GoCiggie31

I have an oem WEBER carb on my 1992 502 and was wondering:

1) what is the CFM?

2) what is the maximum power I can expect out of a (this)Weber.

Currently it is on the 6269316 aluminum intake with spacer- stock.
Been running fine but looked a little crusty so I am planning a reseal. ONly engine mods (complete rebuild) w/ a valve job 551/530 crane cam & a decent exhaust ( cmi's unitops).

Thoughts-thanks

GoCiggie31

AND in a very very heavy deep v twins

rdoactive

It's 750cfm.
Merc put 800+cfm Holleys on their 420hp & 450hp 454s and their 500hp 502 motors. So one might suspect it's at it's limit with 410hp.
The holley and weber are both squarebores, so a holley will bolt up with a new fuel line.
Gary

Reed Jensen

Why switch to a Holley?...

rdoactive

Because I'm assuming with the cam, exhaust, and intake change he may be concerned the carb may be too small. (Sorry, dont know the cam specs or expected hp output).
So what readily available marinized carb is over 750 cfm, cost effective, easily tunable, squarebore pattern?
Holley. Ta Da!
Gary

GoCiggie31

Thanks,

Very good points. Honestly I don't know the real h.p. but must assume it is over 415-450. I have not dyno'd after I have done below mods.
I used the mild Crane 132561; lift 530/551, duration 228/236 with 114 set at 0 with a built-in 5 deg advance. light porting (recontour short turn radius). with roller rockers with a full balance of rotating assy and 5 angle valve job hopefull will net in the mid 400's.
I have read that you don't want to overcarb so I wanted to stay on the conservative side (not really knowing the h.p) until I step up to the afr's and more agressive cam . or after I do some plug readings with the Weber.
In reality I have overblown my budget on above and not sure if this carb would work for the break in process or will it choke to not perform properly. I need more time to pass for the wife to forget about the expenses on this project

Thank again

Reed Jensen

The big problem with overcarbing is the lack of throttle control at midrange. You open up too much throttle area and the response suffers.

rdoactive

A good thread for carb size:
http://www.offshoreonly.com/forums/s...rb+cfm+formula

Griff

The Webers were 750cfm.

I would replace it with an 800 Holley. I just don't know enough about fine tuning a Weber. Also, you will be able make apples to apples comparisons with jetting and tuning it.

GoCiggie31

great info-
replicating what merc has used on their more-than-mild 454/502, they have used 800 Holleys.

Thank you all

BTW, cp just announced this below package on sale-thoughts?

Intake/Carburetor Kit
620-54000


HP 500 Style Intake/Carburetor Power Package

If you're looking to build an HP 500 style motor but are not sure of exactly which parts you may need, then this kit is for you. Nothing could be easier.

We have combined all the necessary items to produce an HP 500 style package in kit form. This kit includes:

(1) 620-53031 Hardin Marine Big Block Chevy Intake Manifold
(1) 710-9022 Holley Marine 800 CFM Carburetor
(1) 620-52001 Intake Allen Bolt Kit
(1) 620-53106 Carburetor Stud Kit
(1) 300-17342 Extreme Seal Intake Gasket Kit
(1) 620-04112 Water Outlet Gasket

Sale Price $804.95 $699.95
(Savings: $105.00)