I think he has 800 Holleys, but I too said the same thing earlier in this thread. Dyno it with your carb, then try a dominator, 950-1050cfm 4150. If it picks up 10 hp, then prob not worth it, if it picks up 25hp, then it may be. It literally takes 5 minutes to swap a carb on the dyno. I think "Rookie" here, even mentioned he would provide the dominator for Tim to try on the dyno.

My opinion, is we are all about custom cams, CNC ported combustion chambers, we'll have a 47 page thread on bumping the compression 1/2 point, arguing over 8cfm on an exhaust port, but when it comes to having the best carb for the application, we get "just run it, it'll be fine".

I know myself, If I just dropped 25 grand plus, on some fresh from the ground up engine builds, they'd be going on a dyno, without a doubt. Especially in Tim's case. He had a pair of 548'ci mills that ended up being a bucket of chit prior to all these. Cheesy cams, chinese heads, slapped together assembly by some hack, that ultimately tossed a rod. They made like 600HP at 5500 RPM? I'd certainly want to know if all the money, time, and thought was worth it, and by how much. Not to mention, the tuning/break in advantages of a dyno session.

26 pages on this topic. There are literally carb CFM calculators plastered all over the internet, and on many carb suppliers web sites. About all of them come up with 900+ CFM. I'd be very shocked, if you called quick fuel, holley, AED, carb shop, Chuck Nyutten, pro systems, Allstate carbs, or any of them, and they spec'd an 800 carb for a 6000RPM hot 540 with AFR heads, custom cam, etc. Can you bolt on an 800 and the engine run great? Absolutely. Will it give up power to a 950, 1050, ? Thats the question, as well as how much power, or will it lose power? Plus, which carb are we talking about? Not all 850's are the same, not all dominators are the same. You couldnt give me a 25 year old 8896 dominator to run on this engine. Would I take a 2015 QFX 1050 dominator, surely would.

I copied this from pro systems website

The wider the range of rpm you're going to subject the design to, the more you need to look at the range of airflow and available options.

I'm sure you remember this old formula:

CID x RPM x V.E. / 3456 = CFM


Well that formula is still being quoted by magazines and companies etc...but times have changed and carburetors are operating on almost immeasurable amounts of vacuum. 10 years ago a carburetor would require 10 inches of water to pull signal and shear fuel. Now they can can pull and shear fuel at only 3. Remember 20.4 inches of water (wet) is the cfm rating guide with reputable designers so we aren't looking to match cfm requirements with cfm ratings.

20.4 = 1.5 hg.

You can see that going from 10 inches of water as a requirement at launch to only 3 inches as a requirement really allows a serious increase in cfm size. This removal of restriction really pays off in cylinder head flow numbers and hp of course. Imagine altering this upstream restrictor when flowing your heads.

Because, most of you have specific application designs, a custom shop/unit is typically the plan.

In the future, use this calculation as a general rule on a modified carburetor:

CID x RPM x V.E. / 2820 = CFM
540 x 6000 x .9 / 2820 = 1034 CFM

Now you'll be a little closer

tim,whatever you do don,t buy a quick fuel 1050 carb,instead call one of the carb guys and tell him you need a 1034 cfm special.

Mine are 800's from 98 HP500's I know I need more then that... The plan was to run them this season because I didn't see the cash at the end for carbs if I wanted in by Memorial Day, I made a few deals and have more money coming in that will allow carbs, I would like to dyno the engines if I can get it scheduled when time comes... I won't wait 4-6 weeks like I am told most guys say it takes, so all depends... Maybe I will toss em in the truck and have beers with Chicago guys one weekend on the dyno lol

com on to chi town,we can dyno both engines in one day.

I am considering it....my machinist has old dyno or I would go there, the other local guy is way too busy so my options are limited... Then I can also get Lou's pizza!!!!

I know Mike Tkach probably has an assortment of carbs to try on that engine, sitting in his spare parts bin. I'm pretty sure that if the engine doesnt make the power you want, he can dig up a 14-71, possibly a PSI blower, or a whipple to bolt on. I may be able to dig up a rochester 2 barrel for you, should be plenty for a 700hp 540??.

If EFI gives you the ultimate erection, and you really wanna save some money on the build, the shop we use is a Holley EFI dealer, installer, tuner, as well. Also, they are a dealer for Whipple superchargers and daytona ignitions if thats a route you'd like to go....just remember. If you go EFI, you might want to invest in an azz pad. Because once you have an EFI marine engine, you'll be getting so many slaps on the azz, that chit will hurt after a while. But, on the bright side, you get a 1 year membership to the local country club so you can golf with the society of automotive engineers, nasa space shuttle designers, and top politicians. Its a very elite club, where you'll enjoy the comforts of many leather bound books, only the finest malts, and a cigar room.

You'll then be able to flogg your engines silly, run the chittiest gas you can find (who cares its got knock sensors), get 27mpg with your boat, and enjoy the fruits of trouble free starting when its minus 4 degrees and your headed to the beach. And best of all, you'll be able to laugh, giggle and poke at the guys stuck in 1957, running carburetors, yelling out "I saved more money" as you cruise past them on your unicorn of a cigarette boat

Speechless....LOL

Its friday. I am in a good mood. Its below freezing here, I can't wait to go out tonight.. I'm gonna go on a quest for watered down 86 octane, rub my nutsack on my knock sensors thanking them for what they do, and when the bar closes, offer to start everyones cold engines, and enjoying the sweet music of cold starting port injection. I am praying, there will some poor bastard there with a 1984 Lesabre with a 307 olds engine. When I see him high idling that pos, I may throw a tomato at him, giggle, and run.

Dude, it must be REAL cold there hahahah

wow,don,t know what else to say!