pearlpurple

BACKGROUND:

141,000 miles the water pump just failed. Opti is OK engine runs great (original Opti).

Decided that if I am going to go through the trouble of diving in I might as well go deep and perform some surgery.

Going to change Opti too (bought an ACCEL unit)
Going to change timing chain set

Since I have to lower the oil pan to get the timing cover off/on I am going to change the oil pan gasket too. To do this I need to raise the motor so I am going to drop the Y Pipe to get at the starter and the motor mounts.

Long intro yes but leading to the questions:

1) am I correct in the above?
2) where do I get the exhaust flange gaskets for stock manifolds and stock Y Pipe unless I am daft I cannot find.

Thanks for any help in advance

pontiacstogo

Others will chime in, but I suspect most would suggest sticking with your current Opti if it's not giving you any trouble or problems. Maybe swap in a good quality cap and rotor? The MSD cap and rotor have a good reputation (but not the complete units) and would allow you to add venting to your non-vented Opti.

moparman

Stick with your OEM opti, unless it's a problem.

Injuneer

Shoebox's cam remove and install guides have valuable info on removal/replacement of the water pump, Opti, crank hub, front cover, and timing set. Just ignore things required for cam removal (like pulling the radiator), that don't apply to what you are doing. Pay particular attention to installing new seals in the timing cover.

4th Gen LT1 F-Body Tech Aids

If you insist on replacing the Opti, the current choice seems to be the Petris unit. I've been suggesting this for a couple of years, after seeing a lot of positive feedback on Corvette forums. Recently had feedback here from someone running the Petris for a full year. Try a “search” on “Petris” for additional discussions. The Petris spline drive unit is vented, and includes the vent hoses.

https://petrisenterprises.com/collections

The oil pan doesn't need to drop much.... should be enough room without lifting the engine. That eliminates unhooking the Y-pipe.

pontiacstogo

When I was looking for a replacement Opti for my 94 Camaro it came down to Petris and the 'Opti Doctor' on eBay;

https://www.ebay.com/str/OptiDoctor?...p2047675.l2563

I went with one of the eBay versions and elected to purchase one with the MSD cap and rotor and a new Mitsubishi sensor. It's worked flawlessly but I only have around 6 months and 1K miles on it since it was installed (my car is mostly a track car).

pearlpurple

Thanks for the replies.
Already purchased ACCEL (not MSD) opti and with 141k on the clock and having dropped fluid on it and OPTI is out on the bench sort of made my mind up on that one.

Nice to know I only need to drop oil pan a bit and not raise engine, should save me some time

Still want to know where people are getting exhaust flange gaskets,,, are they donuts or gaskets,,, I can't remember would like to be prepared in case,, I have original Y pipe and manifolds

Thanks

Chimera96

Well good luck with the Accel....unfortunately many have had issues with it and other "off shore" cheap opti. I would strongly recommend you keep the original AC Delco. If it was working all you would need is a new Cap & rotor. You may find some oil inside the opti so just carefully use a Q tip to clean it and install a new C&R. Inexpensive C&R though can be crap though. MSD had a good reputation for their C&R, I have it on my AC Delco opti but over the last few years there apparently have been issues with their C&R because of the epoxy used in making the caps if I understand threads Injumeer has posted in regarding the MSD opti itself. The MSD Opti has had several issue over the last few years and the one I bought back when they initially came out was bad out of box FWIW

It is highly recommended you use loc-tite on the rotor screws when replacing C&R

Not sure why you feel the timing chain needs replacing. They are not known to be a issue at all especially at your mileage.

Replacing the WP drive and Opti seals on timing cover are recommended on Opti replacement/service. Crank seal rarely leaks and the TC gasket itself also very rare to leak. The WP drive seal is the most prone seal to leak on TC, especially after installing a new opti so recommended you replace it. You do need some form of tool to install it and those are sold on ebay for around $20 and worth every penny. A deep socket or the spline shaft itself can be used as a alternate tool and even a Sharpie pen body. That seal and the opti seal install dry. They are PTFE seals so do not oil them. The FelPro TC gasket/seal set for around $12 at most auto part stores

If you don't have a TC or pan leak now, IMHO, I would leave well enough alone

Local auto part store or rockauto.com should have all the exhaust gaskets you feel you need.

pontiacstogo

That's some excellent advice in the post above.

My Y pipe was removed to fix a split at the converter seam and make it easier to do plugs and wires. I don't recall any gaskets at either end of the stock Y pipe. I actually purchased a Walker replacement Y pipe at the time, but my mechanic convinced me to keep the one that was on the car and simply weld up the split seam on the converter. A previous owner had emptied the cat and he felt the Walker replacement would be more restrictive. I kept the Walker Y pipe in case I ever need it in the future.

Injuneer

At least 22 years since I pulled the Y-pipe on my 94 to install headers, but I do not recall gaskets being present. The 93 factory service manual assembly diagram does not show any gaskets for the LT1 exhaust, which has flat flanges on Y-pipe and manifold, with a projection on the Y-pipe that inserts in a relief in the manifold, forming a seal. On the other hand, the V6 exhaust, which has a bell on the Y-pipe and a ball projection on the manifold, does show a "seal".

pearlpurple

Much appreciation for the replies, taking it all into consideration might hold off removing timing cover.

My thoughts on timing chain are based on older experiences with small block Chevys like the 350 and 305 motors where at 141k timing chains were stretched

What is the difference with the 93 timing chain to make them last, as leaving well enough alone would suit me and simply put two new seals, not have to remove the hub, etc.

David94TA

I think that is a good idea to go ahead and change the opti, especially considering the mileage. For as much trouble as it is to pull the water pump, you are right there--might was well go for it. Good luck with the work. I'm in the middle of an opti swap myself.

Germansheperd

I have to agree with David94TA but just buy an ACDelco or Petris.

Phoenix'97

My suggestion with your ACCEL, coat the exterior seams where the cap meets the inner casing which meets the metal base with dielectric grease. Apply LIBERAL and generous amounts to totally cover the seams all around the optispark. This will help to make the unit all the more resistant to any future fluid penetration be it from future water pump maintenance to oil leaking from the timing cover seals to any rain water from a very hard storm or just taking it through the car wash.

On one last note you may need to replace the timing cover seal for the water pump shaft, especially if you see a layer of caked oil on it. This is an easy replacement as any youtube video would show you.

pearlpurple

Thanks. I am a little nervous now with the ACCEL but will take your advice on the dielectric grease.

I went in and changed the timing chain set so timing cover is off and oil pan in dropped some to gain the access. So will be changing all three seals (ordered the water pump tool off of Ebay)

Now that I have the pan dropped I want to pull the pan off all together as I don't like the way the front of the oil pan gasket looks and I think it leaks anyways. How high do I need to raise the engine to get the pan to clear the crank shaft and oil pick etc.??? I also want to check my oil pick up screen/tube as I have that infamous oil pressure drop when flooring it from a stop.

Thanks again

Injuneer

One of the potential entrance points for coolant is the tower for the main Opti harness connector. It's pointed up, right near the pump weep holes. That has to be addressed as well.