New Secondary Vacuum System for 1990-1995

[Dynomite]

New Secondary Port Throttle Vacuum System for 1990-1995.

See.......Post 234 - Installation of New Secondary Port Vacuum System hoses (https://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-12.html#post1590759176)

See.........Post 284 - New Secondary Port Throttle Vacuum System (https://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-15.html#post1596384583)

New Secondary Port Throttle Vacuum System for 1990-1995.

1. Installed New Secondary Port Throttle Vacuum System for 93'-95'.
Secondary Port Throttle Vacuum System (https://www.ebay.com/itm/Corvette-C4-NOS-1993-1995-ZR-1-LT5-Hose-Secondary-Actuator-10168624/332546365774?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649).
https://cimg1.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/600x500-1/80-1995_secondary_vacuum_94c2fea603cf59fe436441c680e4 7eda8458b135.jpg

This is an absolute Must Do if you Really are serious about reconditioning the
Secondary Port Vacuum System (the original Rubber Connectors are Hard and Deteriorated).

2. New Secondary Port Throttle Vacuum System for 1990-1995.

This complete NEW vacuum system designed for the 93'-95' can be installed on a 1990-1995 ZR-1. For 1990-1992 this can be accomplished by substituting the longer Manifold Differential Pressure vacuum line on the original 1990-1992 ZR-1 Vacuum System for the shorter curled MDP Vacuum line in the New 93'-95' Secondary Port Throttle Vacuum System.

The New vacuum system connectors are New soft rubber and easy to disconnect connectors which are very tight (just twist the plastic tube back and forth and they will let loose). The Original hard rubber connectors are impossible to disconnect without cutting the connector lengthwise (with razor blade) to remove the plastic tube.

https://cimg1.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/600x500-1/80-1995_secondary_vacuum_94c2fea603cf59fe436441c680e4 7eda8458b135.jpg

3. Modifications (re-arrangement of connectors) of the New Secondary Vacuum System to fit 1990-1992.

A. The Tee (T) was moved and a 1 inch long 1/8" Fuel Line PCV/EEC (SAE 30R7 obtained at O'Reillys) was used as a splice where the T was located. The T was installed for the Drivers Side Secondary Canister which is identical to the Stock

B. The Stock 1990 Manifold Differential Pressure (MDP) Vacuum Line was used and added to the New Secondary Vacuum System. I replaced the stock L fitting on the 1990 MDP was replaced with the New L fitting removed when T was re-installed for the Drivers Side Secondary Canister which is identical to the Stock 1990 Secondary Vacuum System configuration.

C. In this case I also used the Stock line with New L fitting from the check valve to the Vacuum Pump line as that Stock line was just a bit longer

https://cimg3.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/800x1100-1/80-secondary_vacuum_s_9cf253031d23be5ac794c8db37b0f71 4c9b96567.jpg

Went for a test drive with the 1990 and ALL is perfect :thumbs:

https://cimg1.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/800x800-1/80-img_2668_4849c97b17221f068dd7f06f30e4a52d8a0934e3. jpg

4. New Secondary Vacuum System Availability.

These New Secondary Vacuum Systems for 93'-95 which can easily be modified for 1990-1992s are offered on Ebay for $100 but one can buy them with an offer for less :D

New Secondary Vacuum System (https://www.ebay.com/itm/Corvette-C4-NOS-1993-1995-ZR-1-LT5-Hose-Secondary-Actuator-10168624/332546365774?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649)

https://cimg4.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/800x600-1/80-f23_ff6ea077da29abbcaa1613fa44c393189605ba83.jpg

[Flyman 27]

My engine is a '92 (in a '91), do you think these would work on a '92?

[XfireZ51]

Boy those vacuum lines look like a Rube Goldberg setup.

[Dynomite]

My engine is a '92 (in a '91), do you think these would work on a '92?

My guess is that these lines will work on ALL ZR-1s 90'-95'.

Boy those vacuum lines look like a Rube Goldberg setup.

Guess you have not pulled a vacuum system before :p

[S.hafsmo]

This kit does not include the hose between pump and plenum, I assume?

[Dynomite]

This kit does not include the hose between pump and plenum, I assume?

That is the hose connected to pump up to about the oil filter which is not included in this kit. And the kit does not include the longer hose reaching under the ECM which Manifold Differential Pressure is located under the Plenum on the 93'-95'. I use both original hoses on the 1990 in those two places.

The two stock original lines used in those two places are external to the Plenum and the Plenum does not have to be removed to make sure the two Ls involved are not leaking (one L to vacuum pump and one L to MDP).

[Ccmano]

Nice alternative for those that want to keep their secondaries.

I, for one, am removing mine. It’s an irrelevant complexity for those not concerned about originality or emissions.
H
:cheers:

[Dynomite]

Nice alternative for those that want to keep their secondaries.

I, for one, am removing mine. It’s an irrelevant complexity for those not concerned about originality or emissions.
H :cheers:

On my 91' I have secondaries removed but it is nice to have that Full Power switch operational on 90's and 95'.

The Full Power Switch and Secondaries are two of those very unique features of the LT5 :D

I have TB coolant blocked at Injector Housing on ALL ZR-1s (You can not tell it as I installed new hoses without installing screw clamps) :thumbsup:

Also have jagdpanzer's (Phil) New Improved Fuel Pressure Regulators (using Delphi FP10016) on ALL ZR-1s :thumbsup::thumbsup:

More Detail on converting the New 93'-95' Secondary Vacuum System for use in the 90'-92's.
I have removed a 91' Secondary Vacuum System which I am sure was the same as the 90' and I am assuming the 92' is also the same as the 90' Secondary Vacuum System.
https://cimg3.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/800x1050-1/80-secondary_vacuum_s_9cf253031d23be5ac794c8db37b0f71 4c9b96567.jpg

[Flyman 27]

The ebay seller raised his price to $125

[Dynomite]

The ebay seller raised his price to $125

I see that the price went from $100 to $125 but you can make an offer which I did. The seller must be running out of stock. Jerry used to sell these Vacuum Systems for $100 but also ran out of stock. That was before I knew these Vacuum Systems would also work on the 90'-92's.

https://cimg1.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/600x500-1/80-1995_secondary_vacuum_94c2fea603cf59fe436441c680e4 7eda8458b135.jpg