Setting up Supercharger
 

I have been toying with putting a supercharger on my 502ci motor. The motor is freshly rebuilt, just about 9:0to1 compression, 226/234 with 112 lobe seperation on the roller cam.
My question is what modifications will I have to make to my carb if I put it on top of a Holley 250 supercharger. I am planning to set it up with a conservative boost level of around 4lbs.
This will be my first supercharger. Any help from others experience will be helpful.:)

it will need to be jetted richer. I wish i had more technical info than that. I am sure somebody will chime in with the actual #s

Sorry about the lack of info, I'm at work and got interupted, the nerve of these people to bother me when i am on OSO!
Anyway, the carb I have is a Holley #9381 a 830cfm chokless race carb with four corner idle and two powervalves.
The cam as I mentioned is a Comp Cams custom grind 226/[email protected] with 112 lsa and installed at 110 ILS roller.
The motor has full roller rockers in it as well.
I have the D.U.I high energy ignition with about 20 degrees in the distributor.
The other question I have is would the smaller 174 unit be enough or should i spend the xtra for the 250, there is several hundred dollars diff.

merc use dthe 174 on the 525sc engine but ath wa s 454. I keep hearing for a 502 youshodul go with the 250. I think that a 174 would work you just might have to spin it faster to make more boost. If your going with new i would go with the 250.

You're going to need to have your carburetor set up to work on top of the blower, or better yet buy one built, & designed to go on top of the blower. The fuel curve is different, Boost ref. PV along with other changes. As for the blower Go with a 250 from The Blower Shop. It blows anything Holley can make away (no pun intended) talk to Marv out there. www.theblowershop.com great guys, and great products.

THE 250 WILL MAKE LESS HEAT AND HAVE A DENSER CHARGE AT THE SAME BOOST LEVEL SO BE SURE TO GO WIT THE 250 OR BIGGER ,,ALSO BOOST REFERENCE THE POWER VALVE AND ADD A 2.5 PAIR OF VALVES AND START WITH 4 SIZES LARGER JET AND MAKE A SHORT RUN WITH NEW PLUGS THEN READ THEM AND ADJUST THEM FROM THERE !
HEY THE GUYS AT POWER MARINE ,IN CHARLOTTE N.C. DID MY CARB WORK AND THERE OLD NASCAR GUYS AND GAVE ME A GREAT DEAL AND HAVE BEEN THERE FOR ME EVERY TIME I CALL !
THE GUYS NAME WAS ROBERT AND PHONE 704-889-3777,OR 704-574-4020,
THIS INFO ,I HOPE HELPS :

If you haven't bought the blower yet, I'd consider a 420. The 250 was designed for a high horse 454. They started making the 420 for the bigger motors like the 502. The air/fuel charge will be cooler with the 420 as well. I ran a 250 w/two 750's on a 454. 697 horsepower with 7# boost, blower cam, ignition and fuel delivery mods. The down side was the 250 is real noisy at speed!

Built a 509 with a 420. Used the same carbs, added an intercooler. 878 horsepower. Nothing like blown power :D Last weekend marks a year it's been running without a hiccup! Hopefully I didn't jinx the next weekend:eek:

Don't scrimp on the ancillaries like ignition and fuel supply!

Craig

I'm running a 1050 dominator with my 250 on my 502 @ 5lbs boost. It has been boost referenced and built for a blower. Is a single 830 large enough? If it is not right, it will be a night mare! Or worse........costly.

Talk to somebody who knows! Shops have been mentioned in this post who may be able to help you. I would use Dean Nickerson at Nickerson performance because I know he has alot of experience with 250 b@M's on various applications. He also is a recognized carb guru. They advertise that something like 95% of their carbs don't require jet changes when they set them up for your application. Some of the others mentioned may be good too. I am currently installing a B@M 250 EFI blower with a Superchiller on a 454. I am about to order my Superchiller from Dean.

I had Dean Nickerson set up my carbs in April. They were spot on!

Even the idle screws were perfect.

671`s with Superchillers/750 Holleys