Hello everyone , I'm hoping to correct this problem before the Ocean City cruise later this week. I'll try to include as much info as I can. As far as I know it's a stock 72 440, I installed an aftermarket dualplane intake and headers. Timing is at about 8 btdc no pinging or running hot, I have the vacuum advance plugged. So Last week I had the car out (71 Cuda by the way) and your eyes would tear from the fumes, idling or under throttle. So I decided to do some adjustments and see if I could figure it out. First I added an Msd box that I had to rule out weak spark. The carb is a holley 750 vac secondary that was rebuilt with 6.5 pv and 72 jets ( got it online, I know, not a good idea). The car has a vacuum of 14 so I assume the pv is good. I re jetted to 69's, adjusted the floats (they were high) and adjusted the air/fuel mixture. Now, when I was doing the mixture I started at 1.5 turns out and it ran best if I turned them in 1 turn, so only .5 turn from being bottomed out, and the car didn't stall out if I turned them in all the way(should it take a minute or be instant?) anyway I've read this could be a bad power valve, so I pulled it and it seemed ok and still new from the rebuild. So after all of this I took it out for a ride, the strong smell has mostly gone away especially at ide and cruising, if I get on it I can smell a little unburnt fuel, but I guess that's good. However it still builds up/stumbles pretty much throughout the rpm's mainly at part throttle, seems to clean up when it's to the floor. I then stepped down to 66 jets to see if it would help, still the same and I assume these jets are too small. Any help or ideas would be greatly appreciated.

 

What kind of cam is in it ? Big cams can water your eyes.. 14" vacuum at idle is low for a stock motor..
Otherwise I would suspect a bad carb...

 

Agree with TV, you should look at cam and ignition timing closer to get the full story on this "stock" engine.

Turning in your idle screws should get immediate responce and 1/2 out should stall engine right away. I had an old Holley doing almost the same thing and gas would puddle on the plenum floor when off. Changed carb, cleared up.

If you turn the idle screws in that much and it keeps running you have gas leaking (being drawn in) somewhere.

 

i think the fuel issues with this ethanol is hard on hollys i had a 600 vac sec. it had the same problems i finally replaced it with a edelbrock
i think the fuel is designed to run in injected motors more than carberated like the boil over issues............ back in the day when we had real gas not this mixed drink i never had these problems
my new motor with the edel has a boil over issue when it starts after heat soaking say im in the parts store come out she will start but then she tryes to flood about a minute and shes fine once the fuel/ carb settles down to a cooler temp
any input on this problem/s would be help full too all of us

 

Thanks guys, I really don't know much about the cam, engine came with the car. I'd say if anything it may have a mild cam in it. When I turn the adj screws it does respond, at 1.5 turns out the vacuum jumped around at 13 to 13.5, then turned it in and I get a steady idle at 14 maybe a 15 at most. I do have another holley 750 on my dart, maybe I'll switch and see what I get.

 

Ok so I had time to work on it today. I bumped the timing to 10 deg and it ran much better, had about 16 vacuum. Now it stumbles just feathering the throttle or lightly on the gas for cruising, half throttle and WOT seem ok. I know there is still an issue with fuel delivery at idle. I had the adjustment screws turned all the way in and I was able to drive around town with no stalling. Seems to be a little stumble at idle but it idles good with the screws turned in. I'm going to get some power valves, maybe try a 7.5 and also change the metering block from a parts carb if it still does it. Weird thing is though I pulled 2 plugs and they both looked good maybe on the lean side if anything, doesn't make sense to me. But either way it ran alot better with the timing adjusted. Also I'll try different acc pump cams and see if that helps with the stumbles at light throttle. I know I shouldnt make 100 changes at once. What do you guys think?

 

Make sure your shooter/pump nozzle shoots gas out as soon as you move the throttle lever back. I just had a problem with a stuck check weight under the shooter in my carb. The E15 gummed it up. I had to take the shooter out and spray some carb cleaner on the check weight to get it to move. If it is not stuck try to go three sizes up on a shooter and the same after that with a pump cam. I did .31 to .35 shooter and had an orange cam that I replaced with a green cam.

 

Stumble at idle ?? You may have the idle transfer ports ? uncovered because the idle screw is turned in too far. Look and see if it has any adjustable set screws on the secondary side of the linkage ? If it does ? turn it in 1/8-1/4 turn then run it and re adjust the idle screw. See what happens

 

Thanks I will check that, I went out and checked and didn't see any screw to adjust the secondaries, Come to think of it the slight stumble at idle is the same through a light pedal (just amplified) but then from half throttle on it seems ok if that makes sense. Going to play with it again tomorrow. I did notice since I advanced to 10 btdc I now get some backfiring on deceleration that wasn't there before. I figure I'll get it the best I can and then try different things at the cruise.

 

on that holly that adjustment for the secondaries is on the bottom of the carb u have to remove it be care-full that the adjustment is at zero u don't want those secondaries open at all until u need them stay with the springs,
TVLynn is right sounds like u got the idle and the air mix screws out of adjustment that would account for the stumble your air circuit is getting a false signal causing a lean situation and stumble your really not running on your idle circuit this will also affect how the power valve would rich-en up the circuit you could possibly running on the power circuit which can give you all kinds of false tuning signals

 

DO the adjustment in very small steps

 

Update. Ok good news, as i'm messing with the carb I noticed that the 2 rear bolts that hold the carb on look like they are not seated all the way. I was able to get about a half turn out if them. The idle is now smooth but was high because of me compensating previously, I backed it down to 700. I was then able to get a better response backing out the mixture screws, still only a half turn out each but a real smooth idle, vacuum gauge showed 16 so I put in a 7.5 power valve. It's raining like hell so no drive to see, but it revved smooth throughout the rpm band. Cant wait for a road test! hopefully just fine tuning from here. I was tempted to change back to 70's while I had the bowl off, 1 change at a time I guess. Thanks everyone! I will update again after the cruise and I dial it in!

 

As long as you are making progress ? Everything is good !!

 

Most of the time idle mixture screws start at one and half turns out. You still might be a little fat.

 

Update, ok so the car was still stumbling off idle. So I advance to 15 degress it ran even better, the mixture screws where more responsive and I was getting almost 18" of vacuum, the plugs were perfect. The car ran nearly perfect, but only a little while, as the day went on it started to stumble again, and a strong rich smell. I wasn't able to check anything because of the rain. Waited until I got home hoping that I didn't tighten the dist enough or something. It is still timed at 15 deg. and acting the way it used to. I don't get it, I had it good and then something changed. I'm stumped, however I had to put it away the way it is for the winter and I'll deal with it in the spring.

 

Forgot to mention, I unplugged the vacuum to attach the vacuum gauge while the engine was running and the idle actually picked up and ran smoother, shouldn't it be the opposite way.

 

the gaskets you used on the holly where they for alcohol
do you have sighs of fuel seepage is the bottom of the carb wet or oily it would be a sight notice because of evaporation maybe a discoloration or a oily puddle at the base of the manifold around the heat crossovers

I use to run hollies all the way back to the 80s on my vehicles they ran great but some thing happen to them after they mixed ethanol in the fuel and my carb started leaking the power valves would start leaking i would pull them apart and inspect them all the gaskets would be soaked with fuel and the metering block/plates would be wet where they should be dry
the local speed shop guy said every one was having the same problem i was buying rebuild kits for alcohol and after a while they would start leaking
now i use the edele avs and have no problems with leaks
the only time the carb runs rich is after its been heat soaked this fuel has a very intolerable boil point
you might try asking santa for a new carb for Christmas

 

Not nessisarily often it will run better with a vacuum leak , do you know what the fuel pressure is ?

 

If it is rich it will pick up and run smoother with a small vacuum leak.

 

get rid of the holley . and put the right carter carb on it. oh did i say get rid of the holley

 

DUMP THE HOLLY AND PUT A EDELBROCK ON IT ON IT I GAVE UP ON THESE HOLLIES THEY CANT HANDLE THE ETHANOL IN THE GAS.
BUT THERE IS SOME ONE ON TH FORUM THAT BELIEVES HOLLIES ARE GREAT
WELL IF YOU WANT TO KEEP DRAINING THE FLOAT BOWL EVERY TIME YOU GET A TUNING ISSUE HAVE FUN!
IF YOU TANK UP AT ONE STATION ALL YOU KNOW IS SHE STARTS RUNNING RICH AND THEN AT A DIFFERENT STATION SHE RUNS LEAN.
HEY GO AHEAD PULL THAT CARB AND DRAIN THAT FUEL BOWL AND SEE IF YOUR ADJUSTMENTS MADE A DIFFERENCE UNTIL THE NEXT FILL UP.
FUN FUN FUN ...
HEY MY FINGERS SMELL LIKE GAS!

 

running a vacuum leak that"s not bad?
not!

 

Dump the eddy & use a tunable carb LOL

 

Dump the Holley, Dump the Edelbrock. People who say this kind of stuff don't truely know anything about carbs.

You can make ANY of them work if you really know carbs, unless that particular carb has something like body crack or other unrepairable flaw

FIX THE TIMING FIRST

You have already discovered it likes more initial. You need to "map out" the timing curve, so you know how far and how fast the advance moves.

Even a factory performance cam, like the 340s, 335hp 383s and the old 440 magnums could use a LOT of initial advance BUT

in order to do so, you MUST recurve the dist. for a shorter, faster advance curve.

More advance WILL clean up the idle as timing has a large effect on combustion. It also allows you to close the throttle some, and get the butterfies back into the idle compensation ports where they belong, as well as causing the thing to be LOTS more responsive off idle and at low speeds.

A little cam I had in my 360, the rough equivalent of the old 68 340 cam, doesn't even "lope" at the initial timing of 15-17. The dist has a short 20-22 curve and I run 34-36 total not including vacuum.

RUN VACUUM ADVANCE if you have one. It only adds to mileage and does not hurt performance at all. As soon as you get into the throttle, the vacuum advance "goes away."

 

to a point I agree there is a lot more to tuning than the carb but tuning certain circuits on Eddys is impossible & they have far less part availability to allow tuning .

 

get THE carb chrysler put on. ill bet its a CARTER.

 

Do you run your hollies as daily drivers, or week end car, or a strip car,
i run my car as a daily, and these are the issues i have come across good gas, bad gas, hot temp, cold temp, high humidity low humidity, power valves leaking, for no reason,{and no it didn't back fire through the carb and blown out the damn thing} other than the alcohol has deteriorated them or gaskets that wont seal because the fuel eats gaskets!
i ran hollies for over 20 yrs and never had a problem with them until the introduction of alcohol in the gas, i ran them on my first hotrod 650 dbl pumper and on my pickup 750 vac. And today the fuel stations 20 to 30 percent alcohol not 10
my last good running 650 vac secondary on my work van was fine until they put this alcohol in the fuel and that's when i started having trouble damn i didn't do anything just drove my van and then it went to ***** the same with my diplomat ran a 600 on that car, vac secondaries, and the same thing.
the guy at the local speed shop "automotive 1" said every one was having trouble with them i bought the gaskets recommended for the alcohol but they didn't last long and if it got really hot forget it, well i decided to use the edelbrock or as formerly know as carter carbs, when i did this last engine and my combo is posted,
now i don't have those issues any more, tun-able well yea holly has lots but i was sick and tired of pulling the carb draining the fuel and putting it back together, the carb would hold fuel for awhile and then start leaking again and/ or it would get fuel in it that would change the mixture this was getting old.
i am satisfied with the performance of the combo i have now, could it be better maybe but i'm not going to start running a hollie on it now, i don't want to pull that carb and drain the float bowels to try a different jet size or secondary plate all i know now is that i did some tuning on this carb and i got fast good results if i need to open up the accelerator pump nozzles i will get out my wire drill bits and increase the size but i didn't have to do that.
So maybe i may race a guy with a hollie and win or loose can i say it was because he had a hollie, or was his combo different, cu inch, cam, gear, car weight, all i know i run up against fords and cheveys and i beat them!
And my brother chimes in now; at the strip it takes us a minute to change rod size and we make another run then we change to a different rod size and make a run while the hollie guy is putting his back together.
So i can do a faster air fuel mix change way faster than the hollie guy and find a faster combo faster than the hollie guy!
And lets say i drive my car during the week and its 95 degrees with a average humidity 90 percent "welcome to Florida"! but that Friday night at the locale 1/4 mile in the evening it s 75 with 90 humidity, i can change rods in a minute, and each run back to back try a different set of rods, while the guy who had his hollie tuned for the same conditions now has to drain the fuel line, float bowl and try a jet combo... "hey hold the light ",maybe even a power valve, and a cam, oh and the air bleeds"...***** i drop it down the carb"any one got a pencil and some duct tape,... ***** it hot working over this engine"... "i'm getting a headache from smelling this gas"! And put it back together"... oh ***** the gasket tore"... what do you mean you don't have a spare or that was your last one!" see if some one here has got a spare" crap it back fired do you got a spare power valve"... well... i will get three runs probably 4-5 to his one easily so if you want to work hard on your hollie go right ahead... on the street i will put my edlebrock up against your hollie any day and if i loose maybe it was the carb maybe!
have a nice day.

 

I actually had a Slant 6 4 spd OD pick I used as a daily driver for 4 years , put over 100k miles on it & it was used when I bought it , I bought a spare head , milled the head .100 , ported it & had the guides replaced , picked up an alum super 6 manifold from the wreckers too adapted a 500 CFM Holley 2bbl to it , I was able to dial in the tuning because all the jets etc were readily available , I averaged 25 MPG drove it daily year round & the only issue I had was the idle mix needed to be adjusted when the outside temp changed by more then 20* F . For a tunability standpoint I will only run Holley type carbs but it is true that all the alcohol in the fuel will mess with carb internals though the power valve, accelerator pump diaphragm & maybe viton tipped needle & seats could be affected , Not sure how well the accel pump seal in he Carter / eddy will hold up any better though .

 

well we shall see. i will keep it posted though, if i have any issues with the soft parts in the eddy, the manufacturer warns against running alcohol fuel no e-85 in the carb but at least i wont have to deal with the leaking gaskets i really hated that the most.