ah crap!
 

Well My chevelle had a little surprise for me friday afternoon when I fired it up. Motor made a very strange noise and then shut down. Good thing I was still sitting in the garage!

http://www.allenitllc.com/hotrods/ch...ne/valve-1.jpg

http://www.allenitllc.com/hotrods/ch...ine/piston.jpg

Looks like it's time for some engine work. :(

ah crap is right. Can't tell from the pic but it doesn't look like any damage to the cylinder wall. Sorry about that, good luck.

Ouch ! I think the words out of my mouth would have been more than ah crap.

lol! yes mine were as well. I had to clean up the language for the post. :)

Ah this looks all to familiar. When I took my motor apart it had 3 cylinders with broken valves in it. Looks like the damage is not to bad like said above. Good luck with the repair so you can get back on the road soon.

Ray

i agree with Ray. I hope you are back on the road soon.

The spring looks like its in one piece still. Did the valve tip snap off or did it spit a keeper? Sounds like a crappy way to start a ride. But Im with ya on, that its better to happen in the garage.

Valve broke right at the bottom. The retainer and everything still looked normal. Actually I couldn't even tell anything was wrong until I backed off the rockers and that spring went up and up and up as I backed it off. LOL

Jeez!!! What does the chamber in the head look like?

Intake seat is damaged and needs to be replaced. Exhaust valve is bent as well.

So far I need one new SRP/JE forged piston, 1 new 2.05 intake valve, 1 new 1.60 exhaust valve and some new valve seats installed. The cylinder wall is ok with exception of a small scratch that I can hone out.

Do you have any idea what caused the valve to fail?

No clue. It's almost like it was defective or weak. I'm sure the solid roller and heavy valve springs weren't gentle on it though.

Have you calculated spring pressure at max lift?

I believe they are at 220# 570#.

Sounds like you did your homework. Whos valves did you use?

They are the Milodon megaflow stainless steel valves.

Ouch! you said it! good thing you didnt try to restart it or have it at high rpms. My grandfathers old 427 dropped a valve and it ended up sending pieces back into the intake and left chunks on the other bank. It ended up needing a sleeve in one of the cylinders and a few pistons and a .030

Well I've got my wishlist all together. I'm keeping the motor all the same with the exception of the solid roller cam and valve springs. I'm going to be losing approx. 80hp with the cam swap, but I should still be over 500hp with the new hydraulic and be much more streetable.

Here's the specs of how it's going back together.

383 stroker / splayed 4 bolt caps

12.5:1 JE forged dome pistons full float
Eagle H beam 4340 rods
GM bowtie iron heads worked over with 2.05 int. 1.60 exh.
Comp cams 12-214-4 Hydraulic cam 305 seat to seat duration .525 lift. 110LC
Comp valve springs
1.6 roller rockers
Super victor single plane intake
Proform 750 double pump carb

I'll update when I get it back in the car. Waving

Do you calculate hp or dyno?

It was calculated with desktop dyno and comp cams camquest dyno. I also had to calculate my dynamic compression and pick a cam that would give me the best dcr for premium pump gas. This setup puts my dcr right around 8.39.