Heater core requirement for new engine install break-in/ test?

[BlazerBill]

I will be installing a new GM crate SP350 engine into my ‘83 K5 Blazer before I get a new aftermarket under dash AC/Heat system/heater core. I have gutted the complete firewall and factory under dash mounted AC/heat system. Will there be any issues with breaking in and running the new engine without the heater core that will come later with the installation of the aftermarket AC/Heat system? The coolant capacity will be reduced without the heater core for breaking the new engine in. If there are no issues, how should I go about blocking off or re-routing the heater core hoses without the core in place? Any other options I should consider? Thanks!

 

[Bloodhound1981]

I will be installing a new GM crate SP350 engine into my ‘83 K5 Blazer before I get a new aftermarket under dash AC/Heat system/heater core. I have gutted the complete firewall and factory under dash mounted AC/heat system. Will there be any issues with breaking in and running the new engine without the heater core that will come later with the installation of the aftermarket AC/Heat system? The coolant capacity will be reduced without the heater core for breaking the new engine in. If there are no issues, how should I go about blocking off or re-routing the heater core hoses without the core in place? Any other options I should consider? Thanks!

No issue at all. When I did the same thing (with possibly the same motor, the GM SP350, 357 HP?) I joined the hoses that normally go to and from the heater core together using an adapter for the two different hose sizes. When it came time for the Vintage Air install, I added coolant and burped the system again.

 

[GTX63]

No issues. Just get a flush tee and a couple hose clamps, tie the two heater hoses into the tee and you are done.