Holley Dominator advice needed

[Hot Rod Todd]

My bucket has run a blown 468 BBC and last year we fitted up a BDS 16 injector efi setup. We had some problems with the computer and shortly after that, the engine melted on a dyno.

It was a very costly experience.

So I upsized to a 540 cube BBC and managed to sell off the old shortblock for a fair price.

Im thinking about ditching the efi and going back to a pair of carbs. Probably 1050 dominators as they will feed the 540 and blower okay. Fuel economy has never been the main objective, but the car is street driven thru the summer months.

Any recommendations for the carbs? Would I be better off with smaller BGs? I started out with a pair of 750 Edelbrocks on the old 468, but think I will need bigger for the 540.

Cheers
Todd

 

[Wild Mango]

Assuming 5lb boost at sea level, 6000RPM on that 540, you'll flow around 1200 CFM.

Take it from there.

 

[GT63]

Edelbrock makes a 800CFM carb. Either in AVS series or Performer series.I would think two of those would feed that beast at 1600CFM.

http://store.summitracing.com/partdetail.asp?autofilter=1∂=EDL-1812&N=700+115&autoview=sku

http://store.summitracing.com/partdetail.asp?autofilter=1∂=EDL-1412&N=700+115&autoview=sku

 

[blownt]

I'd have to say two 1050 Dominators would be too much for the street. But if thats whats ya want then go fer it. Personally I would not go bigger than two 750's for the street on a big block. I got two 650HP's on my blown smallblock and thats pushin it.

 

[409T]

Here's what the BDS web site has to say:

The size of carb(s) or CFM required for a given application can be calculated by the following formula A: {(CID x RPM) 3456} x {Boost 14.7) + 1} = CFM required. The amount of CFM required will determine carburetor size and quantity. If you try to use a carb with less CFM than required, performance and economy may be greatly reduced. Bigger is not always better when selecting carbs that are 30% over what is required, you may encounter problems in fuel distribution.

 

[Screaming Metal]

Here's what the BDS web site has to say:

The size of carb(s) or CFM required for a given application can be calculated by the following formula A: {(CID x RPM) 3456} x {Boost 14.7) + 1} = CFM required. The amount of CFM required will determine carburetor size and quantity. If you try to use a carb with less CFM than required, performance and economy may be greatly reduced. Bigger is not always better when selecting carbs that are 30% over what is required, you may encounter problems in fuel distribution.

Dawn....what he said.........You guys are good!!!!!!

 

[Hot Rod Todd]

Thanks guys,

So using those figures 548 cubes * 6500 max revs and about 10lb boost on the strip, I should need 1731cfm.:lol: And racegas.

But it will be a pig on the street.

 

[Screaming Metal]

Thanks guys,

So using those figures 548 cubes * 6500 max revs and about 10lb boost on the strip, I should need 1731cfm. And racegas.

But it will be a pig on the street.

Yea Tod, but just think of the smile you'll have on your face a you mash on the 'GO' pedal! Ha! It'll probably be 98% from the G's being pulled as rocket down the road! :razz:

 

[Screaming Metal]

If your gonna set it up like that ......why don't you build yourself a progressive linkage.......one for the street and one for the strip......so you can kinda do the dual purpose thing.
That way you can just change the linkage out when you wanna tromp on someone................

 

[Screaming Metal]

I just did a about face while walking to the engine stand........You do know that they have restrictor tubes for those carbs......don't you? Well.....I don't know if thats what Holley calls them or not. Its like a sleeve that fits down inside the throat of the carb......dropping the CFM to I believe 925CFM and if my memory serves me correctly.....they have 2 other sizes. Its another way of detuning that carb of special needs.......

 

[blownchebby]

With a blower the carbs can become the restriction. It all dependes on the amount of boost. Ts are very forgiving because they dont weigh much. So with the right amount of stall it can be maid to work. I do like the progressive linkage idea. The one thing that people are not thinking about, is a 540 with 10 pounds of boost, it will be a beast. It will consume lots of fuel because it makes lots of power.

 

[Chief-T]

How does this formula work with a non-blown eng? Do you just use (1) for boost?

 

[GT63]

How does this formula work with a non-blown eng? Do you just use (1) for boost?

For non-blown engines:

try this:

Calculate Required CFM Of Carburetor


or this :

http://www.carburetion.com/Calc.asp

For a rough CFM use this formula: Engine Displacment * Max RPM / 3456 = CFM @ 100% Volume Efficiency

IE(My engine): 350ci * 6000rpm / 3456 = 607.639 (Round down To 600CFM)

IE (Yours, Will Vary On RPM, But Figure) 327ci * 6000 / 3456 = 567.708 (So Figure With The Bore & Max RPM Approx 600CFM.

Most small blocks 350 ci and over only need 600 to 650 cfm carburetors.

 

[Screaming Metal]

With a blower the carbs can become the restriction. It all dependes on the amount of boost. Ts are very forgiving because they dont weigh much. So with the right amount of stall it can be maid to work. I do like the progressive linkage idea. The one thing that people are not thinking about, is a 540 with 10 pounds of boost, it will be a beast. It will consume lots of fuel because it makes lots of power.

Hey....BlownChebby! Wouldn't it be sweet to ride in the sucker!!!!!!:razz::razz::razz:

 

[Hot Rod Todd]

Well Im getting excited already.

Have managed to borrow a pair of 1050 Dominators from a mates mate to test things out. Will run the 671 t about 20% over for the meantime, and probably run on avgas because the stuff they call fuel down here isnt kind to engines that want to go fast.

I have most of an 871 sitting around - just need a case so if anyone has one sitting around that they want to sell, and can send it on to California in the next 2 weeks, then we can do a deal. Another mate is coming to California for work next week and can bring it back for me.

Just trying to decide whether its time to fit up some wheelie bars and a wing ontop of the cage - winged Express style!

Thanks
Todd

 

[blownchebby]

Heck ya,You and todd are my kind of folks.:twisted::lol::twisted:

 

[Hot Rod Todd]

Just ordered a dominator linkage kit and the dominator base plate for under the carbs from Good Vibrations Motorsport in California. Ive got a mate flying back to NZ next friday so he will bring the bits back for me.

Ive bought other stuf from Good Vibrations in the past and they are great to deal with

Our drag racing club is now talking about running some winter street meets, so I may get to test the new setup before september if we can get the meets up and running

 

[Wild Mango]

Todd watch it with our Avgas. All you can get on airfield bowsers is 100LL, it has a R.O.N. of 94 which is lower than the Ultra pump gas which "rons" between 96 and 98 in some batches. More than a few pistons have gone off to Slug Heaven courtesy of 100LL Avgas.
Better to get yourself a drum of Methanol and mix yourself some rodders E85 with 24% C16 race gas and 1% castor oil. Smells good too as you rumble along and you get a R.O.N. close to 115. Less liable to go pop in the blower as well.

 

[Screaming Metal]

Todd watch it with our Avgas. All you can get on airfield bowsers is 100LL, it has a R.O.N. of 94 which is lower than the Ultra pump gas which "rons" between 96 and 98 in some batches. More than a few pistons have gone off to Slug Heaven courtesy of 100LL Avgas.
Better to get yourself a drum of Methanol and mix yourself some rodders E85 with 24% C16 race gas and 1% castor oil. Smells good too as you rumble along and you get a R.O.N. close to 115. Less liable to go pop in the blower as well.

Yea man.....it'll keep the pops down definately! Don't know if you can still get it or not....if you've got a friend at the airport or talk to them really nice....go for the 'green /blue' stuff. Hi octane....great racing fuel, but dry as hell. Gotta lace it with some oil, keep from getting the 'scuffs', as I call them. Thats where the lubing is washed off from the dry fuel on the cylinder walls.......hard on the valvestems also.....use bronze guides if you can...................... yep....love that smell!!!!!!!! Puts a smile on the old puss!