formula18

while running today and coming off plane i notice my 1989 350 mag (rebuilt ) the worst possible thing happens...I must have the worst luck ever!!!
The threaded rod that holds the airfilter is made of three pieces becuase its adjustable...the piece that holds the 2 rods was brass..,..I notice my motor is stumbling aka running on what seemed like 7 cylinders so i crawl back to the dock still not knowing whats wrong...suddenly it smooths out and is fine...wtf so I rev the throttle and it happens again it start stumbing. I notice my air filter shake i llift it off to find no brass piece. it got eaten...i pulled the intake and the heads...found what seems like alot of it. im wondereng what else i should do...im hoping it will run ok when i put it all back together and that it was just holding a valve open

pray for me....Harry

fireboatpilot

I hate to be the bearer of bad news, but the odds that you passed a piece of metal or anything other than air fuel mixture past an intake valve without bending or nicking the valve and or seat are slim to none. Then theres the issue of it lying on the top of the piston waiting to do some more damage to something. If I where you I would pull the heads and take a look see at the pistons and valves. Then I would toss out those 3 piece stems and get a piece of all thread. Why waste the time putting it back together now, just to find out it needs to come apart again? Good luck!

formula18

thanks for the reply...i have pulled the heads...i found some brass on top of the pistons the walls all seem fine as well as the piston...the heads look fine but i don't know what im looking for...ill just take them to a machine shop...im using vortec heads and had stainless steel valves put in..the engine only has 75 hours on it...

anything else i should do?

fireboatpilot

You need to do a leak down test on the valves to see if they are still seating properly and no seats or valves where damaged. You can do this yourself or a machine shop can do it for you. It should be a pretty fast and cheap thing to have done. To do it yourself the back yard way you need to turn the heads upside down. With the cylnder bowls up, flat and level, fill the bowls with some liquid, solvent would be good like thinner WD40 ect. Fill the bowls to top without over filling. If nothing passes thru then your good to go. It won't take long to find a leaker if there is one damaged. If leaks are found then those valves need to be repaired or replaced. Bring all the pistons up to top and flush out the ring groovesaround the top. Use a spray can with the little tube to force solvent between the piston and cylnder wall. Flush it real good! Then get some oil on them to prevent rust right away.

Young Performance

The odds are pretty slim that there is no damage. I would be very surprised if the engine doesn't need some machine work and some parts replaced. Good luck and if I can be of any assistance, give me a shout.
Eddie

Pwrbt33

Just like my buddy Eddie just said. The piece your looking for is probably beat'n in the top of your piston. At a minimum I would pull the spark plugs and use a bore scope to have a look in and see whats going on before some real damage occurs.

Sorry to hear about your luck. Next time, use RED locktite.

MacGyver

You might have bad luck, but at least you didn't pop a hole in the top of the piston.

obnoxus

Guys,,,, the very first post says he pulled the heads !!!!

formula18

thank you all and fireboat...i will try that leakdown test myself...i have the heads off....i have one question?? when im replacing the heads i dont know which gasket will work best and which thickness...its an 89 block(pre vortec) using vortec heads...

BillK

Harry,
I have seen valves that were just slightly bent still pass the "leakdown" test, usually they will seal on the carbon that is always there. It would probably be a good idea to have your machine shop pull the valves and put them in the valve refacer and just touch give them a quick touch up. That way you will be certain and while they are at it they can take a quick look at the seats also. Its a pretty quick job and should not cost you that much, I figure around $100 or so.

As far as gaskets go, if it has been running ok up till now, I would use the same gaskets that are on it. Why mess with something that has been working ok ?

And .... like the others said, get rid off the three pc air cleaner hold down

Bill Koustenis
Advanced Automotive Machine
Waldorf Md