273 sucked a valve

[CHL2T]

I recently inherited a "built" 273 shortblock with less than 15,000 that sucked a couple of valves....

The two pistons in question don't have any major damage just a couple of small nicks and each one has a "moon" depression where the valves obviously made contact, the pistons appear to be forged TRW with moly rings

Other that that and needing new main bearings the whole thing is in really good shape

Would it be ok to run the pistons as is?

I am also wondering if I can use the 318 heads, pushrods and intake from the Polara or will there be some sort of trouble with the length?

I plan on throwing it into the Polara and really wont be railing on it all that much, basically just a cruiser

Thanks

[jimynick]

Small nicks shouldn't hurt much, but some people's idea of what constitutes a "moon" varies from others and unless said moons are really shallow with no evident cracking or perforation at all, a couple of pistons would be cheaper than re-doing the whole engine when/if they fail. Really, a roll of the dice. If I was going to chance them, when the bottom end was apart for bearings, pop the slugs out and inspect the inside VERY carefully. 

[Challenger6pak]

Post a pic of the pistons.  Do you know why the valves ended up into the pistons?

[the_engineers]

If it's just on a couple, it probably got over-revved.

[jimynick]

I bet Engineer's right because if it'd really sucked a valve, the head of it would have pounded it's way through the piston in nothing flat.

[CHL2T]

From what I understand the previous owner had the thing rebuilt at "supershops" and he had installed a set of used 340 heads in place of the 273 heads for more power.

Sucked tthem shortly thereafter and sat for close to twenty years till my buddy picked it up and gave it to me........

[72cudamaan]

It looks like there is traces of carbon in the indentions. Was the engine running after the head swap?
Looks like something besides a valve was bouncing around in the chamber. Could have gotten caught between
the valve and seat and then broke the valve.

[jimynick]

The one in the top photo on the right- definately not and the other is no beauty contest winner either. Too much damage in/over the ring lands. 

[CHL2T]

Hmmmm.....I gonna try to build this thing on a shoestring budget so if the general opinion is that I should replace it/ them then I will, along with the main bearings as a couple of those are scored pretty badly. looks like the ones who built it forgot to use the caps when popping the pistons in and dinged the crank.
I'll be checking that out too.

[Aussie Challenger]

If it had 340 heads then the valves may have touched the side of the bore, they usually have to be relieved on those small bores. Compression would be very low too unless the heads and or the block were surfaced. Sounds like a real jack leg builder put this one together.   

[Challenger6pak]

What is wrong with the 318 in the Polara?  I see head gasket.  Is that all?  Why not repair it?  Or combine the two motors, if possible, to make one.  Obviously this would be if one has something the other needs.

[72rtchallenger]

looks like the 340 heads were 2.02 valves on a 273 which is not a good idea,,many say use the 340 j head 1.88 valve which I have heard works good on the 273,,as far as those pistons I would change them and rebuild the motor completely

[jimynick]

There's a thread on here that gave some great builds for 318's. 400hp and solid. Sell the 273 to the guy who's anal about his restoration and congratulate yourself on not dumping more money into a pit that the original owners saw all those years ago- hence the long 'sleep'.

[Challenger6pak]

I posted a chart on that thread.  Let me know if it is no longer there.  Depending on the engine parts casting years etc.,  you can use the crank, which should be forged, from the 273 in the 318. That will give you a strong foundation.  I have a 318 here that has the forged 273 crank, the larger 340 rods (also on newer 318's), the 340 heads, and the 340 windage tray.  A set up like that will give you a decent motor that is not real expensive. You can even get decent gas mileage out of it depending on your cam selection.