Holley 600 on na 6 port 13b tuning help
 

I know this topic has been beaten to death in a lot of ways, however while searching im not coming up with much useful results.

For starters, im using a holley 600 on too of an RB manifold. I have converted to center hung float bowls and am using a 1" spacer to so that the vacuum secondaries will work properly. I have done the metering block conversion on the secondaries so i can easily change out jets instead of having to change out metering plates. Im currently running a .64 (i think) on the primary and a .66 on the secondary. Putting a wideband on it today to do some tuning.

The part that i am curious of and cannot find info for anywhere is, what accelerator cam do you guys recommend? Part throttle and full throttle isnt bad but that transition from idle to off idle (which is controlled by the accelerator cam) is rough. She wants to stall on take off. Have to rev it a little and feather the throttle to take off. The cams are different colors representing different shapes for the accelerator pump.

Any input guys?

And please dont tell me to use a side draft. If i could have bought a weber setup for as cheap as i got all the holley stuff i would have but i dont have much invested in all of this. Also i know that a lot o people are still daily driving on holley carbs up op of rotary engines with no problem. So again, please no negative comments. Thanks

invest in this it'll become your best resource
Amazon.com: Modifying & Tuning Holley Carburetors -Volume 2 (Best of Hot Rod Magazine): Explore similar items

First off : Epic Sigh.

The problem youre having is actually an acc. pump thats way too big for a rotary. Thats why the RB versions come with the smallest cam (white cam) and small ap nozzles so as not to flood the engine instantly, as is what I experienced with standard holleys.

aaaaaand, transition from idle to off-idle to part throttle is NOT only the acc. pumps job. Fuel is also literally going somewhere else while it dumps fuel down the barrels to cover that gap, if that makes sense. At low engine speeds and low throttle angles, holleys provide fuel through the idle jets (which are cast, not exchangeable) and when the carb actually starts getting air speed enough to pull fuel through the boosters, fuel will begin to flow from there, in an emulsified state. Which is a totally different can of worms, actually. Bottom line, low speed air bleeds, the difference in rate between them and high speed air bleeds, emulsions restrictions, booster type, idle jets, and manifold height all play a role in your off idle bog.

GL.

Also to post from another thread I made a detailed list of the problems you'll experience with these carbs:

2)Floods easily (30cc Acc pump that you cant change the restrictions for the jet shot size! (Cast metering blocks, total lack of pump nozzle/cam tuning )

Also one other thing, check the gap on your holley's acc. pump arm, should be around .015. And see if theres any wobble in it at all... If there is, your pump arm is already junk, needs replaced or bushed. If its not totally rigid, youll get inconsistent pump shots and the ever-so-loved holley off idle bog.

Happy tuning!

Alright, so replace the pump arm, because there is some wobble.

After spending relentless hours searching, i found where someone recommended the pink cam, and also richening the primary jets because rotarys prefer being rich down low. So i installed the pink cam and put .66 jets on the primary side. The bog is almost gone, that same person recommends upping to the 50cc accelerator pump kit which will replace my pump arm. But im in a lack of current funds. I do have the white cam, so i will try that and see if it helps. Im quite happy as of now, already driving nicer than it did with the efi and bad tps and failing afm lol. This is about the bet i can do for now as i became unemployed. Have some interviews coming up so hopefully something works out :) .


I will definitely by that book soon as i can. Thanks a lot guys for the input :)

Btw, the cam that was installed was the orange one. Its was 466 where the pink one is 330. Will try the white one either tonight or tomorrow.

Were you saying that you think the 30cc pump is too big?9

Alright so after looking at the chart on holleys website, it shows that the pink cam is the least aggressive and the white cam is more aggressive.

Well "aggressive" is referring to what? The white cam if you look at it is very linear but still has some height, using the entire 30cc pump at a full stroke.

I never used the pink cam myself, and yes I would have to say the 30cc is too large. if you want to test that out, drive some where and give the engine a nice blip of the throttle and then immediately let idle down. Does it stutter and wanna fall on its face without you saving it? If it does, the pump is giving more fuel than what the engine can burn effectively, so its just wasted gas...

Thank you for the input, i switched to the white cam an now it only bogs if i wot under 3500 rpms. Very very drivable with the white cam.

Now i need a vacuum gauge so i can tune the power valve.

I learned that racing beat removes the power valve but guel mileage is better with it. Im not 100% sure how to tune the power valve. To my understanding, i check a vacuum reading at idle and then another vacuum reading at WOT and pick a power valve between the 2 of them. Is this correct?

Whats your driving style? 8.5 is the "standard" choice so try that, im heavy on the accelerator so I used a 10.5 in mine, because that way the power valve dips open at 30%+ throttle, so pretty much whenever I WASNT cruising, it was open :P


Also, check your vacuum reading at idle with the RB mani, it wont be totally steady, but thats normal. let me know what it reads, I can help you further and give you an idea of the health of the engine at the same time.

I just hook mine up to the brake booster port, and check there. Make sure the engine is fully warmed up, and choke is fully open. At this time also adjust your idle screws evenly to the highest possible vac reading you can get.

Happy tuning!

Get yourself a wide band and give me a call. I always liked a pink cam and shave the back side on a grinder so it squirts less fuel hat higher throttle possition. No cam from holley is good for rotary you need to modify it.

You also need to press in air bleeds and modify the transfer slot. Dbl step boosters help a lot too but shouldn't be nessassary on a good motor. The only thing better about webber is looks. Holleys run great if you know what ur doing. Mine pass emissions high and low idle test.

Lol

i think you can get pretty much anything to work, its just how far you need to go to do it.

good job on the emissions thing too, attention to detail :thumbs:

Thanks for the input.

The current power valve is a 6.5 which i believe is far too low.

Im borrowing my buddies vacuum gauge this weekend to get a reading. Then invest in a new power valve. Its running lean around 3500 rpm or so. My tuning day ended in a halt when we came to the realization that the power valve isnt working.

Im currently running .66 on the primary and a .64 on the secondary for now. Hopefully i can get the power valve this weekend. I have a friend who has a jet kit and i can use whatever i need and just replace it afterwards to keep it full. Im really excited with how easy she is to drive. She idles cold happily. This carb doesnt have a choke. :)

The engine only has 81k miles on it and pulls 115psi on both rotors on a standard compression tester with the auxillary port sleeves removed. Oh yea, its a 6 port 13b engine thats in an fc, i posted in the first gen section because in the second gen section they frown upon simple carburetors and first gen guys have all the experience.

This isnt my original engine. This engine came out of a beautiful fc vert that showed 75k on the odometer. Engine came out for a 302 v8. I snatched the engine, trans, and everything else :)

I am very happy with the holley so far. On efi the car wouldnt idle cold and on the carb without a choke it idles cold happily. We will see how this weekend goes. Tomorrow is pay day so i hould be able to squeeze the funds for the power valve (i recently became umemployed so funds are tight. But a new power valve will allow smaller jets on the primary which will allow better fuel mileage ;) )

Sincerly, thanks for all the input.

^Nice post. I like it when carbs work out better than EFI.

People around me like EFI, or they think they do. I don't. I'm perfectly content to stick with carbs.

You know, I've tried the aftermarket EFI thing. Didn't care for the experience. At first it wasn't too bad; I can solder a MegaSquirt perfectly. The custom wiring harness was flawless. But when it came time to tune the dang thing (MegaTune software), I was like a deer caught in the headlights.
https://t2.gstatic.com/images?q=tbn:...ySzC36NEDh2OEM
I looked for the image from the end of that episode where he's actually caught in some headlights but this was all I found.

I have an S4 NA 6 port. My friend has one. My other friend has one. All carbed at the moment. One guy desperately wishes to go EFI but would prefer a MegaSquirt (I'll throw mine at him just to get it out of here, but then he requires wiring help, gurr!). The other guy could take it or leave it but wants to know whether a stock S4 ECU is worth all the trouble and if it will run better than his current Edelbrock 600 on an RB manifold, which runs actually pretty well. Some stumbles around corners though. From reading your post, it makes me wonder if the stumbles are worth swapping to EFI just to have a potential cold start problem (amoung a plethora of others) like you did. All the extra crap that's needed to go EFI... You can't see the top of the engine anymore.

Here is when I floor-tested the S4 ECU to make the injectors click and checked for spark.
https://www.rx7club.com/attachments/...-s4naefi01-jpg
It worked. Again, wiring. I find it easy. But testing it for real in a car is the next required step, which we did, but only while parked as nothing was bolted down. In hind sight, I should have installed the ECU in the stock GSL-SE location and bolted the FC coils to the battery tray since I've done a battery relocation and the stock ECU was already gone. Oh well. Now the 6 port is out and a 4 port is in. Too late to test.

Edit: found it!
https://t0.gstatic.com/images?q=tbn:...deXpBZpunuRRGM

in college I met a guy with a quadrajet (780 cfm) running a brigs and strat 10 horse. Thats why I always get a giggle when I hear the "runs great if you know what youre doing" thing.

The quadrojet actually ranges between 400-800cfm in the same carb. Its a really great design when you learn about it.

I have ao far owned 2 different dellorto dhla carbs but both were physically damaged and couldnt find parts for it. I really wanted/want an ida carb but got a great deal on the holley stuff and so far am very happy with it.

Either tonight or tomorrow im borrowing a vacuum gauge from a friend so i can check for a power valve, probably go with the 10.5 upon recomendation though. While were hooked up incan tune the idle mixture screws while im at it :)

Stock efi is a complete PITA!!! I hate it. Sensors fail and theres so many that its tough figuring out which one it is. Cannot wait to inish tuning this thing :)

With the 10.5 power valve, what primary jets are you running? Just an idea to start at :)

I love carbs. Aftermarket efi is good for boost. Otherwise, carbs make me happy. Cant figure out how to post a pic from my phone. Have a pick of a weber 55dcoe side draft draw through large turbo set up. Foud the pic on facebook and was oing to lost it here but oh well.

Start with a 55, work your way up by 5 until you dont feel anymore surging when driving normally (part throttle) eventually itll be smooth, and at that point youll have to go wideband to figure out where in the emulsions circuit to take fuel away at different RPM's (itll be too rich in some places once you find the right size jet for overall transition)

Your off idle stumble could be several things.
Low compression
Timing
Pump cam
But most Likely you need to lengthen your trans slots and change your air bleeds.
This is why my carb is so much better.
Under normal driving ur idle system is doing all of the work. Even at 60mph your driving on ur idle circuit. Your mpg is based on your idle circuit. A proper trans slot will separate ur idle from your cruise circuit. Air bleeds will determine if it gets richer or leaner in early throttle positions. Then there is main jets for higher rpm and secondaries for full throttle. It makes more sense if you watch me build and tune.

One more Holley option for people to ponder.
 

Another option === In the latter years the practice of Holley mods has taken different approaches . One that can be very effective is weather blow through or na is to .. Rather than removing the PV . it is suggested to install a PV 2/3 less than what the engine has for max vacuum so if you have 15 inches of vacuum at idle you would install a #5 PV which means the PV will start to open at 5 inches of vacuum , then note the two holes behind where the PV threads into Knowen as the PVCR -- POWER VALVE CHANNEL RESTRICTIONS . these channels are some where around .65 stock maybe a little less or more depending on model . What is being done is this ,,, (( the channels are drilled out all the way through the block on the same angel as the original ones taking care the last bit to make sure the hole does not chip when going through the last tiny bit , any sharp edges or tiny drill pieces should be cleaned ,without causing any scratching inside the holes . I use a pin vise for the last bit as was explained to me ..))larger than stock somewhere around .75 for most to start at maybe a little smaller and then work your way up .02 or so till you are satisfied this doesn't seem much but if you figure out the actual diameter of the holes you will find that increasing the hole size .10 will actually increase the size by around 55 to 60 % which is huge ( these numbers are not calculated it's just for explanation of the mod . the actual jet size rather than going bigger will be less in this mod . It is also recommended that the secondary side have jet extensions installed to help prevent hesitation from fuel starvation in the WOT . range . The rear power valve if so equipped should be removed due to possible .surges during full acceleration

This mod will allow you to adjust to a very smooth idle and also run very economically as possible at cruse and still give an ample supply of fuel at WOT. A good street mod , gives good low end economy and full balls at the wot mark .

Where as the mod requiring the PV to be removed makes the engine run rich at low power and cruse . the only thing if you don't like the mod is to replace the metering block and start over stock . just another approach and ways to deal with things .

And yes the Holley can be ran on most anything with good success . you will also find that most blow through on most any other engine involves either a Holley or a Holley Type carb . there is a lot of prejudice when it comes to the holley mostly because Most don't know how to tune them . Also you will probably find that you will require a 50 cc squirter to make the little engine happy from idle . Have a good day ..

i've done some experimenting on my Weber, and the idle circuit works based on throttle position, and the main circuit works on airflow. i find this pretty fascinating, as this is something aftermarket EFI doesn't do unless you bought something new/expensive.

so yes anything under about 25% throttle is on the idle jet, give or take

See my list in another thread. The prejudice is well deserved. They are not effective fuel mixers off the shelf for anything but a 300-400 ci V8, and even then youre stuck with bad fuel control and emulsions design...

Anyhow, try the 8.5 Pv to see if youre getting the enrichment at the throttle angle (for a carb, throttle angle=vac level. Lower thottle angle, higher vac.) you want, then change the sizes of the PV restrictions to level out how much you enrichment you actually want.

As another stated, about the xfer slots being modified, is further down the road of tuning. You first need to get the idle circuit the right amount of flow, and ratio before you start changing how freely it covers transition to the booster/emulsions circuit. Making the transfer slots larger also gives you a little more "idle circuit" at higher angles (lower vac) of throttle.

Happy tuning!

Hey guys, sorry been so long since my last post. Hooked up the vacuum gauge, pulls a constant 18.5" of vacuum.

Changed out to the 10.5 power valve which makes light throttle driving a lot better. I can go from cruising and lean very slighty on the throttle and she accelerates nicely. I plan to invest in the 50cc pump when funds become available. I recently became unemployed so finding funds right now is tough. I have access to all the fuel jets i could need though and for that i thankful.

The vacuum secondaries are not opening up as planned. I have the lightest spring installed from the holley spring kit. But it found a tear onthe very edge of the diaphragm. With that said, in order to drive the car efore gettin the new poeer valve, i had to do the screw mod to make the secondaries open almost imidiately. Im assuming it was needed to richen the fuel mixture. I couldnt drive withou the screw on before where now i can with the new power valve.

A previously stated im using a .66 jet on the primary and a .64 on the secondary at the time being. Im not 100% certain that te secondaries arent working, but around 3500-4k revs it begins breaking up completely. I need to replace the vacuum diaphram and play with jet sizing some more. I had put the screw back in to mechanically open the seco daries at about 1/3 throttle input. This helped a alot. She drives rather nicely this way, though i want it working properly. I have another diaphragm that isnt torn but is old, i will try swapping that one in. Its installed on another carb but i forgot tht carb at a friends house. Can pick it up tomorrow.

With this being said and knowing the secondaries ate currently mechanical, i did a 7k pull with my buddy behind me. I will state that even my fiance (who isnt that much of a car person) says it pulls better than it did on efi (i think one of my secondary injectors was only working sometimes). With that being said my buddy behind me said it was black smoking on the high end and all he could smell was fuel lol. As previously stated im using a .64 on the secondary. Maybe i will try goin a little smaller or kust wait untik i can score a wideband o2.

When i was driving the car on efi, the reason inthink one of the secondaries isnt working is because most the time over 3800 rpm (when the secondaries come on) it would cut out. Not like it does now without the screw, it would still rev but would do it slowly and instead of a smooth rev like baaaaaaaaaaaaaaaaaaah it was more of a baaaahbaaahbaaahbaaahbaaah while reving out one gear. I explained all of that so i can say that i achieve a similar problem now when part throttle drivin and bringing the revs up past 3k. Now learning that im part throttle driving on the idle circuit, that makes since because the idle circuit cant provide enough fuel for a thirsty rotary engine to be smooth. If i go any heavier on the throttle the problem goes away almost completley but my mpg goes away too lol. Im debating changing the primary jets back to .64 now that i have the PV functioning. That should help with economy but im weary that its also going to make that slight break up (for lack of words) worse, then again the idle circuit doesnt run of the jets so i should be fine right?

Ghost, when you say opening the transfer slots which ones are you talking about and how far should they be opened? Pics would be great though might not be possible.

Gerald, opening the slot behind the power valve makes since in my head, though im not for certain whih way the should be opened. You stated that the hole is drilled all the way through, but can you visually see the other end of where you will be drilling? Also, what is a pine vise? The person that i know that has the jet kit (i can use whateer i need, just replace them later when im done tuning) also has a full set of jet sizers (they are little needles that matchbthe size of jets. So if the numbers arent on the jets and you need to know what size it is, you would use these guys to poke through the jet until you found the one that fits it properly. Also can e used gor measuring the secondary metering plate or whatever. I cant rhink of the name of them) but for each size needle thing he also has a matching drill bit. This way he can properly redrill jets or whatever. He worked at a machine shop for a good 15+ years and builds v8's on holleys running multiple stages of nitrous. He is good at what does. But importantly, he has some awesone tools. Would those needle things ve the right thing to use to drill the PV slots? Or am i in the complete wrong direction?

Whats important is that the car is driving better than it was and i will hopefully have a new job within the next week or 2, then incan buy more goods :)


Thanks for all the input guys. Its very much appreciated and i am learning alot.

at 18" of vacuum id say the engine is in pretty good shape, perhaps rebuilt?

And yeah, 10.5 would be spot on for you at that high a vac peak.

Opening the power valve restrictions is really a matter of dyno tuning, as they together are a selected size (additional fuel supply to main jets) per metering block. They can be modified, but its usually in a custom application, where a flat spot is in a torque curve if and when the PV is open to cover the fuel demand.

So, a large displacement engine on a dual plane would need larger PVR's because the engine at 50% throttle is radically different than 30% throttle. If that makes sense...

In the 13b's case this is also possible, but ive never had to enlarge them before.

Ok this is my big secret. Hope it helps you.

On any car V8 or rotary the holley has to have a small part of the idle transfer slot visible at idle. If its not visible ur a/f will change drastically from idle to 3000rpm. You need to set idle and take the carb off to see this. From the bottom you will see a round idle hole and you should see a small part if the idle slot. The Idle slot is a long rectangular slot just above the idle hole. If you don't see the idle slot you need to take a hacksaw blade and lengthen it to 1mm below the throttle blade. You will need to remove the throttle blades , base and shaft to do this.