Engine Flush

[ODZKing]

Over the summer I developed a leak in the radiator on the 73 (400 HP). Finally got around to pulling the rad and got it over to be fixed. While there they said the flushed the rad and it was quite dirty. He suggested flushing the engine before putting it all back together.
Since I can't get it to a shop I'll have to do it in my yard which I know will be messy. I checked with my tech and he suggested flushing into the heater inlet and running until it runs clear.
My question is does it matter which inlet on the top of the block? I believe one is an 'in' and one an 'out' but I'm not sure which, and as mentioned does it matter?

[cdr]

order one of these, it is a screen for the upper hose, it works great. it is made by Ganofilters.com

[cdr]

my junker, I put a small magnet in mine, its the larger rust chunks that plug up the radiator, I clean the screen out every 2 years, at 1st I had to do it once a month but now a very little amount of stuff gets in  there, my radiator is clean as new after 5 years

[ODZKing]

Thanks for that info, I will look into that. 
But I still need to flush the engine, so my question is; does it matter which heater hose inlet on the top of the block?
I believe one is an 'in' and one an 'out' but I'm not sure which, and does it matter?
Using one of the heater inlets will allow me to hook the garden hose directly to it with a clamp.

[b5blue]

Fleetguard "Restore Plus" is Cummings approved and very effective. 

[70 sublime]

Thanks for that info, I will look into that. 
But I still need to flush the engine, so my question is; does it matter which heater hose inlet on the top of the block?
I believe one is an 'in' and one an 'out' but I'm not sure which, and does it matter?
Using one of the heater inlets will allow me to hook the garden hose directly to it with a clamp.

The motor I put in my car was a 383 out of a 71 Newport
It has a bigger hose and smaller hose to the heater core
The pipes to my heater core had a T in the bigger hose that had a cap on it for a garden hose to hook up
Why they went to the trouble I have no idea but unless it was to flush the engine on a regular basis
If hook the water hose to it the water would flow both ways and flush everything if you take the bottom rad hose off the motor

[Mopar Nut]

This works good for flushing the rust out.

https://www.evapo-rust.com/thermocure/