carbuerator help
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Senior User
Joined: Mar 2000
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carbuerator help
i have a 65 f100 w/ a 352/C6. headers, duals, with a holley 600 vac. secondaries. my question is can anyone suggest a jet size to start with. it currently has 68's in it, which seem kind of small to me. what its doing is it seems to be bogging down, like it isnt getting enough gas. it also is popping through the carb. but mainly only when it is cold. i was told to check the power valve, which i will do i just dont want to open the bowl up more than i have too. It makes a big mess. i have the good gaskets so reusing them is not the problem. any help is appreciated. if you want to email me my address is
mattbalfanz@webtv.net
thanks
matt
mattbalfanz@webtv.net
thanks
matt
Freshman User
Joined: Aug 1999
Posts: 34
Likes: 0
carbuerator help
If you're getting minor pops through the carb, I'd say you're running slightly lean. I'd try one or two jets fatter and tighten the choke a notch. Your power valve shouldn't be part of the equation at idle or cruise. At high throttle (and usually going uphill) you'll feel the power valve open and give you some extra umpf. You'll usually know if the power valve is torn because you be running REAL rich, and usually see/smell raw fuel in your exhaust. Bogs and hesitations usually are the result of the accelator pump. If memory serves, bogs need a smaller squirter and hesitations need a bigger squirter. Alot of times these can be resolved with different accelerator cams.
Elder User
Joined: Oct 1999
Posts: 917
Likes: 3
From: Kelseyville USA
carbuerator help
Just for starters How is
it when it is warmed up?? I think that the best way to set the carb is look
at the plugs when it is hot! are they `white, `light brown`, or `black
sooty` looking....
white is lean and black sooty is way rich.
NEXT... make sure that your timing is advancing correctly when you Nail it
cold.
A lazy vacuum advance will make it stumble. Try advancing the timing
(Initial only) (like 4 deg) and see if it improves when cold... Don't forget
that this is just a test and re set it for a hot engine....!!! if the timing
advance improves things then you are on the correct path.
Next... if you think that it is just `lean` then Open Up the idle mixture
screws like 1 turn and see if things improve.. that may tell you to go to
bigger jets in the primaries only... OR/and try closing down the idle
mixture screws and see if things are better... AKA Smaller jets are
needed...
You may also be seeing to much fuel from the accelerator pump! there are
Cams that can be changed to help tune things.
If you can replace the power valve then I would at least check it to be
sure! I do think it is OK
The 600 carb should be OK for a 352 type. BUT keep in mind that when you
DROP the Vacuum in the manifold (Open the throttle) the secondary are coming
open also... which may be Too much when cold... you can change the spring in
the vacuum diaphragm to Delay the secondary or Advance the opening ...
Holly sells a `Kit` of different springs.
Each Holly carb has to be `custom tailored to match what you have it on.
Thats why they sell over 200 different `list numbers`..
Now Edlebrock only has 6 or so and they are set up with metering rods and
jets.
What do you have the Initial timing set at? like 8-10 deg. at the crank?
and what is the MAX timing at say 3,000 rpm? you should not have to use
more than 30-34 deg!!
I`ll stop with this and see how things go... Let me know!
Ps: I`ll be out of town next week on Vacation. I`ll check back this Sun
Night before i leave..
__JOHN__Õ¿ö
72 F-250
ICQ#6030753
http://clubs.excite.com/comm/area/pw/welcome/main.asp?cid=188005&auth=
it when it is warmed up?? I think that the best way to set the carb is look
at the plugs when it is hot! are they `white, `light brown`, or `black
sooty` looking....
white is lean and black sooty is way rich.
NEXT... make sure that your timing is advancing correctly when you Nail it
cold.
A lazy vacuum advance will make it stumble. Try advancing the timing
(Initial only) (like 4 deg) and see if it improves when cold... Don't forget
that this is just a test and re set it for a hot engine....!!! if the timing
advance improves things then you are on the correct path.
Next... if you think that it is just `lean` then Open Up the idle mixture
screws like 1 turn and see if things improve.. that may tell you to go to
bigger jets in the primaries only... OR/and try closing down the idle
mixture screws and see if things are better... AKA Smaller jets are
needed...
You may also be seeing to much fuel from the accelerator pump! there are
Cams that can be changed to help tune things.
If you can replace the power valve then I would at least check it to be
sure! I do think it is OK
The 600 carb should be OK for a 352 type. BUT keep in mind that when you
DROP the Vacuum in the manifold (Open the throttle) the secondary are coming
open also... which may be Too much when cold... you can change the spring in
the vacuum diaphragm to Delay the secondary or Advance the opening ...
Holly sells a `Kit` of different springs.
Each Holly carb has to be `custom tailored to match what you have it on.
Thats why they sell over 200 different `list numbers`..
Now Edlebrock only has 6 or so and they are set up with metering rods and
jets.
What do you have the Initial timing set at? like 8-10 deg. at the crank?
and what is the MAX timing at say 3,000 rpm? you should not have to use
more than 30-34 deg!!
I`ll stop with this and see how things go... Let me know!
Ps: I`ll be out of town next week on Vacation. I`ll check back this Sun
Night before i leave..
__JOHN__Õ¿ö
72 F-250
ICQ#6030753
http://clubs.excite.com/comm/area/pw/welcome/main.asp?cid=188005&auth=
Junior User
Joined: Mar 2000
Posts: 95
Likes: 0
carbuerator help
what is the exact area of the "68" jet?? is that .68"? I dont care much for the holleys,so I dont know how they number them.
if that is the exact area of the jet, then look at the metering rods, subtract the size of rod from area of jet, and you should get a # around .22-.35, if you are too lean, try a smaller metering rod, hence you get larger exact area through the jet.
My carb came set at .98 prim./.95 sec.
its now set at .104prim/.101 sec this is a performance mixture, and not too economical, but safe to use . I get about 11-12MPG hwy/8-9MPG city with 2.75 gears and stock height tires
SEANSTER 77' F150 XLT 2WD 400 C6
Edel.cam,intake
CARTER 625 AFB
if that is the exact area of the jet, then look at the metering rods, subtract the size of rod from area of jet, and you should get a # around .22-.35, if you are too lean, try a smaller metering rod, hence you get larger exact area through the jet.
My carb came set at .98 prim./.95 sec.
its now set at .104prim/.101 sec this is a performance mixture, and not too economical, but safe to use . I get about 11-12MPG hwy/8-9MPG city with 2.75 gears and stock height tires
SEANSTER 77' F150 XLT 2WD 400 C6
Edel.cam,intake
CARTER 625 AFB
