does the Holley tuning sticky apply to all Holley carbs? I have a double pumper I just rebuilt and need to tune it...Burns my eyes at idle...What power valve? engine only makes about 8psi vacuum....thanks. Oh, this is a street strip car that isnt drivin dailey

 

you have 8 INCHES of vacuum, not pressure. I would imagine a 4.5 would be a good starting point for a power valve. You should be running at least 22-24 degrees of timing at idle and 36ish total, or just lock the timing out and run it that way, more timing at idle will help burn off the fuel easier and stop that burning eyes sensation.

 

lol....that what I meant...Im running 36 total timing now...thanks for the help

 

initial timing is what will help though, what are u running now?

 

Im not sure. I sent total timing with an adjustable timing light. 36 degrees total. How would a part time street car act with timing locked?

 

it would act fine, just might need a stronger starter to turn it over if you don't have a mini-starter. I installed a switch so I could crank the motor over then flip on the ignition and it would fire right up.

 

ok....I locked out the distriburtor....set total timing to 32 degrees...still getting eyes burning at idle...float level set ok...idle screws at about 3/4 turn out...4.5 power valve...i can back idle screw all the way out and it will idle at about 1000 rpms...what am i missing?

 

turn in the idle mixture screws then. I wouldn't imagine the idle dropping lower than 900 or so at the most because of the size of the cam. How are the transition slots set on the secondaries? otherwise turn in the mixture screws and also check that the boosters aren't dripping fuel.

 

the transition slots on the secondary i havent touched..there is just enough exposed to look like a square, maybe a little more. if i turn in the idle screws anymore it wants to die. I dont mind the idle at 1000 rpm, its just the strong eye burning exhaust...

 

Motor can't want to die out if the A/F ratio is THAT rich and starts to lean out, sounds like all your plugs are fouled. Swap in a fresh set of plugs and try to lean out the mixture some and see where it gets you.

 

How big a cam are we talking about in this motor? 8" of vacuum with the timing locked out at 30+ degrees ain't much.

If it's big, then you will get the eye-watering exhaust no matter what you do. Big cams have a lot of overlap. Big overlap means unburnd A/F mix making it directly into the exhaust. Nature of the beast with big cams.

 

cam isn't that big, it's a hydraulic flat tappet from his sig, it's all in the idle mixture tune or a blown power valve, etc. I think it's fouled out plugs myself.

 

when I said idle screw here I meant the one on the drivers side on the throttle linkage, not the idle mixture screws. The cam really isnt that big, but it does have 1.6 rockers.

 

Shouldn't be running that rich. To test for a blown power valve, lean out your mixture screws all the way (clockwise), but don't seat them too hard. If the engine still idles, you have a blown power valve. If it immediately stalls (in your case), then your power valve is fine. Eight inches of vacuum is way too low, you need to plug that vacuum gauge into a manifold vacuum port. You have four idle mixture screws to set on your double pumper, so it's going to be a little time consuming. Set idle mixture first, and bring it back up to a steady 14-15 inches of vacuum in gear. Don't worry about your idle speed, as this is adjusted during and after you set your idle mixture. If your idle speed is too high with the fast idle screw not even touching anymore, your choke is not set right and/or your timing is off....

 

The carb has the choke horn mill off...no choke. Since original post I fixed a leaking header gasket and vacuum improved to about 9-10 at normal idle. I dont think there is anyway this cam will have 14-15" of vacuum at idle. maybe at 2k...power valve is new...engine will die if idle mixture screws are turned in all the way. I rebuilt the carb with holley kit...just cleaned all passages with carb spray and replaced needle/seats, power valve, and gaskets. floats are set with fuel level just below the sight plugs.

 

did you replace the plugs yet?

 

not yet....Im going to do that next...

 

Can you get a picture of your setup, as I'd like to see which port you have your vacuum advance hooked to, as well as where your getting your vacuum reading from. Your cam isn't too aggresive, you should be getting well over 10 inches of vacuum in gear with no problem whatsoever. Just out of curiousity, who set valve lash....?

 

That is good, this just solidifies a working power valve. How exactly are you setting your idle mixture though? Normally, you will turn all of the screws clockwise (lean) until they lightly bottom out, then back them out about 1 1/2 turns each. From there, with the engine running, emergency brake on, and the car in gear (neutral in your case), plug a vacuum gauge into a full manifold vacuum port (down by the base of the carb), and fatten each screw out while watching the vacuum gauge and counting the turns. The moment it goes up, and no further, immediately move on to the next idle mixture screw and fatten it out the same exact amount of turns. You'll then lower the fast idle screw to desired idle speed, and do the same thing all over again until the vacuum gauge no longer increases in vacuum....

 

^ By the way, your running a Crane saturday night special cam, right, p/n 270-110691....?

 

the ported vacuum port will have ZERO vacuum at idle street lethal, it's like beating a dead horse. He has to have it in the manifold vacuum port.

 

I know that, that's what I said. Where did I say otherwise....?

If your referring to when I said this....;

^ That's just to eliminate the possibility of him using the wrong port for his vacuum advance, because this will cause a rough idle, and unburned fuel. Not so sure what or who your referring to about beating a dead horse, but I currently run a carburetor, and have been doing so for quite some time....

 

For those needing more information about the camshaft being used from Crane, Click Here....

To OP, here's a visual understanding of everything, Click Here, Click Here, and Click Here....

Good luck!

 

That the cam....I set the valve lash recently, but it was on a cold engine... The only changes from my sig are I went to an air gap rpm, instead of a normal rpm intake...Im hooking the gauge to the small port at the front of the carb in the base. I started with the idle screws all at about 1 turn out and have them at about 3/4 now...that as lean as it will go without wanting to die. Im going to try a new set of plugs next. Do you think I should set the valves after engien is warmed up?

 

Here's a couple of pics. Engine compartment a little dusty. Just recently got back from body shop getting painted. Also I have been playing with an inch 4 hole spacer, but it doesnt change anything.

 

sharp looking engine, what rpm are you trying to achieve in gear at idle? I would be shooting for 800-900 or so, I bet that'll help a bit also with the dying out issue.

 

I personally think that your idle mixture screws are way too lean, and need to be fattened up a bit. It's best to do this after valve lash is set properly though, so the engine runs smoother. Otherwise, if the valves are too tight, you won't be able to smooth out the idle, as the vacuum gauge will always read low and be sporadic, and you'll think it's the carb. When you set the valves, do it with the engine off, as there is a very easy method which only requires you to turn the engine over twice to do all 16 of them (8 at a time). Once the valves are set right, then you can tune the carb....

 

thanks...looks alot better cleaned up..lol. Im really not worried about idle speed. 1000 rpm or so would be fine. Its just the very rich smelling exhaust at idle. I always have set the valves with the engine off...learned that along time ago...if i turn the screws out more wont it just make it richer?

 

Only at idle, which is what you need in this case. Your primary and secondary jet selection will determine if the engine is running rich or lean at throttle. I'm running a 406 as well, along with an RPM Performer intake, Holley carb, a slightly smaller camshaft than yours, and I get 19-inches of vacuum in Park at 800-RPM....

 

can't use this method with bigger cams because the larger duration will actually have the valves open slightly. Best is exhaust just start to open, do the intake and intake over halfway open then do the exhaust. Don't want a newbie to be hanging valves.


So you want him to richen the idle when it already is burning his eyes.....

 

I've used this method with much larger camshafts than his and never had a problem....

.... you honestly think he's running rich at idle with that size cam with the idle mixture screws open only 3/4's of a turn each? Now that's something that seriously "is" crazy if you ask me. My idle mixture screws are opened two full turns with a slightly SMALLER camshaft, and I'm pulling plenty of vacuum.

 

xpndbl3, let me just point this out so you can see things the way I do. Most people start with 1 1/2 turns, then FATTEN it for the greatest results thereafter. It sounds like he's doing just the opposite. He started at one full turn, then brought it in a quarter of a turn. It sounds like he's trying to lean it out before it stalls, then thinking that it's tuned....

 

Sure a TWO corner idle system is 1.5 turns out, but a holley 4 corner idle system is usually 3/4 turn out then tune from there. If it's burning his eyes at idle it's either fouled out plugs or he still has them set too rich.

 

Usually being a preference though, as even when running two accelerator pumps most people will open all four to 1 1/2 turns, then tune accordingly. But regardless though, you just clarified my point anyway, as he would still be at the 3/4 starting point if he started at 3/4. He started at 1 full turn, then leaned it back to only 3/4. That's too little, even if he were running a stock camshaft....

He sounds very new to carburetor's. We also can't assume that he has the floats set properly. If I had a dollar for every guy that I know who insisted that the floats were set properly, only to pull the site plugs while the engine was idling and the fuel started POURING out like there was no tomorrow. I personally feel his float level is set too high (if he is in fact running as rich as he's depicting)....

 

yup but being keyboard warriors we can only take someone so far in the tuning. Buying a $12 book on holley carbs or borrowing one from a library would do him more help than asking over and over on a website. Luckily this is why I get paid to fix other people's mistakes on carb cars. Usually it's a buddy or an old uncle who used to have a XXXX car that ran 9s and set up the carb all out of whack.

 

I can pull the site plugs and see the fuel in the fuel bowl. I have it set so that no fuel is coming out at all. Im not totally new to this. Just been out of the game for a while...Never had one run this rich at idle...This combo didnt use to be this way. The car has been setting for a while and also been in the body shop at work....Before it got painted I had to pull it outside during the day and it fouled the plugs, cause it was winter and it never got warmed up. I rebuilt the carb cause it new it sucked alot of dust and since it was backfiring due to the fouled plugs.
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Ive read tons of stuff on holleys...even watched some of the dvds from holley...I think Ive done all of the normal stuff to try and fix it...Is it possible that the carb is just junk? Only reason I posted was because I was stumped...I usually like to figure things out on my own. Thanks for all the help guys...

 

This procedure needs to be done with the engine idling to be absolutely sure. Have the engine idle, and remove the site plugs one at a time. If the fuel "trickles" out very very lightly alongside the carb, then that's exactly what you want. If it pours out, turn the engine off immediately, as the float is way too high. If nothing comes out, even when you rock the car back and forth, it's too low....

It has to be somewhere in the rebuild, especially if it never acted this way before....

 

Not much to rebuilding one...it was fine a couple of years ago before I started redoing it...It has seen much action in the last fews years...

 

I was implying that something might have been overlooked during the rebuild. For a Holley carbureted engine to be running excessively rich, the floats are either set too high, the mixture screws are set too rich, your jetted too rich, or you have a broken power valve. Could even be a leaky accelerator pump. Remember, your idle speed is being effected and is running too high even with the fast idle screw backed off entirely. Something is supplementing additional fuel, and it cannot possibly be the mixture screws at 3/4's of a turn each....

 

any ideas on what could be adding additional fuel at idle? Ive had a new 6.5 and a new 4.5 power valve in it and they both were the same

 

^ The power valve wouldn't affect idle unless it were leaking, and you'll definitely know when the power valve goes bad. The 4.5 and 6.5 just indicate at what point of vacuum in which they're triggered. If you really do feel that your running rich with the aforementioned idle mixture setting of 3/4 turns each, re-inspect your fuel pressure, float levels, accelerator pumps (for leaks, and proper size), jetting sizes, also check for clogged needle valves....

 

you can always unbolt the carb and lift it up an inch or two and see if it is dripping fuel with the pump on, but still why hasn't the plugs been changed to see if that works first?

 

I just havent had time to yet...I will tonight

 

I changed the plugs... also removed the carb again and verified the transtion slots. Reset the front and rear to about .020 (slot looks like a square) it now idles at 950-1000 rpms after warmed up. vacuum is around 10". Still has a stroung exhaust...It is a better. I have all 4 idle screws set at about 3/4 turn out. Going in more doesnt really change it that much. I tried another 1/8 to 1/4 turn in...Anymore ideas ? I think i will try and adjust the valves like xpndbl3 suggested. I did lift the carb up with the electric fuel pump on and nothing is dripping...I just would like to not take a shower after everytime I drive it..lol

 

^ Electric fuel pump lol, didn't know you were running one. Which pump and regulator are you running, and what is fuel pressure set at? Also, again, your at 3/4's of a turn with your idle mixture screws, you don't want to lean them out anymore than that. Your fuel pressure at idle is going to say everything, now that we know your running an electric pump....

 

Gee thanks, thought I suggested that lol.... j/k

BTW, I can't see your pics that you attached in previous posts, what were they of....?

 

the pcs where just engine shots of my setup...fuel pressure is between 6-7 psi..I have an old vdo fuel pressure gauge off of the regulator and it doesnt have all the numbers on its...skips around 0 5 10 15..so best guess it 6-7. I saet the valves recently the way you suggested. I dont think fuel pressure is the problem...

 

How far are the transition slots opened? If your cam is only pulling 8" of vacuum then you might have to drill the throttle blades

 

transition slots are set at .020 front and rear. It will idle at 950-1000 after warmed up (which is fine) But it will die until it is warmed up. It still has a strong exhaust (doesnt burn my eyes anymore) What does drilling the throttle blades do?