Technical 283 running rough and hot

Hi,

my 283 has been running hot since i got it, it gets to 200c within half hour of driving. Also as of yesterday once it gets warm and only when it gets warm it starts bogging down upon acceleration down low. Upon start up and driving when not warm it runs like a dream. It blows black smoke upon acceleration when warm also
Things that should be noted:
• flushed radiator
• heads redone
• new carburettor
• new sparkplugs/leads
• timing is at the top of the tin timing plate
• one of the push rod ends were chewed up
• burnt out valve but fixed
• been rebuilt to 60 thou (thin bores)

any information would be great i dont know what else to check.

 

200 degrees C is roughly 392 degrees F!!! There's no way it could get that hot without boiling over and locking up. Have you checked that with an IR heat gun, seems like that could be a bad gauge or sending unit. Are you running an electronic conversion distributor of some kind? Could be a faulty module causing the power loss when hot.

 

Double boiling point!

I'm sure he put C by mistake. It must be F.

 

Hopefully that's all it is. 200F is not really too bad, all things considered.

 

Check your timing is correct. Dont rely on the timing cover marks, check the TDC is correct to the actual piston position.

 

Likely the heat is boiling the fuel in the carburetor. I would say it should be vapor locking. I would do a careful timing check on it first. Always do the things that are the cheapest before throwing parts at it. Aside from that I would look at the thermostat, if you have no idea how old it is, replace it. You can give the old one the test in a pot of boiling water on the stove.

 

It is still the original distributor mate

 

Your timing advance could be failing. I’ve had similar results when the springs in the distributor for the vacuum advance got soft. Swapped springs and weights and it was right as rain

 

Sorry yes i mean F not C. It gets to 200 within 30 minutes and gets as high as 220

 

Checked timing with the timing light its all good, new thermostat already in it also

 

Thats something I haven't checked, would it be worth just getting a new distributor? The one in it is very old

 

The timing light doesn't show you a thing if you don't know that timing marks are correct.
Chevrolet was famous for using different marks on different engines. Don't know what you are running for exhaust manifolds, but make sure the bypass is opened up if they are stock.

 

200f sounds great to me
But my 350 had vapor lock issues in the 215-220 range.
Runs “hot” at idle?
“Hot” cruising?
Or both

 

Exhaust manifolds are stock mate, how am i to know if th timing mark is correct? The bloke that owned this before me was a clown and did heaps of stupid stuff to the car

 

Runs hot when on the highway mate which it shouldn't be doing

 

Get some timing tape and a solid stop for finding TDC. Look up finding TDC on YouTube and find the true Top Dead Center for number one on your engine. You need to know that to time it accurately. It sounds like it’s retarded. Or the thermostat failed.

 

new springs and weights, they come with a selection in each package. Cost me less than a burger and fries I’d just swap them.

 

That’s a symptom of not enough radiator.
But there are other factors like the ones already mentioned.

 

Its the standard radiator for a 283, as mentioned its been flushed etc

 

Its been timed from TDC and thermostat is new

 

I have never rebuilt one but if its a much cheaper option ill give it a go

 

200F isn't actually "hot" Why guys get their undies in a twisted knot when an engine is running right around it's normal operating temp is beyond me.
You do need to figure out if the timing mark on the damper lines up with the 0 on the timing tab when number 1 piston is on Top dead center though.
To do that:
Remove #1 plug and either by using a remote starter button or by having a helper bump the starter bring number one piston up on top compression by having the piston blow the compressed air past your finger that you have covering the spark plug hole. It may take several attempts to get the mark close to lined up. I like to use a fat heavy drinking straw out of a fountain drink as a probe to stick down in the plug hole and then with a socket and ratchet or breaker bar on the crankshaft bolt rock the crank back and forth until you decide exactly where the piston is at it's highest point.
Then check your timing mark on the damper against the ZERO on the tab.
If it is off most of us would put a new mark on the damper but some removable tabs are adjustable.

Stock timing on most 283 engines is 4 degrees advanced but they tend to like 6 or 8 degreess advanced most of the time.

As far as the rough running, the first thing I would do is a proper compresson test.
All 8 spark plugs out and the choke and throttle plates proped wide open. with the compression gauge in place crank it over and let each cylinder hit five times and write down the results. You are looking for how even the compression is. If it is reasonably even (within 10 lbs low to high).
Plug gap should be .035 inch. point gap should be .019 for new or .016 for used but I'm thinking that I usually set them at .018 if I was using a feeler gauge. Dwell =28/32 if you have a dwell meter.
If you have a vacuum gauge or access to one a vacuum gauge can tell you a lot about what is going on inside the engine. Here is one popular vacuum gauge reading chart that I have saved.

It might be wise to check it with a vacuum gauge first and go from there.

 

I wouldn’t consider changing the springs and weights rebuilding the distributor it’s pretty simple and in plane view. I want to say @porknbeaner and I did mine in 20 minutes with a pocket knife, pliers and a lot of bull shitting and moving slow

 

Runs OK when cool, sluggish acceleration & black smoke when hot, maybe the choke not opening?

 

.060 isn't gonna hurt that block, they bore them out to 4" from 3.875 regularly. Does it run good down the road? I'm talking like fire it up and take off down the road. Has plenty of power? If not then I'd say your too far advance after top dead center. There's no balancer on the 283, just a hub. Pictures might confirm that you have the correct timing tab and hub setup.

 

I like the timing tape, get the timing base lined, you cannot go wrong. You have a basic problem, possibly even 2. I'd pick up a digital thermometer and check the radiator for cold spots, make sure the temp is even, top to bottom. Shoot the exhaust manifolds too. Borrow another timing light just to rule out a bad one.

 

Running too rich or too lean can cause temp issues also. I would deff check timing and make sure the distributor is advancing. Too retorted at freeway speeds would tend to lead to alot of heat soak. Also, make sure your cooling fan is a puller not a pusher, if its fighting against air flow it could be hurting things also. 200 d F isn't too high honestly but you could have other issues like too small a radiator etc that could be a contributing factor here. Water pump could be under driven or bad performer. Thermostat may not open right etc also... Many new thermostats out of the box do not work right anymore. Let us know...

Another thing to consider, temp probe in the side of the head is not accurate the only real accurate temp gauge spot is by the water neck by the thermostat.

Cheers Mate

 

Truth, head temperature will always be higher.

 

I would definitely check the distributor to make sure your springs and weights are working correctly, had found when chasing an erratic ignition problem that the springs had worn a groove half way through the weight pins. A good general cleaning can be a good thing too.

 

If the timing is off - via the advance not working properly- he could be overheating in the cylinder before the head, he would get the shitty sluggish over heating characteristics but the head temp gauge wouldn’t show it until it got warmer and reached the heads so to speak.

It doesn’t take long but if you’ve been climbing g a hill and now your coasting down the other side, or you shut it down because it felt weird you might not see/ have the gauge continue to climb after it’s reached 200.

And yes, 200 isn't crazy high but he’s mentioned it not running right when this happens on top of the gauge reading. Compared to some guys we see freaking out that the gauge reads high while the car runs totally fine and isn’t puking.