LT4 vacuum help needed
Thread Starter
Melting Slicks
Joined: Aug 2004
Posts: 2,906
Likes: 228
From: Oakbank Manitoba
LT4 vacuum help needed
I am installing a LT4 throttle body on my LT1 intake conversion project and I don't know where to connect the (smaller) charcoal canister vacuum line. On earlier throttle bodies this line was connected to a port on the underside of the throttle body. This port also fed the EGR valve. The LT4 throttle body doesn't have this port on the bottom because it has no provisions for the EGR......so where do I hook up the vacuum line for the charcoal cannister. The other (larger) cannister vacuum line on the side by the TPS is still the same as earlier models.
Ken
Ken
Thread Starter
Melting Slicks
Joined: Aug 2004
Posts: 2,906
Likes: 228
From: Oakbank Manitoba
Originally Posted by MarkBychowski
The only vacuum canister line on my LT4 connects via a check-valve directly to a port on the passenger-side of the intake manifold.
Thread Starter
Melting Slicks
Joined: Aug 2004
Posts: 2,906
Likes: 228
From: Oakbank Manitoba
The picture shows the purge solenoid for the vapor (charcoal) cannister, On earlier Corvettes this solenoid was located next to the charcoal cannister. An additional vacuum line should be coming off the cannister and heading back to the engine. According to Mark this smaller vacuum hose is connected to a fitting on the passenger side of the intake. Can you confirm this?
Ken
Ken
Thread Starter
Melting Slicks
Joined: Aug 2004
Posts: 2,906
Likes: 228
From: Oakbank Manitoba
Thanks for the pictures ALLT4....much appreciated. I am trying to figure out how to hook my LT4 throttle body up to a 1990 Corvettes vapor cannister system. On the 1990 setup there are two vacuum hoses...one is hooked into the side (lower fitting) next to the "TPS" as yours is which is the vacuum line that pulls the vapor from the cannister into the throttle body. The other smaller line was connected to a fitting on the bottom of the throttle body which was "ported" and ran back to the vapor cannister. It then splits into a "Y" feeding the top of the cannister and also to the fuel tank pressure control valve.
The LT4 throttle body doesn't have the fitting on the bottom. So I assume the setup must work a little bit different. My Helms manual for a 1990 Corvette has a couple of great diagrams showing the setup in simplified form. Could someone scan and send me the same diagram for the 1996 Corvette.
Thanks,
Ken
The LT4 throttle body doesn't have the fitting on the bottom. So I assume the setup must work a little bit different. My Helms manual for a 1990 Corvette has a couple of great diagrams showing the setup in simplified form. Could someone scan and send me the same diagram for the 1996 Corvette.
Thanks,
Ken
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