I'm in the process of removing Hardblock from an overfilled 400. Total pain in the [censored]. I'd never fill a street motor... Absolutely no benefits and if you're cracking blocks on the street something else is wrong.

Good luck getting that out... major PITA

Spot on AL. This is exactly where I am with my street 528 Cuda, as you say sustained highway use get the temp up. I often wonder how many people are out there without a oil temp gauge ??

Dave If you don't run a cooler with all that fill your first 1/2 hour drive will see 300 on the oil temp.

Dizuster runs a generic small oil cooler on his turbo small block, half fill. Stays cool no issues since install. Plenty of street miles. Many factory Chevy high performance and truck motors run them from the factory. It's not rocket science.
Doug

Does the Hard Block indeed shrink and seperare from the cylinder walls after a few heat cycles as posted earlier? The manufacturers I looked at claim it does not?????

I have heard that both ways. It must depend on the brand of filler you use?

I have a few gauges in the car. oil and trans temp are just a couple. Once I get it on the road I will let ya know what the temps go to before I add the cooler. Can I use a B&M supercooler for oil cooler?

Look at a Hayden oil cooler... a trans cooler
wont flow enough... the diameter isnt big enough..
the one block I bought had a crack in a cyl.. I was
gonna just sleeve the one cyl but when I got around
to it I busted that cyl out to see it was a filled
block... the fill did shrink on it... dont know what
brand it was filled with.. it wasnt much but it sure
wasnt stopping a wall from cracking

Ya, they all claim there's doesn't shrink. I'd like to see proof. My machinist claims they don't shrink. True on the oil cooler thing "it aint rocket science". Many tow packages include them - most police package cars have them. Don't know how well these factory engineered packages would work under our type of racing conditions though. Pressure drop is definitely a consideration. FWIW, oil pressure on fire up @ idle with my 408 = 70psi. At 180 oil temp @ idle = 35psi. At 220 oil temp = 25psi.(10W30 synthetic).

All cements based fillers shrink I've used Moroso block filler once and it shrank away from one freeze plug after it pushed it out enough to need replacing
I've heard that "Hard Block" brand filler is a epoxy filler and doesn't need to cure 30 days and it doesn't shrink also I also heard it does expand and shrink I haven't used it so I don't know about it either way

Over my 40 plus years of racing I wonder how much I've saved by not buying concrete to fill my blocks. LOL

Hard Block is magnetic. It has a percentage of cast iron in it to help it expand and contract as the block warms and cools.

I have heard some crazy sounds the 1st few runs on a fresh fill. Never had a problem with a bore

Moroso is the brand I used . Your scaring me !!!!

Hard block is whats in my block. My machinest recommended it, said it wouldn't shrink. guess ill find out.

i have done this as well... on a tall deck big block, tall fill (bottom of the water pump holes). NO DIFFERENCE in the before and after measurements. at all. that engine lives on as we speak.

good to hear positive experiences. hope to have same

Any updates on street temps?

Not yet. Just installing 511 in the car now. Gonna run without a cooler to start. Will add cooler later.

FWIW, I talked to Jason Pettis who builds/tunes some of the baddest cars around and he said "Good luck keeping the oil cool on the street even w/a cooler"..........1/2 fill maybe but full in his experience is hard to do if not impossible........