Spun #6 Rod Bearing

You know, you just can't resist thrashing your Rivi when you got your new exhaust installed. Anyway while enjoying the thunderous note of an otherwise stock 3800, I heard that suspicious knocking noise which began coming from my engine. I suspected the worst, but as any other GM owner would do, I hoped for the best.

After dropping the oil pan, I found the culprit. It was the ubiquitous (I know that's not the proper use of the word) #6 rod bearing that was smashed to near paper thinness. Dutifully, I attempted to replace the bearing in question with a stock replacement. All to no avail. The crank was just to beaten down to reuse in it's current state.

So, I've decided to rebuild. That's right, overhaul the 1995 Series 1, VIN 1, Supercharged engine. So while my mind is enhanced with a nice Irish red, I figured I would humble myself and seek the counsel of this wizened merry band of rambunctious Riviera Rice Roasters.

What suggestions would you offer? I want to stay Series 1 as much as possible, so I can save the dough for some more Irish. Anyway, it looks like the heads ought to be ported to match the factory headers and port matched to the plenum. Also, I'd like to try and adapt an M90... So lay it on me ladies and gentleman. But remember, I have a fairly tight budget. Also, I'm not ready to put in that 4t80 just yet.

Has anyone tried using a GN turbo cam? I believe it has the same configuration as the 95 SI.

I look forward to the banter and the battering. Cheers!

You can't use a GN camshaft, or any 231 parts. The 3800 is based on the original 231 design, but really everything is different. It was part of the standard -> metric movement. Nothing is the same.

Sorry to hear about the unfortunate fate of your engine. I know exactly how you feel. Good choice to rebuild! It's affordable to have it done, or DIY and save even more. I don't see any reason to change from stock internals unless you plan on building a monster engine.

Assuming you did your thrashing after the engine was fully warmed, we can rule out cold revving as the cause of the spun bearing.

Check piston #6 for chips (an indicator of detonation). A chipped piston can cause bearing failure. If you find this to be the case, have your injectors flow-checked to see if #6 was flowing less. Otherwise this was an oiling issue, or an oil contamination issue.

Send an oil sample to Blackstone labs for analysis. They can tell you if the oil was contaminated with coolant, water, metals, or other foreign materials, causing the failure.

Best of luck with your new build. Hopefully some of the Series I folks will help you decide which parts to use, and the correct plan for attack.

I appreciate the info Derek and AA. I may not have had a fully warmed engine when it happened, now that I think about the timing of the occurrence. I plan on upgrading the injectors. As far as contamination is concerned, I think I would have seen some other bearing biting the bullet. All the rest were just fine. I will inspect all the pistons, with particular attention paid to #6. Fortunately I have a spare engine that needed to be rebuilt. My machine shop told me the cylinder wear was very slight on the spare. So, I only need to hone the cylinders and install new rings, as far as the pistons are concerned.

This should make me feel a little better...
http://www.ebay.com/itm/91-95-Buick-Chevy-231-3-8L-3800-V6-Super-Charged-1-4-Cam-ROLLER-CAMSHAFT-/300743363359?pt=Motors_Car_Truck_Parts_Accessories&hash=item4605b38b1f&vxp=mtr

And there is some competition of sorts...

http://www.ebay.com/itm/91-95-Buick-Chevy-231-3-8L-3800-V6-Super-Charged-1-4-ROLLER-CAMSHAFT-/110933011347?pt=Motors_Car_Truck_Parts_Accessories&hash=item19d41f6b93&vxp=mtr

I believe both ebay ads you posted sell the same camshafts. I dont see the point in replacing the camshaft if the original is not damaged?

If the crankshaft is damaged (likely), it may be salvageable. They can be welded up and refinished. At least that's how mine was fixed.

Hey Dave and Aaron,
It turns out the cams are stock replacements. Mine is fine. I was hoping to find some additional lift and duration. Do you guys know of a source for some longer rocker arms?
Thanks.

Here you go: https://rivperformance.editboard.com/t8000-performance-rockers-for-95-sc#40763

The link on the first page in the Rocker arm thread is expired but Intense Performance does still have Yella Terra 1.8:1 rocker arms available for the Series 1 L67.

Awraght. I appreciate the lead!   

Did you experiment with an asymmetrical set up. Or did you go full bore on both intake and exhaust?

Has anyone had any luck contacting a custom cam manufacturer? I'm going to give that a try tomorrow. I'll be sure to post the results. Good night Chesty Puller! Wherever you are...

I have taken some photos of the pistons and the valves. I can't figure out how to use the uploader for the pics. The link directed me to a another site in French. No see voo play...