First, a note of thanks to my pals Steve R and Kevin R, who spent most of the day at my shop today helping me out with the intake changing duties. Thanks guys!

In our last exciting episode (), I discovered that the Holley 1000 cfm 4150HP carburetor was far from 1000 cfm, and the addition of my Holley 1150 Dominator carb to the Victor intake on my 427 yielded a significant power increase. This morning I ran off to get more race gas (I'm running 110 octane leaded race fuel for all my tests), and also stopped at a friend's house to get his 1050 cfm three barrel Holley. On the intakes with the 4150 carb flange, I was torn between testing the three barrel and the Dominator on an adapter, so I had decided to try them both and see what happened.

Back at the shop, I tweaked the jets and lashed the valves on the engine with the Dominator carb still installed, and made a couple more pulls. The engine just touched 600 HP with this combination, Here's a graph comparing the Victor with the two carbs:



At this point I felt pretty confident that the additional airflow of the Dominator was the reason for the improvement, so it stood to reason that the Holley three barrel would also show an improvement over the 1000 cfm 4150HP Holley. I decided to put the three barrel on the Victor and test that next. This entailed installing my adapter back on the Victor to convert it to the 4150 pattern, and then installing the three barrel.

This morning I read some of the comments from my previous post stating that the mismatch between my adapter and the Dominator pattern on the Victor was the reason for the poor performance of the 4150 carb. I'm not buying one bit of that explanation, because I already tested for that on my 500HP stroker 390 engine. I do in fact have four Victors at my place, two with Dominator flanges and two with 4150 flanges. Testing on the other engine yielded no difference between the two port matched Victors, one Dominator flange and one 4150 flange, using the same 850 cfm Holley carb. Also, using the logic that the flange mismatch was the problem, the Holley 3 barrel carb would not show an improvement over the 1000 cfm 4150 carb. The actual results, however, showed that the 3 barrel carb was nearly as good as the Dominator:



The three barrel I borrowed was a pretty used up carb, and I thought it could be improved with some work to come even closer to the performance of the Dominator, but in the end I succumbed to the logic that three barrels just aren't available these days, so despite the performance of the three barrel I decided to proceed next with the Dominator on the 4150 adapter.

Next we swapped the Performer RPM intake back onto the engine, and installed the Dominator adapter and the Dominator carb. Unfortunately, this combination didn't work out so well. At the top end of the pull, this combination resulted in rough, uneven running of the engine. Where I expected to see this combination pulling away, it basically fell flat, barely outperforming the 1000 cfm 4150HP:



We ran this test three times with the same results in all cases. All the tune parameters, such as A/F, looked pretty good with this combination, but it just went really weird at the top end. Basically, it appeared to us that there was some kind of issue caused by the large adapter spacer, like an intake tract pulsing or resonance, that killed the top end power of this combination.

The conclusion that I drew after this was that I would probably be best off testing the dual plane intakes with the 1000 cfm Holley carb, and using the Dominator on the open plenum single plane intakes. If I had been really thinking this afternoon, I would have reconsidered the use of the three barrel on the Performer RPM intake. Hindsight being 20/20, I could have used to three barrel to prove or disprove the theory that the engine needed more air even with the Performer RPM. In fact, I may actually reinstall the Performer RPM tomorrow to test that; I'd really like to know the results of that test. However, today I just decided to proceed to the next manifold, and use the 1000 cfm Holley for all the dual plane intakes.

My friend Kevin had brought over his 427 MR dual plane intake, so we bolted that one on next, along with the 1000 cfm Holley. This manifold had looked pretty good on both the 425HP 428CJ, and my 500 HP 390 stroker, being down only 15 HP or so from the Performer RPM. On this engine, though, it was another story altogether. Much to my surprise, this manifold was down a LOT from the other intakes, peaking at only 480 HP! It also showed very poor upper RPM range stability, surging and pulsing, as can be seen in the dyno plot:



Again this evening, after the testing was completed, some second thoughts about this test have crept into my mind. I remembered that although this particular intake is a 427MR intake, it has been port matched to low riser ports. I'm using Mr. Gasket 202A intake gaskets on this engine, which match the heads. I'm wondering if the port openings of this intake are extending down below the bottom of the gasket? This would expose the bottom of the ports to the valley area of the engine, creating a big vacuum leak. We noticed during the warm-up with this engine that vacuum was lower than it had been with the other intakes. I have a call in to my friend Kevin to have him measure the port openings, so we can determine if this is indeed the case. So, at this time the results for this manifold should be considered preliminary only.

Finally we decided to install Joe Craine's Victor intake for the last testing of the day. Joe was kind enough to lend me this intake some time ago; it has been ported to flow nearly the same in all runners, at around 450 cfm. This is a 4150 intake, not a Dominator intake, so if I wanted to run the Dominator carb on this intake I would have to use the 4150 to Dominator adapter.

After bolting on the intake with the 1000 cfm Holley, we ran the test. Here are the results, graphed together with my port matched Victor using the same carb:



Joe's intake is up about 10HP pretty much across the board as compared to my intake. This is a very similar result to what I saw on the previous two engines when comparing Joe's ported PI intake with my unported PI intake. In those cases we saw an across the RPM range improvement of 5-15 HP.

(By the way, all the intakes I will be running on this engine are at least port matched to the MR ports, unless like the previous 427MR intake they are already larger than the head ports).

Next we pulled off the 1000 cfm Holley and bolted on the adapter and the Dominator. Man, what a goofy looking setup this is:



I had high hopes that we would see the same kind of improvement with this setup as I saw with the Dominator on my Victor intake. In fact, based on the previous test there was no reason why we wouldn't see 610 HP with Joe's intake. Unfortunately, it didn't work out that way; here is a dyno plot of Joe's intake with both the 1000 cfm carb and the Dominator carb:



The Dominator did not offer any substantial improvement. The only reasonable conclusion, I think, is that the manifold does not like the goofy adapter.

Tomorrow I think I will try bolting the 1050 three barrel onto Joe's intake, and see what happens. If I get back to 590-600 HP, then I think its safe to say that the adapter is the source of the problem. Which means that I can't run the Dominator carb on most of the intakes, and I may be forced to go back to the idea of using the three barrel to avoid limiting the performance of the engine with the different intakes.

I think its safe to say that there's a lot going on here, and I don't have a clear path to testing the intakes on this engine yet. More R&D coming tomorrow...

PS - Barry R! I need more 202A Gaskets! Oh, wait, I already called you about that...





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

And thanks for testing the old three barrel!

Joe

I hope you didn't take my comments the wrong way Jay. Like I said I appreciate what you are doing and definitely enjoy reading your "dyno" posts. It is something I could never do myself and the results aren't always what a person would think.

My point was why run an adapter, especially if you have both Victors there. Run the 4150 Victor with the 4150 carb and run the Dominator on the Domy flange. I would like to see those runs graphed together, and also the 4500 Victor with the adapter against the 4150 Victor with the same 1000HP carb (that would show the adapter and the plenum difference). Another graph of interest and not shown would be Joe Craine's Victor against the RPM with the same 1000 hp carb. I don't think it would be as much difference as you mentioned before.

I think some of the difference is the carb, and some of it is the adapters, and some of it is the intake plenum itself (4150 Victor versus dominator Victor).

Another thing worth mentioning is the best dyno numbers and ET slips can often be 2 different animals, just more variables.......maybe you need to pave a drag strip behind the milk barn for further testing LOL.


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

I didn't mean to come across like I was offended by your post, or by any others. I'm certainly not, and welcome all input. But I did spend some time on the dyno with the last motor, testing the Dominator Victor with my adapter plate and an 850 Holley against the 4150 Victor with a 1/2" open spacer (to match up with the adapter plate) and the same 850 Holley, and found no differences. I'm sure of that, plain and simple. I'll see if I can dig up the data on that testing.

The reason I used the Dominator Victor for this testing was that I could switch carbs without going to all the trouble and expense of switching intakes. Its a lot faster, its cheaper (a manifold change costs me $17 in gaskets, plus about $2 in sealer), and I have confidence that the results will be the same.

I also agree that the dyno is not the end of the road when it comes to tuning the engine for the track. But for the purposes of the testing I'm doing for my book, the dyno results are the end of the road. My problem is to try to find a standardized carb setup, or perhaps two, that I can use to test all the intakes on this engine, so that I have meaningful comparison data. Unfortunately, this is proving to be difficult...

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

Jay interesting info on the carbs. Do you have a spacer with a 4 hole setup you can try? The other question is a smaller carb of the double feed, double pump in the 780cfm range. How much power would you loose. I was reading the Engine masters and the guy that won the 510 event was not running a large carb. I know a limited rpm range but is there not a magic number for vacuum at WOT. Guessing about 1.5-2.5 psi of vacuum. Where is the dyno mule coming in at? Good info looking forward to the book when this is all done. Thank your friends for the extra hands to help with all the testing you are doing. Hope you and the family had a good Christmas. Looking forward to the big cammer rocker arms being fixed for the new year. Rick Lake

Yeah - the 509 year was won with a small carb. Kaase won with a big carb on a 400 last year. Always a combo deal.....

Barry Rabotnick
Survivalmotorsports.com

Your shared findings and specifics are much appreciated.

Hopefully you'll be able to correlate and cross reference this recent data against that of some of your previous findings to correlate the mountain of data you must have by now.

I agee with your comments about how a more standardized carb testing line up would have probably saved you some double-work and headaches to this point, but hey - at least you've been lucky enough to have some crack volunteers on hand at times to help out along the way, and to share in the dyno excitement...

Keep up the good work!

for truth in advertising with those carbs! I had always wondered if carbs offered by many shops, and eventually Holley itself (that offer 950-1,000+ cfm ratings for what are essentially 750-850cfm base-plated carbs) did flow those numbers. Apparently not! Now, although the tests show the 3-bbl did flow more air, I also wonder if it the carb you have actually does flow the claimed 1,000 cfm?

I'll ask if engine builder folks like Barry R. or Keith Craft have actual documentation of the flow rates of 4150 based carbs from various aftermarket suppliers? If so, from who and part numbers please. The reason is the latest 3-bbl test, although proving well the point, offers up a carb no one can buy! A true 1,000 or 1,050cfm carb based on the 4150 series (if they exist!) would be generally available to purchase today and not be the proverbial cork in the bottle.

Hey, and thanks Jay for all the work. The Performer RPM testing is great in particular since these intakes are so available, affordable and seem to perform very well in all engine types, not just FE's.

i think a couple of weeks ago someone posted that they were told by HOLLEY that they have a different way of mesuring cfm now as to how they used to. maybee that factors in on the differences jay is descovering on these carbs? don't know just asking questions. gopher

I bought a new holley 570 street avenger for a small block a year or so ago, the thing never ran right. no matter what I changed. and I was tuning with a F.A.S.T. dual air / fuel gage. sent it back, they said it was ok, tried it again, still not right . THEN I got the real story from a tech guy at holley, since most people over carburate, they down size the carb to correct for this. so he said the 570 I had only would flow about 490. So he took mine back and sent me a 670 at no charge. he told me it would flow 580. (Thats what I wanted)

I got a similar response but a bit more vague.
My conclusion is that MOST of the SA carbs (the 570sa, 670sa, and 870sa) are flowed at about 2.0" Hg or maybe it is 28" Water which is 2.06" Hg. This gives the following cfm for these carbs at the standard 1.5" Hg

570sa=490cfm
670sa=580cfm
870sa=750cfm

The 770sa I believe is rated at close to the standard 1.5" Hg - perhaps 1.5" Hg but dry flowed, so

770sa=750cfm

by the standard most of us use.
Very confusing and these are just my best guesses based on your Holley response, my own "Carbolator" cfm program, my own response from Holley, and the link below:

http://www.carreview.com/cat/parts/carburetors/holley/PRD_2173_2889crx.aspx

Consistency would help, I wish Holley (and others() would clarify their flow conditions.

By the way, this same 2.0" Hg reveals the infamous "600cfm" rating of the 1.12 Autolite 4100 carb. I believe the 600cfm - but only at 2.0" Hg. This matches the 520cfm average that Bob Sprowl got when he had some 1.12 Autolite 4100s dry flowed at 1.5" Hg.

As for the Holley HP series, that is a different set of guesses again!

I put a dissertation on sizing in the older post below. The punchline on carb flow is that the older carbs were sized at 1.5" of vaccuum drop under the open throttle plates with fuel (actually spec fluid) flowing on the WWII vintage orifice box at Holley. The orifice box was a really big flow bench - powered by a pair of roots mineshaft blowers each the size of a tipped over refrigerator. It was calibrated with a selected orifice - hence the name - that served as a leak to generate a specified rate of airflow while the blowers ran at WOT. Each orifice was about the size of a toilet seat. The box could wet flow test a tunnel ram and two 1150 Dominators and still generate the correct vacuum. I have no idea what happened to that piece of equipment once Holley closed up shop in Warren, MI and moved down south.

The newer HP line was sized - or more appropriately "labeled" in response to all the carb modifiers out there - the "950" or "1000" designations have nothing to do with the flow at all. I suspect that the guys at Holley now know that this was a mistake. A 750 with an 850 base plate will not flow 950 - it will not even flow 850. It may be (and is) a better carb due to the relationship between venturi and plate diameters - but it won't move more air.

A lot of carb tuners have rated their products with dry flow on a SuperFlow 600 bench. A nice piece of equipment - but nowhere near enough volume to generate any sort of comparable data. I suspect that Holley and others have the data - but nobody is sharing....

The three barrel was an engineering accident as they chased more airflow in the 60's for NASCAR big blocks. They kept going larger in venturii size until they literally ran out of room and cut through the casting. Somebody decided 'why not" and they just whacked the middle right out of one & epoxied it up. Kinda worked and away they went. The general feeling from the guys I knew there was that the 950 was pretty good but the brass tube 1000 was not so good. As soon as the Dominator was released they s-canned the three barrel deal. The Dominator was the first carb Holley designed as a true ground up racing piece - and they considered it to be a better part.

Barry Rabotnick
Survivalmotorsports.com

Barry, your comment about 950 and 1000 Holley carbs not being related to cfm is interesting. I'd guess that is probably true from the Holley engineer's perspective, but if you go to any parts reseller, like Summit for example, they say right in the literature that the carb is a 1000 cfm carb. Here is the carb I'm running, from Summit's web site:

http://store.summitracing.com/egnsearch.asp?N=700+4294925239+4294839063+4294919007+400178+4294891681+4294902726+4294902725+1051506946+115+4294900251

Something tells me that the Holley marketing guys got involved before this carb was released LOL!

Based on my testing, and other comments I've read here, this is obviously not a 1000 cfm carb. But most people are going to assume that the advertising information is correct, and that they are purchasing a 1000 cfm carb. Just goes to show that there's more to this stuff than meets the eye, and there is no substitute for actual test results.

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

For your comments and Jay's follow-up too.

It's apparent (and sad too) that the carb 'modifiers' and Holley are both at fault for literally advertising flow rates of 900-1,000 cfm from carbs that can't even come close to that rating. This has bothered me for some years since I could not understand how in the world even a 850 cfm based carb could be worked-over enough to flow an additional 150+ cfm! Yes, a few percentage points more due to thinned throttle shafts and plates, re-shaping of the upper venturi area, etc. But that much more?

http://www.holley.com/data/Products/Technical/199R10016-2.pdf

Now we know! Frankly, I am now amazed that someone hasn't literally sued these folks for false advertising....and I'm not kidding as many if not most actually do state "our carb flows xxx cfm"! Now, perhaps some heavily modified 750's do flow 830 cfm and some 850's up to say 900 cfm. But, the point is many do make unsubstantiated claims that lead us, the unwashed masses (!) to purchase what we assume to be a carb capable of flowing more cfm (like a lot more!) than a std. carb.

Guess we'll need to rely even more so in the future on dyno or track testing just to be sure.

this 2005 article. Interesting commentary that's apparently true!

http://www.thecarburetorshop.net/bigger2.html

...that's fool'n 'round with CFM numbers. On the 460 "Dream Engine" I won from Hot Rod Magazine, the rules stated that it had to have an Edelbrock carb. I chose the 800cfm Thunder Series carb. Dyno results showed 588hp, but the engine was pulling 3" vacuum at full throttle.
When the "official" tests were over, I installed the 950HP that was on the 427 in my Mustang. With no additional tuning, the engine made 614hp and .5" vacuum at full song.

Draw your own conclusion.

by the old testing method only flows 815 cfm, so the Edelbrock is fudging pretty bad or is running into serious turbulence. I put the 750 AFB top, air valve and secondary boosters on the 800 AVS and it runs much better. I don't know what it flows but it really woke it up alot less crap to intterupt air flow I guess. I put the AVS top on a 750 AFB and it worked way better on the 352 (as you rode in it, it performed pretty well) Both spewed fuel at WOT and went rich at WOT. I blew a bunch of filings out of the float vents, emulsiom, and idle circuit on both cars. I had to put 8 jet sizes back in (almost the original calibration) to get it right,and the floats were all whapperjawed on both. I think it was building air pressure in the bowls. The vents are too small. No more spewing and very good response out of both carbsnow, but it was hardly a bolt on deal.

I am wanting to get my mitts on a 750 4010 Holley(Summit) and play with it. If I could find a base plate for an 850 reasonable. I would put it on my 750 DP. I have taken the Carter about as far as it will go and I think my home rolled 950HP would do better.

I have tried to flow several carbs on my flow bench, and can only flow half of the carb at a time, or in the case of the Dominators, one venturi at a time. I made up several adapters so I could dry flow the carbs. The problem is--at what number? 10? 25? 28? If you dry flow the primaries and secondaries of a 1850 carb, and add the totals, it is very close to 600 CFM. If you do the same thing for a 4779/750 DP, it is more like 800 CFM, and if you flow each venturi of a 1250 Dominator, it totals nearly 1400 CFM. What I ended up doing, was dry flowing each carburetor on a manifold of known flow rating, and seeing how much difference each carburetor made on the flow. There is definitely a difference in the drop of flow values according to the size of the carburetor. A 750 will flow 10 cfm more than a 600, a Dominator will flow nearly 30 cfm more than the 600, which would verify Jay's increase in HP when using the Dominator over the 4150 style 1000cfm carb. Joe-JDC.

Ie on the 1850 what did the primary flow? Half of 600cfm=300, or more like 270? What did the secondary half flow? 300 or more like 330?

Same on the 4779 carb, what did the primary and secondary half flow?
Did both carbs have air horn and choke plate intact?

There are a lot of mysteries left here, thanks Msgt Joe for flowing these carbs!

I'll have to get back to the bench, and my record book. I will try to give an exact number on several carbs early next week. Joe-JDC.

Sheds a whole new light on carbs. I guess you need to do a ton of homework first like anything else. Neat info about the old Holley tester.

Product marketers, ya gotta hate 'em.

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 )

Any EFI inductions on the 427 mule? It would be interesting to so how they stack up to the carb.

Thanks for having me over yesterday. It was very enjoyable!! Steve

Steve, thanks again for coming over to help. I don't have any EFI manifolds that will fit this engine, so I'm not planning to any EFI testing.

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

Jay, I do not know if you have fooled around altering plenum volumes in your Engine Analyser Pro but an engines
characteristics can be thouroughly messes up using to large a volume. Looks like this happens in real life also.
Don W

The Dove single plane intake has a HUGE plenum, at least twice the size of the Victor. On the tests with my previous engine this resulted in a large drop in the torque and HP curve all along the RPM range; the Dove intake came back up to equal the peak HP production of the Victor, but was down substantially everywhere else. Seems pretty clear that this was plenum related.

I think I'll be running one of the Dove intakes today, so that should also provide some interesting results.

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

Quick Fuel modified Holley 1000 CFM? There has to be somebody you know who would loan one to you.

Still confused on why the Holley Dominator with adapter does not at least equal the three barrel. Maybe a different adapter?



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

If I had to guess, I'd say that adapter may work on some manifolds, and not on others. Obviously its not working for me. Royce, do you know of other adapters that may be available?

I think maybe an aftermarket modified carb may be the answer in the end...

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

Jay, we had a Moroso adapter on the 410. Shown here:

http://www.moroso.com/catalog/categorydisplay.asp?catcode=32016

Like Barry said, the combination is everything. Maybe the adapter works well with some intakes, not so good with others.



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

Also might suggest the use of the 'stuffer' that's a sheet metal plate sandwiched between carb and manifold with butterfly-sized tubes extending down into the plenum. Sorta has the effect of making the plenum smaller and raises the venturi effect. Sometimes works well with a turtle to help the charge make the turn into the runners. Particularly effective with Dove-sized plenum, but the plenum is still there. Have your cake and eat it too.

Jay, first of all, I want to say the same thing everyone else has about appreciating all the work it takes to do this. It is even hard to think straight, at least for me, when in a hurry testing stuff on the pump. So, thanks alot for your effort and info.

I have an idea that one reason the info isn't showing a defined pattern is that the 1000 rated 4150 carb probably sucks for the application. Barry mentioned that he liked the big carb because it maintains a venturi relative to the baseplate size(I'm interpreting that from his post). I totally agree with that idea. I have tried just changing main bodies without changing anything else and found bigger not to be better on a 4150 because on a 4150 you lose the size differential between the venturi and the throttle bore. As I said, I love booster signal, which goes away when you increase the venturi WITHOUT increasing the throttle bore. At "1000 cfm" ratings, Doms will get better signal because the larger frame allows for larger throttle bores. Take a look at how very little change there is in the size of a "1000" 4150 between the venturi and the throttle bore.

The last time I did this, in September, I ended up 30+ hp better with an "850" annular than with a "1000" with standard boosters. I also saw a power DROP when we tried the Dominator on the adapter. I'm along way from Minnesota, but I've been reading all this, and have a few speculations that might help you standardize your testing. No guarantees just some ideas. I understand you are under the gun to get finished and don't have alot of time to fool around, but if you get a chance, give me a call. Thanks again for your efforts and dedication to the FE and the crowd who reads and posts on here.

Jay and Blair, I`m at work right now, so I don`t have acess to the dyno sheets for my 428. but I remember that there was a line on the sheet that displayed CFM thru the carb. I`m guessing that the flow numbers are based on the fuel flowing thru the 2 float bowls, as well as the air going thru the funnel air vane "thingy" that sits on top of the carb. On my engine, the flow was showing in the 750-770 cfm range, my carb is a 3310-1 Holley vac sec unit rated at 780 cfm. I don`t remember is there was any significant manifold vacuum at WOT, but I`ll check the sheets when I get home tonight. I do know that my VE numbers were above 100% from above 4500rpm to well over 6000 rpm, peaking at 107%. I don`t think that I was running out of carb, as my buddy with the dyno didn`t seen concerned. (He ran 9.7`s in his 3550 lb SS/F 375HP 396 66 Chevelle using a 780 vac Holley as well.)

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

I've had numerous Forum members over the years contact me directly with questions/comments and I try to steer their inquiry/answer back to the Forum ---that was a great subject you were going off on. I'd like to hear the whole thing...

RE:I understand you are under the gun to get finished and don't have alot of time to fool around, but if you get a chance, give me a call. Thanks again for your efforts and dedication to the FE and the crowd who reads and posts on here.

Here's a link from my carb builder that explains it better than I can:

http://www.pro-system.com/scoop11303.html

I am having a 1000hp built that will flow 880 to 980 cfm when done.

As a side note I'm still waiting for Holley to send me more parts AGAIN to fix my 850 Holley I bought from them.
I'm 60 days into my 90 day warranty. The last time I called them it was like starting all over again.
Needless to say I'm not impressed with Holley so far.

compared to the great wet flow ------------but then again (with respect to I see the benefits of wet flow) That wet flowed carb is bolted on any one of numerous manifolds and/or engine combos and then the shit hits the fan EVERYTHING CHANGES AGAIN
Wet flow not a panacea but surely a big step in the right direction

The wet flowed carb is bolted on to a specific intake manifold and engine combo.
Otherwise you might as well buy a carb out of the box from Summit.
Here's a link to the carb info needed:
http://www.prosystemsracing.com/quote.html

EDITTED: Noted this is under the wrong post. I'm on vacation and my only link is via a dial-up line. Another, earlier post stated that wet flow testing would show higher total CFM values.

First, air is transversing the all openings in the venturi so air is coming through the boosters via the metering blocks and other fuel delivery circuits into the testing device. Wet flow testing would use a liquid which would not flow as easily - think about turning corners - so would decrease the total flow into the throttle bore. Wet flow testing would decrease the total CFM, not increase it.

The shop where we tested those 4100s started by testing a 600 CFM 1850 Holley first as a baseline and got the expected 600 CFM corrected for air temperature and pressure. We then tested my carbs. (They test lots of Holley 2 BBLs for class round track racing and and also had both 350 and 500 CFM two BBL base line carbs they used prior to testing customer carbs.)

Bob

1966 7 Litre Convertible

1959 F-100 (under construction)

2005 GT40 (in my Dreams)

website suggests that wet flow increases CFM????

He says:
You see, the larger the fuel cone that develops at the booster the more air is impacted and slowed, thus a reduction in cfm and an increase in atomization. Not to mention the fuel consumes cfm which has to be calculated into the equation.

I take it as just the opposite, that the fuel decreases cfm.

n/m

soon as you(Jays) started to test the manifolds on your new engine. We would all be learning about carbs, CFM ratings, and effects so quickly. Great stuff here Jay! Thanks!

Is that the whole inlet tract is a system with its own resonance values. Its almost like eight Helmholtz resonators sharing the same source of air like Uilleann reed pipes, except in order to meet your goal of even wet distribution, the resonance has to match the same sonic signature (play the same note) in the whole tract of eight at variation speeds that would make you dizzy trying to quantify. Huge task for any one carb because it calls the tune and the pipes have to play it. If one hits a sour note pops popcorn the game is over