94 chevy 350 motor issues?

bought a 94 chevy k1500 4x4 repairable! truck has 157000 miles on it. when i bought it i was told motor was need of work! the motor starts right up but misses, shakes, very fuely smelling out the tailpipe, oil appears dirty but to my surprise not gassy? as the engine warms up it acts like it runs better! here is what i did to attempt the repair>

i put new ac plugs in, wires, pcv valve swapped out idle air solinoid, presure washed engine, new cap and rotor, dioelectric jelly on all connections, took carb cleaner to tbi. new fuel filter!

the truck appears that the fuel pump has been changed! when i took plugs out all were black as the ace of spades!!

motor feels and sounds tight!

hooked up my otc genysis to it, that says lean? but all signs show rich?

please help! i just bought a used tbi and a refresh kit for it, gonna try that maybe??

With 157 K+ miles, I'd change the O2 sensor too. It could be bad saying "lean" to the ECM, and the ECM's then trying to enrich the fuel mixture and retard the timing to correct it.

well i rebuilt the tbi and used another tbi unit, also changed out the o2 which was bad! the o2 was probly the main problem! still runs bad! pulled a compression check and i have none on number #7 cylinder?? does anyone think that a lifter may collapse and cause this?? or probly not?

A collapsed lifter would make the valve not open enough. It wouldn't have any effect the compression. If you really have NO measurable compression, that's a major concern. Broken rings, burn't valve, blown head gasket...hole in piston...In your case, hopefully its just a head gasket.

After sitting here thinking, your 100% right! since the o2 said lean , forcing the tbi to dump too much fuel down the throat, i bet i have a hole in the piston! that plug that was in that cylinder was clean as a whistle! all the rest were black again!

found an engine w/109,000 rounds for $200 and i can always get $50 for my block! any idea if these 350's have the 4 bolt mains??

You said the oil wasn't gassy, if there were a hole in the piston, you'd be getting lots of gas in the oil. Take the oil cap off and put a piece of paper over the fill hole. If the paper sticks to it, there is probably not a problem with losing pressure to the crankcase. If the paper flys off (shield it from air from the fan, outside, etc.), then I support your hole in piston theory.

Your right...there would be LOTS OF GAS in the oil. Here is my question....Before you go and pull this motor why don't you pull the head off and see what is going on..... You say the spark plug was amazingly clean. Would you say it looked as though someone "steam cleaned" it? That's what it would do if you had a bad head gasket and antifreeze was POURING in and steaming off during combustion. It will "steam clean" everything inside that cylinder.

HOLD THE PHONE!!! you must read my post 94 5.7 engine running rough.Your symptoms sound just like mine did .Mine started as a blown head gasket then put on reman heads. Thought it was 02 sens and all kinds of other shit BUT turns out my new heads were bad also!!!Just read my postings it was long and PAINFULL!But now it looks like we got it !Be carfull just cuz people say they know whats wrong w your truck doznt mean they know shit!!!This includes me.weigh all the info BEFORE you just tear into it blindly!.Please post or email me to let me know how its goin .Sounds to me like a bad valve or guide

thanks for the help people! i pulled the head off and found the top edge of #7 piston gone! no head issues that i could see also no leaks on the headgasket or signs that is! i pulled the engine and have everthing off it including the heads! i'm going to get this motor off a 91 chevy w/109,000 miles! getting this engine for $200! i have a buddy that demo's and wants to buy my engine! what is a fair price for this block and heads? also what issues should i look at before installing this used engine! i plan on new intake,exhaust, waterpump gaskets! should i put new timming chain on also?

ps i noticed that the main oil leak on the old engine was due to the rear seal of the intake!

thanks kevin

How much do you want to spend????