Just rebuilt 425 .030 over new cam, pistons, valve train and water pump. It has a new 2 core aluminum radiator and a 180 degree thermostat. Car will get up to temp quick and will not run over 190 while driving but at idle will get up to 210 quick. Also if you shut it down it will get up to 220 while sitting. I am thinking it is probably because of the overbore and the flex-fan with no clutch but just wondering. I am planning to replace the fan with an electric puller on a thermostat but could there be another problem?

 

Your ok dont worry that is normal for a rebuild and actually normal for a regular BB Olds, flex fans never worked too well except the 7 blade large square bladed not the pointed fiberglass ones, but I have found on the street nothing beats the 7 blade factory fan with a GOOD clutch. I also run a 160 thermostat and water wetter 2 bottles and it runs nice 180 around town and at long lights it get to 195 and after its shut off 210 which is OK. I also have run a pusher electric fan on the front with the factory setup and make sure you have a shroud. How many miles on the motor??

 

It has about 300 right now. Just making sure there wasnt any underlying issues. I just fixed my low power issue(bad resistance wire to coil) and am having a slight surge while driving and the running hot.

 

That's typically caused by too little timing and/or a lean condition, both of which will cause it to run hot.

 

I have the timing set at 5 btdc and has 32 degrees advance at 3000 rpm. I know the fuel is also a problem, I have a 600 edelbrock on the motor and know a 750 is where I need to be. One other thing I noticed it the amount of heat going through the intake crossover. Its probably whats causing my hard start after 10 minutes or more when hot. I found a set of intake crossover plugs from edelbrock that I am thinking of installing. I am also going to switch over to electronic ignition and 8mm wires.

 

Like Mark said it is too little timing and too little fuel, you can jet up the 600 but that is small for a 455 especially if you have had it bored or a larger cam and headers,but to the issue of the heat crossover yes they can create some heat but your problem is like Mark said to little timing bump it up a little to 34 total that is a good spot for most BB Olds but check your plugs and they should be tan to light brown, if they are snow white your too lean!! and that will create alot of heat and not good for the motor.

 

I will bump up the timing. My plugs are a brown color so I know I am not lean but the crossover and the timing are slowing me down.

 

Bump the timing to 7 or 8 and make a short 50 meter run and shut it off and coast to a stop and pull a plug, but do it where you can safely, some old back road and remember wot for 50m then shut if off but dont lose control with your power steering or brakes, and that way you get a true reading on your plugs. The thing that will help is to go to a 750+ carb 600 is too small unless your just driving to get groceries!

 

Check the heat riser valve on the exhaust manifold. It may be stuck closed.

 

my first thought also. when those pieces get old, the bi-metallic spring tends to lose tension, and the valve sticks too.


bill

 

^^^THIS!

Flex fans are crap. Throw it as far away as you can. Get a factory style clutch fan and don't look back. Also, your temps are nothing to worry about. Keep in mind that at 15psi, water doesn't boil until over 250 deg F. It is normal for the temp to go up after the engine is shut off.

 

Agreeing with Joe here, those flex fans are crap. Get a nice clutch fan.
My last (and only) flex fan and WP shaft went through my radiator at 6k. The hole in my radiator and the one in my wallet were about the same size.

 

This can easily happen with any fan when a bearing goes out in a water pump. I've been running flex fans for 45 years with no abnormal issues. I agree there are some flex fans that are garbage, but lets not stereotype. There are some clutches that are garbage also...

 

No argument (unless, of course, the crappy, out-of-balance flex fan caused premature bearing failure... )

 

And of course if frogs had wings....

I agree, it really boils down to, you get what you pay for. In my case I don't have the room for a clutch fan.