87 chevy truck smoking

[str8bloc]

head was bad they replaced it. truck sat for 5 years. fuel pump was bad so i fixed it.now when it warms up the exhaust smokes like crazy but the man said he rebuilt the motor.it has no other issuses other than smokes it runs great and very strong. the exhaust is stock fm 87.do i need to replace the cat and muffler?its a tbi motor too

[bake74]

     Have you checked the fuel and gave it a tune up ?  If it has been sitting for 5 years it might smoke for awhile until you run it a couple of days.  How bad is the smoke ?
     There is a way to check to see if the cat's are bad with a pressure check, though they would not make it smoke like you are describing, it sounds like a engine issue.  I would give it a tune up and when I was in there I would do a compression check on each cylinder, that will tell you loads about how yhour engine is running.

[Fairlane514]

What color is the smoke?

[jaredts]

Heads were replaced 5 years ago or just one head?  The engine was rebuilt before that or someone considered a valve job an engine rebuild?  A cylinder leakdown test is very valuable for this kind of issue.  Color of smoke would be helpful.  If it smokes for the first several minutes until warms up its probably due for a rering.  Even if that's your problem you can drive it for years like that sometimes.

[str8bloc]

well we got it from an uncle who has cancer and he told us he redid the motor. smokes white but no smell its a heavy smoke also. id ask him more but hes been under kemo and is to weak to talk. ill run a compression test and get back to you guys

[bd]

Thick white smoke is most generally coolant, but also can be ATF. 

Coolant:
Could be a leaking head gasket.  Perform a cooling system pressure test.  If you don't have a gauge, remove the spark plugs and check for evidence of moisture on the insulators.  Crank the engine over one or two complete revolutions with the plugs out and watch for fluid spraying out of a spark plug hole.  Or run a compression check.  Also, check the oil dipstick for mayonnaise.

ATF:
What transmission do you have?  If you have a TH350 or TH400 automatic and the modulator valve has a ruptured diaphragm it can suck ATF into the engine and billow clouds of profuse white smoke.  Pull the vacuum hose off the madulator and check for red ATF.  No worries if it's a 700R4 or a standard trans.

[str8bloc]

its a th400 i totally forgot about the modualtor thanks bd ive been runnin 700r4 in my truck and forgot.

[rickyharp]

I had a 305 in my 85 silverado and I lost a cylinder,we put new heads on the old block[didnt want to do that but did do to wifes advice].The cylinder I lost had the ring washed down by gas,they never reseated and it smoked and used oil until it died 2 years ago.I al;so had a modulator valve on my tb350 trans. go bad and boy did it smoke,it also slipped out of gear real bad.