radiator??

autoxcuda said

Weird that is will idle fine. But only when moving, it will get hot. Usually that's radiator clogged or too small.

What is the exact radiator you have now? How many rows?

Have you tried an 17-18" factory viscous fan? Those blades are much wider than a flex fan.

I have a 421 stroker with about 450 HP and cam close to yours: Comp XS274S . I get 15-20 degrees from top to bottom of radiator.

Could you old motor have dumped rust/debris in your radiator and clogged certain portions?

Have you heat gunned different sections of your radiator core to see if maybe a certain section is clogged?

When I did my motor I hand picked the coolant passages clean of rust build up and debris. And water+shop air gunned the passages. I can't see how modern hot tanking could have chipped off that rust scale.

Click to expand...

Sure is weird isn't it!

It's a 2 row. Their 1" rows. I don't remember the brand but I bought it from FBO. I told Don I was planning on building a 408 that'd make about 450 hp and he said it'd be plenty radiator for that.

No I haven't tried a viscous fan but that was my next step. But by how much air I feel it moving it'd surprise me it'd help.

Thanks for confirming the temp drop on yours. I was thinking I should see at least a 15 degree drop.

My old 360 was loose but I don't think it was rusty. From what I can tell the temp is real uniform all over the radiator but I will say this temp gun seeems kinda finicky when it comes to trying to get a reading off a shiny object. When I look down the fill neck it looks like it's flowing good. Wish I had a scope so I could look down inside the inlet side to verify it's not clogged as it sure seems like a radiator issue to me.

What radiator are you using?

I also spent a lot of time hand cleaning every passage when I built my 408. I shined a light through every passage and used anything and everything including 100+ psi of air to blow every last bit of trash out of it that I could.