more cooling pressure without restrictors?

Mike Grafas

Mike Grafas

Location
Point Pleasant, NJ
I need more water pressure in my cooling system I think but I cant use any restrictors.

its a b1 with a 760 ported and polished and Coffman rocket pipe 200psi comp

I bought a fcv to put on it except I need the fcv barely on any threads for it to open at 1/4 throttle, basically I can see the oring that seals it because its screwed all the way out

I have one on my sj and its almost all the way screwed in and opens when I like it.

problem is that I'm already at 140 head temp or so in 80 degree water, I tried putting a 4mm restrictor on the bypass before the fcv only but I feel that the pressure is going to flow out the side of the head outlet instead, therefore I would need a restrictor there as well which I don't want to do and get too hot

now ive heard of cutting the fcv spring to allow less pressure and therefore I can close it more which I may do

but is there a way to get more pressure in the cooling system without restrictors or am I better off cutting the fcv spring?
 
Harbor

Harbor

Location
Stockton
I have one fc set with oring showing, works fine. The other is cranked all the way in like yours with a 2mm or so restricter after it.

But in your case you have the right idea, cut the spring to get more threads.

Does that boat have dual cooling ?

Edit: if it only had single cooling you could go parallel dual cooling, exhaust is on its own circuit, and be able to restrict just the exaust for more pressure. Be more work than cutting the spring though
 
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Quinc

Quinc

Buy a Superjet
Location
California
You should get plenty of pressure from one. You may have a leak somewhere. Or some blockage at the pump side. You can also drill out your npt fillings so more water is able to flow through them.
 
Quinc

Quinc

Buy a Superjet
Location
California
I have the same setup dual cooled b1 760 with coffman pipe and she has tons of pressure coming out. I also found she runs better with a 2.5mm restricter at the stinger and no fcv.
 
Quinc

Quinc

Buy a Superjet
Location
California
a1965gt said:
How do you have your dual cooling hooked up?

Are you running your second cooling line from the pump to the bottom of the head pipe and dump both cooling lines from the head overboard?
Click to expand...

From the pump ( I had onepump fitting break once and didn't figure it out until I removed the pump, it looked fined while pump was installed) From there I have them going into the bottom of the manifold. One pisser off the head and a T before the stinger.
 
Mike Grafas

Mike Grafas

Location
Point Pleasant, NJ
I recently did the dual cooling and the way I have it set up is as follows
2 lines from pump, both lines to bottom of manifold
one line from head to bypass(overboard)
one line from back of head to bottom of head pipe, then chamber right after coupler to "T"
straight leg of T to fcv to stinger
T to bypass
 
a1965gt

a1965gt

Location
phoenix
Mike Grafas said:
I recently did the dual cooling and the way I have it set up is as follows
2 lines from pump, both lines to bottom of manifold
one line from head to bypass(overboard)
one line from back of head to bottom of head pipe, then chamber right after coupler to "T"
straight leg of T to fcv to stinger
T to bypass
Click to expand...


How long is the hose from the T to the bypass. You basicly have atmospheric pressure at the bypass. You probably have plenty of pressure/flow in the cooling system but if the hose from the bypass to the tee is short (too close to atmospheric discharge point) you wont have much pressure at the T and FCV.
 
Mike Grafas

Mike Grafas

Location
Point Pleasant, NJ
a1965gt said:
How long is the hose from the T to the bypass. You basicly have atmospheric pressure at the bypass. You probably have plenty of pressure/flow in the cooling system but if the hose from the bypass to the tee is short (too close to atmospheric discharge point) you wont have much pressure at the T and FCV.
Click to expand...
Ah ha, that could be the issue, the hose is only about 6 to 8in long, I cut the spring down on the fcv and now I can pull air through it easily, going to tune it today and see how it reacts with water
 
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