opti question
Thread Starter
Instructor
Joined: Jan 2002
Posts: 172
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From: Garland TX
opti question
I just finished reading the tech info on venting the opti on the early models (have a '93)and have a question ...it seems that if you never take the unit apart and seal very well with some perm. it would not get moisture in to begin with so would venting be "risking " getting this thing wet simply because your opening the system?I starting my opti swap this friday if you guys say vent than vent it is!!!!I've already ordered the '93 model from jeff so if I do vent does this mean I must drill?any sugg.'s greatly appreciated!
Thanx,Tony
Thanx,Tony
Melting Slicks
Joined: May 2001
Posts: 2,143
Likes: 7
From: San Diego CA
Re: opti question (flubuyu2)
Two big problems with the early opti.
1) It is vented. There are 3 small holes in the bottom, problem is they let moisture in as well as out.
2) The seals between the layers of the opti get hot. They will shrink and get brittle. Therefore, stop doing what seals are suppose to do.
You will need a vented cap and the vacuum lines to complete the job.
See this discussion:
http://forums.corvetteforum.com/zerothread?id=268698
Cheers,
1) It is vented. There are 3 small holes in the bottom, problem is they let moisture in as well as out.
2) The seals between the layers of the opti get hot. They will shrink and get brittle. Therefore, stop doing what seals are suppose to do.
You will need a vented cap and the vacuum lines to complete the job.
See this discussion:
http://forums.corvetteforum.com/zerothread?id=268698
Cheers,
Burning Brakes
Joined: May 2001
Posts: 790
Likes: 2
Re: opti question (John Row)
Corvette Fever Feb 01 has an pictoral tutorial on this job. I followed it to a T. Basically, get a new opti, drill out the three vents on the bottom, into those you place a 90, and two t's...the 90 on the passenger side, a T in the middle and a T on the drivers side. A vacuum line hooks up to it and goes up to the snorkle. You also have to put a hole in the new distributor cap and put an inverted Y fitting on it with epoxy. the other vacuum line hooks up to it and goes up to the intake manifold.
I understand that you can use an early style base and a later style cap. That cap already has the vacuum line outlet that goes to the manifold...but you still have to drill out the base.
I believe this is also on the tech section.
But...definitely vent it.
I understand that you can use an early style base and a later style cap. That cap already has the vacuum line outlet that goes to the manifold...but you still have to drill out the base.
I believe this is also on the tech section.
But...definitely vent it.
Race Director
Joined: Sep 2001
Posts: 14,659
Likes: 750
From: NEwhere Ohio
Re: opti question (flubuyu2)
I would take it apart, and inspect for damage. The one on my 1993 with only 32,000 miles had a shot bushing (bearing?), and was rusted on the inside. I got occasional high RPM hesistation likely attributable to the bad distributor.
I ended up putting an aftermarket cap with a vented harness (to supply the vacuum), and then epoxying a small diamter hose into one of the three vent holes at the bottom. The other 2 I epoxied shut. I then had the whole thing (including the electrical harness connector at the top) sealed in RTV permatex.
This has worked so far.
The vacuum hose comes off the manifold, and the air inlet hose to the distributor goes into the air intake hosing after the air cleaner.
You don't need to spend $200 on a vented cap. All you need to do is follow that article's advice and melt a vacuum tube into your opti's cap.
BTW the reason you can't just buy a late model 95 or 96 distributor complete with vacuum air inlet/ air outlet caps is because the baseplate won't work with your timing chain cover. They changed the timing cover. Hope this helps
I ended up putting an aftermarket cap with a vented harness (to supply the vacuum), and then epoxying a small diamter hose into one of the three vent holes at the bottom. The other 2 I epoxied shut. I then had the whole thing (including the electrical harness connector at the top) sealed in RTV permatex.
This has worked so far.
The vacuum hose comes off the manifold, and the air inlet hose to the distributor goes into the air intake hosing after the air cleaner.
You don't need to spend $200 on a vented cap. All you need to do is follow that article's advice and melt a vacuum tube into your opti's cap.
BTW the reason you can't just buy a late model 95 or 96 distributor complete with vacuum air inlet/ air outlet caps is because the baseplate won't work with your timing chain cover. They changed the timing cover. Hope this helps
Advanced
Joined: Aug 2001
Posts: 68
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From: Ft.Myers Fl.
Re: opti question (dizwiz24)
I just purchased a Mid America vent kit. Question is, will I be O.K. to "T" into the vacuum line that enters the cruise control. Reason being is that the "T" that comes w/the kit will only fit the larger vaccum line at the cruise control?? Thanks
Melting Slicks
Joined: May 2001
Posts: 2,143
Likes: 7
From: San Diego CA
Re: opti question (BLIZZ)
That's were I'm planning on plugging my lines. Does the Mid-Am kit have a vaccum limiter valve in-line? If so, then I believe you'll (we'll) be OK. Anyway, it's easily reversible if it causes a problem.
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Melting Slicks
Joined: May 2001
Posts: 2,143
Likes: 7
From: San Diego CA
Re: opti question (BLIZZ)
I don't know if it's absolutely necessary, but it comes on the GM vacuum line kit. It probably has more to do with maintaining the proper vacuum at your source than effecting the operation of the opti. I don't think the opti needs a wind to keep it dry, a gentle breeze should do the trick.
Are you sure it's a filter on the Mid-A kit? If it's on the line that supplies the vacuum, it would be too late to keep contaminates out of the opti.
Try blowing on the tube to see if it flows freely or not. (Just a thought)
Are you sure it's a filter on the Mid-A kit? If it's on the line that supplies the vacuum, it would be too late to keep contaminates out of the opti.
Try blowing on the tube to see if it flows freely or not. (Just a thought)
Burning Brakes
Joined: May 2001
Posts: 790
Likes: 2
Re: opti question (John Row)
I have the GM harness on mine. I can remove the tube going to the snorkle and blow through it, but when I start up to see what kind of vacuum I'm getting, I can't tell if there's vacuum there or not...if there is, it's AWFULLY gentle. Is this normal?
Melting Slicks
Joined: May 2001
Posts: 2,143
Likes: 7
From: San Diego CA
Re: opti question (emoshn)
I'd have to check. Can you disconnect the vacuum line between the source and the limiter, to be sure you have vacuum that far.
I wouldn't expect that not very much air is moved through the opti. It would only need enough air to pull moist air out and not enough to pull dirt in.
I'll have to rig something up to measure how much air actually is moved.
[Modified by John Row, 12:08 PM 4/4/2002]
I wouldn't expect that not very much air is moved through the opti. It would only need enough air to pull moist air out and not enough to pull dirt in.
I'll have to rig something up to measure how much air actually is moved.
[Modified by John Row, 12:08 PM 4/4/2002]