Dropped valve seat.

[a_guy67]

Hey guys i need some help on some decisions with my caprice's engine. A week ago my l77 decided to decided to drop a intake valve seat into cylinder #7 and shattered piston #7 in the process. I have not personally overheated this engine in the year i have owned this car. My question is if i should replace my other valve seats or what should i do to keep this from happening again.
Engine has 111000 miles with 9800 idle hours and 11000 running hours.
Engine has a sloppy stage 2 cam ( 283/286, .585/.585, 112 deg), pac1218 springs, btr trunion kit, ls7 lifters, hardened rods, and stock valves.

Any help and advise will be much appreciated.

[bstoner]

This is the first I have heard of a stock head dropping a seat (without overheating, expanding metal, etc.). What you do depends on your budget. Broke. Buy a junkyard block and transfer your goodies over. Got money. Buy a junkyard block, have a machine shop go through it, send the heads out for work, and transfer what is still good to your new motor. Finances no issue. Get a 418 or 427 aluminium block, good heads, and the usual work up for the engine.

Is the block trashed?

[a_guy67]

Block is good except for the sleeve. I'm gonna rebuild it with a new piston, new rings, all new bearings, and new seals. Block is gonna get a new sleeve and a deck and I'm getting a replacement head. I'm really just curious if I should get new seats or or get the current ones pinged in place or anything that could help prevent the others from dropping.

[bstoner]

I would also do cam bearings for sure. Not sure if you meant all bearings or just the rods and mains. While you got the heads out I would send them out personally. Lloyd Elliot did mine and he did a great job! Have a valve job done, check for cracks, port it, maybe even mill it for a high CR if you are staying NA (depending on final deck height). New springs (depending on how many miles on your Pac springs) and new valve stem seals. I would switch to the LS3 lighter hollow intake valves and run titanium retainers as well. How do your valves look now? Mine were pretty beat up with lots of pitting and I ended up replacing them. I went with the LS3 hollow intake valves and the Manley Race Exhaust valves with the intention of going FI down the road. I would imagine your valves and valve seats have a lot of wear on them and if you are pulling the heads I would not let it go or just lap them back in and call it a day. Pull a valve and see what the valve and seat look like.

Lastly if it was me having the work done on the block I would probably strongly consider a stroker kit or other upgrades while you are into the short block anyways. You are already paying for all the labor.

[GammaFlat]

The cause of your problem is likely a ton of run hours. 111,000 miles plus 9800 hrs (9800x33=323,400 theoretical add'l miles) puts many parts at risk... not surprisingly. If you are tearing it apart, it makes sense to replace or at least check as many parts as reasonable. These engines do seem to be able to put outrageous numbers up in terms of miles/hours but lower hours will generally yield more reliability. On average, more new or fresher parts will work out best in the long haul.

I'm fine with using used parts but try to shy away from parts with the equivalent of 400 thousand miles .

If you are going to replace the block or crank, consider the differences between cubic inches in terms of horsepower (more bore and/or stroke). Each additional cubic inch will be worth more than 1 horsepower. We have 364 cubic inches. If you go with a 4 inch bore (what we have now) and 4 inch stroke (swap out for 4 inch crank), you're at 402 cubic inches. 38 more cubes is good for more than 40 horsepower. Also, adding cubic inches makes your engine tolerate larger camshafts better (will idle better among other things). A 4 inch crank with rods is expensive but also a lot of bang. Getting an LS3 block (4.065 bore) will set you back more and yield less HP. On the downside, you'll generally lose MPG's with more cubes.