Big block running hot. Can’t figure out the issue

[nvrenuf]

Not sure what was in it originally, it appears to be the original rad. I ordered a replacement off rockauto

FVP RAD730 Radiator | Shop Now at RockAuto

FVP Cooling System Parts and More for Your Vehicle at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.

www.rockauto.com

With only 2 rows and 1-9/16" core thickness, that looks pretty small.

 

[Slooptin]

With only 2 rows and 1-9/16" core thickness, that looks pretty small.

Interesting. I thought it said 4 row on the description. Oddly enough I just slapped a similar radiator in my suburban with a 2-1/4” thick core so if this one is thinner, I might just put it in my suburban and put the suburban radiator in the k30 since they both are 19” tall radiators

 

[mtbadbob]

I believe so. When I burped the system initially it looked like there was fluid flowing once the t stat opened up.

I haven’t paid attention to the lower hose but I’ll check it out. I also don’t suspect the t stat since the new one didn’t change anything.

As far as the water pump, it should be a reverse rotation since the front accessory drive came from a gen 6 motor.

And yeah I made sure to use the right gaskets. Fel pro 508sd I believe.

Thinking I might order another rad cap and make sure the overflow line isn’t plugged too

Yes, the incorrect cap will make it run hot with too much pressure for sure!

 

[Grit dog]

Adding to the discussion maybe it will help although I’m not well read on reg vs reverse rotation, but I have a Gen VI 454 bone stock in the 86. But it has old fashioned v belt system. Presuming the water pump was swapped for a v belt pump when the engine went in.
So do they cool the same reg or reverse rotation? I’d think so. IE it doesn’t matter which way you push the coolant through the engine.
But reverse cools the heads quicker (aka the 90s lt1 engines, early aluminum head 350s).
Not sure if this helps w your issue or just rambling.