There is a check valve in the suction side of the opti venting system to help keep the vacuum loss to a min. Also the vacuum used for the venting is minimal. I have a vented msd cap on a non vented opti with no issues. As for pressurizing the opti, there are commercially available 12 volt DC small air pumps. You would still need to allow the pressure to be bled out of the opti to move the moisture out. Also the air being pumped into the opti needs to be filtered and clean, and the pump needs to be oil less and free of parts that could break off and be forced into the opti . All in all I see the general idea, but I don't think I would go this route. It was a poor design 20 years ago, I was even told that by Scott Settlemire. There are better options now with 24x and ltcc. It all depends on time and budget

 

I guess Ill throw my .02 in. Instead of using a pump to pump air into the opti, why not use a DC vacuum pump to draw filtered air through the opti? Then you wouldnt have to worry about the pump breaking apart and forcing pieces of whatever into the opti when/if it fails.

 

That too..

 

jaysz2893, yes but the check valve doesn't affect the vacuum leak at the shaft at all. The design works where the computer accounts for the air at the air intake hose after filtration, then it is routed to the intake. It makes use of the vacuum, but the vacuum is not used up somehow in that concept of the design.

I am talking about the shaft leak and original potential of the original units that did not have such a possible leak. The vacuum gauge doesn't lie. This is now absolutely clear. Do the test yourself if you don't believe.

A fish air pump has a rubber diaphram with no metal parts going to break off and fly into the distrib. However I was merely proving the principle and ofcourse an aftermarket company could make an awesome upgrade unit for this which beyond question would be better and more widely respected.

Zfbod94, remember guys the pressurized idea is better engineering because contamination will not creep in at the shaft area of the distrib. This could be from leak, spill, or splash(3 possibilities). Also it avoids a kinked hose from causing the distrib to collapse and damage. Drawing air in would be a step backwards again.

 

So why not ensure the parts are new and working? A new complete hose assembly is $75.

 

I have a speed density car and my computer does not monitor the the way a MAF car does so I guess I dont really care if the shaft leaks a tiny amount.
The route of the air in the vented system is suction at the intake pulls air through the opti via the hose at the intake (which is filtered) and is after the MAF so the car already meterd that air. The amount that leaks past the seal should not affect the car as there is quite a bit of fudge factor in the tune. If you are worried about the shaft seal leak there are many other poorly deisgned areas of a Lt1 that leak like a sieve. The China Wall, the EGR, the AIR fitting on the intake, etc.. I am not poo-pooing the idea and every leak you can fix is a plus. As an engineer i just see a few areas in your plan that can be problematic. Can the fish pump(or any pump) can withstand the underhood temperatures? you need to see exactly how much air it can move vs the area inside the opti it needs to pressurize to get an efficient air exchange to remove the gasses and to have enough pressure to keep outside "junk" out. What do you do if the pump fails? Then ther is no air movement in the opti and the Ozone (one main contributer to opti falure) cant escape, and if there is oil or coolant leaking on the shaft and there is no pressure to blow it out it will wick in. My MSD opti (that i am not running now) has a bearing and its own shaft seals that dont leak. The OEM style Opti was a poorly thought out way to make a compact ignition system and hence it was only used 5 years. Having a non vented car i will say the vented system put in by GM was way better than what it was. It was not perfect, but nothin on the Ltx platform was.. hence its demise only after 5 years..

 

Ah, but we are talking about the distrib shaft leak. How much is that to fix, I really don't know. This unspoken leak is overlooked I guess. If cheap I will be doing this weekend, lol.

Can you please check your vehicle today.
Step one.
Disconnect the hose coming from the distrib at the first check valve(the big one that way we bypass the check valve operation to test the distrib for leaks).

Step two.
Remove snorkle from distrib to air intake hose.

Step three.
Plug one end and apply vacuum or pressure and tell me if yours holds vacuum.

Step four.
Report back here and prove that some distribs seal, and some may loose seal.

Thanks

 

I was thinking of having it in the car rather than under the hood.
The air flow is sufficient. It would need a backup plan, for example in a fish tank we used to have two air pumps so if one failed the likelyhood of the other failing right away is low. But in that example it was easy to see the failure of no air bubbles, where with the air pump it can only be heard a little bit inside the car or felt because it vibrates.
Could have a distrib cap with it built in, like ACCEL MSD or something cool like that. They could do it well I bet.

 

I would rather have a leaking OEM unit with a reliable optical sensor over an aftermarket POS.

 

Dude, you replace the damn seal in the timing cover.

GM part number 10128317 for unvented, 12552428 for vented.

I just don't see what you're trying to do. If the vacuum harness is in good functional condition and the opti seal in the timing cover is in good shape there is NO NEED for a vacuum pump on the opti.

The opti is not designed to hold a vacuum. It is sealed to keep moisture out NOT air. There are a TON of places for air to leak in even under as small as a 1" vacuum, like all 9 plug wire connections, the opti harness connection, around the cap, etc. The vacuum provided by the intake manifold is MORE THAN ENOUGH to displace the incredibly slim volume of air in the opti with fresh outside air.

If you understand FULLY how the system works you'll realize that what you're making is identical to what the OEM system does.

For the record I too am an engineer specializing in the design and operation of high pressure steam boilers and industrial refrigeration systems so I know a thing or two about vacuum and pressure.

 

I bought the set of seals, that has nothing to do with the leak I am talking about. That is where you slid off onto a tangent.
You didnt do the test(post #22) huh, it figures.

 

What was the actual vac loss shown in your test?

 

If there are responses like, I am not going to test my distrib because I know it must not be leaking is borderline arrogant, right? You dont wanna be that guy. Just sayin.

 

I did not do the test simply because of what I mentioned in my post. I'll reiterate it here again in even bigger bolder underlined letters. I wonder why you omitted this segment of your post in your quoted reply...but here goes...

The opti is not designed to hold a vacuum.


Of course it won't hold a vacuum. It is not a sealed pressure vessel. There are penetrations all around it - MORE than just the shaft seal.

 

Dude get over yourself. We only see if it holds vacuum for test. It was never designed to have vacuum applied at all if you knew anything about the history. They had to scramble for something, and settled on this design that may or may not work the 100k is was designed to do, because I've seen a lot of lower mileage cars with optispark problems.



Good question, when it was cold start if mattered the most it was 1.2 difference. It was showing 19.9ish to almost 19.70ish, then with leak when warm.
There is literally no resistence when performing the vacuum hold test. So the total amount can be leaking not sure about all of them ofcourse depending on brand or wear.

I have some images... I didnt do the video cause i was like heck who the hell cares then as long as I know.