[BVR421]

quote from Tech-BG
"but as I stated earlier the number or CFM rating on our carburetors is not a direct correlation number off of a flow bench it is an average or median off of engine testing based upon recommended application usage."

That makes it sound like "650" or "850" or "1000" etc are just arbitrary part numbers assigned by BG marketing. Do you rate fuel pumps the same way? I wonder what my BG400 pump really flows? I wonder if its any better than the cheap Holley Blue on my other car. LOL
Modern marketing techniques have trashed formerly stable indicators that a customer could use to know WHAT THE HELL THEY WERE PAYING FOR.
I guess it really doesnt matter, if its shiney and has a cool name it must be what we need.

[george kujanski]

Rich, you sound bitter, but I agree with you. Give me REAL specs any day.

george

[BVR421]

Not bitter George, OLD and bitter. That gives me a balanced perspective. (8-)

I gotta respect Tech @ BG, he is a loyal employee and doing the best he can to help the end user. Been there and tried that, sometimes its an uphill struggle.

Now I wonder if the cylinder heads I just paid thru the nose for are rated using a real calibrated flowbench or if the flow sheets were "an average or median off of engine testing based upon recommended application usage"

I -hope- the guy that ported my heads hasnt come to that. I dont think so, but then maybe it all comes out the same in the end.

"Toto, we're back in Kansas! Isn't it wonderful to be home!"

[Cliff R]

Cliff: I'd like to send you an email regarding getting one of your books, but your profile says you do not accept emails............

George, send me an email directly to ruggles@ecr.net and we'll get an order form sent to you ASAP.

We just found out last night that Barnes and Noble will be stocking the book, available in mid-July.....Cliff

[Tech @ BG]

Originally Posted by Skip Fix

I can convert probably to 20" have to check the Superflow charts. I threw the 850 on last night, don't think my bench can flow a carb by itself.It could on top heads and intake and see a difference but not enough motors to pull vacuum on just the carb.

Skip,

Not many benches can pull that hard. Spent hundreds of thousands of dollars to be able to do it. Our current bench can pull up to 20” Hg at 2000 CFM. The big problem that you’re going to run into is just pulling dry air you don’t take the fluid volume into consideration.

[Tech @ BG]

455-4+1,

It was our intention that every single carburetor was flow tested before shipping. No deception was intended. Once we were able to determine that he was not doing his job thoroughly and competently he was dismissed. At that point a new person was trained and other checks were put into the system to eliminate these problems from happening.

Your quote is 100% correct, “I expect some tuning changes and customization of fuel delivery (that is why a carb with adjustable circuits is purchased) but basic machining, cleaning, assembly, function and its ability to NOT FALL APART during use should be expected!!” and this is our goal as well.

[Formula jg]

455-4+1,

The first was suposedly inspected by #36, the second by #34 and the third by #3.

[Tech @ BG]

Mike,

On most engines between ¾ and 1-1/4 full turns out is where you’ll wind up on the mixture screws. Tuning to the highest vacuum is a good starting point, but not necessarily the end all be all. You still need to set everything to where the engine runs best. You may need to go in a touch (1/8 turn or so) on the mixture screws for optimal drivability. If you’re running that rich cruising down the road the first thing we’d want to look at would be the float levels, and PV. Set your float levels to about ¼ of the window (bottom line next to the site glass) as a starting point, and check how much vacuum the engine is producing at your cruise speed when you’re having this problem to make sure we have the appropriate size Power Valve in the carburetor for your combination.

[Tech @ BG]

Originally Posted by BVR421

quote from Tech-BG
"but as I stated earlier the number or CFM rating on our carburetors is not a direct correlation number off of a flow bench it is an average or median off of engine testing based upon recommended application usage."

That makes it sound like "650" or "850" or "1000" etc are just arbitrary part numbers assigned by BG marketing. Do you rate fuel pumps the same way? I wonder what my BG400 pump really flows? I wonder if its any better than the cheap Holley Blue on my other car. LOL
Modern marketing techniques have trashed formerly stable indicators that a customer could use to know WHAT THE HELL THEY WERE PAYING FOR.
I guess it really doesnt matter, if its shiney and has a cool name it must be what we need.

BVR421,

Actually as I stated in the earlier post the numbers aren’t “arbitrary” as you state, but numbers that we have come up with through our testing based upon two factors. The first factor being what type of actual CFM flow the engine sees, and the second factor being the rough industry standard for sizing of the venturi/butterfly combination. If I had my way we wouldn’t have “CFM” numbers on any carburetor since what a carburetor flows on a flow bench is irrelevant to what it’s going to flow on an engine, but that is a whole other discussion.

As far as using these numbers for comparison you really can’t for a couple of reasons. First each manufacture tests their own carburetors in a different manor, it would make life much easier if there were an industry standard that was used but there is not. Second some other manufactures publish numbers on their carburetors that aren’t possible regardless of how you test them. That is where marketing comes into play.

This is also where you need to choose which manufacture you want to deal with (whether it be for cylinder heads, camshafts, or even a carburetor) and trust their judgment based upon their knowledge of their products. I know anytime I’ve had a doctor tell me I’ve needed to have surgery to repair one thing or another that I’ve broken or screwed up I’ve trusted his advice or maybe got the advice of another doctor, but don’t think I’ve ever asked the guy who runs my CNC equipment if I should get it done or not.

As far as your fuel pump question goes. Your BG400 fuel pump free flows 440 GPH, and flows over 340 GPH @ 18 PSI. Your Holley Blue is 70 GPH @ 9 PSI.

Numbers are just numbers, the bottom line is the product (ANY PRODUCT) has to give you what you want from it. That may be HP, throttle response, drivability, cost, or even looks.

[TTS]

ponchoshop, over a year ago we had the same problems with one of the cheap carbs- road demon jr?. Someone here made the comment that BG tech should be contacted before choosing a carb. After considering an "upgrade" for a customers ageing Holley collection, we followed the BG chart for carb selection and the vacuum sec. JR series seemed to be a fitting alternative to the 1850-3310 series Holley on a near stock Ford FE truck engine. After countless attempts to tune the engine, and a return to BG the product would not work on an engine. We later tried it on a 454 and a 318- trying to sell it with no luck. The BG tech told us we should have bought a "?" model instead. They suggested a +/-$600 street strip model would have worked better. I have no doubt it would! Needless to say, the 3310 got a freshen up and went back on the truck and worked flawlessly- again. The BG was sitting on a parts shelf in the shop last year, and now at least it doesn't piss me off every time I see it.

[Rugratman]

So it must be everyone else, not the quality. LOL

[Region Warrior]

Originally Posted by shaker455

Mike,
I set mine for best vacuum which should fall about one full turn from seated in all four corners and sometime I open it a little past best vac when any driveabilty issues show up during testing.

What's your jetting and combo and how do you know your plugs are over rich?...color?...they should look tan or coffee colored.

Was gon'a start a new post, but since we'r here already...
This thing runs ruff at idle, like it has a bigger cam, regardless of rpm(600-1000) and vacuum level.
Also, midrange feels lazy. Not like a IV cam.
Could use more gear. Has a 3.42

462/e-heads(9.5)Crower raiv w/1.65's, RPM int/850 Demon, 1 3/4 Hedmans, Poineer balancer(rubber bonded type), Digital-plus/blaster3/hei with 1 med & hvy spring, 3" exhaust.
Jetting; havent checked yet.
Screws @ 1 1/8 @ 14" vac @ 650rpm in drive(right now)
Were about 1 3/4 @ 11" @ 850rpm when i started.
Fuel level; 1/4" in sight window
All plugs have tan centers and 80% on ground strap, but the outer ring is black as coal.
They were completely black before i started.

Exhaust burning eyes like it's to lean, but smells rich.
Can get idle down to 500 in drive.
Using vacuum gauge, not at highest * of vac, but steadist, which is about 13*
I know i'm close, but just doesnt feel/sound right...

It runs best(steadist) at idle with about 30* before tdc. Was off the map before i started tuning.
Below 20* it starts run'n ruff(with or without vac can)

Been over 10yrs since i had one.
Does that sound right?
Balancer moved?
3" exhaust fool'n me?
Maybe a 400, not a 462?
Need to make sure timing is right 1st

Thanks.

[Tech @ BG]

Originally Posted by Rugratman

So it must be everyone else, not the quality. LOL

In my earlier posts I commented that we have had issues, and that we’ve implemented changes in order to prevent them from happening in the future. I’ve also mentioned that we work very hard to eliminate problems, and will continue to make improvements to prevent problems. You’ve stated that our production and quality procedures are flawed, we’re open to any feedback you have on how we should improve it.

[Tech @ BG]

Mike,

Something doesn’t sound right. Most engines regardless of how radical the camshaft is don’t respond to increasing the timing (at idle) past about 18 or 20 degrees as far as idle quality. Something is making sense on your timing. Is your 30-degree number with the vacuum advance hooked up or not hooked up? If that is with it hooked up what is the timing without it, and does hooking it up make a difference? With your cam you should be able to find a happy spot where it idles smooth. Since you’re saying it almost sounds lean, try this; when you’ve got the idle set gently press one of the accelerator pump arms without moving the throttle. This will add fuel without changing the amount of air the engine has, and let you know if it does indeed want more fuel.

[shaker455]

Originally Posted by Tech @ BG

You’ve stated that our production and quality procedures are flawed, we’re open to any feedback you have on how we should improve it.

Doug,
I'd like to extend an invatation for Barry to join us here as I have some suggestion on how you can further implament quality improvements.

Mike,
You have mail and a PM

[Tom Vaught]

First off, Thanks BGTECH for replying to some of the PY board's questions again.

I would like to comment on a few of your quoted posts.

Quote: (By BGTECH)

"Here ya go, but you still don’t have an exact comparison (I’ll get to that in a second).

10” H2O = .73559” Hg
20.4” H2O = 1.5” Hg
28” H2O = 2.059565” Hg"

Tom V: I agree with your inches of Water to Inches of Mercury conversion.

Quote: (BY BGTECH)

"Now here’s where it gets interesting. Each carburetor company rates their carburetors differently. We for example rate the “CFM” by using a median or average flow number if the carburetor was installed upon an application that we would recommend. Meaning if you were to install a 650 Demon on an engine that we’d recommend it on it should flow about 650 CFM at WOT if you were measuring the amount of air going into the engine. So when comparing a Demon carburetor to most other brands we are rated more conservatively, so we normally will use a “Smaller” rated carburetor to achieve optimal performance. The reason we do not use the 1.5” Hg number is that it’s not a realistic number for real world performance. In most performance applications if your engine was pulling 1.5” Hg at WOT you could make more HP by going to a larger carburetor."

Sub Quote:

"Each carburetor company rates their carburetors differently."

Tom V: That may truly be the case today BUT for many, many, years all of the OEM manufacturers of carburetors used the same standards: 20.4" of H2O (or 1.5" of Mercury) for a 4 barrel carburetor. The one barrel carbs and two barrel carbs were rated at a higher 3" of Mercury. ALL CARBS were tested with Stoddard Solvent (same SG as gasoline) flowing through them. Barry Grant and some of the Hot Rod carb builders many years later converted to wet flow benches. It was not the other way around, contrary to many press releases stating otherwise.


Quote: (BY BGTECH)

Here are some flow numbers off of a few Mighty Demon carburetors so you can get an idea. The WOT number at 1.5” Hg will be with an average A/F ratio of about 12.5:1.

650 Mighty Demon at 1.5” Hg will flow 753 CFM Wet (Air and Fuel)
750 Mighty Demon at 1.5” Hg will flow 920 CFM Wet (Air and Fuel)
825 Mighty Demon at 1.5” Hg will flow 982 CFM Wet (Air and Fuel)

Now if the engine any of these carburetors were on were to pull more than 1.5” Hg the flow would be higher, less vacuum lower."

Tom V: I have a serious issue with the above airflow numbers (as being wet).

Quote by Skip Fix:

"OK your Speed Demon 850cfm has 1.562 venturi, and 1.75 butterflies. The Race Demon 1000cfm has the exact same specs. No choke tower, and even if it has thinner throttle blades or downleg different boosters they are NOT going to make a 850 a 1000cfm carb. I can see maybe 50-70 cfm. The same goes for the Holley 850 DP and the 1000 HP carbs-same exact specs, has to be different flow pressures. The same size hole will flow the same cfm unless you change the pressure tested at, at least they do on every flow bench I've used."

Tom V: The Holley 850 CFM spec above is based on 1.5" of Mercury at Standard Temp and Pressure with Stoddard Solvent (Wet Flow). Has been rated that way forever! The 1000 CFM rating was in response to BG and others in the Hot Rod
carb builders world using 28" of water and flowing dry.

Quote: (by BGTECH)

"As for your first question you would need to either set your flow bench to 20.4” of H2O or mathematically convert from whatever depression you’re flowing at to 20.4” to give you 1.5” Hg. With that being said, dry airflow vs. Wet airflow can make a tremendous difference in CFM number."

Tom V: Agree! The flow number will go DOWN when fuel is added, not up.

Quote: (BY BGTECH)

"I cannot speak for how Holley is rating their carburetors, but as I stated earlier the number or CFM rating on our carburetors is not a direct correlation number off of a flow bench it is an average or median off of engine testing based upon recommended application usage. You are correct, similar size holes will have similar flow numbers when measured on a bench or the same pump (engine)."

Tom V: The benchmark which the industry used for over 50 years was to test at 1.5" of Mercury at Standard Temp and Pressure. I would think that physics would not change as related to Orifice flow. Agree with the same flow numbers comment
when measured on a proper wet flow bench at standard test pressure/temp.



Quote: (BYBGTECH)

"That makes it sound like "650" or "850" or "1000" etc are just arbitrary part numbers assigned by BG marketing. Do you rate fuel pumps the same way? I wonder what my BG400 pump really flows? I wonder if its any better than the cheap Holley Blue on my other car. LOL
Modern marketing techniques have trashed formerly stable indicators that a customer could use to know WHAT THE HELL THEY WERE PAYING FOR.
I guess it really doesnt matter, if its shiney and has a cool name it must be what we need."

Tom V: Agree! People want a standard that they can use to compare with that does not change due to marketing policies. For many years the OEM carburetor industry had those standards. When the OEM car builders quit using carbs the standards went to H*ll as the Hot Rod carb industry moved away from solid engineering documentation to marketing.

Quote: (BGTECH)

"Not many benches can pull that hard. Spent hundreds of thousands of dollars to be able to do it. Our current bench can pull up to 20” Hg at 2000 CFM. The big problem that you’re going to run into is just pulling dry air you don’t take the fluid volume into consideration."

All of Holley's flow stands in Warren, Michigan were WET FLOW stands. I have a Holley Carburetor book by HPBooks that shows on page 4 Holley's Orifice Bench.
This bench was one of the benches left over from the WW-II aircraft carburetor testing days and could flow over 3000 cfm (wet flow) at STP and Standard Temp.
When I worked at Holley this bench was used often for high flow engineering programs. How old were you in 1972?

In Conclusion:

Thanks for owning up to some quality issues with your carbs. Every manufacturer
potentially can have the same from a disgruntled employee. Hope they are corrected based on your earlier comment. It will take years to get past the falsified documents deal though. Takes a long time to build back the trust.

I still have an issue with your carb ratings as being accurate with "wet flow"

Possibly you could send me info on your Mighty Demon carbs by e-mail. I have the DEMON book with the other carb info.

Thanks

Tom V.

[David Holmberg]

Tech @ BG, on behalf of the staff here at Performance years BBS, I'd like to thank you for taking the time to reply to the members questions. The fact that you're willing to reply to even the not so nice posts shows the direction the BG Co is trying to go in.

If you stick around and continue to help the members the general confidence in BG products will improve greatly.

Thanks again!

[Region Warrior]

Me too, thanks!

I agree, the timing deal isnt right. Thats the way i received it.
Probly end up degreeing the cam, check it with another balancer, then go from there.

[Tech @ BG]

Shaker 455,

Barry actually does check in on the boards from time to time. Right now we’re up to 227 that we monitor on a regular to semi regular basis. Whenever there is something pertinent (like thread like this) he (and a few other people) gets copies of it. He normally won’t post on the boards to avoid pissing matches with people. But, please let me know any thoughts you have (you can always send me a PM) I’m always open to ideas to improve what we’re doing.



Tom,

I’m sure you’ve probably forgotten more about how carburetors were built than I could ever wish to know (not being sarcastic) and while I do agree with a lot of what you say I will have to respectfully disagree with others.

Back in the carbureted Muscle car days carburetor CFM ratings were varied within the exact same specifications. This was in the same time frame that the OEM’s had a dial on the crank to determine HP levels for the government. In the same token we, and every other carburetor modifier is guilty of numbers due to the fact that we would port a carburetor and then get an increased “Dry” air flow number which was published. With the proper porting you can easily get a 750 carburetor (at least one that started that way) to flow over 1000 CFM at 1.5” Hg.

Not exactly sure what you doubt about my flow numbers, but I’ll gladly send you an email about this in a few days so we can discuss it. I still have your email address. Taking a few days off for the holiday, and I’ll be up in Charlotte doing some dyno work, but I’ll get something off to you. I know my numbers can be backed up on a wet bench, while the numbers from Bowling Green do not. I’m not here to slam anyone nor do I want to get into that.

I agree better standards would help some (like yourself) in our industry that understands what they are looking at, but I think at this point would actually confuse others even more. Again I would personally rather do away with CFM numbers totally, and get down to the venturi size required.

If it really matters to you I was born in 1972. I’ll leave out any wise comments, or history about me since it really isn’t needed.



David,

Thanks for having a great site. I just wish it would be able to send me notifications when there are replies to a topic I’ve posted on. (Just had to throw that in there) Steve said he’s working on that.

Mike,

Once you get your timing deal straight. We should be able to help you through this pretty easy.


To All,

Have a very Safe and Happy 4th of July!!!

[speedshopmike]

bg tech,
you can subscribe to a given thread by choice and select instant or other styles of nitification.
this board's a little weird int hat regard, as on occasion the choices haven't "stuck", but it's been pretty good of late.

click on "quick links" then select subscribed threads, and you can check the ones you'd like.
go to bottom of page and move them to the category you wish.

you're doing a fine job being objective under all this tar-and-feathering, by the way.