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Old 03-12-2019, 04:35 PM
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Default Intake water distribution


Anyone ever plumb this way. I've always married both sides with a T fitting and dumped a single with a ball valve out the transom. I'm curious as to what would allow the most consistent water temps.
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Old 03-12-2019, 10:02 PM
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i run a -4 line from the rear outlets to a t,then overboard.only necessary on 502 blocks.no need on a 454 block.
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Old 03-12-2019, 10:30 PM
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I had blower motors that had -4 lines they where plugged up I deleted them at same time we added 100+hp with cam and some rpm. Have not seen a problem. My friend adds a hole in head gasket for cooling on rear not sure or it helps or not.
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Old 03-13-2019, 07:39 AM
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I run a similar setup, I had the rear of the intake drilled and threaded and used T's at the front with -10 lines. It was recommended by my engine builder. I check my head temp after running hard and barely a degree difference between the front and the back. I'm also running a crossover without a circulation pump so I wanted to be extra careful. I opened up the area where the water flows into the exhaust on my headers and hand ported my stainless sea water pump as well. At idle it dumps a ton of water, at full throttle it barely opens the thermostat.
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Old 03-13-2019, 08:04 AM
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Originally Posted by mike tkach View Post
i run a -4 line from the rear outlets to a t,then overboard.only necessary on 502 blocks.no need on a 454 block.
Do you mind elaborating on this? I have a 454 block bored with dart heads and a blower...was going to do just like you said...-4 lines dumped overboard off the back of the intake...why would it not be necessary on a 454 block?

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Old 03-13-2019, 08:12 AM
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I run 2 -6 lines to a Y-block then -10 overboard
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Old 03-13-2019, 07:46 PM
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Originally Posted by mike tkach View Post
i run a -4 line from the rear outlets to a t,then overboard.only necessary on 502 blocks.no need on a 454 block.
My 454 blocks had pistons knocking the valves out of the heads from excessive heat when I changed to crossovers. The only cure was to drill, tap and plumb the rear intake. I had huge temperature discrepancies, cheap insurance. I run -10 with flow restrictors in them to my headers.
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Old 03-14-2019, 06:39 AM
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Good enough for me!! Thanks rook!! lol
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Old 03-14-2019, 09:57 AM
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Originally Posted by Rookie View Post
My 454 blocks had pistons knocking the valves out of the heads from excessive heat when I changed to crossovers. The only cure was to drill, tap and plumb the rear intake. I had huge temperature discrepancies, cheap insurance. I run -10 with flow restrictors in them to my headers.
what kind of power was it making??
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Old 03-14-2019, 10:18 AM
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I ran my S/C 468s for a long time without those rear water reliefs. Never had an issue with valves or anything. Ran crossovers with no water stats.

One thing I learned from articfriends and his dyno testing with eight o2 sensors, is that single carb NA setups suck at life. Hes seen on many occasions where the fuel distribution is so bad, one cylinder may have an AFR of 10.5, while another one on that bank can be at 14 afr. Meanwhile the tailpipe one is reading 12ish. I can see where running a cylinder lean like that could lead to tuliped exhaust valves, exhaust valve seat erosion, etc. Might not be lean enough for it to detonate , but certainly cause some heat issues on the valves. Most good valves can withstand 1500* temps, i cant see how even running them with a water jacket temp of 240* would cause tuliping

Ive always noticed on single carb NA setups, the EGT's would vary big time from coolest to hottest. Where on most S/C dual carb stuff , they are much more in line with each other.

the water flows into the front of the engine block, and should flow towards back and up into heads, then back forward out the thermostat housing. Now if you have a GEN V/VI block, and use the wrong head gaskets, or if the gaskets water holes get plugged with chunks of rust , youll starve the rear cylinders of water flow.

I dont think i have ever seen a factory GM or mercury engine with water lines coming off the back of the intake. One thing they do have, is a bypass hose that keeps coolant circulating when the thermostat is closed. Thats one of the reasons i dont like alot of the crossover systems in boats. Most have a bypass that simply feeds the exhaust with water until the thermostat opens. However, when the thermostat is closed, the water becomes stagnant in the block, and i dont think a couple small pee holes in the thermostat are good enough to keep a good circulation of water within the block, and you get hot spots.
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