here's another pic of the bypass hose. this is a 7.4 MPI

Thanks qaberdeen!! I will have to inquire about doing that on the SBC setup!?!?!?

Revd Up how much does the Bblades props go for.. looking at a 28 bravo.. and whats the difference between that and the labbed bravo 28 that teague sells..

thanks

D,

What you're doing is bypassing the closed thermostat which Mercury accomplishes in two manners that I know of. Either a one piece thermostat housing and a by pass hose between the water pump and intake (like the 7.4 MPI diagram) or a 2 piece thermostat housing which does need the extra hose as the t-stat is not mounted flush on the intake but on top of the main t-stat housing therby letting water circulate. This was the arrangement on a 350 Mag/4 barrel 270 HP (Design 1 cooling). I have seen some 2 barrel 5.0L/5.7L arrangements without a bypass but I guess Merc feels this is fine for 200 - 230 HP.

Thanks guys for the dialogue, so it sounds like it's just best to drill, because my motor was built i guess to replicate the 7.4l so i could transfer a few parts and would not have to make to many changes. so if i'm correct Revelocity your saying to drill.

The engine builder just got back to me and stated this.. (" You have constant flowing water to your exhaust system at all times specially when using a thermostat. If your thermostat blocks the flow of water and does not bypass for the exhaust cooling you need to drill the manifold and bring water above the thermostat. If the housing has water to the exhaust with no restriction you need do nothing to the manifold. The bottom line is the cooling system needs water at all times, you cant have the thermostat block water off when the engine is cold")


so in other words it sounds like i don't have to drill using the Stainless Steel T Housing in the picture because it does not block the water..am i on the right track..just wanting to make sure..

qaberdeen, I was under the impression that the plastic inserts were to let the water bypass while the therm. is closed!! The therm. installs up inside the housing with the plastic insert between it and the intake...... Again, don't hold me to that!!

That being said, I have had mine on my motor(s) for 2 seasons now without any overheat issues and I don't have it bypassed!! (325hp on the first motor, 600 hp on the one that's in it now!!)

I agree that you'll be fine since the responsible thing is simply to warm the engine up first before burring the throttle!.

Woman and engine, you should warm them up before burring the throttle.

Fixxed it for ya!!