ok i bought a nother 79 ford it has a 400 in it all stock except for a proformer 400 intake and carb just woundering if anyone has this 1406 carb on a stock 400 and what meteriong rods and springs and such are you useing it runs rich at idle and has a big stumble at mid rpm 2500-4000 kinda flat after 2500 rpm so if you have a 1406 carb on a stock 400 and it runs good with crisp throttle responce pleas let me know what you have done to the carb my carb is all stock and i really dont have the time right now to get in depth and tune this so any help to get me in the ball park

 

lol well i guess no one runs a 1406 carb on there 400's

 

I would suggest maybe picking up an Edelbrock "strip kit" (they can often times be had on ebay for under $35) the kits contain an assortment of metering rods, jets and step-up springs so you can experiment with different combinations and dial in the carb to your own liking.

 

thank you i got the mid rpm probs worked out now its just right off idle there is a big stumble i wish i had more time to work on this carb to get it right any input is a help i have moved the pump arm to all the diff holes but still a off idle stumble its not a bog so to speak and i dont think the 400 needs more gas when i punch it i dunno im lost as of where to go from here.

 

I have a 1406 on my 351 and I have to wait until it's warm to be able to drive it with any kind of snappy response. But the engine has other mechanical downfalls at the moment.

 

Off idle. Your problem is more than likely that you need to increase the accerator pump shot. Raise it one notch and see how she does. Also look in he carp and pump the throttle to make sure you getting a shot of fuel from it. If not you need to replace the diaphram. They sell the whole pump in a small rebuild kit for it.

 

I agree with co425.
My 302 with the Edelbrock kit stumbled off idle until I set iy up to the highest acc pump setting, from then on it was dead on.

i would look at the spray in the carb due to, I bet there is none!!!

 

He said he's already tried increasing the accelerators pump setting.....are you pulling ported or manifold vacuum for your vacuum advance? if the latter you may have a "dead spot" just off idle before the mechanical advance kicks in, should be using ported vacuum on a street engine.

 

Ported vacuum is for smog equipment vehicles. Manifold vacuum is for pre smog or race vehicles. Quote from the best explanation I can find. "You can run ported, manifold vacuum, or strictly mech. advance.

Reason why you would run manifold vacuum from the carb:

If you set the initial timing to 5* BDTC and run vacuum advance at idle for 15-20*, you get two benifits. 1

1) Since you initial timing @ cranking is pretty much 5*, your engine does not have to fight the advance timming to start (less stress on the engine). Then once the engine is idling, your manifold vacuum is kicking in to give 15-20* at idle and low RPM cruise speeds. Higher timing @ idle and cruise will give better gas mileage, better throttle response, and little more power on you low rpm range.

With manifold vacuum advance method, the manifold port vaccum drops as the throttle blades open, but at this point the engine is picking up RPM and as the vacuum advance retards, weighed advance picks up till you reach total timing. You should have the proper weights and springs so you don't have a dip in the advance curve.



You don't have to run it this way, heck I ran only mech. advance before - race engines don't use vaccum advance. Lot of guys run ported vacuum, but if this is a daily driver and you do a lot of cruising (rpm range), then you'll benefit more with manifold vacuum port for better gas mileage."

 

ok thanks guys ill try running it from the manifold and setting the timeing like that the acc pump is working good i look in there is a healthy squirt of gas

 

try all of that stuff first ... those are good suggestions.

if those don't get you where you want to be, try softer step-up spings. If you get the tune up kit, it comes with step up springs from 2mmHg to 8mmHg (or something like that). try putting springs on your metering rods that allow the motor to get up on the "power circut" at a higher manifold vacuum.

if that dont work, then you need to decypher the chart in your edelbrock book. it sounds like your cruise circut may be too lean. if all the above does not work, and you still have a stumble, then you will need to change jets, and then likely the rods after that.

you may have to look at that chart and envision where your carb needs to be. i.e. stepping up your cruise circut, without stepping up your power circut. they give you combinations on the cart, but there are many more possiblites if you get creative.

let us know how you turn out. I'll be looking at doing this swap here pretty quick, but on a 460. so a starting point would help a ton.

good luck

 

thank you guys for all the help i will do a little tinkering when i get out of work and update ya

 

I'm not sure who the author of that quote is but that's flawed logic, the ONLY time manifold vacuum is higher than ported vacuum is at idle, once the throttle blades are cracked open ported and manifold vacuum equalize and they are the same.