holley carb choices

[silvermonte]

Hello, i was at an event the other weekend and ended up with an award for my choice of a holley carb. I went and talked to the shop that helped my build and pick out the parts for my motor and they suggested i get a 4150 double pumper 650cfm http://holley.com/0-4777S.asp . As i was looking thru my options in noticed the ultra 4150 aluminum line http://holley.com/0-76650RD.asp , is there any reason i shouldnt get the ultra as cost is not an issue? This cam is rather small and i plan to bump up the size down the road a bit better to match the heads as i think they a bit on the larger size for a 350.

the specs on the vehicle are

S10 truck that is about 3000 lbs
700r4 with 2300 stall and 3.73 gears in the gear
350 bored .060 with 9.5 compression iirc
heads are pro-comp aluminum with 210cc runners
cam is a comp cams XE268h
adv dur 268 280
dur @.50 224 231
lift .447 .480
lobe sep 110

[Thephranc]

The ultra is a better carb for what its made out off. The Alum allows for less heat transfer to the fuel and less warpage from heat. The Holley carbs have a reputation as hard to keep tuned because of this heat expansion. The ultras fix this problem. They also flow better and weigh a few pounds less and.

I'd get the ultra.

[Ron Sutton]

I would suggest 700 cfm, if available.

[silvermonte]

My choices in the ultra are 650 and 750. Ive always used edelbrocks so I wasnt sure what to pick and I was told to stay away from the avenger line of holleys. To me the DP's and the ultras seemed to be the same except for the ultras being made out of aluminum and such.

[Thephranc]

750 is too much.

Here is Holley's calculator: http://www.holley.com/applications/CarburetorSelector/CarbSelection.asp

I doubt you'll get over a 650.

[Ron Sutton]

If you use the Holley calculator, it suggests everything from a 660 to a 750.

But, being familiar with these heads & cam characteristics, this 360" engine would work great with a 650 or 700cfm in a 3000# truck with 3.73 gears. The 700cfm carb will allow you to optimize the bigger cam you're planning to change to in the future.

[Derek@ModernSpeed]

Go with the 650 on your application. Is this a truck that gets auto-x or just a cruiser?

[silvermonte]

Its going to be used for auto-x, give or take 15 times a year. That seems to be about how many events I can make it to in a summer, plus ill be driving it to the events.