I have an 86 Z-28 with a factory 305. It has been smoking since I got it about a month and a half ago and it has steadily been getting worse. Now, when you accelerate, the valves chatter like it is out of time. It has lost some power as well. I checked to see if the distributer was loose thinking it might be the timing but it is very tight. I am stumped. I have a sb406 that I am gonna put in it, but that might be a month or two away, still gathering stuff for the swap. anyones help would be appreciated.

 

Id go ahead and shut those valaves up by gettin some 40 or 50weight oil and some Lucas Oil Stabilizer (thick as molasses)
Id recomend to completly drain the old stuff and get some synthetic stuff .. Mobil 1 or Castrol is what I usually get

Luckly your got that other motor, wish I was in your shoes .. lol

unless yor engine savvy and can rebuild the topend, its gunna tick whether you like it too or not.
What color smoke is it? chances are, piston rings cause the smoking in most high mileage cars .. but it can be alot of other things.

Start from the basics, common sense first ya know?
use "search" for these commen questions .. these have all been asked before.

as for the rattling, alotta things rattle in the engine bay .. maybe pop the hood and give a good listen??

 

had the oil changed about 2 weeks ago, had them put 4 quarts of hav. 20-50 and a quart of lucas. It was not rattling then. it just started about a week ago

 

Thats insane .. 2 weeks later and its ticking?
Begginging to think oil pump or something

you overheat or smoke while your driving?
maybe your burning it all up .. lol

 

no overheating and oil pressure is great. I am baffled???? One of the old tymers at my friends shop said that since it is burning oil, that it may have a layer of oil built up on the piston raising the compression?? I know on a rebuilt a while back that smoked, it had a thin layer of oil and carbon build up.

 

I forgot to add the fact that it is popping out the exhaust sometimes at random, its not real loud like a backfire but like a random miss or something.

 

it only pops out the exhaust when idling by the way

 

you have 1-2 months till you get that 406??

are you capable and or have the knowledge to do repairs to your car?? or do you rely on a shop or dad ??

 

Have you actually checked the timing?

When was the last time you replaced your cap? rotor? wires? plugs?

 

yes I have the ability to work on cars, although since I had back surgery I try to have it worked on by someone else. I already have the 406, I am just getting everything together to do the swap. I did not check the timing, but if the distributor is tight as hell, and the car was in time when I bought it a month ago, I would not think the distributor had moved. Its possible I guess.

 

Very possible.

Check the timing. If it is too far advanced, it can kick in the knock sensor and kill performance. If it is too far retarded, it will kill performance (but doesn't explain the rattling).

 

I don't think it is hooked up. I know that the carb was changed to an Edelbrock and there are alot of wires unhooked under the hood, but it has been this way since I got the car and it was running fine.

 

With an Edelbrock carb, it is certainly non-functioning.

You may have thought it was "running fine", but if it still has the original distributor, it was not. It's now gotten to the point that it is simply running worse and worse.