have a problem!

69grande · Feb 25, 2004

Alright, i just put in a new cam weiand stealth intake and holley street avenger 670 cfm carb in a 69 351w, but now when i take off it starts off really slow! I thought by upgrading to a new intake and cam and 4bbl carb that I would at least get a lot better start off the line, but it just seems slower. At about 30 or 40 it really takes off though. What can I do to help me off the line?

jesserose17 · Feb 25, 2004

What's your rear gear? What type of transmission? If auto, are you using stall converter?

GaPonyFarm · Feb 25, 2004

Answer the questions above and you're on the way...

rbohm · Feb 25, 2004

when you say it takes off slow, do you mean you have a giant bog when you launch, then rpm builds slowly?

Jonstantine · Feb 25, 2004

rbohm said:
when you say it takes off slow, do you mean you have a giant bog when you launch, then rpm builds slowly?

first things to check are vacuum and timing

buuut you might have a bog caused by your carbeurator...
lowering your floats, is what i'd do if you find that you have a good vacuum and your timing isnt way off

69grande · Feb 26, 2004

I believe my rear gears are only 2.73's, its an auto fmx, and no stall converter, but with my stock cam, intake,and 2bbl carb i had a much harder and faster launch.I can't even smoke the tires now! The floats are set to where the gas is just visible and yes the rpm builds up slowly. Any suggestions??

paintballtommy · Feb 26, 2004

what kinda cam? some aftermarket cams require the use of a higher rpm stall converter and since you said you dont have one you might wana check that. what does she idle at while in gear?

mfp4073 · Feb 26, 2004

Similar to another post I just made, but you may need to tune the carb to the car. I am talkin jets, accelorator squirters, accelorator cam, and such.

mustangracer · Feb 26, 2004

Mine's the same way. A mild cam, wiend stealth intake & holley 650. i've tuned and tweaked, and come to the conclusion it's the rear gears. I've still got 2.73 in the rear end, but I have a 5spd, so if I manage to launch it around 2500rpm the car takes off, but from idle or so where a stock auto takes off, it's pretty slow til about 2500...then it builds quickly

Jonstantine · Feb 26, 2004

i had the exact same problem with my 289 when i went to a 4barrel...

i reworked the carbeurator, and it fixed the problem
i changed jets and rods and stuff.... little change
or if it did change, i had another problem like leaning out on the top end

i finally lowered the floats, and got some high flow needle and seats
lowering the floats from stock, gave me my low end power back, but i was stalling out high up (the bowls were emptying)
the high flow needle and seat allowed it to flow more gas while refreshing the bowls

problem solved
i spent over 2 years trying to figure it out/learn about carbs on my own

i also have a stock stall and 2.8 gears
a better stall might solve it too
but im pretty sure tuning the carb will solve it also...
carb adjustment is much cheaper than a new stall

69grande · Feb 26, 2004

Maybe ill try changing some stuff on the carb first. What size jets should I go with, what needles? and how do i tell if the carb is set up for the car like the jets, needles, accelator pump, and all that stuff?

have a problem!

69grande

jesserose17

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rbohm

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mfp4073

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