When you disconnected the fitting on the block, did any water come out???? If not, your obstruction is in the block at the fitting. Just use a piece of wire or similar into it and clean out that area. BTW, if you are doing this on a hose, you may not see anything on the guage. Mine shows 0 on the hose and about 20 at WOT.

My water pressures are where Griff's are. (Same pressure we run in the F-275 FOUNTAIN GMC 18-24 lbs at WOT). As to location, I have found different readings if mounted by the intake as opposed to the lower block area. It's the pressure in the block that counts, not the incoming pressure, although both are related. Anything above 35 lbs. and you'll soon be blowing gaskets or in some manner experiencing water seepage.

Steve

If the pressure line is just above the oil pan....MOVE IT !!!
The tiniest bit of rust or sand will plug the line. Install it into the intake or the thermostat housing....if you are not running a thermostat. Mine never worked until I moved it.

I've had them in the thermostat housing (on the input side)coming from the oil cooler with no problems. And that 's in the scuzzy Delaware river .

Mopower,

Now if the Delaware is scuzzy, I'm wondering what you would call the Schuykill at Norristown/Port Indian? We use to race our 7 Litre Hydro there in the 80's and heaven only knows what that "stuff" was that we stepped into and then sank about 18 inches. I think I have an idea, as anytime anyone flushed along the "river", the water level rose...... YYYUUUCCCCCKKKKKKKKKK.

As to where you've plumbed your pressure guage, did you (or anyone) notice a change in the pressure readings from the block sending position (assuming at some point it was reading OK?) and the T-Stat housing area??

Thanks,

Steve

SD ,
Can't say if the pressure changed from the lower block to the thermostat housing , because any time I drained the block(down bottom) I had to stick a screwdriver in the hole and break things loose to get the water flowing. For that reason I never used the lower holes
I used to go up there for the races in the late 60's , as a friend of mine had a 16' hydro in the "150" class. 6 cylinder Falcon with Algon fuel injection running on methanol. Boy would that stuff burn you eyes. Actually the river has gotten better...some times you can see your ankles in knee deep water
BTW
This winter I'm putting Graffrigs in my Formula (including water pres.) and again I plan to use the thermostat housing..
My main reason is to detect those plastic bags in the water BEFORE the engine/engines get hot. Been there...done that

Thanks MoPower!

The 150 class was & is awesome. Today they are called 2.5 Litre modifieds, with a wide array of engines. Everything from Datsun 240 Z engines to older BMW in line 6's to Fieros', sleeved and destroked 215 alum. Buicks, full on 2300 CC Pintos, etc.

I had some great rides in that class, mainly in A-82 HONCHO, a Sooy hull with a 240 Z engine, A-122 owned by Dick Kelly with a Pinto built by Alderman, in Cahoots, a Staudacher with an exotic in line BMW, turned over 9000 RPM and didn't break.

They are running better than 130 MPH and averaging almost 100 on a 1 2/3 mile course. Imagine that in a 16 foot hydro with app. 155 cubic inches!

Thanks for rekindling yesteryear

Steve