doesn't a 496 run some sort of high pressure like 40-43. why are they different if this is correct

496 is closed cooling. That is only pressure to the heat exchanger.

Do what you have to do limit the pressure . Limiting the volume to kill the pressure is not a good idea . You need that volume to carry away the heat . Overboard dumps or dumping from the rear of the intake to the headers is more viable in my humble opinion .

Ran it today and I have no volume issues. I also added a pressure relief valve along with the restrictor...I still blew another water pump gasket. When the imco intake is AT LEAST 4 times bigger than an XR I dont see a problem with trying to get it back to where it was.

Try 3M weatherstrip adhesive for that waterpump gasket.

I sugest that because RTV is probably letting you down.

Then again, I've never had to replace a factory waterpumps housing gasket.

Side note to go along with the thread:

I had an engine on the dyno that went 40+psi water psi (I think it spiked to 60) and the motor leaked water thru head gasket and intake gasket.

The issue for the high psi was a t-stat was left in the housing on a crossover system with no bypass.

Bypass was added, a few small holes drilled in t-stat, and a Merc water psi regulator was added. Replaced gaskets and problem solved.

I had to stack 2 gaskets, I used permatex between them and glued them with gasket spray adhesive on the mating surfaces.

I have pick ups I`ve been trimming down to get the pressure to where I want it, I also have 2 -4AN dumps on the back of the intakes and a 15psi -8AN pressure relief valve . I`ve finally gotten to below 20psi @ wot.
12ish cruising.


Nice thing about a relief valve is that you wont lose pressure down in the lower rpm range.

I have reduced discharge EMI tails so I think the dumps might work well.

OK, I added two 1/2" dump lines, one out of each manifold. I have the relief valve right before the oil cooler. I removed the restrictor before the water pump. Took for a test drive and water pressure went over 35psi at 50mph. Put the restrictor back in and it put me right where I needed to be at ~25psi. I still could not believe the amount that pumps out the dumps at idle even with the 1/2" restrictor.

I have 5/8 and 3/4 lines and fittings to try but atleast I know I can go boating without blowing out gaskets.

JRider

Why do the pressures get so high?