I am at a stuck point with my 383. It has not been on the road yet because it overheats. It was running 230-240 at idle and this was in the winter. I messed with the timing and now it is running 200, but still wants to spit out the overflow tube. Also I took it out around the block and it wants to die. Also noticed while driving the motor sounds like it surges. It will run and then go down in RPM then go back up. I got an aftermarket balancer so it is hard to figure out what the timing is, but it appears to be around 9 degrees. It is a new engine with everything new, new radiator, fan shroud, new eddy 625 carb. If the timinig isn't the issue where do I go next? Any help will be appreciated.

maybe take the rad cap off when cold let it worm up and see if you get some flow in the rad. may also take out themastat put in a pan with water on the stove and see if it opens all the way up. Ive seen new ones that only open 1/2 way.

Mark

Surge may mean lean and lean is hot. Timing may not be helping either. First step is to get the timing right. Next step is to get the carb/mixture right. I'd find a shop that can help get those dialed in first. It would be money well spent to protect your new engine.

After that, focus on the cooling system.

If you have a new balancer and do not know where TDC is that would be the first thing I would do is find TDC and set your timing then carb.

It is flowing through the radiator. My Dad built this motor and before he could tune it, moved out of the country. He degreed the cam when he built it. The carb was new out of the box and I have not done anything with it except make sure the fuel air screws were out 2 1/2 turns. It also idles at 800 rpms. I have not got to the point of putting a new thermostat in. Thanks for the suggestions.

You do understand that the 2.5 turns is a starting point and not the final adjustment. You need to tune it correctly and then see what you've got in the way of heating,

Thanks Stumpy. Yes I know it is not the final adj. It really ran well where it is at. I will fiddle somemore. Also how much would the temp lower running antifreeze? When I put in my new radiator I only used water, since it was coming out I didn't want to waste the money?

In my opinion, checking or replacing the 'stat is one of the FIRST things you should do. Quality parts aren't what they once were. Remove the 'stat, go to the grocery store, and get a "candy thermometer." Put both in a pan of water, and observe WHEN it opens and how far. If there is ANY doubt, buy a new one and put BOTH of them in the pan.

TIMING:

There is NO REASON to fight questionable timing marks, it will only take about 1/2 hour to put them 'right.'

Get or make a positive stop like this:



Take a plug, hacksaw off the rear crimp. Drive the guts out and cut off the ground. Weld a nut on the back, or thread through the middle for a bolt. Play with bolt length as needed.

UNHOOK THE BATTERY!!

Remove no one plug, feel around for clearance, and screw in your stop

With a wrench, rotate the engine gently until it stops.

Make an ACCURATE pencil mark on the wheel under the TDC timing mark

Rotate the engine the opposite way until it stops, make a SECOND pencil mark under TDC.

Your true TDC is halfway between the two marks. Now just figure the "degrees / inch" around the wheel, and you can mark the wheel from there clear up to 40-50 degrees, or just buy the proper size timing tape. Be sure to check the tape!!

FAN

What fan are you running, are you sure it's not installed backwards, and is the clutch 'good' if it's that type?

Pulley sizes, belt slippage?

Does the car overhead on the highway?

Wind the car up to "high cruise" RPM and hold it a few seconds, and observe the lower hose. Any signs of collapse?

Does the heater put out "good?" If not you may have a pump problem

Extremely lean carb conditions may worsen overheating problems

How about plugged exhaust, is there ANY chance of something there? Running stock manifolds? Is the heat riser butterfly opening?

I have had overheating problems with 3 smallblocks That have been rebuilt. For some reason the block vapor locks and does not allow the water to fill the block completely. I just keep the puke tank full and after getting hot in the garage running and being turned off they eventually take all the AF in the tank.

Overheating at idle may be an airflow problem through the radiator. Are you running a fan shroud? Also, what fan setup, and how much distance from the radiator.
I have read that an air pocket in the engine can cause problems, usually the fix is to drill a small hole in the thermostat so the radiator fluid can push the air out of the engine when the engine is cool (before the thermostat opens.)
Also, make sure the lower radiator hose is not restricting coolant flow (not kinked or getting sucked closed when the engine is running.)

I am running a fan shroud, with a 18" flex fan. It is about 2 1/4 inches off the radiator. It is installed correctly. I would want it closer but I am running the longest fan spacer available. I will have to check the bottom hose. It is new but it is not the kind with the spring inside.

Also another thing I noticed is when I bring it up to higher RPMs it gets hotter, once it goes to idle the temp will drop a little.

A surge sounds like too much timing,or lean.air pocket in the cooling system??Fan should be about 3/4-1 in away from radiator.Put a sheet of paper on the front side of rad,(grill side) see if the fan pulls it into the rad.
remove t-stat and pull the center out(spring and plunger) and just run it as a restrictor plate. will flow fine,no chance for air pocket.Did you add a stall convertor?? might need an extra trans cooler.Any possibility of a vacuum leak??all ports sealed off.pcv valve, brake booster.
Usually hotter- higher rpm and then idle cools down is a flow problem.plugged radiator.Might be fan distance in you're case.

I finally had time to tinker with it. I pulled my t-stat and seen that the coolant was drained back. Would this indicate the block isn't full? Most of the ones I have taken off in my lifetime usually the coolant starts flowing out. Thanks

#1 find tdc & set timing. I turn the dampener to 5 btdc & screw the positive stop tool in to hit the piston then turn the crank the other way & see if it stops at 5 atdc this saves me from having to make any marks on the dampener that will further add to my confused state & I put one of those plastic vac caps on the end to keep from nicking the piston. To check you could also just take the thermostat out,it's not going to hurt anything not having a fast warm up just this one time. best way to eliminate airlocks is to raise the front end of the car & run it(w no stat) & burp it just like you would a baby. I had way retarded timing once & it got hot FAST. Good Luck.

First, running with the thermostat out proves nothing. It IS POSSIBLE to reach a situation whereby running with no stat can actually cause overheating.

If you pulled the stat housing/hose and there was no coolant at that level YOU DO NOT HAVE THE SYSTEM FULL

I used to bleed the system on these cars simply by leaving one heater hose off, and filling until the coolant came out that port.