vacuum ports???

[ocbaud]

okay, what all vacuum ports do i need to use? since the carb is hooked up and all, i need to hook everything else up.

also, i have a quick question about the carb.the box says its for:

mild performance chevy truck engines with:

-dual plane alum. intake (i have)
-headers(i have)
-comp. ratio of 8.5 - 9.5:1 (i have right around 10:1)
cam specs @.050: min. 210 degrees
max. 222 degrees(i have 235/240@.050)


i guess its not that different, but i was just wondering

[79BIG10]

I used the HEI line to the full port on the carb, then the brake booster to the back of the carb then and the heater vacuum hose from the ball on the passenger side to the T behind the carb on the intake where it hooks up along with the tranny modulator line. That's the only ones I have now since I'm emissions free.

On the carb it's like a guideline for someone looking for a carb. You can always fine tune by rejetting etc.

BTW: What carb did you decide on?

[ocbaud]

jet qjet stage2

[Newt408]

Originally posted by 79BIG10
I used the HEI line to the full port on the carb, then the brake booster to the back of the carb then and the heater vacuum hose from the ball on the passenger side to the T behind the carb on the intake where it hooks up along with the tranny modulator line. That's the only ones I have now since I'm emissions free.

On the carb it's like a guideline for someone looking for a carb. You can always fine tune by rejetting etc.

BTW: What carb did you decide on?

Why did you run the hei to a full port vaccum source instead of the timed source? Just asking because my distributor guy told me the same thing but my holley instructions say differently.

[low 84]

Originally posted by Newt408


Why did you run the hei to a full port vaccum source instead of the timed source? Just asking because my distributor guy told me the same thing but my holley instructions say differently.

every one and their brother has a different opinion on where to hook it and why. just use the one that seems to work best with your motor

[TIMSPEED]

Originally posted by low 84
every one and their brother has a different opinion on where to hook it and why. just use the one that seems to work best with your motor

Yup, that's what I do. With the "timed" port, my motor doesn't like it, because it pulls too MUCH timing at idle (my carb is messed up I guess)

[ocbaud]

there is a big vacuum port on the back of the carb in the center of the bottom. something looks like it screws into it?

[apstguy]

That would be the brake booster.

[79BIG10]

Originally posted by Newt408


Why did you run the hei to a full port vaccum source instead of the timed source? Just asking because my distributor guy told me the same thing but my holley instructions say differently.

Like Ryan mentioned everyone has their own choice on this. I went with full port since I've tweaked with the HEI guts. Off another board that I used to frequent alot was a guy named ignitionman. This guy is the guru of distributors. He taught me the way to tweak with the HEI I have with the ZZ4 and make more power. It did make a difference for sure. Not leaps and bounds but enough to realize I did something good He told me to put it at full port since I've limited the vacuum advance on the HEI curve with a stop plate.

[Newt408]

Originally posted by 79BIG10


Like Ryan mentioned everyone has their own choice on this. I went with full port since I've tweaked with the HEI guts. Off another board that I used to frequent alot was a guy named ignitionman. This guy is the guru of distributors. He taught me the way to tweak with the HEI I have with the ZZ4 and make more power. It did make a difference for sure. Not leaps and bounds but enough to realize I did something good He told me to put it at full port since I've limited the vacuum advance on the HEI curve with a stop plate.

I'll try running on full port since I do have the vaccum advance limiter plate installed.

[ocbaud]

Originally posted by apstguy
That would be the brake booster.

what fitting do i need for it?

[apstguy]

Originally posted by ocbaud
what fitting do i need for it?

It should match up exactly with the old line.

[ocbaud]

i believe the old line was tied into the cruise control

[apstguy]

No it isn't. It should be a big metal tube, half way it turns into a rubber hose.

[ocbaud]

chit. i know what it is now. it was running through the stock throttle bracket/cruise bracket.

[CRRoy71]

Originally posted by ocbaud
chit. i know what it is now. it was running through the stock throttle bracket/cruise bracket.

Yes, that's the one. Mine runs the same way.

[Destructo]

If you have an open port on the intake behind the carb itself you would be better off hooking it up there instead of through the carb, but thats usually for aftermarket carbs which didn't have that port. I'v heard that you get more vacuum that way and better brakes. But either spot will work just fine probably.

And I like to run my advance off the ported vacuum, it will give you a better idle sound I think and should run better, I didn't like it when I put mine on full vacuum. Too much timing at idle I think.

[ocbaud]

does anyone have pictures of exactly what needs to hook up to which port on the carb?

[apstguy]

Why don't you look on the emissions sticker on your firewall under the hood. It has all the connections.

[ocbaud]

its kinda confusing for a non emission engine

[apstguy]

Then you won't need 3/4 of them.

[ocbaud]

http://www.ocbaud.com/pictures/engine/engine22.jpg

as you can see in that picture, most of them have already been capped at the factory jet was also kind enough to install a fuel filter in the carb before shipping it here

in that picture, there is one big fitting on the front that isnt capped, and there is also one you cant see on teh back top of the carb. where do i need to hook the dizzy up to? the pcv should be hooked up to the very bottom one in the middle on the front, correct?

[NeCrOmAnCeR]

Yes, PCV to the large one in the middle. Just to give you some info about what should go where. Looking at your picture. the small one to the left and below the fuel inlet would be for an EGR valve. The one to the right of the fuel inlet which is still plugged, but just below the unplugged one is where you should hook the vac advance. I believe the one directly above the "R" in fuel filter is a full vacumme port, which you could hook to the dizzy if you decide you do not like ported vacumme for it. And the one directly above the fuel inlet pointed down and to the left is a bowl vapor line which goes to the charcoal canister.

[ocbaud]

Originally posted by NeCrOmAnCeR
Yes, PCV to the large one in the middle. Just to give you some info about what should go where. Looking at your picture. the small one to the left and below the fuel inlet would be for an EGR valve. The one to the right of the fuel inlet which is still plugged, but just below the unplugged one is where you should hook the vac advance. I believe the one directly above the "R" in fuel filter is a full vacumme port, which you could hook to the dizzy if you decide you do not like ported vacumme for it. And the one directly above the fuel inlet pointed down and to the left is a bowl vapor line which goes to the charcoal canister.

sweet, thanks