1990 ZR-1 secondary actuators binding?

[mmkkpro]

Hi guys, I pulled my plenum off yesterday to install new parts. So I'm checking secondary vacuum lines and all associated parts and I noticed the actuator arms that attach to the linkage seem to be off center. I know they look bad but they are not leaking down and seem to open properly, however upon releasing vacuum the only return about half way back to the closed position. Is this normal? Does engine assist the return to closed when it's running?
Thoughts on secondary delete? Thanks.

[A26B]

First part answer: The actuators were intentionally installed that way at Mercruiser. If you will notice in your first photo, the actuator centerline is aligned with the linkage pin. The arm has a 90deg bend to where it attaches at the center of actuator diaphragm. The pull is actually straight, but looks angled because of the bent arm. Engine assemblers thought it looked odd and experimented with rotating the actuator 180deg, but doing so actually did cause binding.

Second part answer. Actuator not returning to the the fully closed position is probably due to the linkage binding. The most probable cause is carbon on the SPT butterflies (valves).

Last part, regarding SPT delete. Tuning has progressed over the years, making deletion of the SPT system a recommended option.

[mmkkpro]

Thank you for the reply, greatly appreciated. 👍👍🏁

[Dynomite]

Originally Posted by A26B

First part answer: The actuators were intentionally installed that way at Mercruiser. If you will notice in your first photo, the actuator centerline is aligned with the linkage pin. The arm has a 90deg bend to where it attaches at the center of actuator diaphragm. The pull is actually straight, but looks angled because of the bent arm. Engine assemblers thought it looked odd and experimented with rotating the actuator 180deg, but doing so actually did cause binding.

Second part answer. Actuator not returning to the the fully closed position is probably due to the linkage binding. The most probable cause is carbon on the SPT butterflies (valves).

Last part, regarding SPT delete. Tuning has progressed over the years, making deletion of the SPT system a recommended option.

i would say that a bit differently...........Most of us keep the very unique Full Power mode simply because that function is very reliable especially if you replace the vacuum lines and connectors for a mere $100 (the secondaires will last a very long time maintenance free). Not everyone can Delete the secondaries and I guess not everyone can replace the secondary vacuum lines either

Lets just say...........Having the Full Power switch functional on the dash is a BIG part of having the ZR-1 with the LT5. Oh ya....I have a 91 with deleted Secondaries and several other ZR-1s with secondaries upgraded with new vacuum lines and Full Power option completely fiunctional.

[A26B]

Originally Posted by Dynomite

i would say that a bit differently...........
Lets just say...........Having the Full Power switch functional on the dash is a BIG part of having the ZR-1 with the LT5. Oh ya....I have a 91 with deleted Secondaries and several other ZR-1s with secondaries upgraded with new vacuum lines and Full Power option completely fiunctional.

I have both, a functional Valet Switch (key fits, turns to On & OFF position) AND deleted SPT. Just takes a little press with the right foot.

[mmkkpro]

Hello Dynomite, I do agree that the full power option is very important for this machine. My vacuum pump is dead, actuators are not leaking and do function, they don't look to swift. The vacuum lines are surprisingly in decent shape, so I priced the actuators at 65 bucks each, vacuum pump around 100 or so that's aftermarket the one im looking at is almost identical to the original one. I don't really want to delete the system. I reckon I will pull the IH, clean it and see if I can solve the sticking issue. I have gaskets on the way from Jerry's, got new injectors also. I appreciate and respect your guys opinions and knowledge, it really helps me decide, I thought I would have her running by now but I work a lot and I'm kinda on a budget, I have made a lot of progress though, hopefully she will be running in a couple of weeks, can't wait , thank you.

[Dynomite]

Originally Posted by mmkkpro

Hello Dynomite, I do agree that the full power option is very important for this machine. My vacuum pump is dead, actuators are not leaking and do function, they don't look to swift. The vacuum lines are surprisingly in decent shape, so I priced the actuators at 65 bucks each, vacuum pump around 100 or so that's aftermarket the one im looking at is almost identical to the original one. I don't really want to delete the system. I reckon I will pull the IH, clean it and see if I can solve the sticking issue. I have gaskets on the way from Jerry's, got new injectors also. I appreciate and respect your guys opinions and knowledge, it really helps me decide, I thought I would have her running by now but I work a lot and I'm kinda on a budget, I have made a lot of progress though, hopefully she will be running in a couple of weeks, can't wait , thank you.

You cannot go wrong with Jerrys gaskets.....the parts are perfect, super packaging, and the shipping is usually two/three days. Matter of fact I just broke the oil pressure sensor (gauge) changing out a Belt Tensioner Pulley (New one from jerry is Prolly in my mail box now)

[mmkkpro]

Sweet, everyone says he is the man. 👍I think that's where I checked the price of actuators. I'm going to check the resistance on my wires and test the coils, need to clean the valley out its dry but some oil and debris, I don't even know how many miles is on it. The instrument cluster needed to be rebuilt so I sent it to Bryan at Batee.com, he did a fabulous job on it. Have not put it back in yet, guess I will see the mileage when I do. I have spent a lot of money and time on it so far and want to hear it run! The closer I get the more I want to rush but I gotta be cool a couple more weeks. I want it to be right before I even try, once I get the plenum back on I need to prime the oiling system, fill coolant and such. No telling what else I'm going to need like sensors and all. Just want to make sure the engine is OK before I spend too much more, but either way I'm committed to this build. I'm kinda jealous of you guys, yall got running ZR-1s. 👍👍😁

[Paul Workman]

Well, you just knew someone would come along and kick sand in the eyes of those speaking the praises of having the "switch".

After about the 2 or 3rd time under the plenum for SPT issues, OUT THEY CAME and good riddance!! Gone for good. Always in FULL ENGINE POWER mode and loving it! (And, with my 37.5mm porting, the SPTs wouldn't work anyway

Just sayin....

[lfalzarano]

Who drives their Z in valet mode? Sinners repent!!!! Turn the key to full power and never change it!


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