It seems that otto has a general dislike for Holley carbs, but the real reason for this column was to help someone out with a problem on a Holley carb, not to have someone jump up on their Edlebrock soapbox and crow about how good they are. Edlebrock carbs are a dang good product, no doubt, but they too need tuning on occassion to match there application.

Todd
BB79RANCH

 

Well, I think every carb design has it's good points and it's
bad. I do think though, that edlebrock does make a more user
friendly carb. I think Holley has realized this, and edelbrock
must be taking a big chunk of their business because Holley has
just introduced a new line of "Street Avenger" carbs. Everytime
they describe a new feature it starts with the words "No trouble". Thats kind of admitting they use to have trouble?
I was impressed with the thick booklet that comes with the
edelbrock carb too. How I gained respect for Holleys is I have
a 65 Mustang with a stock 68 302. I put a brand new 600 cfm
carb on that thing 10 years ago and it still runs perfect. It's
covered in road grime (daily driver) and I've never had to fool
with it.

 

Otto, not to trash the AFBs, but I currently have a 1405 in the tank now for a rebuild. Bought it new, never ran right. Tinkered, still falls flat on its face. Temporarily running my brothers Holley with NO trouble. Hopefully the rebuild fixes it, if not, Holley will sell another carb. Just my experience.

Nathan

 

If the holley runs good on there i would keep it on there

 

I'll throw my 2 cents in.... Edelbrock's are great, I run one on my 351W with no hassles, but you won't find too many at the circle tracks or drag strips....You will find Holleys and other tempermental carbs that require a lot of tuning, but also allow you to tune to track conditions, atmospheric pressure, temperature, altitude, and humidity. Edelbrock doesn't give you the variability that most Holley's do...but it almost takes a carb degree to tune one those dang things.

'82 F150 2WD w/351W (orig 300 I6)
Slik

 

Oh, and I think NASCAR rules only allow to run a specific Holley carb. The small tracks, I believe, require a 350cfm carb and the big/medium tracks require a 750 and I think everyone has to run the same carb.

'82 F150 2WD w/351W (orig 300 I6)
Slik

 

Railman,
My friend has a 351 Cleveland with 4 bolt mains and 4 barrel heads. The thing has a big cam in it and runs like a raped ape. But, he can't pass the emissions test with his 650 double pumper. It passes at the higher speeds (have to pass emissions at two different speeds here), but will not pass at idle. We have tried all the carb adjustment routes with no luck. We also have drilled holes in the throttle plates to move more air, and it idles great without the throttle plates exposing the transfer slots. We even changed carbs to one of those emission type carbs with the idle air screws. No luck. We are back to the 650 again, and now we are investigating limiting the amount of fuel that goes to the Idle Well with a small diameter wire to partially block the Idle Feed Restriction.

Yes, it's a big pain, but it's worth a shot. I don't think it will be to hard to do and it beats getting another carb. Thing is, it just runs soooo good the way it's set up right now.

Todd

 

Ok guys ,I just checked the float level on my carb. The level checked out ok. The fuel level is maintaining at the bottom of the sight hole where it should be. Just to see if it made a difference,I adjusted the float on the primary side down 1 turn, but could not tell any differance (still idling too rich).
Changing the power valve to a smaller 3.5 size was recommended by one of you. What size or number power valve do the 4150/4779 carb have from the factory? Oo

 

4779 =8.5 pwr valve, 75 pri jets, 76 sec jets
4779-1=8.5 pwr valve, 70 pri jets, 80 sec jets
4779-2=6.5 pwr valve, 70 pri jets, 80 sec jets
4779-3=6.5 70 73
4779-4=6.5 70 80
4779-5=6.5 70 80
4779-6=6.5 71 80
4779-7=6.5 71 80

 

Railman, one other thing that I have'nt seen mentioned is the idle speed screw for the secondary plates. It cannot be gotten to by a 'normal' flat head screw driver when it is mounted on the manifold. it sets the initial plate opening for the secondaries at idle. 'If' it is too open then all the adjusting on the primaries won't help if the secondaries are too open and dumping fuel. since there is no idle mixture screws for the secondaries then that is the only other way to vary the fuel at idle with out tearing into the back bowl and changing metering plates(my experience is only running #1850's and they don't have the block in the back for seperate main jets like the primaries).good luck.
Eric

Proud owner of a '73 F-250 4x4 High Boy, 460 V8, NP435, NP205
And a '68 Bronco 289 v8 , NP435 , Dana 20

 

Just checked the Vacuum on my engine. At idle (900-1000 RPM) it has 10 In. vacuum. So what size power valve should I be running? Upon inspection of the secondaries, they apear to be open about 0.15"-0.20" is this open too much? I gave some false info on a preveous post. Its a 6709 not a 4779 like I mentioned. According to the Holley catalog the 6709 has #65 pri. jets, #76 sec. jets and the power valves are 65 pri/35 sec.

 

OK I was reading a little bit in my Holley carb books and they
said you should have a power valve with a value 1 to 1 1/2
lower than your lowest vacuum reading. Theoretically your 6.5
should work unless your vacuum guage is not reading quick
variations below 10in. I'll leave that judgement up to you.
They also said that the throttle adjustment is critcal to idle
mixture adjustment. They say the transfer slot should not be
exposed too much or it will run rich and your idle mixture
screws will have no effect. The proper position of the throttle
plates will leave .045 to .060 inch of transfer slot exposed
below the bottom edge of the throttle plates. They talk about
two choices. Drill a 3/32 hole in each primary throttle plate
and if the engine is radically modified drill holes in the
secondaries as well. The second choice is opening the secondaries more with that little stop screw under the base of the carb. They say this will increase idle air flow without
significantly increasing fuel flow.

 

When checking manifold vacuum at idle for power valve changes make sure the readings are taken after you: (A) Set idle. (B) Turn idle mixture screws to obtain the highest manifold vacuum. (C) re-adjust idle to proper level. (D) Record idle vacuum reading with engine idling in gear (in Drive with emergency brake set). This will be the reading that you will base your power valve selection to.
I had a similar problem with my vac. sec. Holley 750, here's how I solved it. After setting a baseline ( setting float level, choosing jet sizes & etc.) I,(A) Changed the power valve by using the above mentioned procedure (ended up with a 5.5 power valve). (B) Using the secondary idle-speed adjustment screw, open-up the secondary throttle plates 1/2 to 3/4 turn away from having plates seated in bore. (C) Drill one 1/8" hole in each throttle plate, on idle transfer side of plate (front of carb side), start with smaller bits first so you don't go too far and make sure you de-burr the hole! The key here is to get idle mixture screws to be most effective with 1 to 1 1/2 turns out from being lightly bottomed in the primary metering block. As far as jetting goes that depends on what type of performance you are looking for, but I'd say for a 351W 66-68 primary & 70-74 secondary should get you started.
I hope this helps.


Todd
BB79RANCH