Major engine SNAFU! Any advice?

[Scott70Chevy]

I also posted on another site, so you may have already seen this:
My 350 has been running strong, but choke wasn't working (hard to start) and it was sucking gas. Carb had leaks and looked like it needed a rebuild or replacement. So, I bought a reman Q-jet (all new internals, came from Mr. Carburetor in Cedar Hill, I've heard good referals for them). Put it on and it fired up great. Choke worked fine, engine had great sound to it, I could tell it would run like a new truck. A minute later, start to hear some clanking noise. I thought I had left something loose and it was banging something or being hit by the fan. It quickly turned into bad sounding noise (knocking), engine started running rough, and it died. I wish I had immeditately realized something had fallen in the intake! Thing is, I did not have any missing pieces (I think I was pretty methodical during the install). I took the carb back off and did not see anything loose or missing (compared it to the old carb). Now I have three questions:
1). Are there parts in the Q-jet that I can't see through the butterflies that may have fallen out after starting the truck?
2). Does the 350 SBC have an interference fit between valves and piston? (that is, if something held a valve open, would the piston slap the valve?)
3). Before tearing down the engine to check the damage, what am I most likely to find? Is there a chance I (with minimal mechanical experience) will find something I can fix without a ton of dough? Is there reasonable chance it can be fixed with just a new pushrod and valve? Or should I look for a new engine?
Sorry for the long post, but I'm really kicking myself and I don't have the money for a new engine. Thanks!

[jhow66]

1--No
2--Yes
3--Take out the plugs-if something fell through manifold chances are it will also hit the plug(ask me how I know). If you find one with the electrode bent-(^%%$#)-you found the noise. Bring that piston to Top Dead Center (by hand)-take a piece of wire and see if you can feel what is in cylinder. If you are lucky(I wasn't) it might come out spark plug hole. Got mine out(a small washer) by leaving that plug out and starting engine and speeding engine up a little--believe it or not it blew out the exhaust valve!!!! (this was back in the 70's-wife's car-was changing air filter-got done could not find washer that went under wing nut-wife found it the next day--bang bang knock knock LOL) Have you started it since then?

[texnician01]

I have seen firsthand what happens when a highschool student thinks it's funny to put machine screws in a 350. not too bad. you can see thread marks in the piston top but nothing major. the big thing will be to pull off the head. check the valve, pushrod...you know. the next thing to check is the edges of the piston top. if it hit really hard on the edge of a piston it could have smashed the ring land and pinched a ring. NOT saying this will happen just could, something to look for. much easier to fix a couple things now and pay for a head gasket than to have to do a full rebuild later cause something was bent or broken. I also had a small nut fall into a 292 inline 6. made a horribile noise but we pulled the head and there it was, totally unrecognizeable but there. would have prolly gone out the exhaust soon. it's a lot easier to check and fix things now that will cause problems later. a miss you can't figure out may be that bent pushrod, or a bent valve that now has destroyed a guide and a seat cause it leaked all this time. Just check things over good at best you'll only be out a head gasket but still have the piece of mind.

[Scott70Chevy]

Thanks for the advice. Maybe it isn't as bad as I thought, but it may be a while before I can do much with it.

[Fred T]

Another "quick" check is to pull the valve covers and look for a valve stem that doesn't come back up when you turn the engine over by hand.

[jeffnstef]

I had a friend that was working at a Mercedes Benz dealership and his milk money was in his shirt pocket. You can guess the rest. He claims to have just pulled the head and pulled his nickel out, Threw a new head gasket on and gave the car back to the customer.

[arkracing]

I agree with jhow66 on this one.

i had a brand spanking new rebuilt 350 with all the goodies..forged flattops etc.

one day i was switching carbs a bunch of times to see what worked best with the motor.
well on the last try i put a big holley 750DP that had been sitting on the shelf for a while...taped up so i figured i was safe.
put it on ..it ran fine (at idle!!!!)

took it out on the street..jumped on it, when the secondaries opened - bang klang "F*&@!!!!!!!! WHAT WAS THAT". i thought the flywheel broke the center out and was spinning around in there...nope something in the motor!!!!!!!!! must have been in the secondaries cause as soon as they opened...funny noises came from the car

started taking plugs out..found the bent one. put all of them back in except for that one...started it up - "ping" you could hear against the inner fender- yeh it came out the sparkplug hole.
put the plug back in and it was fine...never took it apart (never wanted to, didn't want to see what happened to my brand new pistion.)

Drove the motor about 1k and then sold it (cause the fact that happened bothered me - if it was a beater i could care less, but all that work and then that happend, i didn't want to know what happened to the piston or the newly cut clyinders)

start taking plugs out see if you got a bent one

[EyeH8the24]

fired my dirt track car up with two shop rags still stuffed in the carb dunno how it fired up....or kept running...it ran great one minute then started skipping....blew the rags out headers in small pieces...but didnt even bend a valve!!.....and boy was i happy!!! now i never fire one with out triple checking everything ! maybe you will be as lucky !