[71 T/A]

I've seen ads online for companies who sell race holley cards that have had seemingly everything done to them. Are those worked over carbs any better than if you bough let's say, a new Holley HP carb and got the tuning right than buying one of their "improved performance" carbs?

[shaker455]

I do custom builds & I found it best to build to customers specs & live test them as well as wideband O2 sensor verify the AFR.

That assures a good build & working with the customer dialing in on there own combo in the end.

I don not believe there any other place out there that will stay with you thru the entire process....just tech lines & they did not build your carb.

[Tom Vaught]

Shaker can do a very nice job for you with a Holley carburetor.

If you had a 427 Chebby Corvette (where Holley offers a direct OEM replacement type deal then the Holley carb out of the box would be really close to the factory calibration done in 1969. That being said, a lot about carbs has been learned since the late 60s (especially using the Wide Band O2 sensor technology).

You DO NOT NEED a "Holley carb that has had seemingly everything done to it" to have a great carb, especially from a carb guy like Jeff, (Shaker455).

Tom V.

ps I think I am the only guy on the Pontiac Boards who actually ever worked for Holley Engineering in the 70s and I personally like Jeff's work.

[77 TRASHCAN]

It really helps to have any carb tuned to it's specific application. We are blessed here, to have many that can help out in a big way!!!
Thanks all!!!
Tom, Jeff, Cliff, Jon, many others!!!

I am a member of a Chevrolet pickup website, don't go there that much. Seems like everyone there knows EVERYTHING!!!

The 1406 E-carb, is the ruling carb there!!! Buncha dufus'

[Johnny406]

Another vote for Jeff (Shaker455). I can't wait to have a engine worthy of the carb he built me...

[Big Mike]

As far as a heavily modified Holley carb for big $$$, I'd keep it simple and purchase a Holley HP series carb. I tried using a Barry Grant modified carb back in the day and can tell you it never ran correctly. The worse part was a stumble from a standing start. After ditching the Barry grant unit, I installed a new 950 CFM Holley HP out of the box and the car ran some of the best 60 foot times it ever ran.

In the end, I did make a few small changes to the accelerator pump cams only because I brought the engine up on the converter and left at a throttle position above idle.

I am sure with the 02 sensors and computers of today, you could refine the jetting to something beyond what Holley puts in the carb from the factory. Unless you have some crazy setup (like a tunnel ram or a huge plenum), Holly hits the mark very closely out of the box.

I'd pay someone to refine things with the O2 sensor setup on a dyno rather than buy something that is built to look impressive. The fuel doesn't know if the carb has anodized parts...

[screamingchief]

Not a fan of the HP series Holley carbs myself.
Nor the "trick of the week" high zoot "builder" Holley carbs.

I'll take a "classic" 4160/4150 Holley over the new ones anyday,then I'll make any changes/mods as needed.

Most of the "new breed" Holley carbs are going to require some sorta mods to run right,especially in the fuel emulsion set-ups they all tend to use (high IFR & such).

Those that DIY their Holley carbs likely already know what I'm talking about.

JMO/FWIW

Bret P.

[Tom Vaught]

Originally Posted by screamingchief

Not a fan of the HP series Holley carbs myself.
Nor the "trick of the week" high zoot "builder" Holley carbs.

I'll take a "classic" 4160/4150 Holley over the new ones anyday,then I'll make any changes/mods as needed.

Most of the "new breed" Holley carbs are going to require some sorta mods to run right,especially in the fuel emulsion set-ups they all tend to use (high IFR & such).

Those that DIY their Holley carbs likely already know what I'm talking about.

JMO/FWIW

Bret P.

Most of the 'issues" with the HP950 (750 cfm carb) and the HP1000 (850 cfm carb) (when compared using Holley's flow stand equipment), is that Holley put the Idle Feed Restriction at the top of the metering block vs at the proper location (in the original spot) at the lower part of the metering block. Most EVERYONE in the carb forums has gotten religion on that deal and switches the IFR back to the old Holley 4781 (850 cfm) location.


The second thing is 99% of the old Holley carbs worked fine with 2 Emulsion Holes in the metering block (on each side). So Holley, at some point said "if 2 emulsion holes is good maybe we can make it better with 3 emulsion holes on each side, then they tried 4 emulsion , then they tried 5 emulsion , etc. I worked on a NASCAR Carb one time that had 10 Emulsion Holes per side.

The 5 Hole stuff works good on restricted cfm (350 cfm) circle track carbs but is not really necessary on most of the V-8 stuff. (The 10 Hole Emulsion Hole stuff was an attempt to save gas on caution laps). Most of the time with the 5 hole stuff at least 2 of the holes are plugged ALL THE TIME. So you have ONE EXTRA HOLE possibly doing something??? (But for a lot more money for the "High Tech" carb vs the normal 850 cfm 4781 carb).

There is a place for that technology, just not on the normal racers engines. Not necessary.

Then there is the "Make the Idle Air Bleed orifices Smaller" to get the fuel curve closer to being "right" deal. (because you screwed up the emulsion circuit stuff).

Shaker, a guy named 'Tuner" (posts on some carb boards and the turbo forums), "Shrinker" (an old "Down Under" buddy who understood carbs RIP My friend) were my friends who really understood the history of the carbs over the years and how to fix the Holley.

JMT

Tom V.

Shaker can do a good job for people.

[shaker455]

Originally Posted by Big Mike

As far as a heavily modified Holley carb for big $$$, I'd keep it simple and purchase a Holley HP series carb. I tried using a Barry Grant modified carb back in the day and can tell you it never ran correctly. The worse part was a stumble from a standing start. After ditching the Barry grant unit, I installed a new 950 CFM Holley HP out of the box and the car ran some of the best 60 foot times it ever ran.

In the end, I did make a few small changes to the accelerator pump cams only because I brought the engine up on the converter and left at a throttle position above idle.

I am sure with the 02 sensors and computers of today, you could refine the jetting to something beyond what Holley puts in the carb from the factory. Unless you have some crazy setup (like a tunnel ram or a huge plenum), Holly hits the mark very closely out of the box.

I'd pay someone to refine things with the O2 sensor setup on a dyno rather than buy something that is built to look impressive. The fuel doesn't know if the carb has anodized parts...

I hear ya Mike, I've had a lot of flashy stuff come my way that just didn't work.

I've also get a lot of stuff from big builders who claim trick of the day things & the unit is all stock...

[carbking]

Originally Posted by shaker455

I've also get a lot of stuff from big builders who claim trick of the day things & the unit is all stock...

In any field, there are always some self-annointed experts....... Most of the "trick of the day" tricks come from these experts.

Most of the useful "tricks" were published by the original manufacturer to their service reps. In alphabetic order; Carter, Holley, Rochester, Stromberg, and Zenith all published tech bulletins. I have binders full of them.

But then there truly are some experts (I believe most of these would prefer the word "technician" to expert) that frequent these forums.

Jon.

[Cliff R]

When it comes to Holley carbs and the "street section", what makes one need to spend money to tune them is for the "normal" driving range, not so much full throttle. Although we don't work on Holley carbs at our shop, or at least turn all that work away, we have a LOT of experience with them. I've been at this hobby long enough to see that design worked over from top to bottom, front to back, and side to side. In a racing application the average hobbyist can get very good results with the better ones right out of the box with a couple of jetting changes on a test and tune night.

To get one to idle flawlessly, super smooth right off idle, and efficient in the "normal" driving range, in almost all cases you are NOT going to find that deal with jet and PV changes. The guys that have went into the metering blocks and air bleeds and figured out how to get a super clean fuel curve from idle to transition and at low throttle openings are the ones to spend your money with.

It takes a LOT of time to do this with an LM1 and street testing. You will be heli-coiling the MB for the bowl screws before you nail down the tune exactly for what you are doing. I've been there and done that with that design.

If you are a drag racer and just want a good out of the box carb to get it done, NOTHING at all wrong with the Holley HP series. We've used a good number of them over the years, and for pretty big HP applications they aren't all that bad. I actually tried one for a while on my 455, but it was just a tad lacking right off idle and a bit "sluggish" in the normal driving range, but if one wasn't looking for a problem with it, it did a fine job of moving my car around, and ran pretty good at the track as well.

When I decided about 12 years ago to put some effort into building my own Holley and custom tuning it to my engine, Tom Vaught was instrumental in cutting quickly to the chase with that deal. My swap meet 4781-2 850 DP carb, when we got done with it was absolutely FLAWLESS at every rpm, any gear and any vehicle speed. We used it for a "dyno mule" for years here when we were doing a lot of engines, and the dyno shop on more than one occasion told me to "never touch that carb"!.......Cliff

[Lee]

My old Firebird had a simple 4779 750 double pumper on it. The PV and jets were tweaked, but nothing custom at all. The previous owner, the subsequent owner, and a few other people all felt that the carb was holding the car back, and a variety of high-$ carburetors were tested on it - NONE of them ever made it run any quicker than that 4779.

IMHO, you are better off buying a good "stock" carb and spending money getting a good wide-band and some tuning supplies, and learn to tune it yourself.

[Tom Vaught]

When I was at Holley in the 70s, (and I have posted this before), Holley had their employees buy 18-20 (I forget the exact number today) of the carbs built by the "carb experts" at the time.

Each carb was flowed on the test stands in the "Air Box" rooms with the proper fuel pressure to the carbs and a curve was generated for that carb. Air Flow vs Fuel/Air Fuel Ratio. (carb guys do the ratio opposite of the engine).

Then the carbs were disassembled and pictures were taken documenting each carb and what was done to it by the modifier.

In many cases the carbs actual calibration was untouched and the mods were purely cosmetic. Difference was only $$$ spent on the carb for the 'mods'.

In many cases the carbs actual flow numbers were the same (plus/minus .5%) which was within the normal quality control of a production carb. So again a lot of money for say 3-5 cfm gain ...the mods were purely cosmetic.

Some added screw in air bleeds and screw in PVCRs which allowed some fine tuning but the calibrations were the same as the Holley deal. This was one of those 'charge for the machining to be able to change the carb calibration BUT leave the actual calibration as Holley Engineers did it (playing it safe at the end of the day).

Today most of that stuff can be found in the better versions of the Holley carbs BUT if the stock #4781 calibration will do the job then the fancy parts bought you nothing as you are not going to change the carb calibration.

Food for thought.

Tom V.

ps In Cliff's case on his #4781 carb I gave him a few suggestions on what would get him close with the carb and he did the final tweaks. As his post said, he and the dyno people were very happy with that #4781-2 (OLD CARB) when it was tweaked properly.

[hectore3]

Originally Posted by Tom Vaught

Most of the 'issues" with the HP950 (750 cfm carb) and the HP1000 (850 cfm carb) (when compared using Holley's flow stand equipment), is that Holley put the Idle Feed Restriction at the top of the metering block vs at the proper location (in the original spot) at the lower part of the metering block. Most EVERYONE in the carb forums has gotten religion on that deal and switches the IFR back to the old Holley 4781 (850 cfm) location.


The second thing is 99% of the old Holley carbs worked fine with 2 Emulsion Holes in the metering block (on each side). So Holley, at some point said "if 2 emulsion holes is good maybe we can make it better with 3 emulsion holes on each side, then they tried 4 emulsion , then they tried 5 emulsion , etc. I worked on a NASCAR Carb one time that had 10 Emulsion Holes per side.

The 5 Hole stuff works good on restricted cfm (350 cfm) circle track carbs but is not really necessary on most of the V-8 stuff. (The 10 Hole Emulsion Hole stuff was an attempt to save gas on caution laps). Most of the time with the 5 hole stuff at least 2 of the holes are plugged ALL THE TIME. So you have ONE EXTRA HOLE possibly doing something??? (But for a lot more money for the "High Tech" carb vs the normal 850 cfm 4781 carb).

There is a place for that technology, just not on the normal racers engines. Not necessary.

Then there is the "Make the Idle Air Bleed orifices Smaller" to get the fuel curve closer to being "right" deal. (because you screwed up the emulsion circuit stuff).

Shaker, a guy named 'Tuner" (posts on some carb boards and the turbo forums), "Shrinker" (an old "Down Under" buddy who understood carbs RIP My friend) were my friends who really understood the history of the carbs over the years and how to fix the Holley.

JMT

Tom V.

Shaker can do a good job for people.

"Shaker can do a good job for people". That's the quote of the day. Jeff did an astounding carb for me and I'm happy with on my 428. Keep this guy in your rolodex.

[Sun Tuned]

Al b.s. Aside....
Best thing to do if you're thinking about wanting to anything at all is this...

Pick up the phone and call Jeff or Cliff or Tom or Jon and tell em what you're thinking about and what you want to do and let them tell you what you should do before you buy anything at all.

Then you get exactly what you need the first go around and may alleviate backtracking over anything that might could have been better chosen armed with the right info on the front end.

Phone calls are cheap....

[unclescratch]

I'd like to make those calls right now, but I'm not that far along putting the car together. I have accumulated a couple of Holley 6210's, 6910's, even a 3310-3, as well as a QJet 17058513. Then on the shelf I have a 1970 RamAir IV, Holley Street Dominator, Torker I, and cast OEM intake of 1969 vintage. Have an AEM 30-4110 wide band too. I'm looking forward to trying this stuff out and have some fun tuning. Got me a G-meter too! I was cautioned that when I retired I should have something to keep me busy. LOL.

[OCMDGTO]

I am probably the least knowledgeable on this thread, but I have 2 Holley 4150's, w/o choke. One is a Holley 750HP, & the other is an AED prepped 750HO. Both run great out of the box at a similar price. AED is great to deal with, and was recommended by a local speed shop. I don't have any track #'s to back it up but I would be surprised if they vary much. On the street, the HP idles a little smoother but is very strong. The AED HO seems to have a little more snap off the line, and is very strong as well. You can't go wrong with either.

[shaker455]

I usually suggest that people get a wideband installed as they are cheap enough now like this one on Amazon:
http://www.amazon.com/AEM-30-4100-UE...s=aem+wideband
A good tool for anyone to verify where they're AFR is at.

[ta man]

That's a good price..the new one is listed there comes with everything...any feedback on this product from anyone?

[shaker455]

I have them running in quite a few cars here on street & track as well on Lenny Caverly's dyno, no complaints.