Jet sizing question

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robertodonnell

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Hi everyone,

I'm running the ubiquitous 600 sq bore vac Holley on my 318 in my Valiant. It's running the 64 primary jets it comes standard with, and the 65 PV. The the car is running well, but a tad rich at light cruise.

My AFR gauge is telling me I'm in the 12.5-13 range at light cruise, 2000 RPM. Can anyone suggest what size jets I should go to in order to get this down to the mid 14's?

The engine is a mild rebuild, KB167's, very mild headwork, and a Comp XE262h stick. I run a T5 trans and 2000 revs is right about 65 MPH. Would be great if I can knock some off the consumption at freeway speeds.

Cheers in advance,

Robert
 
.64 jets, with a 6.5 power valve ,is different.... My advice: Jet down two sizes,at at a time . Buy the damn Holley jet kit, your gonna need it..
If it's an old Holley carb, you might to want to check out the Proform/Holley air bleed adjustable 4150 main body..
 
robertodonnell said:
Why do you say it's different? It's the standard specs for the list #.

It's a list 80457, model 4160.

Thanks for the advice on 2 sizes, I didn't expect I would be doing it one size at a time, but I don't know.

Cheers,

Robert
Click to expand...

Holley has done so many different modification 's on the basic "Holley 600",it will blow your mind.
On not knowing: You came here to learn. (Frustrating sucks, (I had/have good people to save my *** ,as well) Ask lots of questions, throw the whole combination out there. ( Serious talent here, present it correctly) You're in right direction...
 
C'mon guys, you know better!

Your cruising at 2000rpm, your firmly in the idle transition circuit. You need to get the idle fuel restriction sizes and air bleeds in check. SUPER common tuning issue with Holley. Main jet sizes won't do dick. At that speed you can run the car without them!


Read this:

http://www.burtonmachine.com/documentationtechnical/

and this

http://ls1tech.com/forums/carburete...t-level-holley-tuning-serious-ocd-tuners.html


Invest in a cheap electric drill, and a 1-60 drill bit set. Some 6-32, 8-32 and 10-32 brass set screws AND same sized closed-end hole taps from mc-master carr, and a 61-80 drill bit + pin vice combo from Amazon. MUCH cheaper than shooting blanks at pre-made Holley bleeds n feeds... PM me and I can give you a hand with it, or sift through 20 some pages and draw a your own conclusion. Depends on what your in the mood for... :D
 
Mate, that has to be the best carb tuning document I've read. Many thanks for your input. I'd actually wondered as I was typing my original post, whether or not i was still in the transition circuit, and you've comfirmed my suspicions.

I have fitted this carby to get the car drivable while I resolve some issues with a Holley HP EFI system that I was having trouble getting right, so I'm not sure how far I want to dive into the carb, considering it's only a temporary solution. The car runs and pulls really well, so it may be time to leave it alone and enjoy it, and get back to resolving the reason I pulled the EFI off in the first place.

Cheers

Robert
 
Wow, that Burton Machine one is intense...Great, but intense. :)

I love to tinker, but I gotta admit, I'd be saying "good enough" well before that fella. :)
 
PoisonDart74 said:
C'mon guys, you know better!

Your cruising at 2000rpm, your firmly in the idle transition circuit. You need to get the idle fuel restriction sizes and air bleeds in check. SUPER common tuning issue with Holley. Main jet sizes won't do dick. At that speed you can run the car without them!


Read this:

http://www.burtonmachine.com/documentationtechnical/

and this

http://ls1tech.com/forums/carburete...t-level-holley-tuning-serious-ocd-tuners.html


Invest in a cheap electric drill, and a 1-60 drill bit set. Some 6-32, 8-32 and 10-32 brass set screws AND same sized closed-end hole taps from mc-master carr, and a 61-80 drill bit + pin vice combo from Amazon. MUCH cheaper than shooting blanks at pre-made Holley bleeds n feeds... PM me and I can give you a hand with it, or sift through 20 some pages and draw a your own conclusion. Depends on what your in the mood for... :D
Click to expand...

Thereyago
And if I may................................TIMING. That combo will like at least 45* of cruise timing at 2000rpm. That would be mechanical plus vacuum advance. If you give it what it wants, you will be able to drive with less throttle, at the same speed,which will expose less T-port to vacuum and thus draw less fuel.
If you don't have a Vcan............you lose,lol. You will need to experiment with the exact amount of cruise timing, but I venture to say that it will like even more than 45*. Check your can and try to get at least a 20* can. This can will also improve your part throttle response as well as tip-in. It is well worth spending a few hours, getting it right. Playing with the PV timing is another thing you may find advantageous.I like to delay the PV as long as possible, for a sweet transition.
That burtonmachine link is on the money good tech!
Good luck.
 
Well,going over the obvious here but,100% sure float level isn't a tick too high on
the primary side? Also,you didn't state what your idle A/F was,as stated if that is set too
rich you are using most of that circuit at that speed for your fuel.
Set a customer up who had a 670 Street Avenger on a Chebby 350 /World Product
heads,etc.. Complained of a flat spot out of the hole after the initial hammer down,& some
smoke/black plugs after some full on pulls,total timing 25deg.(fast burn rate chambers work).
Welded bungs in, and hooked up the F.A.S.T. A/F monitor, showed exactly as per
cust's complaint. Lean on initial pull,rich on the top end.The cause?Float level on pri. side too
low,and too hi on the secondary side,as shipped from holley.Set them and numbers were on
the nuggets.Simple,basic,and problem solved....happy customer!
There are lots of great books on the most raced/modified carbs in history,but don't
re-invent the wheel just yet before making sure the basics are solid first.I ran the same carb
on a 318 4spd. dart,crane blazerII,dual plane eddy & 3.23's.Easy driving combined mpg's 18-
20,depending on the roads,never did a hi-way only check(couldn't keep My foot out of it that
long!)
 
Just go down to the music shop and get a .008 and .010 and a .012 extra guitar string, starting with the .008, bend 1/2" cut-off into an ' L' and stick them into the idle feeds see what happens! It should be an elegant and temporary solution to get what you want for the time being.

Keep in mind; it seems all Holley's this side of a 1970 build date are gonna be rich as all hell in the transition; you can thank the 'modders' for messing up the vintage arrangement, which worked perfectly for pretty much everything; even huge cams suffer rich conditions.. Just ask the last guy I helped see the light...



On your next holley, make sure it has screw in air bleeds; then, you'll only have to do slight modifications to the metering block. :smile:


Hope that gets you to where you need to be,

G'day!
 
PoisonDart74 said:
Just go down to the music shop and get a .008 and .010 and a .012 extra guitar string, starting with the .008, bend 1/2" cut-off into an ' L' and stick them into the idle feeds see what happens! It should be an elegant and temporary solution to get what you want for the time being.
Click to expand...

Thereyago again.

I've used that method.The hard part was finding little rubber plugs to seal the top of the idle wells. I used single strands of various gauges of different kinds of electrical wiring, but the selection was limited.I had to really hunt.
 
That's the most elegant solution! Excellent idea!

It doesn't help with my tall gearing either. I built the car as more of a grand tourer, than a suburban street warrior.
 
For a cruiser-car, once the car is moving, gearing isn't that critical. With taller gearing it just stays in each gear for a longer period of time, due to less ROAD-footpounds being delivered per second.Road ftlbs per second;hmmmmm; that would be road-horsepower then..................But calling it torque per unit of time is more descriptive of what you are experiencing. Which is why I use a DP carb. With the secondaries wide open, I can get away with a little less gear,cuz the open secondaries restore some or all of the torque multiplication I lost with the change to taller gears. If I get into wheelspin,when I don't want it,(Hah), it's just a matter of backing out of the throttle.Plus I hate waiting for the secondaries, at low rpms; if you can't get wheelspin the secondaries can be agonizingly slow. Or so it seems. When I mash the gas, I demand (lol) action;instantly.If I can't jump the other guy, I'll be skulking home.I hate skulking..........
And DPs are hard on gas, cuz, well you know, they're just so much more funner, I'm always rompin on it! My bad.
 
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