, decent headers, single plane intake, MSD ignition stuff......WTF.....
Oh, and I wanted to add, Ive got the 650 model on my Coupe, and it runs pretty good, not like a Holley but not like this piece of crap on my buddies roadster.......
I'm just a hack, so take this for what it's worth but most the time when I've had something "bog" off idle it's cause it's too rich, not because it's too lean.
How many turns out are the idle mixture screws? Did you check and set the float level? Are you running a fuel pressure regulator, and if so, what pressure is it set at?
We set the idle using a vac gauge, i believe 1.5 turns out, to the highest reading, then turned em in about a 1/4. Initial is like 20, advance all in right at 3000 w 36 deg. Vac advance unhooked....... Someone else told me it was too rich, but the plugs are white/tan, and its only a little 600 on a warmed up smallblock, it had the stock jets and rods in it when we started.....
the 1406 is jetted more for economy , the 1405 more for performance do you have the manual? if not you can down load one online from their website. it gives tips on tuning, you may have to get a recalibration kit
I had the same thing on a 215 Buick motor with a 500cfm Edelbrock on. It ran great, apart from the initial push on the throttle, press... pause.....BWAAAAAAAA and off it would go. I never did find the problem.
3Window, he has that kit, we used the chart in the manual to go one step rich on the primary and secondary, it has 31 squirter in it, now a new accel pump on the highest setting.....we tried turning the idle adjustment out another 1/2 turn to the rich side, to see if that would affect off idle acceleration, but didnt seem to make much difference. We didnt know the carb was the econo-box version until we got the manual....POS...ive got a 650 DP Holley sittin on the bench....we are fixin to throw it on!
Morrisman.....that is EXACTLY wat this dam thing is doing.....give it gas, coming off a stop sign lets say....it feels like its gonna go but then it stumbles until you give it some more then it takes off. Give it a good shot on the loud pedal and it kinda goes dead for a second then spins tires....damdest thing....it cruises and runs good at speed. Can give it a good shot on the gas and it perks up and goes without issue. Just the low end is messed up......
the Holley would give you a power valve to tune to cam and vacume i like to run full maniold vacume to the dist, on accel it backs off if you got good ign i like to go to plug gap of 065 more fire in the hole may be a good time to have a scope and check for total available secondary voltage and a gas analyzer even a 2 gas is good and will improve your mileage by setting the air idle jets to best operating mixture instead of a recalibration kit you can buy the jets and rods from jegs or summit one of them has them in stock
eugene....my bud bought the kit that has an assortment of jets and rods, also has the various springs for the rods (open at various vacuum).....we are assuming the springs on the rods are like the power valve on a Holley.....we didnt change the springs any....would we set them according to the idle vac, or just below (or is it above)....ie, if it idles at 12 inches, then put in a spring for 8 inches, so when you give it throttle the vac drops off and richens up the circuit...??
read that manual again , i believe your problem is discussed in it i've yet to find an Edelbrock carb i could not make run properly
What step up springs are in the 1406? To select the correct ones, take half the vacuum inches at idle with vehicle in drive.
thats what i was referin to, the rod step up springs.....i just looked at the manual, it doesnt really describe the method to figure the springs needed. So 1/2 the vac at idle would be the spring range....when i get home from work, im going over there and we will try it.....
You aren't kicking it hard enough it is flopping open the secondary air valve is it? We had one that we added weight to to delay the opening and that fixed the bog . It was a 318 that was a two barrel and we had swapped on a four barrel setup with an older AFB. Tom
Voetom, ya know, it acts like it has a large hole, like the secondary is trying to open....so how the heck to you add weight to the flapper gizmos?
We bolted some lead to it somehow to make it heavier. Seems we added weight to the valve plate that is in the airflow path. Trying to remember how we did it now.
Yes, this is the method that has worked for me well as the step up spring aids in transition from the idle circuit to the primary circuit. Once you check your idle vacuum and get the corresponding springs, let us know how the engine reacts.
Correct fuel pressure and float level is very important with the Edelbrock carbs...Most high performance and even some stock fuel pumps put out too much pressure for the carb...
I will let yall know sumthin tomorrow...cudnt make it to the car tonite. Hotrodarchee.....we checked float level as one a the first things. Fuel pressure by mech pump set at 6 psi
Isn't the difference in the 1405 and the 1406 is that one is manual choke and the other electric? I've never read anything about the 600 being for economy. Anyway, is it possible something was done to it before you guys got into it? It sounds like it's running rich. I've played around with the screws on mine and they like being 1 3/4 to 2 turns out. Go through the setup in the instructions and try again. Straight out of the box, the screws are 2 turns out. And check that fuel pump. 6psi is all these carbs want or need.
yes.....the 1405 is mechanical choke and the 1406 is electric choke they are also jetted completely different read this http://www.edelbrock.com/automotive_new/mc/carbs_acc/performer.shtml
Thanks, I never knew that. I don't use a choke here in Houston, but it's always nice to know how these things work.
pull your idle screws and take the top off the carb. Use a low pressure air to blow out the idle circuit. I bet you got a bad batch of gas and now have some crap in the idle circuit
You can slide the little cover that is over the rod and spring over and visually see if the vacuum is pulling the rod down or not. It's been awhile since I messed with my Carters but each metering rod is either fatter or skinnier to allow or restrict the fuel coming through the jet. I would put a thinner rod in there with about the same height on the taper. All my notes are out in the garage but i kept a pretty good record of the results with each metering rod change. You will also feel a surge if it is to lean going through the transition phase, say if you were tooling along at 1900 it would surge trying to transition to the next step up.
The Jalopy Journal
