Originally Posted by jkkaz

Those are some nice pics. How did you get in there to take those pics? Do have hands like the burger king tiny hand guy?

I don't know if they would actualy run very good, but it's interesting to see. Notching the block may not be impossible, but it looks like it would be in the ring area of the piston. I'd make it work and run it if putting an engine in was as easy as changing your clothes and I happend to have a spare block with L-92 heads sitting around.

Originally Posted by the_merv

^^


I guess the GM Engineers don't know anything either..

Originally Posted by fast377

I'm in the middle of building my forged 347, and since I just finished the shortblock, I thought I would stick these heads on and see what a 3.905 bore would do.

Guess what? The valves open...both of them. Now I don't know if this is enough to unshroud the valves, but it's interesting.

Would this be safe to run?
Would any power be gained over something like a 243 head?
Will the combustion chamber be obstructed too much?

It would be nice to get some input from one of the pros on the board.

Originally Posted by FastKat

I'm sorry but I don't understand - you need to explain this to me real slow like I'm a third-grader. You have a 3.905 bore with an L92 head on it... earlier in the thread you said that there was no interference with the valves closed, and now you are saying that there is also no interference with the valves open?! How is that? What did you do?

Originally Posted by fast377

Earlier I said I had it bolted to a STOCK bore, and the exhaust valve would not open. Then I put the head on a 3.905 bore, and the exhaust valve was able to open. Either way, it's still way too much head for an LS1.

Originally Posted by FastKat

Wow, I didn't realize it was that close, and that .007-8" would make that much of a difference. Are the exhaust valves angled so that they travel closer toward the cylinder wall as they open?

If they do not travel closer to the cylinder wall as they open, I wonder if you could put the exhaust valves on a lathe and take about .010" off the edge of the valve, still have the valve seal properly, but also not come into contact with the cylinder wall?

Originally Posted by Paint_It_Black

You really think just barely clearing the cylinder wall would make these work?

Originally Posted by fast377

It's not the giant intake valve that is the problem. It's actually the exhaust valve that hits. The pictures are of stock L92 heads milled 20 on a stock bore LS1 (with no head gaskets). Both valves are open quite a bit also. You might be able to notch the side of the cylinder to allow the exhaust valve to fully open...it doesn't lack much. Now once it's all bolted together, I don't know if there would be any issues with the intake valve, but as it sits it fits. So there you go. They fit, but they don't.

Now the combustion chambers are obviously big bore also...so there is another problem.

Originally Posted by black00ssFL

But please try it on a stock sleeve.....let alone not evenly boring out the whole cylinder. Just grind it up at the contact point. I'm sure there won't be any problems.

Originally Posted by black00ssFL

Haha, I think that you are thinking I was supporting the idea and that grinding away in just the area it contacts will work.

Originally Posted by kmracer

are you really saying you're going to notch the cyl wall for valve clearance?

Originally Posted by FastKat

I put the heads on my shortblock myself - I know how thin the sleeves are. You know how thin the sleeves are, because you probably installed the heads on your LS1, too... or did you read it somewhere? Or maybe see a picture in a book... or better yet - saw it on the internet!!

Originally Posted by John@Scoggin

Strange question, but are the valves seated in the heads? Or did you drop the valves down from the inside of the cyl when you bolted the heads down and turned the engine over?