a 750 holley double pumper??

[oldsman71]

a guy brought a 750 holley carb for me to put on his car
specs chev 355 .030 .250 dome, 461/2.02's plained .040, old single plane tq'er, old 292 hydr comp cam, 1.6 rockers

anyway, couldnt find any vac. leaks, 6.5 psi, not flooding

would only run with the mixture screws all the way in, no idle

so do you all think they might have have the wrong metering plate gaskets, or warped metering plates
I hate messing with someone elses crappy old carb rebuilds

[TC]

If it runs with the mixture screws turned all the way in, that is a sign of a blown power valve.......Or in this case maybe someone left out the power valve gasket........

[oldsman71]

maybe so, long vertion of the storie, when I got over there, he had the carb half off/ on, he has been meesing with the fuel pump (holley red) and had ran it
with out a fuel filter and with a unknown fuel cell , anyway he got some crap in the needle and seats and let the pump run and run and run........ so I drained 3 gallons of race gas out of the oil pan, replace oil and filter and primed the oil system ....
you know... (light bulb) ...... he could have blown the power valves trying to start this turd befor i got there? damn.......

[min301]

How far open are the throttle blades?

[oldsman71]

wayyy open!! had to turn the idle way up for it to run

[oldsman71]

my first post seems to misslead but tried to make it simple..... I so dont like cleaning up someone elses mess!
but got 5 qts of race oil and a new napa gold filter for my trouble today

[Bamfster]

Try to balance the primary and secondary idle stops, ie .... close the primary down and open the secondary up a touch. Do this until you gain control over the idle circuit and fine tune from there.

[Scott Liggett]

Another reason for rich fuel mixture could be floats too high and fuel dripping out of boosters.

[oldsman71]

thanks guys!! , ill try to look at it later this week, its not at my house now

in the box of left over parts :P (someone else built this carb) , he had, there was 1 powervalve and 1 powervalve plug,
he thought the fronts jets were #71 with a powervalve, and the rear was #80's and a plug
I have heard if you plugged a powervalve they had to go up 10 jet sizes (to make up what the powervalve supplied). why would someone take out a powervalve
except to run 2 carbs? or for more control (not trusting the powervalve)? I guess Im not as sharp as I thought I was :P

[Bamfster]

And remember Cobey .... its more than just the carb. Like was said before .... initial timing plays a huge role too. A vacuum gauge is a good tool to have as well.

[oldsman71]

Scott- no fuel dripping from the boosters
Dan have 36 deg. locked threw the msd with 25 deg retard at start

[Huskinhano]

wayyy open!! had to turn the idle way up for it to run

If you have the primaries open too far, you're going to uncover the idle transfer slots rendering the idle mixture or idle circuit useless. A common trick is to drill a small hole IIRC, about .125" in the primary blades. This allows the extra air while keeping the idle circuit in play.

[oldsman71]

If you have the primaries open too far, you're going to uncover the idle transfer slots rendering the idle mixture or idle circuit useless. A common trick is to drill a small hole IIRC, about .125" in the primary blades. This allows the extra air while keeping the idle circuit in play.

I was thinking of this 1st, may have to check how far open the secondarys are also,
like Dan was saying, hopefully ill get to mess with it tomorrow, thanks guys

[TC]

I was thinking of this 1st, may have to check how far open the secondarys are also,
like Dan was saying, hopefully ill get to mess with it tomorrow, thanks guys

Start with the secondaries open 1 1/2 turns.......Basically turn the screw out until the blades are closed then turn the screw back in until the blades start to move then give it 1 1/2 turns from that point...... You can do the same for the primaries to, bolt it on and see how if idles. Last carb I setup like that started and idled at about 900rpm.......

[oldsman71]

now the jack ass (that guy#1) took the carb all apart, and then took it back to the other "that guy #2" that messed it up to start with.
I guess ill get better at this stuff by fixing #1 and #2's mistakes. It is really nice when people dont mess with junk u work on