[DRevil]

On New years eve I went to start the car and she broke an intake valve in cylinder #4. See pics. Now I am in the market for a new short block.

 

[jcs003]

Sorry to hear. Time to get with Thompson Motorsports.

 

[Blown376]

I think you got your money out of this block. 😀 It would be pretty exciting to be shopping for a new shortblock setup.....oh the possibilities!

 

[Ctarb1]

That’s a hell of a run, are you going to do a full on build now or just go back stock?

 

[loweredd]

Dang!

 

[SilverSedan]

Any mods during that >300K miles?

 

[Blades1_99]

On New years eve I went to start the car and she broke an intake valve in cylinder #4. See pics. Now I am in the market for a new short block. View attachment 155907

View attachment 155906 View attachment 155906

Did you have any indication that it was about to fail?

 

[DRevil]

No indication. In fact it ran like new with no oil burn. In fact, it broke the valve during start up. I had several basic mods 2.5 pulley, ported tb, weaponx heat exchanger, borla exhaust and Cai. With aggressive tune. All done around 40k. I plan to rebuild it as a 416 with stage 2 cam. Plan to put another 300k on it.

 

[Blown376]

No indication. In fact it ran like new with no oil burn. In fact, it broke the valve during start up. I had several basic mods 2.5 pulley, ported tb, weaponx heat exchanger, borla exhaust and Cai. With aggressive tune. All done around 40k. I plan to rebuild it as a 416 with stage 2 cam. Plan to put another 300k on it.

I was going to say that the block would still be good, you caught it quickly when it failed. New heads for sure, but you probably didn't even score the cylinder wall.

 

[DRevil]

From what I can tell. The head may be ok. Most of the damage is on the valve seat. A new valve seat. The connecting rod is no longer attached to the piston. I will have the motor out over the next couple of days to see if the block is OK.

 

[pepn3385]

Stock stroke would help in going another 300k. I’m not as knowledgeable as some, but I’ve heard the 4” stroke doesn’t have the longevity. I might be wrong, and maybe I’m just thinking older ls stuff, with shorter sleeves.

 

[SilverSedan]

If the piston isn’t attached to the rod, how do you know the rod or rod bolt didn’t break first and cause the valve breakage? I’m thinking a broken rod more likely to cause valve damage rather than a broken valve causing a rod to break.

 

[jcs003]

Stock stroke would help in going another 300k. I’m not as knowledgeable as some, but I’ve heard the 4” stroke doesn’t have the longevity. I might be wrong, and maybe I’m just thinking older ls stuff, with shorter sleeves.

You are correct. The added stress/strain due to the strokers rod angle creates a less reliable assembly. Hence why I went 388.

 

[deshars313]

What does it sound like when something like this happens?

 

[RedTXV]

Too soon?

 

[DRevil]

I think you may be right. The rod mayhap broke first taking out the valve. Good advice on the stroker. 388 may be the solution. Strange thing is that I can turn over the motor by hand and no noise from the connecting rod. But it still pushes the piston up if I push it down by hand. Can't hear the rod touching any metal. Will pull it in the next couple of days. Hopefully the block is OK.

 

[jcs003]

Pat g just tuned an 388 with stock ported ls9 heads to over 1,000 wheel horsepower.

 

[DRevil]

Sorry, voice to text. As I ment to say. The rod most likely broke well before the valve. I still have no idea as to why it's not making any noise. I will know as soon as I pull the motor.

 

[Blades1_99]

Saw this

http://instagr.am/p/CYl-t2SAHoq/

 

[jcs003]

Saw this

http://instagr.am/p/CYl-t2SAHoq/

I can't wait to get mine.