z28luva

i just got a new 402 put in and the engine is smoking, running rough and every now and then misfiring. it doesnt always smoke however. i have 2 theories and was wondering if either one was correct.

1-my valves are out of whack and the engine is burning oil. i assumed this to be the case because of how rough the engine is running. but the smoke is white, which means that its most likely coolant being burnt correct?

2-the coolant is being burnt, which would explain the color of the smoke. and most likely i need a new head gasket. but would this make the engine run so rough? also my last engine (396) threw a rod out. when i drained the the oil tank there was a lot of coolant in there, so most likely this is the problem, atleast thats what i think. but once agian could coolant getting in the cylinders cause the engine to run rough and misfire like it is?


i also considered the timing being off, but the two above theories are what i am leaning towards. any help is appreciated.

edit-i would also like to point out that a lot of the smoking of the exhaust occured today. i didnt start the car yesterday and it rained for two days straight, could that have something to do with the white smoke?

byrons1502

i have seen intake gaskets cause that same problem... most bbc intakes are very old and likely warped or not cleaned completely. it will draw oil from the lifter valley and cause a vacuum leak at the same time. because it is under the intake it will nto show up with carb clean on the edge. a good test is run the carb clean upside down until no fluid comes out and spray into the valve cover, if the idle goes up the gaskets are bad. try this test while it is running bad. most of the gaskets leak hot or cold not usaully both unless really bad. quick test to try

11secgen

you need to check the cooling system for leaks. at most auto places they can rent or sell you a tester, it is a pressure guage that goes in place of the radiator cap,then you pump the system up with air and if the guage goes down over the corse of several minutes or even seconds then you have a leak some place.this will detect a bad headgasket.if the leak is bad enough, then the cylinder can fill up with coolant and hydro lock it, bending rods and messing up your new engine, so do not start of even turn over the engine untill you are sure whats wrong.
how old is the gas in the car? it could be contaminated
this is not your old block from your last engine is it?

z28luva

no this is a new block. thanks for the advice everyone. i am going to run these tests this weekend and see whats going on. but i would assume the guy who put the new engine in wouldve changed out the old gasket or atleast informed me of it. then agian i shouldnt assume. but i am pretty sure the valves need adjusting, i can hear them when i run the engine, very noisy. hopefully thats what is making the engine run rough and also causing some misfires.

byrons1502

if your valve train is making noise i would pull the valve covers and look for broken springs or valve train clearance. the valve springs on stockk bbcs suck,suck,suck... thay are lucky to handle 450-470lift. if it has a cam and not springs bad things could have happened

z28luva

well i got the engine looked at, apparently the lifters are shot. 900 dollars.