My 1979 z28 seems to be having more issues than most small countries, My two biggest problems are that my car overheats on warm days (which is everyday around here) and the motor skips on i believe 3 cylinders, And I adjusted the valves in the beginning and I'm new at this, so maybe I just don't know what the heck i'm doing but, I started cheap and replaced the rotor, rotor button, and distributor cap. It's a fully rebuilt motor and I don't know where to go from here, I was told my next best test would be to do a leakdown test, to see if any air goes past the piston's or if the valves are adjusted to tightly and causing the skip.

About the motor overheating, I don't know if the skip could have something to do with this, or if something else is wrong. It only overheats when I'm running 45-above. Also to throw in, i was told by the previous owner that the car ran around 2400 rpm at 60mph, but ever since I can remember it was around 4000. Maybe I just don't remember when I first got it and it did run around 2400 or if it was 4000. I don't know where to go from here, any and all help is appreciated.

 

To tight a valve will show up on a compession test. Misses can be tuff to figure out and overheating is not something you want to do to many times before you get it fixed. I would pressure test the coolant system for starters. What type of fan system do you have? Basic, Clutch, flex?
Maybe you should just break down and take to a mechanic.

 

Its a clutch fan that was replaced last year. And i would take to a mechanic, but its the only car I have to drive right now. Now that i think about it my coolant resovoir has a hole in it, and it doesn't hold nearly enough coolant in it, could that be a cause for overheating?

 

The coolant overflow is just a place for coolant to go as it expands. Your system should not need to be a very large. You don't even need an overflow tank except the tree hugers don't want you droping a quart of poison every to you top off you radiator. I don't think that is your problem. You keep driving that car while its over heating and it will not matter that it was just rebuilt cause it will need it again. I would think finding a few hows to a mechanic to check the car out would be easier then dealing with a blown head gasket or a craked head.

Sorry I am venting a little, I have had so many cars come in with shot motors only to find out it have been overheating for a month. I have even had customer blame the car, "Its a piece of junk, Its been over heating on me all month and now you tell me the motor shot"

If the motor has been modified your coolant system may not be big enough, Your timing could be to far advanced, you could be running to lean, Even tho it only a year old your fan needs tested. Any obstruction in the grill? Bugs in the condensor. How is the flow in your radiator? What is your compression ratio? The the motor has never worked right since it was rebuilt someone could have the wrong/defective intake gasket.

Next time you start to over heat run your heater full bore high fan and see if that helps. That would tell us you are most likely lacking in rad size.

 

I better just suck it up and let someone who's know's more about this fix it, rather than me attempting to fix it. Atleast then I will know for sure what its going to take to fix it correctly.

 

Fixed a few of the problems today, The exhaust valve on number #2 cylinder was to tight, ran a compression test on it. It had around 50 psi, loosened it up and the psi went up to 148 so that was a relief, and the skip seemed to clear up for the most part. As for the tach, My buddy from work happened to have an after market tach in his toolbox so me and him threw that in there and fixed my tach problem, And as for my overheating, I don't use the ac on my car so my dad and I pulled the ac condensor out and blew out all the crap on and in the radiator, Haven't driven it enough yet to see if that makes up the difference but as for the ride home it did. The car feels like it needs some improvement still, but so far has a total change in power and all around performance. (no more killer vibrations at idle from the skip... thank god)

 

I've found a small skip still in the system, on #3 cylinder... And this one seems to be a very odd skip. I think its on the intake valve, but when I tighten it up at all it pushes air out of the top of the rocker arm, makes a pssh pssh pssh noise then it will quit after 2 or 3 seconds, almost like its pushing compression past the valve, anyone ever have this problem before???

 

You should get that beast scoped. It would put light on most of the problems you describe. How long since you had the cooling system flushed? Does it seem the same temp all over the face? Or are there cool spots? As Gorn expressed, there could be many reasons for your issues. You could go broke or crazy trying to figure it out yourself.

 

To start with, you need to get your valves set. Even though you are somewhat inexperienced it is quite easy to do. You will want to go to the auto parts store and buy a set of oil deflector clips for the rocker arms and will need a 5/8" socket. Remove the valve cover on one side and install the oil clips. Start the engine and keep it at an idle. Loosen the rockers one at a time, back off the nut until you hear it ticking. Then tighten the rocker until the ticking stops and finalize the setting with an extra 1/2 turn. Do this with each rocker on both sides.

For your overheating, check the flow in the radiator with the engine at operating temperature. You should be able to see the coolant flowing through the cores if you look down into the filler neck. If there is not good flow it could be plugged cores, bad water pump or bad thermostat. You said the car has a new fan clutch. Check the clutch to make certain it is engaging fully. When the car is hot (and turned off) see how easy it is to spin the fan by hand. There should be some resistance, if not throw the fan away and get a solid hub flex fan. They are noisy but really pull air.