Loose Opti bolts = damaged valves/pushrods?

[Scoobie]

LT1 smartones.
If an Opti-Spark is not tightened onto the Cam shaft properly, would that cause the bolts to shear off of the Cam Shaft? Could that in turn cause PTV damage? My mechanic will be sending pictures soon I hope. He said he took pictures of everything and has saved the bolts that were sheared off the cam shaft. The bolts were so loose that he removed them with his fingers, didn't need any tools to get the bolts out. The timing chain looks fine. Could this also be a result of a Non-Vented Opti being installed on my 97 by accident? (A new Opti was installed less than a 1/4 mile of drive time before this failure by a seperate shop, I am in Afghanistan) Would the longer (.700) Cam dowel with a Non-Vented Opti cause this sort of damage? 6 valves are damaged and I have 6 bent pushrods. I am tyring to figure out how that is related?


Scoobs

[cocobolo95]

You can't install the type 1 non vented opti on your 97, unless you change the timing cover, and cam gear. The type 1 opti has a much smaller splined drive mechanism that won't work with the type 2 timing cover and cam gear you have on your 97.
As for the damage, who knows I guess anything is possible. But unless the opti shearing the bolts off cause timing to jump several teeth on the gear, I don't see this hurting the valves/ push rods. If it did jump time there would probably be piston damage as well.

[95 Firehawk]

The Opti is not bolted to the cam. There's no way for an opti to alter valve timing events.

Over tightening the the rocker arms will add lift, and insufficient springs can cause excessive valve float to where a piston hits a valve. Any other details?

[Scoobie]

The car just had a new Opti installed 1/4 mile before this incident. The Mechanic said the Cam Dowel is completely sheered off. Right away my wife said the car was "vibrating a lot " when she started it. She said it vibrated funny up until the point it died, she heard the "dragging" and was unable to restart it. If the Cam Dowel does not connect to the Opti, than what is it there for 95 Firehawk? I was thinking maybe the Cam walked after the break, valve events were off and eventually valves hit pistons. I am no mechanic, just an enthusiast so that is why I ask these questions.

[cocobolo95]

As stated in above answers, unless the cam pin shearing off caused the cam gear to jump time or broke the timing chain, there's no way for that event to cause valve piston contact.

I would have your wife, or better yet, a friend who knows his/her way around engines, go to the shop and take pics of the torn down engine, just to make sure your mechanic is on the up and up.

[Scoobie]

Guys, updated thread here with more info.

This week the car was towed to local shop. I called the shop tonight from Afghanistan and spoke to the mechanic. This is what he told me. He pulled the Opti off and the timing cover and the chain and sprockets are fine. However, all 3 cam bolts and the Cam dowel pin have been sheered off. He seemed to think that the Opti wasn't installed properly and was the likely cause. He believes that the cam stopped moving once the bolts sheered off and that is why I had Piston to Valve contact. He said everything inside was stock, but that the bolts looked new that were sheered off. To his best knowledge, the timing cover had never been removed before.

What the hell would cause the bolts to be sheered off? Like I said, it was hard to follow the Mechanic. He is sending my wife the pictures though and I will upload them. The Heads are still on the car, they will pull those next. What I do know is I have 5 or 6 bent pushrods as I had my brothers friend pull the valve covers when I thought it was the chain that snapped.

[cocobolo95]

Read post you linked up, what I see wrong with your mechanics theory is, if cam seized up, timing chain and crank gear would not be in good shape, the crank would have kept turning until stopped by valve and piston. This would have either chewed up chain, crank and cam gear, or broke the chain with damage to both gears still likely.

[Racy Roadmaster]

In your first post you said the mechanic was sending pictures, well if he hasn't he or you need to send pictures,possibly we may be able to deduct more data from them. ed

[sweetbmxrider]

I think you could jam a spline drive onto a newer motor. Like you said coco, the spline drive is smaller. The vent opti timing covers are a larger opening and could accept the smaller drive into them.

As for the bolts shearing off, either they weren't torqued properly and backed out or they were incorrect and never tightened correctly.

[cocobolo95]

I agree, you can jam a type 1 opti into the larger type 2 hole, but, and this is a enormous butt, There are no splines on the type 2 cam gear to turn the opti, so car wouldn't run at all. If it could, can you imagine how much oil would pour out of the empty space around the seal.

[95 Firehawk]

Originally Posted by Scoobie

If the Cam Dowel does not connect to the Opti, than what is it there for 95 Firehawk?

The cam dowel does connect to the opti. I stated earlier that the opti isn't bolted to the cam, which it isn't. The opti is bolted to the timing cover/block. The dowel pin drives the opti for cam/crank position reference for ignition timing, not valve timing. Valve timing is a purely mechanical operation through the timing gears/chain, camshaft, lifters, pushrods, etc. and has nothing to do with the opti.

Originally Posted by Scoobie

However, all 3 cam retaining bolts and the Cam dowel pin have been sheered off. He seemed to think that the Opti wasn't installed properly and was the likely cause.

I believe he means the cam gear bolts. There are only two cam retaining bolts in the cam retainer, which I doubt had failure. There are three cam sprocket bolts, along with the dowel pin that would sheer off with an abrupt stop of the valve train.

I do not believe this had anything to do with the opti at all. I also don't think the bolts and dowel pin were the cause, but rather the result of valve/piston contact. I suspect someone just tightened down the rocker arms, not knowing how to properly set valve lash causing valves to be held open even where the lifter was on the base circle. Was someone messing with the rocker arms when the opti was installed?

[Scoobie]

Thank you for the reply's, as mentioned before I am writing from Afghanistan so this forum is very slow to load.

The only modifications to the Car to my knowledge when I bought it was a K&N air filter, panhard bar and ORY. I shipped the car to a popular LS1/LT1 shop for storage/work while I'm gone. They drove the car and reported a slight miss. I had them install Kooks Headers/Catted Y, MSD wires, new spark plugs and a new GM Opti. No one to my knowledge for any reason touched the stock 1.5 rocker arms. The mechanic working on the car now is in his mid-40's and has been doing this kind of thing for nearly 30 years. He said the original gasket was on the timing cover and everything was "stock".

My question is, do the Cam gear bolts get removed/re-installed during an Opti-Swap? Why is it that when the cam dowel and these bolts sheered off did the car die and now have 6 bent valves?

Pictures are coming, I've been waiting but it is nearly midnight here. I hope to have them soon :/

[Racy Roadmaster]

Sorry for jumping in here, I believe you said the cam bolts and cam dowell pin sheared off,is that correct or did the bolts that hold the opti distributor shear off ? Just confirm that for me. Anyway if the cam gear bolts and dowell pin sheared off ,one heck of alot of force had to be involved. These things are hardened steel. I HAVE INSTALLED A FEW OPTIS IN MY time so I think I am safe to say that something way wrong happened here, especially bent push rods and valves,I dont think if an opti locked up that it would have the structural ridgidity to break 3 hardened bolts and a hardened dowell. MY COMMON sence tells me we cant do anything else unless we have pictures. I cant see commenting any longer unless we have something to look at. ed

[Scoobie]

Pictures.



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[Scoobie]