Holley carb questions

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prairiehotrodder
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Holley carb questions

Post by prairiehotrodder » Wed Jun 13, 2018 2:50 pm

i'm trying to understand the jetting on my Holley 750 track warrior carbs. They are factory jetted at 80 / 90 which according to all other 750 CFM carbs is very rich. But on the other hand they have lots of holes in the emulsion well. According to what I've read in my DV Holley book, more holes in the EMJ (emulsion well jets) makes it leaner ? Am I correct on this ? DV says in his book that a holley carb rarely needs to go up or down more than a couple jet sizes from the factory calibration. Well I have 2 of these carbs on a tunnel ram and i'm trying to tune them correctly. I am wondering if these carbs correct the Rich main jetting by having lots of EMJ holes. Also from what I think I understand, a TR application doesn't really require much different jetting than a single carb but mainly just smaller idle jets. Am I making sense here ? I need to know if i'm right or wrong in these ideas. Thnkyou
Brian T
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F-BIRD'88
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Re: Holley carb questions

Post by F-BIRD'88 » Wed Jun 13, 2018 4:30 pm

I think you are basicly on the right track.
I cannot tell you a dame thing about those specific carbs
thou.... Except you will need to start from "ground 0"...
Does the manufacturer not give any support?
This is why I build my own carbs.
I would have used 2 edelbrock carbs on that.
I realize that that does not help you much now.

But following....
the high speed air bleed also has an effect.
the style of the venturi booster has an effect too.

Also Joe Sherman would tell you to get a forward facing hood scoop.

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Re: Holley carb questions

Post by bigfoot584 » Wed Jun 13, 2018 4:46 pm

Most single carbs are to rich at idle when setup on TR application.
If your not aware of this site try it, has all types of info on just
what your doing.

https://www.tapatalk.com/groups/racingf ... etors-f18/

prairiehotrodder
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Re: Holley carb questions

Post by prairiehotrodder » Thu Jun 14, 2018 11:00 am

bigfoot584 wrote:
Wed Jun 13, 2018 4:46 pm
Most single carbs are to rich at idle when setup on TR application.
If your not aware of this site try it, has all types of info on just
what your doing.

https://www.tapatalk.com/groups/racingf ... etors-f18/
I've used that site and had some good help there. thanks. I'm also waiting to hear back from Holley as to my original question. Nobody seems to be using these "track warrior" carbs. They seemed to me like a good deal when I bought them because they have lots of options for a good price. I just need to understand why they are jetted the way they are.
Brian
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www.therocketshop.blogspot.com

statsystems
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Re: Holley carb questions

Post by statsystems » Thu Jun 14, 2018 3:49 pm

prairiehotrodder wrote:
Thu Jun 14, 2018 11:00 am
bigfoot584 wrote:
Wed Jun 13, 2018 4:46 pm
Most single carbs are to rich at idle when setup on TR application.
If your not aware of this site try it, has all types of info on just
what your doing.

https://www.tapatalk.com/groups/racingf ... etors-f18/
I've used that site and had some good help there. thanks. I'm also waiting to hear back from Holley as to my original question. Nobody seems to be using these "track warrior" carbs. They seemed to me like a good deal when I bought them because they have lots of options for a good price. I just need to understand why they are jetted the way they are.
Brian

If you post up exactly what you have I'm sure Mark Whitener and Tuner would help. You are dealing with what sounds like what I'd call an agressive emulsion system. Without knowing the sizes and locations of the emulsion holes, and the MAB and IAB it would be me guessing. Actually, I'd be guessing anyway but I'm going to ASSume with a bunch of emulsion you'll need a bigger jet.

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Re: Holley carb questions

Post by BradH » Thu Jun 14, 2018 4:57 pm

prairiehotrodder wrote:
Thu Jun 14, 2018 11:00 am
... I'm also waiting to hear back from Holley as to my original question. Nobody seems to be using these "track warrior" carbs. They seemed to me like a good deal when I bought them because they have lots of options for a good price. I just need to understand why they are jetted the way they are.
Brian
Ummmm... don't hold your breath waiting for a valid answer from Holley on why they set up their "new generation" carbs the way they do. I think one of the most common questions on Mark W's web site linked above is how to get the new carbs to run clean down low without going lean up top.

I, too, think the Track Warrior series looks like a pretty decent value, if they have a size that suits your purpose. I have searched online for anyone posting "real world" test results from track and/or dyno and haven't found any.

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Re: Holley carb questions

Post by F-BIRD'88 » Fri Jun 15, 2018 12:01 am

You air going to need to treat idle and low speed cruise
(the idle off idle circuit) and drag race ower getting as two different separate issues . And deal with each on its own.


You dtivr it around on the street , right? This allows you to work on the idle,,, off idle , and low speed c ruise.


A vacuum advance diz is a help here too.

.be paient... You will get it right..

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Re: Holley carb questions

Post by prairiehotrodder » Fri Jun 15, 2018 1:38 pm

Holley got back to me today and said that the track warrior is a race specific carb that is calibrated to give a proper Air / fuel ratio with those bigger 80/90 jets.

This causes me to easily see why my first track outing was less than acceptable. I drove the car on the street last fall and it seemed very rich. I did some research and was lead to believe that a 750 carb should be jetted more in the neighbourhood of 70 / 80 so that's what I did. Well that's a pretty drastic leaning out and the car just didn't pull on the top end. I was down at least 7 mph. My AFR gage was telling me that I had a good mid 12's AFRatio but I think that gage is being fooled somehow. I'm not experienced at reading spark plugs so I trusted the gage. I tried jetting up and down a little but it didn't make much difference. the richest I went was 76 / 86.

Last year with my old carb (single 1050 QFT dominator) I was always getting AFRatios of mid 11's on my gage and anytime I tried to lean it out the car went slower. That was with jetting within a size or two of the factory calibration from QFT.


So now what I've done is change these 750 carbs back to the factory jetting with the exception of the Idle jets and IABleeds. I changed them from .036 IJ and 73 IAB to a .031 IJ and 67 IAB. Hopefully I can get a decent cruise AFRatio for driving to a car show or two and get back my performance at the track and find out what this tunnel ram will do. Thankyou all for your help. Don't be afraid to tell me if i'm way off base.
Brian
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www.therocketshop.blogspot.com

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Re: Holley carb questions

Post by F-BIRD'88 » Fri Jun 15, 2018 2:03 pm

Good move... be sure to run new fresh spark plugs for next outing at the track. If you can, also get at least a carb scoop for the carbs. A forward facing hood scoop is best.
It need not be actually attached to the hood.

The best carb main jetting for basic WOT 1/4 mile drag testing
"should" be + or - 5 jets sizes from out of the box.

The rich ness you found it to be was probabily more about the idle and off idle being out of wack on the TR.
This kills the plugs quick making the car seem "rich overall"
making you want to start leaning the jets to fix that.

on a TR with 2x750 most all of your street driving around is on the idle and off idle circuit which has nothing to do with the main jetting.

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Re: Holley carb questions

Post by F-BIRD'88 » Fri Jun 15, 2018 2:06 pm

i think you are right to not trust the afr gauge.
Thats why I don't use a WB gauge.
I just use a NB as a warning indication of "getting just way too lean"
I start with plenty rich main jetting and progress towards leaner jetting as needed while watching he ET and MPH and plugs..
The afr gauge is ( AT BEST) just a indicator to keep you out of trouble ( being too friggin lean.)
It will want the jets it wants.

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Re: Holley carb questions

Post by F-BIRD'88 » Fri Jun 15, 2018 2:11 pm

Often a car at the track will need a bit richer jets than it did on the dyno. so.....
I proved this to my friend on his dyno tested engine(18deg 406 SBC) when we got it to the track.
it ended up with+4 jetting from off the dyno best tune.
The more jet we thru at it the faster it went down the track.
it was extensivly dyno tested and dial in Yet still needed old school "track Tuning"

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Re: Holley carb questions

Post by randy331 » Fri Jun 15, 2018 2:47 pm

Why bother taking it to the dyno if you just have to go through the whole tune up at the track again.

I'd get a better dyno set up and or better test procedures.


I've never seen the tune up need to be different at the track, other than for air changes.

Randy

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Re: Holley carb questions

Post by steve cowan » Fri Jun 15, 2018 5:05 pm

Brian,
i had a look at the track warrior carb on holley website and they look like there is a lot of tuning features which is nice as long as we dont get out in left field.
most of holley billet metering blocks have 5 hole emulsion but normally 2 are blocked,the emulsion well is to add air to the fuel hence to emulsify.
i have been street/strip tuning for the last couple of years on my car 383 sbc 500hp weekend driver and i have never had any luck without putting a power valve in the rear and taking secondary fuel jet down and square jetting,this is my observation and people may disagree and thats fine as long as we dont become disagreeable.
i have 2 x auto meter air/fuel sensors in the collector of mine and i believe they are a good tuning aid,as well as looking at the spark plugs,i run my car as lean as possible on the street 15-16 AFR
and i screw the fuel pressure way down 4psi,now this is for chugging around the street only obviously,and when i get to the track i bump up fuel pressure and reset idle mixture back around 13 afr,the main jets are for hwy cruise only and your PVRC is for WOT tuning.
on a drag race only most people dont use a power valve in the rear block and thats fine,but on the street i believe fuel will be metered out of the secondary jet ever so slightly if there is a low pressure area,the booster signal will always be weaker on a tunnel ram engine requiring a bigger main jet to compensate,your carb has provisions to change PVRC JETS for WOT tuning,standard they are probably around 55 and on my carbs i have added 15 sizes up to compensate for taking fuel out of the main jet for highway driving,i will be the first person to say it is very difficult to find a correct carb tune for all parameters of a street/strip deal and some people will not agree with some things i have said but these are my observations on my car with my different engine combinations,i have a 830 annular,850 demon,and 950 hp,and spent a lot oftime playing with a 675 QFT adjustable VS on my uncles hot rod 350 vortec 400hp,even on the QFT i resorted back to power valve secondary and took fuel out and ended up backing the electric choke off because it was causing pig rich cold start problems,as far as the vacuum advance deal theres a lot of work in that deal as well and i have never had much luck on a performance engine and i just lock my stuff up,i am sure there is great tuning and fuel burn advantage as i have a good vacuum advance deal on my cruiser 6 cylinder driver but it is bog stock engine with a 350 holley carb and would not pull the skin off a rice pudding so we are not comparing apples to apples here.
i also recommend going onto mark and tuners site,i check it out all the time and they are a wealth of knowledge and i have learnt a lot,i suggest you dont stray to far away from stock emulsion,IAB,MAB,settings as its easy to get lost and change one thing at a time the A-B-A testing that we all hate doing because we want it now kinda thing but most of the time we change one thing and it changes 3 things and we dont even know it happened,if it becomes to hard or time consuming then the dyno deal is there as been said but who do you know and who do you trust.
good luck Brian and keep us posted
steve c

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Re: Holley carb questions

Post by CGT » Fri Jun 15, 2018 8:55 pm

F-BIRD'88 wrote:
Fri Jun 15, 2018 2:11 pm
Often a car at the track will need a bit richer jets than it did on the dyno. so.....
I proved this to my friend on his dyno tested engine(18deg 406 SBC) when we got it to the track.
it ended up with+4 jetting from off the dyno best tune.
The more jet we thru at it the faster it went down the track.
it was extensivly dyno tested and dial in Yet still needed old school "track Tuning"
Sounds like a bad tune up on the dyno or the track, barring some major weather change or bad carburetor etc.

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Re: Holley carb questions

Post by F-BIRD'88 » Sat Jun 16, 2018 1:00 am

I never sIx dyno tuning was not important Randy..

The guys thaf di d the dyno work on this are my friends and they are good..

Don't be so retorical Randy... The dyno work was critial to the sucess of this project...

We learned a lot.

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