for a holley 650 dp (hly-4777)how do i adjust the accelerator pump linkage? i see a red screw and a bolt that goes to the lever. do i have to have throttle open to adjust it or closed? also is it better to have spring spread apart or closing (making it smaller) to help the adjustment? my car is stalling and bogging big time when i hit the gas when in park. any help is appreciated.

 

If I understand what you're looking at - That's just the screw that is adjusting when the free play before the accelerator pump engages. You want to take the gap out of that and then play with the little cams that the pump linkage arm rides on - Holley has a kit with cams that are more and less aggressive.

If you're suffering from a lean tip in condition then you need to increase the "shot" of fuel - this can be done one of two ways and each has it's place depending on how you want it to react - either adjust how fast the accelerator pump diaphram is pushed (cams) or how large the squirter orafice is.

 

ok so i wouold make the spring longer or smaller to make the accelerator work better?

 

I went and was going to look for a picture so I could explain how to adjust it to take out the slack but the second thing that google came up with was Holley tech posted a video on youtube on this...


Take a watch and see if you have any questions afterwards... I didn't watch it fully but the intro said it was going to cover the adjustment, the cams and the squirters....

 

Open the throttle all the way with one hand, and hold it there.

Push the lever that's up under the spring downward with your second hand, and hold it there.

With your 3rd and 4th hands, adjust the length of the bolt/nut inside the spring, until there's around .050" of clearance between the lever and the bolt head. Too little clearance, and the pump will bottom out during operation; too much, and if it's enough too much, it will make the pump do nothing at all right off idle.

Once you get all that done, let go with all 4 hands, and let the throttle close. The lever should be resting against the bolt head. The slightest movement of the throttle should move the lever and pump some gas.

 

ok good information guys. the video says .015 lash? which should i reference the .015 or .050? i want to hit the road this week, i had eddys before and never tuned a holley. alot harder then the eddy ill tell u that

 

Yes.

All you want to do, is (a) make sure it doesn't bottom out, which is to say, you need "some" clearance"; and (b) make sure it delivers the full stroke starting at the very top, which means, you don't want "too much" clearance. Basically anything between "some" and "too much" is fine.

Now that you've gone all the way through the Holley tuning sticky at the top of the page and got the carb REALLY working RIGHT, you probably already realize that you pretty much don't need the pump at all, because the carb works so good at delivering fuel at all the right times that it no longer needs that "crutch"; but since it's there, you might as well at least get it into the right range, even though you can probably disconnect it now and not even notice most of the time.

 

ok adjusted the acc pump right and the carb is still doing it. i adjusted the floats, fuel psi to 7 and adjusted the metering valves till i got about 8psi at idle. is that to low? also would i need a bigge squirter since i have an air gap intake?

 

How's your progress through the process outlined in that tuning "sticky" coming along?

Tuning is A PROCESS: you isolate the characteristics of each system of the engine, one at a time, and optimize each one, in its turn, with as little interaction as possible with parts that have already been optimized (i.e., in a planned pattern to reduce iterations through the process). A little bit like working out at the gym, where you target specific muscle groups apart from each other. Systematically, in an organized and logical process, with a flow from one step to the next. It's not, "my car does such-and-such, what screw do I turn?"

Finish the Holley Tuning sticky and come back once that has been carried fully through, to perfection; and THEN we can work on whatever is left.

Leave the squirter, and EVERYTHING ELSE about the accelerator pump. ALONE, until you have gone through the entire Holley Tuning sticky from start to finish.

In case no one has mentioned it yet, there's a Holley Tuning sticky on the carb board, that contains the answer to your problems. Look it up.

 

Lets start at the top, timing, where is it at? What's your initial and are you using vacuum advance? That's critical for tuning the Carb. Lets say its at 18 initial. With all vacuum ports plugged. Good starting point for a mild SBc, now make sure your at stock jetting and squirter size to start. #28 squiters, and 67/76 jets. 6.5PV
Flip the Carb over and check your transfer slot exposure. Should be perfectly square, if u don't know what I'm talking about just Google "transfer slot".
Once they are squared off reinstall the Carb.
Set your floats so that your just seeing a tiny bit of fuel at the sights, if you "bump" the car a tiny bit should leak out the sights.
Set the idle screws clockwise until they bottom out, now turn them counter until they are 1.5 turns out each side.
Turn your pump arm screw and close up the spring you were asking about, u should be able to run your feeler guage between the nut and the arm with minor resistance at .015
These settings alone should have you up and running and close.
adjust your idle when warm until its at app 8-900 rpm, should drop to 650ish in gear.
If a vacuum guage isnta available, have someone in the car, foot on brakes, in gear, slowly turn the idle screws in until you feel it start to stumble, then back them out a quarter to half. Do them equally on both sides.
Now back in park, plug your vacuum advance line into a manifold source right at the base of the Carb, not at the metering block.
Again, your idle will now jump up, adjust it back down until you see 850ish while in park.
This should get you up and running pretty decent. Further tuning will require a vacuum guage and reading your plugs but it should now be a decent baseline you can work with. I run a 750dp on a mild motor, undergeared, fairly heavy car, and with some time and effort it runs like an injected car. You would be shocked.....and it pulls real nice too

 

my timing is at 14* and get between 36-38 total timing. the floats are set properly as well as the metering blocks. the thing i noticed is that the accel spring and bolt slowly slide down once the throttle is opened all the way. like when its cracked open u see more bolt then spring and they slowly meet together. thats not right is it
?

 

Yes that is exactly right. That's what it's there for.

That spring is called the "duration spring". If it wasn't there, the incompressible fuel in the pump, would either not let you push the gas down faster than some certain speed, or you'd bend linkages, or something.

It makes the pump shot last longer and not be like just dumping a bucket of fuel into the motor.

Sounds like it's time to leave the pump alone, since it's working right, and tune the carb.

Heard about that Holley Tuning sticky on the carb board? It's got a terrific process in it, takes all the guesswork out of it. Turns tuning Holley a into a science. You should check it out.

 

i read the carb sticky and it helped, but im still really rich under wot. how should i start jetting? i went from a 31 to 28 discharge nozzle, 6.5-5.5 powervalve. i bought a jet assortment kit just not sure how far i should lean it out, and only the secondaries or primaries also?

 

So you're good at idle, part throttle / cruise but really rich at WOT only?

If that's the case *and* you have a progressive throttle linkage which opens the secondary set of throttle plates after the primaries then yes - reduce the jets in the secondary side of the carb. Also if you've got a power valve in the secondary metering block then you might want to reduce it's rating and/or plug it if you driving style on the street is primarily on the main circuit and not into the secondaries (unless having 'fun').

If you're looking to "fix" one part of the carb's running parts a quick reference to where to start to look:

Idle: Idle mixture screws
Transition: Accelerator pump (and a little of the PV)
Part throttle cruise: Primary circuit (main jets - vacuum should be above the rating of the Power Valve to keep cruise lean)
Heavy acceleration (to WOT): Primary + Power valve + secondaries

 

ok thank u good to know where to start

 

What cam is in the motor now?

 

From the sticky:


You went backwards.

From the sticky:


From the sticky:

After reading the sticky, try following it. The steps, process and procedure given in it, will work as well for you as for anybody else. It is POINTLESSLY STUPID to start right smack dab in the middle of it without doing the initial parts, and EVEN STUPIDER to do things that don't need to be done at all (squirters) before doing the things that REALLY MATTER.

There's a reason that sticky is there: it's to help people like you, who are not experienced with Holleys, without us out here having to answer question after question after question, and to spare YOU the frustration of endlessly dinking with it and getting no results. Try it, you'll like it.

 

edelbrock performer .480/.510 lift

 

im confused on why i would want to up the power valve when its running rich already? i guess im not understanding that part. so would 4 jet sizes be "too much" to reduce on the primaries. under wot wouldnt it be the secondaries making it run rich also?

 

BECAUSE YOU HAVEN'T STARTED AT THE BEGINNING.

Start with the jets. Get them right, as described.

THEN AND ONLY THEN, go to work on the PV.

If the jets aren't selected properly, NO OTHER WORK CAN BE DONE YET.

I have no idea. That's why you TRY IT and see what happens. Reduce them, say 3 sizes; drive the car; if it doesn't lean-surge, reduce them some more; drive the car; if it STILL doesn't lean-surge; reduce them some more; when you finally get it to surge, go back up 2 sizes.

Follow the instructions, from the top, to the bottom; NOT starting somewhere in the middle.

This is not that tough. We can't tell you, take out 3 of these, put in 2 of those, crank this screw one turn this way and that one a half-turn that way. Every engine/car/carb combo is different. YOU HAVE TO GE OUT THERE AND FIND WHAT WORKS.

 

would these adjustments be the same for d.p.s as for the vac sencondary holleys?

 

Yup; they all work pretty much the same, regardless of the motive force that opens the back 2 barrels.

99% of tuning is the primaries, anyway; all you do to the secondaries, is set for max power.

 

Hey Sof, I agree with "start at the beginning" but that's why I keep poking him with cam and compression questions, he is running 14* initial on a cam with 234/244 @.50
To get a decent clean idle that's not going to make you cry its going to need a ton more initial. Then we can worry about jetting and PV.
To the OP
You need to set up the dist to limit mechanical advance, a 10-12* curve. Then you can start at around 24-26* initial. And keep the total around 34-36* then using an adjustable vac advance can (crane makes a good one) you can add in another 10-12* vacuum to your initial. This is going to let you have alot more adjustability with the Carb and really really clean up a rich idle, and its going to perform far better then it does now. The rest of the Carb I would set back to a baseline like i stated earlier. The factory jeting and PV are going to get you really close.

 

Quick edit here, if you do pull the Carb for any reason, might as well throw in a 4.5PV cause with that cam its going to want something close to that.

 

i have a msd ignition box and vac advance disconnected.

 

i messed with the carb somemore, jetted the primes down to 64 and the secs to 65. 5.5 powervalve and 28 nozzle discharge. its still running pig rich. im going to put the 31 nozzle back in adjust the metering valves again. is going below 64 jet size going to hurt the car (lean)? im thinking maybe a 60 prime and leave sec at 65

 

Your not listening sunshine......stop jetting down so far, your gonna hurt something without a wideband or the experience to read plugs correctly. If you still basing your "I think its too rich cause it stumbles and bogs in park" then you can take as much jet out as you want, its not going to change fk all. Set the transfer slots, reset the idle screws to 1.5 turns out, put the stock jetting back in, put the stock squirters back in. Leave the 5.5PV alone for now as its not relivant. Your timing curve and advance is completely wrong for this combo. FIX THE TIMING like i mentioned before, then come back and thank me when it actually runs decent and performs like it should. And get a vacuum advance can, they are like 30$. It will make a difference. What your doing is simply wasting time and hurting parts.....

 

Tell you what, for a small science experiment, set the Carb back to stock, then pull the springs and weights on the mech advance, hang them all the way open with a zip tie. Now your timing is locked, set the dist so you have 34-36 degrees right at idle. The idle is going to jump way up, so set it right, use the vacuum guage to find the highest setting in gear, then go drive the damn thing and hang on. That cam will be fine with the timing locked and it will show you what I'm talking about. Whole new animal...trust me. It womt start once its hot, so this is just a simple "I told you so" experiment. Then we can limit timing and set a real advance curve.

 

its not bogging or stumbling in park, its doing it when i actually drive it at wot. i have the timing set that when i start to get chatter i back it down a few degrees, its around 32. ill mess with the timing somemore and put the stock stuff back in. whats the vaccum advance can going to do? i never had one before. i appreciate the help

 

The engine does not care what the number stamped on the jet is.

All it cares about, is how much fuel it's getting.

It will tell you in uncertain terms, when it's right or wrong.

The advice above about timing is however, right on the money. I have been making the assumption, which got left out of the sticky when Apeiron created it, that your dist is already set up properly. If this is NOT the case, then you MUST get it right before even ATTEMPTING to mess with the carb.

For that horrible mismatch cam you've forced on yourself, you want your dist set up with about 18 - 20° of "initial" timing (what you get when you twiddle the dist body), about 16 - 18° of centrifugal advance, starting just off idle (1200 RPM or so) and "all in" by about 2700 or thereabouts, for a "total" timing of about 36°. You can use the tie-wrap method he described to set "total" timing FIRST, and then let the "initial" fall wherever it may, with your particular springs, weights, & dist cam. But whatever method you use, don't use a "dial-back" timing light; instead, make marks on your damper at 10, 20, 30, 40, & 50° BTDC by setting the engine at 10° and making a mark on the damper that lines up with the 0° on the pointer, then setting that mark to 10° and making another mark at 0° which will now be 20° BTDC, and so forth; so that you can leave your light set to trigger at the instant of spark. All of this is to be measured and perfected with the vac adv line disconnected. You'll want around 15° of vac adv on top of that, such that when you're cruising down the highway, the actual timing will be around 50°. You'll most likely get best results by hooking your vac adv to hard manifold vacuum instead of the "ported" source on the side of the carb; again, your cam is a completely bad choice, and totally hostile to street tuning. But it's too late to go back and undo that mistake now, just gotta work WITH it instead of FIGHTING it.

But before you can even do any of that successfully, you need to verify the timing mark itself, independently of the "mark" and "pointer". A piston stop is the best way to do this. Since you already measured it to a high degree of accuracy while building the motor initially, (you DID, didn't you???) all you should have to do now, is add the other marks.

Then once you get the timing right, go back to working on the carb. You will find that if you altered the timing to any significant degree, it DRASTICALLY affects the carb's behavior, thus rendering any tuning you've done on it so far, irrelevant. Whatever you've done to it so far, UNDO ALL OF IT, put a fresh carb kit in it, put all the metering parts back to STOCK, and start over, going through the steps in the sticky, one at a time, in the order they're given, from start to finish. Don't just start randomly dinking with stuff like you've been doing: use discipline, logic, and common sense to maximize each subsystem in it while its effect is isolated from the others and exposed, like the sticky tells you how to do. Don't worry about what "number" your jets are, or any other part; if the motor is too lean or too rich, IT WILL TELL YOU. Listen to it, it knows whether it's happy or not. But you HAVE TO do it IN THE RIGHT ORDER, so that you can make one adjustment without interacting with all the others; otherwise, you'll be dinking with it every day for the rest of your life, and it'll NEVER be right, prolly not even by accident.

IF IT RUNS GOOD, IT IS GOOD. It's just that simple. Conversely, if it DOESN'T run good, then it's WRONG.

Don't outsmart yourself. Just follow the instructions.

 

good info there sofa. one more "stupid" question. with me not having a vaccum advance on the dist and having the msd box, do i need the advance hooked up? i was told by "summit tech" that i dont need it due to having the ignition and timing controlled by the msd.

 

I can't imagine any MSD unit somehow "replacing" vac adv.

Think:

Does it have a vac connection on it?

Then how could it POSSIBLY perform that function?

What dist & box have you actually got? (part #s only, please)

Your dist needs to have vac (load sensitive) and centrifugal (RPM sensitive) automatic adjustments. Without that, you'll REALLY never get it to run right by dinking with the carb. No amount of messing with a carb will make the spark occur at the right time.

 

i have the msd 6al. and an accel distibutor not sure the part number on it. ok ill hookup back up the vac canister that was originally on the dist when i got it and run the vac advance line to it.

 

and just to "kick the bucket" is there a way to time without having a vac advance hooked up?

 

Listen to Sof again, he is bang on. To set the timing you DO NOT WANT THE VC ADVANCE HOOKED UP. The can at the dist can be left unplugged, but make sure its blocked at the Carb.

 

i was referring to NOT having the vac advance AT ALL.

 

ok prob gonna get bashd but here we go. i have the timing at idle at 42* without vac advance. i havent ran vac advance with my eddy and never had this many issues as i do now. it runs, drive and has 12hgi of vacuum and idles at 950. it seems no matter where i put the timing it runs rich in cruising mode and wide open throttle. i still get the stumble before it launches. i left evrything the same. now to releve the stumble i can up the squirter size, but still dont have the richness handled.. i have the metering valves 1 turn out equally where i get max vac. if i turn them in all way motor dies. im starting to get the concept or so i think. is my timing still out of wack? and can i do timing without the vac advance still?

 

Timing at 42* is going to hurt something, is it locked or do you still have the mechanical advance hooked up? You get that you had 14* initial, and 36 total when we started. If all you have done is set your initial at 42 with no other changes it seems completely likely you have hurt something trying to drive it like this. 64* will do that lol.
Fine, skip vacuum advance for now, is the Carb completely back to its out of box settings like I explained at the beggining? Assuming you followed that advice, make sure your transfer slot exposure is right at 0.020 or completely squared.
So now we have a "stock" 650dp
Not trying to be ignorant here but explaining how to use a screw to limit advance isn going to be wasted for now. Your not there yet.
Instead zip tie the advance completely open, reinstall the dist.
Google search this if you don't know what i mean.
Now that that's done, get your light, I know sofa mentioned not using a dial back light as they get weird sometimes with msd boxes. I haven't personally experienced this but I do know it happens. That being said I'm going to guess you haven't marked your balance with a tape or verified its accuracy so lets roll the dice and use a dial back light for simplicity sake.
Get the thing running, set your light at 34*. Rotate the dist until you see the mark on yje balancer line up with zero on the timing pointer.
Tighten the dist hold down. Set your idle down as its now going to be real high.
Now the idle and timing are set.
Don't shut it off yet. Using manifold vacuum, again, bottom front of Carb, pull the rubner cap you have blocking that port and install the guage.
Set brake, chalk tires.
Put in drive.
Use mixture screws, find highest vacuum, try and ensure they are balanced.
All done?
Good, reinstall little rubber cap on vacum port. Go drive it. Have fun, report back later.
2 small edits here, replace the plugs first, by now they are fkd.
Second is, what converter is in this thing? Cause if its stock, your screwed anyways with that cam.
Anyways, I assume a decent 3000+ converter and hope you change the plugs.
Go drive it, report back.....and don't say the Carb is back to stock settings if it isn't, if you don't help yourself, we can't help you either.
Good luck

 

And no, its absolutely not going to start when its even remotely warm with that much timing. But if you like it drives we can fix that problem later with an easy sub 10$ fix.

 

lol ya i put the timing at 34. and i had it at 36 when this thread started so not really a big change there. i have a 2800 stall convertor.; i put everything back to original settings, and followed the sticky and yet its still rich. i talked to holley tech and they said they believe theres an internal fuel leakage somewhere so i might be swapping out this carb.