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Author Topic:   pulling vacume
Dirt Roller

Total posts: 13
posted April 27, 2002 07:56 PM
Ok I know I am probbly asking a stupid ?. What I need to know is what cam would be best to pull 17# vacume. Also what type of corb would I need to run? Here is the rules I have to abide by.

1.all late model body rules apply
2.14"aluminum wheels
3.D-55 or MD-56.must check (60) or harder at any time.
4.weight: 2450 Lbs
6.stock ignition only
7.gas only
8.any intake
9.any carburetor
10.stock water pump & pulleys
11.stock manual fuel pump in stock location
12.any tranny with at least one working forward & reverse gear & will be able to crank & pull into gear on it's own.
13.any rear-end
14.any cam that will pull 17" of vacuum at 900 rpm by the tracks gauge
1.$600.00 engine swap. ($100.00 goes to the track points fund, $500 goes to the driver.)
2.must finish in the top 5 to claim the top (2) finishing engines
3.Top 5 finishers must report to the tech area as soon as they cross the scales.they have 10 minutes to claim an engine
4.A car can claim only (3) engines per season
5.If a car refuses claim,he forfeits all winnings & points for that night.each car can only refuse (2) claims per season
6.both parties involved in an engine swap keeps the following:
b.distributor & plug wires
e.radiator & hoses
f.power steering & accessories
g.transmission & accessories blade & adaptor

What kind of corb and cam do I need?

Dirt Freak

Total posts: 310
posted April 28, 2002 09:56 PM
Call a cam manufactuer or email sbnc29 he got the answers to these ? ofr knows someone who does

Dirt Maniac

Total posts: 115
posted April 28, 2002 10:28 PM
your valve overlap and duration are what kills your vaccuum. look for a cam with a low duration and run 1.6 rockers with it.

Dirt Full Roller

Total posts: 57
posted April 29, 2002 03:52 AM
how about variable duration (bleed down lifters) that should add some
vacumn and allow for a bigger cam. dont know how well they servive in a race engine

Dirt Forum Racer

Total posts: 90
posted April 29, 2002 08:02 AM
I agree with Birdcage on the bleed down lifters. Ran them in my street stock (3280lbs) with a Comp Cam 274H-3 (474in lift/486ex lift) with 1.5 lifters and could pull 17#'s at 1,000. They held pressure well up to 6,800 (my max rpm). The 274H might not make the 17# at 900 for your rules. You might want to drop down one level. The 274H was rated between 1,800rpm to 6,000, but pulled well above 6,000. Going to run it again in a small mod engine with 1.6 lifters. I ran the Comp fast bleed lifters, but I've heard that Crane fast bleeds are better in bleed rates. Hope that helps.

Dirt Full Roller

Total posts: 43
posted April 29, 2002 10:00 AM
We ran the Crane bleed downs last year and I don't think they were bleeding down like they were supposed to.It looks like high pressure oil pumps and thick oil would make them not work like they're supposed to.A buddy ran Rhodes lifters and they seemed to work better.
I've heard that those lifters don't help over a certain amount of lift

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