Carb help for 408 stroker

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Mustang5882

New Member

Oct 22, 2008

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Aug 8, 2009

#1

• Aug 8, 2009

• #1

i have a 408 stroker i recently put together it has eagle forged rotationg assembly with pro comp 210 heads roller rocker vic jr intake and pretty large cam. i had a 850 speed demon i purchased used and it seems to pour to much fuel in. i am wondering if i buy a new one or have that one rebuilt or what? any advice?

 

mustangman9812

10 Year Member

Jan 14, 2004

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Mars Hill, NC

Aug 8, 2009

#2

• Aug 8, 2009

• #2

i would run a demon 750cfm if it was mine. Demons flow about 100cfm more than they same so i always go lower in the size with them.

 

3

347HO

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Jan 13, 2008

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Seattle

Aug 8, 2009

#3

• Aug 8, 2009

• #3

mustangman9812 said:

i would run a demon 750cfm if it was mine. Demons flow about 100cfm more than they same so i always go lower in the size with them.

Click to expand...

Is that "wet" flow????

 

M

Mustang5882

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Oct 22, 2008

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Aug 9, 2009

#4

• Aug 9, 2009

• #4

should i get a demon or a holley or what? i just need a quick fix idc if its $600 lol

 

F

FoxGT87

5 Year Member

Aug 1, 2009

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St.pete FL

Aug 9, 2009

#5

• Aug 9, 2009

• #5

i swear by eddelbrock carbs don't like holly and never had a demon.

eddelbrock 750.

 

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Mustang5882

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Oct 22, 2008

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Aug 10, 2009

#6

• Aug 10, 2009

• #6

does anyone have any other help?

 

srtthis

the guy doing it does every local racers rear end

15 Year Member

Jul 3, 2009

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Aug 10, 2009

#7

• Aug 10, 2009

• #7

what size fuel jets are you running?

 

M

Mustang5882

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Oct 22, 2008

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Aug 10, 2009

#8

• Aug 10, 2009

• #8

im not sure thats why i am asking for advice/help

 

srtthis

the guy doing it does every local racers rear end

15 Year Member

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Aug 10, 2009

#9

• Aug 10, 2009

• #9

im not sure if these directions will help with your carb but

pull the bowls and the jets should be on the metering blocks should be a small number stamped on them...

 

90 lx convert

Stanger

Founding Member

Aug 13, 1999

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Falling Waters Wv.

Aug 10, 2009

#10

• Aug 10, 2009

• #10

How about we start with what you already have. What do you mean when you say seems to pour too much fuel in? What does it do i.e. hesitate? buck? backfire? Is it out of the box stock or has someone had their hands in it? Depending on rpm the 850 is borderline too large but I'd bet with some tuning it would work. Mike

 

M

Mustang5882

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Oct 22, 2008

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Aug 11, 2009

#11

• Aug 11, 2009

• #11

i am currently deployed in the middle east until october so i cant take it apart or anything right now but its an 850 speed demon that i bought at a swap meet and it floods the car. should i have the 850 rebuilt with differant jets or just pay a few hundred and get the right carb? if buy new what what should i go with?

 

srtthis

the guy doing it does every local racers rear end

15 Year Member

Jul 3, 2009

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Aug 11, 2009

#12

• Aug 11, 2009

• #12

id stick with the bigger carb and jet it down as much as needed... the smaller carb may choke off the motor of air

 

O

oldbonesracing

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Jul 14, 2009

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Aug 12, 2009

#13

• Aug 12, 2009

• #13

I have a 408 with AFR205 heads and a Holley 950 HP carb and it's not too much carb for my combo, although, I am having other issues with high idle, stalling, etc. Besides the issues, I do not feel that cfm carb is out of line. The car runs pretty decent... I haven't made a full pass this year yet, but i pulled a 1.49 short time, and last year, I couldn't hook for the life of me, a 1.8 60' time and 10.62 @ 133mph. Once I get her back out, she's going run that low 10, high 9 pass... I swear!!!!

 

Rick 91GT

Mustang Master

Nov 29, 1999

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PA

Aug 12, 2009

#14

• Aug 12, 2009

• #14

Whats the compression of the motor, how many rpms are you turning it? Depending on those answer you may or may not have the right size carb. It does sounds like something is going on with the carb you have, a good rebuild wouldn't hurt and if it is too large you could sell it.

FWIW....I just got off a Stuska engine dyno with a 10.65:1 408, AFR205, Super Vic and a 750cfm Holley Street HP and I actually jetted it down 3 sizes to get it all into check.

 

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Mustang5882

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Oct 22, 2008

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Aug 14, 2009

#15

• Aug 14, 2009

• #15

its 10.5 compression and prolly spinning like 6500 max