Vacuum problems
Thread Starter
Intermediate
Joined: Oct 2009
Posts: 33
Likes: 0
Vacuum problems
Hey guys, I know this is probably everyone's FAVORITE subject on these old things, but I'm about to pull my hair out trying to figure this out. Here's the deal...
I replaced my engine because it was knocking. The new engine I know for a fact runs like a champ because I took it out of my own truck and I know the history of it. The problem is that I swapped out the intakes so the new engine has the one off the original that came in the car. For the life of me, I can't remember how to hook up all the vacuum lines!! Does anybody have an easy way to fix this? What lines can be plugged off and not re-connected? Or at least tell me where the brake booster line goes?
I replaced my engine because it was knocking. The new engine I know for a fact runs like a champ because I took it out of my own truck and I know the history of it. The problem is that I swapped out the intakes so the new engine has the one off the original that came in the car. For the life of me, I can't remember how to hook up all the vacuum lines!! Does anybody have an easy way to fix this? What lines can be plugged off and not re-connected? Or at least tell me where the brake booster line goes?
Thread Starter
Intermediate
Joined: Oct 2009
Posts: 33
Likes: 0
Sorry. I know better than that... it's been a stressful week. It's a 1978 L-82. Stock quadra-jet carb. Pretty much stock everything. Right now the brake booster has a canister on the hose that's sitting right next to the PVC breather. The vacuum port at the back of the carb has some fitted line going to it, and those lines go down under the booster for something (I don't know what it's for).
I can't add attachments yet, but we'll see if this works instead...
I can't add attachments yet, but we'll see if this works instead...
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Sorta unfriendly.EDIT- Here was the first line..."If you bought elsewhere - seek them for help."
Last edited by ...Roger...; Jul 28, 2010 at 04:12 PM.
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
well that's a shame if Doc Rebuild is pulling his diagrams out of his catalog. OP should have the AIM though. Should be considered a "required" book if you do any work on your vette yourself.
I'd refer OIP to my website where I have TONS of pics from when I was redoing my '78 L82 but I doubt any of those pics are detailed enough to see what he needs to see.
I'd refer OIP to my website where I have TONS of pics from when I was redoing my '78 L82 but I doubt any of those pics are detailed enough to see what he needs to see.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Barry , he's starting to remove some of those diagrams. I went the other day to look for a diagram and it said something like if you bought from Z** go there for a diagram. Sorta unfriendly.
EDIT- Here was the first line..."If you bought elsewhere - seek them for help."
Sorta unfriendly.EDIT- Here was the first line..."If you bought elsewhere - seek them for help."
Last edited by Willcox Corvette; Jul 28, 2010 at 06:32 PM.
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Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Here, I did this on the fly and I hope this helps you!
Barry K is correct! You can get pictures similar to this one from the assembly manual.
Assembly Manual On CD ships for free can be found at this link. http://willcoxcorvette.com/product_i...ducts_id=25581
Willcox
Barry K is correct! You can get pictures similar to this one from the assembly manual.
Assembly Manual On CD ships for free can be found at this link. http://willcoxcorvette.com/product_i...ducts_id=25581
Willcox
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Thanks Roger-
You need them, I'll do them up..
I've put that one up on the help and repair side of the site so others can find it when needed. http://willcoxcorvette.com/repairand...lp.php?hID=299
E.
You need them, I'll do them up..
I've put that one up on the help and repair side of the site so others can find it when needed. http://willcoxcorvette.com/repairand...lp.php?hID=299E.
Thread Starter
Intermediate
Joined: Oct 2009
Posts: 33
Likes: 0
So by looking at that diagram, I can get rid of everything that has to do with the EGR? I had new exhaust put on with headers and eliminated the EGR completely.
Still can't figure out where the booster line goes. Nothing coming out of the carb is big enough to fit the line except the two in front (one for PVC breather, one for I don't know what, but it goes toward the driver fender) and the one on the back of the carb which has a fitted steel line on it. Which one did I hook up wrong?
Still can't figure out where the booster line goes. Nothing coming out of the carb is big enough to fit the line except the two in front (one for PVC breather, one for I don't know what, but it goes toward the driver fender) and the one on the back of the carb which has a fitted steel line on it. Which one did I hook up wrong?
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
If your running headers you can eliminate most of it. Find the nipple for manifold vacuum(vacuum at idle) and run to the dist. If I remember right the booster and HL vacuum both come off a fitting in the manifold.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Never going to live that one down am I... 
Roger is right, on the back of the intake should be a large fitting for the power brake vacuum to attach to! Should be at a min. two outlets on it and one of them should be large enough for the power brake booster hose.
Willcox
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
here are a couple pics from when I was taking my '78 L82 apart for a rebuild.
Not the best pics but they should do to show where the PB vacuum line connects to the intake manifold:
in this pic look to the rear of the carb (on the right side) but in front of the distributor there is a fitting in the intake manifold. That fitting has two rubber vacuum hoses attached to it and a metal hardline (from the auto trans) attached at the top of the fitting. One of those large rubber vacuum hoses go to the PB booster
In this pic from the other side the distributor has now been removed but you can see the metal hardline from the tranny and the 2 large rubber vacuum hoses connected to the intake manifold fitting behind the carb.
Here is the fitting with only the tranny hardline attached and a lot of other stuff out of the way
hope this helps
Not the best pics but they should do to show where the PB vacuum line connects to the intake manifold:
in this pic look to the rear of the carb (on the right side) but in front of the distributor there is a fitting in the intake manifold. That fitting has two rubber vacuum hoses attached to it and a metal hardline (from the auto trans) attached at the top of the fitting. One of those large rubber vacuum hoses go to the PB booster
In this pic from the other side the distributor has now been removed but you can see the metal hardline from the tranny and the 2 large rubber vacuum hoses connected to the intake manifold fitting behind the carb.
Here is the fitting with only the tranny hardline attached and a lot of other stuff out of the way
hope this helps
Last edited by BarryK; Jul 30, 2010 at 05:57 AM.
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
Roger, it was 2005 when I did my '78 L82.
I couldn't remember if the PB booster was running to the baseplate of the carb via the metal hardline that's attached there or to the fitting in the intake.
It could go to either place and either one would work and with my pics I can't for sure which way it goes. I thought it was the intake fitting but could be wrong.
I no longer have my '78 A.I.M. to check since I gave it to the guy that bought my '78.
It should work fine hooked up to either of those two locations anyway since both will provide full manifold vacuum
I couldn't remember if the PB booster was running to the baseplate of the carb via the metal hardline that's attached there or to the fitting in the intake.
It could go to either place and either one would work and with my pics I can't for sure which way it goes. I thought it was the intake fitting but could be wrong.
I no longer have my '78 A.I.M. to check since I gave it to the guy that bought my '78.
It should work fine hooked up to either of those two locations anyway since both will provide full manifold vacuum
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
Hello Barry,
It's been awhile! I sold my 1967 in 2008.
The booster steel tube connects to the back/base of the carb via a brass threaded fitting. The intake fitting is for the modulator valve in the case of automatic transmissions and other vacuum duties.
Shown is a 1974 with TH400.
It's been awhile! I sold my 1967 in 2008.
The booster steel tube connects to the back/base of the carb via a brass threaded fitting. The intake fitting is for the modulator valve in the case of automatic transmissions and other vacuum duties.
Shown is a 1974 with TH400.
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
Hi Paul
nice to talk to you again!
thanks for the clarification. Like I said, it's been since 2005 since I did my '78 so couldn't remember positively one way or the other but it seemed like the carb baseplate would have been the correct hook-up for the PB booster but I couldn't remember for sure and I couldn't tell in my pics 100% one way or the other
nice to talk to you again!
thanks for the clarification. Like I said, it's been since 2005 since I did my '78 so couldn't remember positively one way or the other but it seemed like the carb baseplate would have been the correct hook-up for the PB booster but I couldn't remember for sure and I couldn't tell in my pics 100% one way or the other