This afternoon I swapped the Performer RPM off my 427 dyno mule, and installed a Victor. I had decided that I wanted to see how the Victor would do right away, because in the past when switching from a dual plane intake to a big single plane, the HP peak has shifted up, and I wanted to know if the HP peak would go beyond 7000 RPM with this intake (if it did, I would need to run all the intakes to 7500 or so to get comparison data).

The dyno results with the Victor were very surprising. Below 5000 RPM, it underperformed the Performer RPM, as expected. However, although it equaled the Performer RPM around 5000 - 5500, it actually fell off from the Performer RPM numbers above that! It showed less peak HP, and a wide band at the upper range of 25 HP or so down from the Performer RPM! A totally unexpected result; I was figuring that the Victor would be worth at least 20 HP over the Performer RPM.

Being somewhat paranoid due to my recent SOHC problems, I was concerned about a potential engine failure, so I took the valve covers off and checked all the valvetrain components, but everything looked fine. I reviewed all the dyno data and didn't see any glaring problems. The only thing that I noticed, again with this intake, was that the vacuum at WOT at the upper end of the RPM range reached 1.4 inches.

I had noticed the same vacuum situation with the Performer RPM intake. The carb I had used for both setups was a 1000 cfm HP 4150 Holley. Holley 4 barrels are rated for their flow using a 1.5 inch vacuum across the carb. My dyno air turbine was measuring around 800 cfm of airflow through the carb, with nearly 1.5 inches of vacuum across it. Hmmmmm....

I know that Holley's "950" cfm carb is misnamed; it used a 750 cfm throttle body and an 850 cfm base plate, as I recall, but they still call it a 950. I began to wonder if the 1000 cfm carb wasn't just a glorified 850, and didn't really flow 1000 cfm. It certainly seemed that way from the dyno data.

With no other potential explanation for the poor performance of the Victor, I decided to try a bigger carb. My Victor intake is actually a Dominator flanged intake; I have made a 1/2" aluminum adapter so that I can bolt on a 4150 carb to the manifold. I pulled out my 1150 Dominator, took off the "1000" cfm 4150 and the adapter plate, and bolted on the Dominator.

The first pull went to 597 HP, about 30 HP over what the Performer RPM did. That was more like it! Furthermore, the A/F was lean, running about 13.5:1, so there's more power to be had there with a jet change. Vacuum under the carb was zero for most of the pull, and only increased to 0.5 inches at the top end of the RPM range.

So, now I have a new problem. The "1000" cfm Holley is clearly going to limit the power production of this engine. I have a couple of other 4150 style carbs I can try, an 850 Barry Grant carb and a standard 850 double pumper, but I doubt that they will be any better. I really don't want to run into the same situation with this engine that I did with my 428CJ, which was having a bunch of the intake manifolds look the same for peak HP, just because the heads and cam were maxed out on airflow. This is the second highest HP engine I'll be testing for my book, and I want to let it all hang out as much as possible.

The problem is that most of the manifolds I will be testing will only accept a 4150 carb.

I have two ideas on how to solve this problem:

- I have a friend with a Holley three barrel that I could probably borrow. This will give an honest 950+ cfm. It will require an open spacer on some of the dual plane intakes to clear the third barrel throttle plate, but that's not a big deal.

- I also have a 4150 to Dominator adapter plate, which I could use to bolt the Dominator on every intake. I'm not sure how well something like this works, but I think it would have to help.

What do you guys think?

Jay Brown
1968 Shelby GT 500 Convertible, 492" 667 HP FE
1969 R code Mach 1, 490" supercharged FE, 9.35 @ 151.20, 2007 Drag Week Runner Up, Power Adder Big Block
2005 Ford GT, 2006 Drag Week Winner, 12.0 Daily Driver
1969 Ford Galaxie XL, 460 (Ho Hum....)
1964 Ford Galaxie 500, 510" SOHC

I like the idea of running the dominator adaptor better. As the 3 barrels are not as common and the average person would step up to the dominator almost 100% of the time. Your'e test is sure showing that the victor wants big air and alot of fuel.
The adaptor plate on the dominator may have been skewing the results for it also.

on the RPM to see how it compared to your testing last week. As long as the 'necking down' does not cause any problems, it sounds like a great idea.

Some one spending $$ on a 600 HP+ engine will probably think really hard about figuring out how to gain that extra 30 to 50 HP by fitting a Dominator on either by adapter or by intake modification, or a intake specifically for that. If they dont, then they can just use the HP on an RPM and call it a day.

Makes me wonder if ROSS's 489 engine isnt held back, i think he was using the 1000HP(?).

Are there any modified Holley 4150 flange carbs out there that actually flow 1000 cfm?

************************************

1967 FE 390GT engine: 416 CID 233/238* @ 0.050 Solid Lifter w/ 4 spd TL.
1968 GT/CS Mustang. 289/c4
1995 Mercedes e320 I6 DOHC, 216 HP wagon.
2003 Tundra SR5, 4.7 DOHC, 4x4.
Another Galaxie (one day.)

Oh and a Bicycle - daily driver to save gas for the 'F'un 'E'xcursions.

the dominator on the RPM manifold (and other 4150 manifolds) necked down may not, show any gains? And, may hurt their performance. I'm sure Jay will find out.
My guess is that you really need a dominator for a dominator manifold and 4150 for a 4150 manifold.

Hi Jay,

I would choose to run the three throat Holley. I do have some biased reasoning however, since I have one . My father told me he used to run them back in the 60's with great success in illegal street racing in Concord and Pleasant Hill. I'd like to see how well it does on your stout motor. If you'd like, I can send mine out to you next week if you're not able to get your hands on the one near by.

Take care and Merry Christmas

Joe

The 1000HP is actually an 850 DP with a swoopy top . They do not flow anywhere near 1000 cfm but certainly over 850cfm. (@1.5"Hg) I am not impressed with Holley's marketing approach on the HP 4150 line as far as cfm ratings go. They may be flowed at some new SAE flow depression standard?
I'd also like to try one of those Model 3160 3 barrel Holleys myself some time. I think your engine would warm up to that carb. May be a pain to get the secondary transition circuit working proprely, but worth the effort. Besides, it looks cool and looks smaller than it is.

I was a bit surprised to see a drop in power with the Victor, especially at the top. It's good to see the power going in the right direction with the 4500, though! Good news!

The Dominator won't work very well on a 4150 4 hole flange. Might make a skewed comparison.

3V should be OK. But i do question whether the cfm was the limit or the Dom had something else going for it. You'd think 800cfm would be enough for that.

950+ CFM to 1150 CFM

http://www.4secondsflat.com/Carb_CFM_Calculator.html

http://www.wallaceracing.com/intakecfm.php

************************************

1967 FE 390GT engine: 416 CID 233/238* @ 0.050 Solid Lifter w/ 4 spd TL.
1968 GT/CS Mustang. 289/c4
1995 Mercedes e320 I6 DOHC, 216 HP wagon.
2003 Tundra SR5, 4.7 DOHC, 4x4.
Another Galaxie (one day.)

Oh and a Bicycle - daily driver to save gas for the 'F'un 'E'xcursions.

It isn't really fair to test an intake designed for a Dominator with a 4150 carb and adapter and it really isn't fair to test a 4150 style manifold with a 4500 carb. The proper carb on the Victor kinda proves that simple thought. But as with all of your testing a lot can be learned.

I'd say after finding the power potential of the Victor with the properly tuned Dominator going back to the RPM for a round of carb testing would make sense. Find the best performing 4150. Test the Dominator and adapter combo.

From there I'd say use the chosen 4150 on each manifold along with the Dominator and adapter and see what you learn. Look at it this way at least you didn't test all the manifolds and then find out the carb was killing your HP.

JMO

1967 GTA Fairlane convertible
1969 GT Torino original 390 4 speed

If the surf is flat I'll turn a wrench

of "Racing a Dyno" and the rather high RPM capabilities of your engine x Displacement induced requirements of your engine combo = It needs a bunch of Flow. Fact of Life Dominators are what you see on the Drag Strip on similary endowed race engines. Unfortunately resorting to three-barrels and Dominators in a land of 4150 Carbs on street/track cars kind of hurts the reality issue for the typical guy.

When max power is desired I hate to think that shear CFM wins but unfortunately (especially with respect to your testing manifolds) It looks like in this instance Size Matters. I think I just restated your problem but JMHO don't go with a carb with three holes if you ask me.

Don"t ever forget Ford used two (2) Dominators on 302 Trans Am Mustangs for some reason until they were outlawed

plate and Dominator on all the intakes unless you can find a 4150 that flows

enough to not be a limiter. That's the only way to prove the intake variations

that you're trying to find. JMO,Aaron

We had a 750 CFM Dominator laying around and decided to try it on a friend's 416 CI FE on top of his Holley Street Dominator intake. Guess what, it picked up 4 tenths even though the "little" Dominator was only rated 750 CFM and the 850 DP did not need an adapter.

I like the Holley 3V too but nobody else has one.



1912 Model T Ford touring Salmon (ugh!)
1913 Model T Ford Touring original Black paint
1915 Model T Ford Roadster Black
1915 Model T Ford touring Black of course!
1967 Cougar GT 390 Cardinal Red / Black
1968 Cougar GTE 427 Augusta Green / Saddle
http://www.supermotors.net/vehicles/registry/15029/50071-2

You can't get the 3bbls so why use then as a test standard. Test them once for comparison data.

Bob

1966 7 Litre Convertible
1959 F-100 (under construction)
2005 GT40 (in my Dreams)

.......manifold has the Dominator pattern, but I've only run the 4150-780 using an adapter. I was in no hurry to swap to the 1050 I have 'cause the 780 pulled great to 7,600rpm. If the carb hadn't been sitting for the past 12 years I'd send it out for you to try. I imagine the gaskets might not be up to snuff, JMO, Rod.

Mickey Thompson's 63 1/2 #997 S/S Hi-Rise 427 Lgt/Wgt Galaxie,

1957 C-600 Cab-over carhauler w/390-4V, 2-speed rear-end

FGCofA member #4908

MCGC member #75



"There will ALWAYS be an FE in my LiFE"

Try each intake with the 4150, and the Dominator w/spacer. It would be interesting to see how each intake works with each carb.

In other words, you need to do some more testing.

------------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220

Always have since I butchered up a Street Dominator intake in the 80's to put a 4500 on it. I am not real surprised to see those results - every EMC test I ran always did better with a big carb. What Dominator were you running - there are several.

You may find an incremental benefit in another 4150 carb - but the airflow drivers are going to be venturi diameter, booster crass section and plate diameter. The rest is just "glitter".

As for the testing - I think you are "stuck" with a 4150 flange carb. Otherwise you are entering a spacer variable as well. You could include a Dominator/spacer pull on the intakes that emerge as "players". After all - the 4150 carb, 4500 carb, multiple carb choices are going to be illustrated by the testing - and those choices need to be made by the purchaser as well.

Barry Rabotnick
Survivalmotorsports.com

Hi Jay, I have a 1050 3-barrel that i bought year's ago to try but never did, it just sit's on the shelf. If you would like to try it just let me know and I'll ship it your way. Again i never used it so i have no idea how it would work, just let me know............Tommy A.

something doesn't sound quite right. A good 750 DP will make 750+HP on 397CI SBF here. Most of the SS racers have to use the 780 CFM Holley, and they make more than 600 HP. I think you need a different 4150. JMO-Joe-JDC.

did not work at all for my engine. I had a rather crude homemade dominater to 4150 adapter on my engine and Ron wanted to try a manufactered adapter that he has as mine hadn't been shaped yet. Well guess what if I remember right we lost around 16 hp. Needless to say we put mine back on. Also we lost around 18 hp with The shops 1000 cfm 4150 carb over my old 4500 series carb. I have since done some shaping on my homemade adapter and still use it as it WORKS. These good breathing engines like a larger carb JMHO.

I`ve tired all 3 of these on my Fairmont, although when I tried the 1050 Dominator, we used a Weiend tapered adapter to fit the carb to my 4150 based intake manifold. I think I was running the Offy Port O Sonic at that time. The Dominator ran no faster (or slower) than my "old faithful" 3310-1 Holley 780 vacuum carb. I had also tried a 950 Holley 3 barrel, which is basically a 780 with the material between the secondary venturis and blades removed, and it too offered no performance increase. Be aware, Jay, that there were 2 different sizes of the 3 barrels, a 950 and a 1050. Easiest way to tell them apart is by looking in the secondary "grand canyon". A 950 will have 2 conventional looking boosters, while the 1050 will have 2 straight brass tubes that point downward into the throat. Kinda crude, but I would have to guess that the reduced size of the tubes simply allowed that much more airflow thru.
One question Jay, is the Victor in "out of the box" condition, or has it been opened up? I tried my out of the box Victor on the Fairmont a few years ago, and it was a bit slower than my modified Sidewinder, although the as cast Victor ports are smaller than stock. Maybe over the winter I will finally get around to opening up the Victors ports and trying it again next year. If DaleP`s offer still stands, his Tunnel Wedge /660`s combo may make a guest appearance under the Fairmonts hood too. A similar TW/660 setup was 1 1/2 tenths and 2 mph faster on the Fairmont back when it had a automatic, hopefully it will show similar gains with the stick.

428 powered Fairmont drag car, Best ET:10.03@132.11MPH, best 60 ft: 1.29
59 Meteor 2 dr. sedan 332, Ford O Matic
74 F350 ramp truck 390 4speed

My buddy across the street who owns the local speed shop has done quite a few stout 460-type engines, including one in a friend's steel-bodied '56 that was running in the 8's (unfortunately, it recently got chummy with the guardrails at Sacramento-several times). I was looking to get a Victor 460 for another friend's '66 Fairlane with a 466/ SCJ heads, has a tunnel w/ 2 660's now. I was figuring on a Dominator setup, and he swore that the 4150 flanged intake with a Dom adapter ran way better than the regular Dom flanged intake- back to back on the dyno, and on the track. Makes you think a little, as the area of the 4 throttle bores of the Dom are probably still smaller than the open flange area of the 4150 manifold. Seemed to get a more homogenous fuel/air mix, and was more responsive to jetting changes. Considering all the different runner length/ plenum volume/ shape combinations that get massaged, it wouldn't be the first time that something that doesn't seem to make sense actually works LOL

I'm surprised no one else picked up on this. Jay you need to compare apples to apples. All your tests with the Victor are flawed! I wondered why it didn't do well in the previous tests and now I know (I think I know) why.



Your victor is the Dominator flange you say....? It is a cloverleaf carb flange then and you are running an adapter that is most likely a square bore correct. That will have a very poor flow into the plenum from the carb through the mis-matched adapter, I am sure you would lose power. If by chance you machined the clover-leaf out of the plenum (into a sq. bore), you would also have lost power. How much? I think everyone would like to know for sure! A friend dyno tested a 438 SBF with Blue Thunder 4.3 heads and their single 4 Dominator intake. It has the clover leaf Dominator flange also. The ran it (with a Domy carb) and made around 940HP after final tuning, and then milled out the flange to square bore looking for still more power, and re-tested. They lost over 50 HP!!! They then re-welded and cobbed up the plenum back to a clover-leaf shape and picked back up 44 HP and called it good.



A better test would be to buy the 4150 flange Victor (and port match the runners.... you did that didn't you?) and re-test with your base carb. That would be a fair comparison since you are comparing manifolds not carburators.


These are very interesting results and tests and it is fun to see your results. I am not knocking you at all and appreciate your hard work. Just hope this may shed some light on your post. It would be interesting to see if I am right, partially right, or wrong.....


I have the Dominator flange Victor and run a Dominator carb. I massaged the plenum (tried to copy Barry R's mods. from a picture. I left the clover-leaf on it just radiused and bended the plenum into the port roofs.









68 Cougar XR7 street and strip car, 428 4-speed, 3560# of fun, new best 10.43@131.2 1.47 60ft.

Hi Thor. What you said about using a square opening adapter over a cloverleaf plenum makes sense if part of the cloverleaf is an obstruction.

About removing the cloverleaf and using a dommy carb, loss or gain of power might be engine specific. Kaase didn't seem to lose power removing the cloverleaf on a BBF:

http://www.460ford.com/viewtopic.php?t=20251&highlight=cloverleaf

http://www.460ford.com/viewtopic.php?t=9471&highlight=cloverleaf

As for high flowing 4150 style carbs, I asked the guys at Quick Fuel about their 1050 4150 carbs and was told they flow an actual 1050 CFM even with the annular boosters.

I am sure it can be very engine specific (and intake and carb and cam and ....).



Kasse did use a "tapered" spacer (super-sucker) above the milled square bore flange, so he still had a "cloverleaf" under the Dominator carb, that blended to the open plenum on the 460 EMC engine. He did that to increase the size of the plenum, and help "average" numbers across a wide powerband.



A spacer is very different than an adapter, an adapter is a compromise in most cases. That being said in some (limited) applications it may help. I would like to see what Jay's spacer looks like as well as the plenum of his Victor, how about some pics and info Jay?



Just trying to offer a possible explanation. I am sure Jay will figure this out. Anyone have a standard flange Victor 427 to send Jay?

68 Cougar XR7 street and strip car, 428 4-speed, 3560# of fun, new best 10.43@131.2 1.47 60 ft

is my 'vote' if the idea is to show the max hp to be rung out of the combination.



Understand it's an intake manifold comparo but......or, use a different 4150 carb (never did like the bigger 3 bbl. myself, crude is what someone else mentioned and I agree fully!) on all the intakes (or the first few) and see what happens.



However, methinks the answer is already forthcoming as the decrease in under carb vacuum from 1.5" to only .5" (and that as you stated only at high rpm) pretty much tells the story: the 4150 carb was the cork in the bottle!



As for operation, long ago A/ED dragsters (NHRA, single carb only, lbs/cid class, auto trans...mainly PG's, minimal head porting, etc.) used primarily 4150 intakes (on BBC's, BBF's, etc.) since the availability of single carb 4500 series intakes were pretty limited. IIRC, all ran quite well with 'reverse' spacers and often the Dommy's stayed on after back-to-back testing.



Similar and interesting results (+30 hp) from a recent Mopar test:



http://www.moparmusclemagazine.com/techarticles/engine/mopp_0709_cam_carburetor_modifications/dyno_testing.html

Have you been able to put it to the test yet?

but my only testing is on the 1/4 track, unfortunatley I made other "wholesale changes" to my engine and car both. I did pick up 3 tenths and 5 MPH so the changes helped but how much for what is another story...



68 Cougar XR7 street and strip car, 428 4-speed, 3560# of fun, new best 10.43@131.2 1.47 60 ft

That would be comparing apples to apples---Just a suggestion. Joe-JDC.

and try to keep the comparison apples to apples as best you can, as that seems to speak to the most validity. It's too bad the RPM doesn't come with a Dominator flange. If I had a standard flange Victor to loan you for testing I would, but don't have one yet, as was I waiting to see more of your latest test results...

So far as 4150 carbs go, I'd think sticking with a more commonly sourced carb for use would make better sense, and stay away from the three barrel.

On the 4150 design side, I've had good success using the Barry Grant race R/S (removable sleeve) carbs, changing out sleeves to bump flow up to 1050 as needed. They're the older versions - prior to the Holley lawsuits and subsequent Demon styling - but the R/S technology is still the same, and in the right hands can go a long way in tuning. I've not had it flow checked with the various sleeve sizes in place to verify a one to one flow match to its stated specs, but they have worked well along with changing jets, etc. when I've used them in my applications. I believe I may still have a new one in the box here, if you'd want to borrow it for testing purposes...

Regardless, thanks again for all your continuing dyno efforts. I look forward to seeing the product of all your efforts come to fruitition in the form of publication.

I think the very large plenum is not getting along with the small carb. The fellow that mentioned the cloverleaf removal and power loss is on to something. I have done that.......same story. If a carb is too small, you need a small plenum to pull harder on the boosters. The Dom can flow the demands of the engine with less signal, but it would be a turd in an acceleration test anyway. The small carb will still flow the demand of that engine, I guarantee that, but you have to make it suck on the carb harder, which means less plenum volume.

It may apply to anything, I'm not sure, but write this in your book when it comes to FE's: If the plenum volume is too large for the engine combo, it will absolutely kill it. It was the combo that killed the power, not the carb by itself. I have made 775 hp with a 780, but it was pulling about 900 cfm. I have made 740 with a 735, again pulling near 900 cfm through the flow meter on the dyno. The 406 I used at EMC made more power with the 4150 flanged carb than it did with the Dominator and a goofy adapter.

None of these reasonably modified, less than 8000 rpm, mid-400 inch engines we play with will need the Dominator. It will sometimes show bigger dyno numbers, but it will make a sluggish pig on the street with a huge plenum. A VERY smart carb guy proved to me that you only want enough carb meet the demands of the engine. They are all different, but it's safe for me to say that in the case of that engine and rpm, it don't "need" 1050. It may not even need 850. It needs a small plenum. The 406 rig I took to EMC pulled 747 cfm at 6500 through an 850 main body with annular boosters. The plenum was very small, so the small carb worked well. It would also accelerate better than big stuff with the same numbers. I have had to work with "legal" carbs alot on class engines, which makes us look really hard at things like plenum volume and design. I just think you have to be careful throwing carb and/or plenum at an engine just to see a dyno number IF that engine really wouldn't require that much cfm to operate where it is running. Doms have their place, which in my opinion is reserved for BIG engines, high winders, or something with a power adder of some sort. I'm not saying a Dom won't show a big number, but I am saying that the average FE enthusiast that reads your book or this forum will be better served with a nice annular style 4150 in MOST cases. Plus, the driveability of most 4500's sucks if it isn't idling or wide open.

I recently dynoed a Super Stock High Riser with a fairly large-plenum tunnel ram. It only required 1189 cfm to make well over 800. It had two 715 OEM Holleys. In that case, where the plenum is large, you will have to over-carb it to make peak power. It didn't require 1430 cfm, but most likely would have lost power with smaller carbs UNLESS I also put on a smaller plenum in the process. I couldn't do this because those are the only carbs it can use. Then it comes down to figuring out the best plenum volume with no choice on carbs.

With all that hot air out of the way, I think you should try to test that with 4150 flanged carb and manifolds to give a more matched setup to the engine underneath it. JMO. I have a pretty sporty annular 850 sitting here in a box, and some UPS labels right here in the drawer. It may or may not need a jet change, but it was on 417 inches of FE about two months ago.

Especially on mildly modified/street engines, booster signal make power. Small plenum make booster signal. Me like small plenum. Wow, sometimes I talk too much.

You need the smaller plenum for the 4150 style carb. I have found that when we use the W-302 intake from Roush, or Ford Motorsports, it will make better power with the 750 DP carbs because it has a very small plenum area, and when we go to the Victor/Super Victor, it needs more carburetor to make the same power and torque. It's all in the combinations. Are you testing manifolds, carburetors, or trying to make it make a target HP number. Let the testing tell you what it will tell you. We all learn from each other's experiences when we give all the results, whether good or bad. Joe-JDC.

try different sizes see if filling up the plenum helps?

The testing I did today doesn't really support your conclusions, Blair. The plenum size on the Dominator Victor really isn't much bigger than on the 4150 version, and the adapter is only 3/4" thick. There isn't a lot of difference in plenum volume.

I tested the 1000 cfm Holley on Joe's intake today, and it didn't do any better than it did on my Dominator intake.

This is still kind of a mystery to me...

Jay Brown
1968 Shelby GT 500 Convertible, 492" 667 HP FE
1969 R code Mach 1, 490" supercharged FE, 9.35 @ 151.20, 2007 Drag Week Runner Up, Power Adder Big Block
2005 Ford GT, 2006 Drag Week Winner, 12.0 Daily Driver
1969 Ford Galaxie XL, 460 (Ho Hum....)
1964 Ford Galaxie 500, 510" SOHC

But I think you're still missing Blairs' point about drivability and acceleration. Dyno numbers dont equal real-life performance. Im not trying to yank your chain Jay, like Joe said, we all learn from your testing and ensuing discussions, but it must be taken as a factor and not the end-all.



Thats what Im gathering from all this testing and varying results.....that each intake is sensitive to a particular carb (even air intakes etc.) and vice versa. Long time racers like Rory and Tom have a multitude of stories of disapointment when something was "supposed" to work. In the end through, the ET slip dictates what works and what doesnt.



Again, dont take my thoughts the wrong way. I appreciate your testing and work on these engines as much as the next guy. I cant wait till you get back to the SOHC engine.

Doug

----------------------



69 Mach 1 R-code - 427MR 4-spd

68 F-250 4wd - 390HP 4-spd

58 2dr Del Rio Wagon - 390 4-spd

63 Mercury Comet 4dr 170ci 3-spd. (24mpg)

65 Galaxie 500 2dr hrdtp - 390 (automatic )

rather than the newer one because it seemed to "fit better" here. My feelings are that there are no absolutely right answers to the big carb/small carb question. Racers have been battling this out forever and there remains no clear winner to this day. Blair is correct in one comment though for certain - it's the combination!

The first thing we need to establish is that the flow ratings for carbs and heads are arbitrary values assigned for comparison to like products. Those values are nearly MEANINGLESS for engine operating demands or comparison to unlike products. Carbs were originally flowed at an SAE agreed 3" of vacuum drop below the plates because you NEED a restriction valueb to establish a measurement. When four barrels were developed they decided on 1.5" because it was half the two barrel restriction. There is NO scientific reason for the rating value. The same holds true for cylinder heads - the common 28" reference was arrived at due to limitations of the test equipment readily available - not from some engine demand analysis formula. Some development is being done these days with reference vacuums of over 100". This does not invalidate development or testing done on carbs or heads in any way - directionally correct is still directionally correct - but it does and should impact blanket statements that "the engine does or does not need" a certain value item.

Now - back to carb sizing. My feelings are that if I see any significant vaccuum in the intake there is a restriction in airflow - and airflow plus the requisite amount of fuel means power. Bear in mind that the location of a vacuum tap will generate a signal of it's own as a result of passing airflow - hence a small reading should likely be discounted.

When the engine is running it will get the air it needs up to a point through any available opening until the orifice becomes sonic, unstable or turbulent. The question lies with the introduction of fuel delivery and the amount of work "wasted" on pulling air through any small orifice. I can restrict an overly large carb orifice (one example would be skirted or annular boosters), and do things to improve duel delivery - I cannot make a small carb bigger without compromising the venturii shape needed for it to function. Hence the reason I like big carbs.

As to the acceleration and "down the track" advantage often quoted for the smaller carb - that is a transitional behavior that is very tough to simulate on a dyno. What we can do is look to the current EFI guys to see how large they are making the air valve on their engines. If we see an advantage to a smaller total throttle area on a comparable carbed application (where we should require more area due to the inclusion of fuel) that is a clear indication that the problem lies not in sizing but in fuel management. I am slowly coming around to the opinion that plenum size/volume is a more of a transitional behavior "on track" tool and that runner size, shape and length is the driver for many of the variances we see in Jay's testing.

Sorry for the long "answer without an answer"....


Barry Rabotnick
Survivalmotorsports.com

N/t Thanks for answering this up above!

Its too bad they stuck them mostly on small carbs, a real 850 DP with a set of annular boosters would have to be the ultimate carb. People who say they are too big forthe street are just as you so eloquently put lacking in the ability to match the fuel to the air with their combination. The just don't have the velocity to get the boosters going. Well said! There are quite a few tricks to fool the carb into delivering fuel faster and that absolutely is the problem, not air.

An example is a Qjet. I had an 850 Buick carb that had primary pullover enrichment. The secondary response was ho hum at first. Primary response was perfect, accelerator pump perfect, and the pull over feeds really made a difference. Then I ran across this book by Doug Roe who reccomended drilling little holes in the secondary pickup tubes, and cutting slots in the air valve in front of the pullover feeds on the secondary, and finding an old A or B hanger along with a performance camthatlifts the secondary rods. I think I used an "AX" rod, I also drilled some orfices out in other places, one to make the bowl fill faster.

Well,I was successful to a degree. It was a screamer with perfect driveability. That thing was a beast, you hit it anywhere and there was no bog and it was all business for about 10 seconds. Then it had drained the tiny little fuel bowl Fast as all get out, and seamless until the fuel was gone. Oops. I had the biggest needle and seat you could get in it (a .156) and it still couldn't keep up. Ran like a son of a bitch, but you just couldn't get the fuel in fast enough.

Holley sells it as a "chokeless race carb", my brother had one on his 408 and it is one sweet working carb.
Sold to a friend who put it on a 499 Mopar stoker and worked excellent on it too.
They both went to dominators and picked up with them but the 830 was a good carb.

I just don't how you could top it. Nice!

at the local machine shop that has a dyno, their 830 annular is the "dyno" carb. They put that on first to baseline every engine first, then install the customers carb (they have a "dyno" dominator carb also as needed). The 830 pretty much always makes more power than everyones "trick" 4150 carb and several have tried unsuccesfully to purchase it after seeing the HP loss once removed.



68 Cougar XR7 street and strip car, 428 4-speed, 3560# of fun, new best 10.43@131.2 1.47 60 ft

I've been running a 9380 850 carb which is similar to the 9381 830 carb but the throttle bores are 1/16 larger. Been pretty happy with it.

z

The dump tubes on the secondaries with no boosters and the pullover holes on the primaries could just honk the fuel down. A drive with a couple of little punches would drop the fuel guage quick. It just needed about twice the fuel capacity. I had pump pressure, volume, and line, it just couldn't get through the needle and seat fast enough to keep from it from pulling it down. It would sure get it on until it ran out of fuel though.

Doug, I understand your point about driveability. It's really the same point that people make about the dyno being a tool, but the best combination for the track is not necessarily the best combination on the dyno.

Unfortunately, what I'm working with is the dyno. I have no other frame of reference to make judgements. The book I'm trying to write is simply about dyno results. No inferences with respect to driveability are possible with WOT dyno testing.

What I'm trying to accomplish here is to pick one or possibly two carburetors that will give reasonable results with all the intake manifolds I want to test. I was able to do that with the other engines I've tested, and I got good results with those tests.

This engine is posing a problem because the engine seems to need more air than can be delivered with most commonly available carbs, except for the Dominator, and the Dominator can't be easily made to work on most of the manifolds I'm testing. I'm trying to avoid a carb limiting situation, where the HP output is limited by the carb, rather than the intake. This is what I encountered with my first Victor test; I put the 1000 Holley on the Victor, and it made about the same HP as the Performer RPM at the high end. With the Dominator, the Victor was up 30+ HP, which is more like what I expected.

Right now, the 3 barrel is looking like the best bet to deliver results that are consistent from manifold to manifold, but I certainly have more testing to do to figure this out for sure.

Jay Brown
1968 Shelby GT 500 Convertible, 492" 667 HP FE
1969 R code Mach 1, 490" supercharged FE, 9.35 @ 151.20, 2007 Drag Week Runner Up, Power Adder Big Block
2005 Ford GT, 2006 Drag Week Winner, 12.0 Daily Driver
1969 Ford Galaxie XL, 460 (Ho Hum....)
1964 Ford Galaxie 500, 510" SOHC

I sure dont mean to be-little all this dyno testing. It for sure is showing what basic combinations work better together and what particular direction to take with certain like combos. I love the fact that all your test engines are very "real world" engines, ie; could easily be ran on the street.

Actually I think theres just as much, if not more to learn from the questions that arise as to what appears to work.

Doug
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69 Mach 1 R-code - 427MR 4-spd
68 F-250 4wd - 390HP 4-spd
58 2dr Del Rio Wagon - 390 4-spd
63 Mercury Comet 4dr 170ci 3-spd. (24mpg)
65 Galaxie 500 2dr hrdtp - 390 (automatic )

i agree there is a world of info in jays work and the questions being asked..not every high zoot build works. but we also find out that if we study the results of these tests you can pick the parts that makes a real reasonable priced fe engine that makes good power.its really valuable info . thats why i gripe about posts that have nothing to do with fe engines or hot rod cars with fe's. they push the real posts out to fast. i look beyond the first page some times but i try to do the front page about twice a day....JAY B-BARRY R-BLAIR PATRICK..keep up the good work......i also enjoy everyone else comments and questions.......gopher