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1,702 Posts
The variable flow restrictor, is more to stop cavitation and the resulting core erosion that goes along with it.
One would surmise that the size of restriction needed at high engine speeds in the LT1, would seriously affect heat output at low RpM, hence the variable part. Also to dampen shock from abrupt speed changes.
Again, I'd love to know if there's any meaningful difference between
ACDelco 155423 (B- & D-cars)
ACDelco 155511 (F- & Y-cars)
because I can't see any meaningful difference.
That said, I agree completely with, and stipulate to, the above quote; it makes more than enough sense, that I cannot think of another reason.
Not an issue with electric.
Also, the electric pumps do not flow as much as the LT1 mech at full song, so I would tend to agree with 1slow96' thoughts about the restrictors merit with electric.
Having operated an HDMeziere on my previous wagon for several years, I stipulate to this as well, if only to add something obvious: any given LT1 electric H2Opump operates at its own fixed flowrate. Since the restrictor is meant to dampen changes in flowrate, it is pointless to use the restrictor with any of the electric H2Opumps.
Think of this but in reverse when thinking of coolant speed and heat transfer.

In my world we run pumps slower to reduce cavitation and to reduce parasitic power loss.
Gerry, it's your world. We all just live in it. ? ?

Premium Member
4,921 Posts
The difference between those two valves is hose size.
Working those numbers backwards into a FourSeasons catalog, one is 5/8, other is 3/4

Right or wrong, with silicon hoses , I use Motorcraft Gold antifreeze.
The main reason was smell,
Dexcool and "normal" green permeates silicon hose and the car smelled like it had a leak.
My research was less than scientific.
" well ford uses it in some all aluminum engines, and it doesnt stink"

Drivejunk, out of interest, where was your rad cap in relation to the coolant flow?
As in , high pressure engine outlet side, inlet side ( surge tank), etc
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