Best Holley Book for 4150 Performance Tuning?

I have a 950 Street HP 4150 on my big block and it is ready for some tuning. The motor is still in the break in stage but it is running rich.

I seen a post on here recommending Emmanuel's book but I also found one by David Vizard.

Any recommendations?

I'm looking for one that will tell me what steps to take for tuning for performance.
I understand about jets, air bleeds, power valves and such I'm just not sure of a step by step approach to tune it.
I have an A/F gauge and I'm running rich off idle.

Any suggestions on a book?

Thanks in advance for your help.

I have Vizard's book (the "new" 2013 edition) and it is worthwhile reading

That is the one I'm leaning towards. I was able to see sample pages online without buying the book and it looked like it had a lot of good information.
I wanted to check into the Emmanuel book first since a few members have mentioned it.

can you post a pic of it. My Holley knowledge is borderline & I'm read his stuff before & was impressed

Personally, I don't think there is a book that does a really good job. Probably because tuning the idle and transition circuits gets real complicated real quick. And because carb tuning is as much about sensing what needs attention as it is about reading the O2.

Main jets, power valves and PVCRs are not hard to get a handle on. But bleeds, slots, and emulsions are another matter entirely. And just to further complicate things, all those circuits and items come and go with most overlapping each other making it extremely difficult to understand what is causing what.

It takes an enormous amount of time experimenting with different tweeks to see how your particular combo responds. That is AFTER a good amount of reading books and studying the different circuits of your carb.

The best thing to do is to start with a carb that has a tune in it that is as close as possible to the correct tune that your combo wants. The farther off the initial tune is, the more circuits or items that will have to be corrected making the job just that much more difficult.

Or you could contact someone like ThumperDart to get the tune close enough that you can tweek it on in without having to understand the entire low speed design of your carb.

https://www.amazon.com/Vizards-Modify-Holley-Carburetors-Performance/dp/1934709654

I would suggest also exploring this site in addition to the book mentioned above.

http://racingfuelsystems.myfunforum.org/index.php

I just bought the Vizard book; haven't gone into it in depth but just a quick scan reveals some good info on emulsion & understanding how the various systems work. Better than the old book I have, which is from HP Books from the '70s. That book goes into various (old) models & history and hits on a lot of things, but Vizard's book seems to have more "how & why" in it.

Books
Normally I recommend starting with Urich and Fisher's Holley Carburetors and Manifolds because it provides a good foundation without being overwhelming. Its better than Emanual's version in my opinion because Urich was a Holley engineer so his descriptions are more accurate. Also the HP Books format allows more to get packed in.

However in your case, neither probably have enough depth for what your looking for. Vizard's new Holley book is probably a better choice if you just want one. If you can get a used copy of Urich and Fisher in addition, you'll find a few gems in there. For example, the sidebar on throttle to transfer slot relationship is very clear on why and what to do to get it right.

As noted above, Vizard's new Super Tune and Modify Holley Carburetor book is more thorough. Just be careful with generalizing too much from a specific example. Been there; done that. ouch. A specific area I'm not sure he gets into the subtleties of how an airbleed can do the opposite of what you think it will.

Steps
Not sure any one book will quite cover this.
Generally start with the ignition curve and then work the idle circuit (including transition) first. Then the pros like to go next to the primary mains at cruise followed by WOT. However that can result in the primary mains being a bit lean for the WOT pass. In any event do the steady state conditions first and be prepared for several rounds as one system effects the next. Starting with idle - transition minimizes this because it will effect the mains more than the mains will effect the idle.

One real difficulty most of us have to overcome is fully accepting that the engine is on "idle" for most street driving except interstates.

Search here for threads on carbs like yours.

These are also useful and the books they come from are cited.
AFR Relationship to Throttle Opening (Load)

Importance of Position of Idle Feed Restriction

editPS. I agree with all the posts above from Dave, Oscar and DrCharles which I didn't see until after posting.
As far as rich at idle, as you dig deeper you'll be able to determine whether this is a problem or not.

All noted. thank you!

Thanks to everyone. All good information.
I realize it takes a lot of experience to get good at tuning carbs for street / strip performance.
I would like to get mine dialed in close enough so I can get it to a performance shop that has the know how and a possibly a dyno. Right now the plugs are sooty. I have it close on idle around 12.5 AFR or so but just off idle (around 1500 RPM) it goes fat. About 10.8 to 11.2 on my AF gauge. The carb is out of the box 950 street HP without any tweeks. I haven't checked manifold vacuum yet so could part of the problem be the power valve?
Everything is fresh. I might have 25-50 miles on it. (505 "B" block, trick flow heads, Comp Cams XE282S-10 cam)
I like to do a lot of my own work so I would like to get a good book so I can read up and at least understand the more complicated areas of tuning. I will get it close then hand it over to the pros.
Thanks again!

I know that all applications are different, but there seems to be a lot of evidence that the 950 is pig fat through the transition for just about everyone.

The Dyno is good for WOT. If the dyno has a load cell and the owner is pretty sharp, the dyno can be used for some other stuff.
But the low throttle position stuff you'll do off the dyno.
Since you have the interest, don't be surprised if you become the guy with the know how. Anyway, get the idle and street stuff running cleaner. Your plan is good. Just be prepared for a journey.


Not likely. The idle restriction is much smaller than the main jet. It doesn't matter if there is more fuel available (power valve opening) because the main jets are not restricting. See post here for link to video. Bruce 'Shrinker" Robertson outlined the situations where the main well pressure is effected. But the simple version is that carbs aren't normally that way.

What is probably happening is that the manifold vacuum is under 14" at idle and then going up as the throttle is opening. The carb will need to deal with this - its pretty common on modified engines.

Vacuum gage will be a big help. Its a good indicator of load and therefore an indirect way to estimate throttle position.

Lots of things effect the idle mix. Idle air bleed, idle restriction are the ones we'ld like to use. But transition slot acts as a variable feed and air bleed, so throttle position comes into play. Fuel level effects pressure so that can make a difference. Also whether it is two corner or four corner idle.

I'd poke around the racing fuels website and see if anyone has mapped out that same exact carb (list number). If not, then add that to your todo list. With that you might get a sense of what probably needs to be done to start moving in the right direction.

with Mattax.

The transitions before main jet actuation is absolutely the most complicated and difficult area to tune. And is the area most likely to need attention out of the box. Depending on how far off it is will determine how much attention. Most of the time, the main jets and their bleeds are not far off and can usually be brought in by testing at the track.

In order to clean up your low speed, you have 3 routes to choose from;
A)have someone else re-calibrate it,
B)have someone else try to tell you how to re-calibrate it, or
C)buy the drill bits, taps, bleeds, jets, and books and start experimenting.

I will offer a shortcut that has worked well for me. Strip out some individual strands from some electrical wire. Mike them and assort them by diameter. Since your carb is too rich, you probably need to reduce fuel flow somewhere. You can try a wire in the T-slot restrictions and then a wire in the idle restrictions to see how it responds.

Now wires in restrictions is a bit like using and axe for a scalpel job, but will quickly show you what needs attention. Then you can buy the drill bits, taps and bleeds to fine tune those areas.

poke around the racingfuelsystems website or just google holley idle feed restrictions.
assuming you have yr prim thorttle plate in the right spot, leaning out the 1500 rpm range probably only will involve a smaller idle feed restrictor (or sometimes called idle jet, or IFR). do the metering blocks have replaceable IFR's ? they will be up high most likely, in the upper outside corners.

you probably want to go down in size about .002, so say .035 to .033
you can also hone in on the afr's some by going larger on your idle bleed which should be adjustable on that carb.

this is just a page i pulled from a websearch, it shows the IFR location in most holley blocks.
http://tmpcarbs.blogspot.com/p/blog-page.html

Shoot, Isn't an idle AFR of 12.5:1 fat to start with?

R.

The pictures are nice but be careful with anything from Troy He won't acknowledge what he doesn't know but continues to argue ad infinitum. It got so bad he was tossed from Speedtalk forum.


It depends greatly on the specifics.
Considering the OPs combo, its ballpark.
See link to AFR-Throttle Position/Load in my earlier post.

Question IS your carb a true 950 size or a 750 size bowls?
I ask this because alot of people don't realize that the 950 is actually smaller than a good 850.
a 750 size would be causing you more trouble.
I would start by enlarging the idle air bleeds and see what your air fuel is at idle i would shoot for 13.0 afr.
then restrict the idle feed to around .028 or.026 and see where you are .
my car used to run like yours and i did this and now i am 12.5 pretty much all the time cruising.
make sure you are idling on the idle circuit that is a must and most important thing.
I would also start with 84 primary main jet and 90 secondary main.
jetting affects the whole picture.
You have a A/F so you will see the improvements or not and then know which way to go.
Don't put a very low opening power valve like 4.0. run vac gauge into the car and tape to dash.See what the motor wants. I bet it would be good with a 8.5 opening point that motor needs fuel enrichment asap after you are off the T slot or transition.
measure the size of the pvcr and most likely open to min .070in
the bigger the pvcr the smaller the main jet can be the cleaner the idle will be to a point.
this is just a suggested starting point you will see real quick if the changes made are improving things,

Suffice to say that I agree with almost nothing in this post and recommend that these suggestions be ignored.

I'm sure that was posted with the best of intentions. A lot of stuff on the internet is. However, I have to state that I agree 100% with Dave's assessment. Not going into specifics because that's not fair to the OP. Just read the books and links discussed.

OK not here to start a war, every one tunes carbs different.
What I ment was the smaller carb will have a much stronger signal.
I was just suggesting to start with the idle circuits and then move onto the rest , he is pig fat rich I was trying to get him in the right direction the op says he want to do it himself and has a A/f and sounds pretty competent.
know one can give the perfect tune over a forum.
Was just trying to help sorry my helpfull nature got in the way of the forum police.
It was never mentioned to be the final word on the tune.
But hey I will admit do one change at a time is 100% correct.

cjs, I really appreciate your input. I did hear something about the 950 not being a true 950. I'm not sure if that is the case here but it could be.
I appreciate everyone that has given their thoughts and ideas to help me with this.
Some of the information will take me time to absorb. I have a pretty good basic knowledge on how carbs work, I just don't have the experience on fine tuning one.
I like to learn how something works then I can understand how a "change" will affect it and I am a firm believer on "one change at a time". I did change the idle air bleeds to get it to where it is now. It was so fat my eyes were watering!
First thing I am going to do is get the book and do some reading. Then I will make some changes and see if I can get it dialed in a little better.
I will post some of my findings and I hope you all will chime in and help me out.
Thanks again everyone!

You should be able to kill the engine by turning in the idle mix screws. If you can't the engine is running on the transition circuit because the throttle is too far open at idle (or you have a fuel leak into the intake manifold). Leaning out the idle by installing a larger air bleed will also lean out the transition circuit (low speed, just off idle).

Instead of buying one or more books I suggest doing your research online. In my experience, most books are filled with fluff and just tell you do tune jets, pumps, squirters and such but never get into the real good stuff. And if those basic tuning tools aren't enough most authors suggest getting a different carburetor. You can do better. The Edelbrock site used to have a fairly extensive tuning guide for their AFBs, Holley may have something as well. Your best source is internet forums, just don't accept the first things you read, read a lot and look for some sort of overall consensus before diving in. You don't need to ask questions, most have already been asked and answered before in many forums out there. Maybe just start a thread here regarding the tuning sequence for your particular carburetor.

I'm pretty sure I've read every Holley book out there and in my opinion none of them are very complete. They all cover the simple basics but none of them really walk a person thru the process of tuning a Holley on a hot street engine with a cam that is a little too big. This is the most common issue that hot rodders have so I'm not sure why nobody covers it.

The key tuning trick on a street engine is to start with the idle circuit and work your way to the power valve circuit. So idle, transition, mains and then power. You build a carb like you make a cake, one layer at a time.

And get your ignition timing correct before you start messing with the carb. Most "carb" issues are caused by the ignition timing.

That is cool man i was in your shoes a couple of years ago so i unstood where u were coming from.
I was just not let anyone scare you into not trying to tune your self.
You can do it just make small changes and error to rich side , problem is many carbs out of the box have a very rich tune and to get them running good it takes some time.
I did see something in your picture that i thought i would mention .
I don't see a PCV system on the valve covers you should be running a pcv on one side of the engine and a breather on only one side for proper ventilation and ring oil control for the street.
I have the same valve covers on my stroker 440 and had to knock out the plug on the right side and add the correct grommet and pcv valve hose to manifold vacuum.

Ok, got my book. It makes for some good bedtime reading. I agree with everyone that the books are pretty basic and don't go into great detail but I did learn a few things.
By the way cjs I do have a pcv you just can't see it in the pic.
I don't know how I had 12.5 at idle as I mentioned earlier. I may not of had it up to temp or something. I went out last weekend and warmed it up to about 180 and took some readings.
First, vacuum at idle is at 15 after that it goes up to around 22 at 2,500 to 3,000 rpm.
Here's what my A/F gauge is telling me:
800: 11.5 (To make sure I was on the idle circuit)
1000: 11.4
1300: 10.9
1500: 10.6
2000: 10.5
2500: 10.6

For it to idle around 950, my idle speed screw is turned in 1 1/2 turns. I don't know how far into the transition slot that puts it.
I don't know if the carb has replaceable idle jets or not. I plan to pull the fuel bowl so I can note what main jets and power valve are installed so I can look and see then.
The carb is a 950 street HP so it doesn't have the adjustable idle air bypass screw like the ultra models.

I bought a calibration kit that has jets, power valves, squirters and gaskets. I also bought some air bleeds.

As far as timing goes, my initial is at 14 and all in around 3,000 if I remember correctly. I will confirm that.
I have a MSD billet distributor (with both light springs installed)and 6AL box as you can see in the pic.

My plan is to go out and pull the bowl and make notes then check my timing again.
Then I will start with idle and work my way up like Andy mentioned.
Feel free to chime in. I appreciate everyone's input.

With all the mixtures "ballpark close" I would finalize the dist initial/total/springs/vac can (if used) IN ORDER then as Andy said work on the carb systems in order also. First one for instance, cuz you are on the idling circuit when you are setting the initial & use the "vac gauge method" for it & with an initial number in place, back off a degree or two of timing as needed IF the starter is cranky when hot (or use an ign bypass). the vac gauge method itself includes finishing by backing off the INITIAL to get the vacuum to drop 1 in hg to get your final INITIAL amt & that is in the main procedure & is unrelated to whether when done the starter will require another 1 or 2 degrees of TIMING reduction. just so there is no confusion.

If your AF gauge is correct then you are dead rich at idle. For a street car you should be in the 14's or 15's at idle.

Add some ignition timing and see what happens with the AF ratio on the gauge. Screw in the idle jets and see what happens. Depending on the camshaft you might want to run as much as 20 degrees at idle. If the AF ratio leans out as you add timing then that is a clue.

If you have billet metering blocks then there should be idle jets. If you don't have billet metering blocks you might want to buy a set since the tuning will be easier. You can modify your existing metering blocks but it is a hassle. Personally I throw away any of the older metering blocks and just switch to billet but other people enjoy doing stuff the hard way.

Pull the plugs and see what they look like. They should look really rich if your AF gauge is correct.

Seems reasonable.


Presumably this is in gear, driving at steady speeds.
Tracking this as you have started is a good way to help tune the idle circuit.

Tip. Next time the carb is off, measure the transition slot visible for every 1/4 turn in of that screw. Now you'll aways know. If you can, measure the t-slots length and width as well for future reference.
The transition slot visible at idle should be between .020 to .040"

Probably not and they're probably in the wrong place anyway. Tap and relocate as explained in the link.

The PV and MJ can be looked up the on Holley's list Numerical list. Links to it in the Holley Stickies.


No biggy. IF needed, you can make your own or drill the throttle plates. The former is convenient to adjust, the latter provides better mixing of the fuel into the airstream.


Great! To find out what size bleeds the carb has now, you will have to measure. For this you'll need micro-bits or gages. Bits are cheaper and can be used for drilling your own bleeds and feeds if needed. Then take the blocks off and map it all out. Many of the new carbs have three or more "emmulsion bleeds". Using just two tends to produce a better, more consistant flow. However this shouldn't effect your idle circuit tuning.


That is a good idea. Plot the timing from idle until it flattens stops advancing. Intial timing seems a bit low on for that engine and cam. Barry Grant used to have a chart on-line for selecting carbs that also had intial recommendations. Try between 16 to 20 and it should be able to idle with less throttle opening. (This assumes no vacuum advance at idle)

Tip. Keep note of how much the idle mixture screws are open.

Tip. Make sure to check the fuel level in the bowls. Old style starting points is just at bottom of plug. Big window style is usually mid-window, but follow whatever instructions say.


Remember, the name "Idle Circuit" is misleading. The car will be cruising 40 or even 50 mph on the idle circuit.

edit: I agree with Andy on check the spark plugs. Always see what they can tell about what is actually happening inside.
I disagree on the idle AFR. Depending on cam, it may be more efficient and powerful down around 13:1 Even many production cars ran best with richer than stoich idle (through the late '60s for some non-CAP vehicles). See the AFR - Load graphs in my earlier link.

UPDATE:
I downloaded the Holley chart so I won't need to remove the bowl just yet.
Andy, I bought this carb just last fall so it will have whatever metering blocks they come with out of the box.
I don't have a problem buying billet if that's the way to go. Do I need one for the secondary side too?
It's raining here in Washington (Imagine that) so I can't go for a drive however:
Timing is at 19 initial. I didn't have a buddy with me so i can't check when it all comes in. I have no vac on the distributor.
I adjusted all 4 idle mixture screws until they were out just under one turn. They were out around 1 1/2 turns. Idle speed did pick up some so i was able to back off the idle speed screw.
At 900 RPM my afr gauge says 12.5 or so in park. When I put it in drive it goes to 13.5.
Vacuum is still around 15 at idle.
My idle air bleeds out of the box are .025. Right now I have .027 for all four. I have .030 available that I can put in if it might help.
I haven't pulled the plugs out lately but the last time i did they were black.

I'd save your money and just tap the blocks you have. Its not hard.


You should be able to do this without a helper (even though its always nice to have one). However a tachometer is crucial.
If it is 19 at idle, but idle is 950 rpm, then its still possible the initial base timing is 14 degrees. Here's the issue; its not a biggy but it can make it a little more difficult to get a consistant idle. When the car is warming up or put in gear the engine slows a little, to say 800 rpm. Then if the timing drops off with rpm, at 800 rpm it is only 16 BTDC.

To check the curve without a helper, use the idle speed screw to open the throttle. That way you can read the timing and rpm, write it down, then open the throttle a little more. I try to record every degree or every 200 or 250 rpm. It really is whatever is easiest with what you're working with.


Good.


If what you're seeing on the AFR gage is real, it is due to the engine rpm slowing from the slight increase in load. As mentioned above, lower rpm *might* be accompanied with less advance. It almost certainly is also losing a bit of manifold vacuum. Think about what happens when there is less vacuum (pressure difference) across the idle circuit with no other changes. So that's probably why you're seeing that on the AFR gage.

Check that. Those seem small for idle (except two corner idle secondaries). Those sizes are more like Main Air Bleeds, at least for the 4150/60s I've worked with.

I know it sounds like a pain, but be sure the primary side t-slot relationship is ballpark correct before making changes to the bleeds. Have you read yet that the T-slots are an air bleed too? So if that t-slot to throttle blade relationship is changed after changing the idle airbleeds, you will almost certainly have to change the bleeds again.

When it comes to larger air bleeds or smaller IFR, you'll probably have to experiment methodically. Just remember a larger bleed can sometimes cause the fuel to start moving earlier, making it richer when you expected it to be leaner. Vizzard's books and the posts at Racing Fuel Systems will help with that.

As a few others said above, idle circuit tuning is important but time consuming.
Try to clean 'em. When the AFRs are looking better, definately get a clean set in.

on the idle mix screws, alot will say the ideal position is 1.5 turns out.
but as you are getting started with the tuning, you need to lean them out as much as the motor needs.
screw the idle mix screws in until the rpm's quit rising (at that point maybe richen it back up the smallest amount you can turn the idle mix screw).
also, readjust the idle mix whenever you make any change to the tuning...

also, pull the carb as you are getting it close so you can look at the transition slot and make sure it looks good, roughly it should look like a square. if it's off you can use the secondary blades to help bring it back in place.

The idle air bleeds sound like is where your problem is .
the idle ones are the outer closer to the out side of the air horn or top of the carb .
The mains are closer inside near the squirters.
my engine always ran leaner at idle when i increased the out air bleeds this is why i suggested a .070in idle air bleed on the primary side first.
.025 is the reason you are so rich if you are sure of the position.
.025 is the main air bleed size for sure.