Forgot to add. What are you running for timing? That can have an adverse affect on heat when at elevated rpm

 

^^^ Retarded ignition timing can lead to overheating.

 

Thanks for all the helpful info. Can anybody explain why my offset fan was not an issue before the rebuild, but would be now? Is it because new engines have more friction because everything has not mated yet, creating more heat? I definitely made sure the head gasket was on properly - none of the water passages were blocked. And yes, I used the plate between the water pump and the block.


Let's talk timing for a minute. I set initial timing by putting the crank at 10 BTDC, then putting the distributor on the #1 plug. With the RPMs at 2500 (no vacuum advance) the timing was still spot on at 10*. Since I am pretty close on "base" timing, should I just go ahead and hook up the vacuum advance?

 

Yeah hook up vac adv. And at 2-2500 try having around 25 degrees at least. I'm not 100% what BBFs like timing wise. But most everything I've ever put together was all in at 30-36 degrees by 2500-2700. As for the fan. How often did you sit stationary at elevated revs? I'm not suggesting its totally the problem, but may be one part of the whole problem.

 

The fan shroud is an issue because the engine doesn't normally turn 2500rpm at an idle/stand still. Can do it with a shroud,without there's not enough airflow through the rad. No biggie when the truck is moving.

 

You should be showing advance at idle and certainly "all in" by 3k.

Have you set the timing by removing the Spout plug **before** adjusting the distributor, and locking it down then reinstalling the Spout plug?

Are all the other sensors plugged in and functioning?
Are you able to pull any codes?

I could see why you would be locked at base timing if the Spout were not reinserted or the computer was not working.

There should be **a little** more heat as lifters polish cam faces and rings seal against fresh cylinder bores.
This is the whole reason to run in at elevated rpm's. .... flushing lots of oil to carry away heat and abraded metal.

 

Just caught this. The over heated runs where with no vac advance only base timing?

 

Efi engines shouldn't have vacuum advance distributors.

He does say there is a carb, but is this engine swapped to DSII, or is it still running a tfi distributor?

 

An '87 460 is not an EFI engine.

 

I know, I'm driving one right now.

This is the same guy with a '90 efi engine in a truck that used to be 351???

Pics of the setup might help.

I would run it in with no thermostat, but like i said if it is erupting on shutoff there is a hot spot in one of the heads.
A $20 laser ir gun will find it.

 

My '87 460 would overheat on break-in as well as standard driving. Kept trying to diagnose it as the aluminum radiator shouldn't have any issues transferring heat...

Putting the fan shroud back on instantly fixed my issues. Modify your shroud so that it easily pulls air across the radiator.

 

Yes, the overheat was with 10* base timing and no vac advance. I didn't realize timing could have such an effect on temperature, but it makes sense now that I've thought it through. As far as my setup goes, it is a carb with 1984 heads, the DSII control, C8XX distributor. There is no computer to pull codes from. This is essentially a 1984 engine in a 1987 body.

 

I'm pretty sure I've narrowed it down to messed up timing. I am going to try it this afternoon and report back.

 

Final update: I hooked up the vacuum advance and with a little occasional mist on the radiator with a garden hose, she stayed right at 190*F for a full 30 minutes. My cam is officially broken in and I'm a happy dude! It's always the little stuff that gets you....

 

Great to hear!