Newbie.....Oil presure sending unit????

**BBSPURGEON** · 08-31-2009, 11:50 AM

hello I recently started redoing a 1971 Marlin Jet Boat. I currently have a Olds 350 Rocket engine in it. I am putting all new gauges and sending units in the boat. I know where the water temp unit is and I know where they had the mechanical oil pressure unit but when I installed the new electronic sending unit I found i had to put a 3 in extension and the instructions say they do NOT recommend doing this. Is this a good area for the unit or am I missing somewhere else where I could put this???

**Last Mohican** · 08-31-2009, 01:59 PM

Originally Posted by BBSPURGEON

hello I recently started redoing a 1971 Marlin Jet Boat. I currently have a Olds 350 Rocket engine in it. I am putting all new gauges and sending units in the boat. I know where the water temp unit is and I know where they had the mechanical oil pressure unit but when I installed the new electronic sending unit I found i had to put a 3 in extension and the instructions say they do NOT recommend doing this. Is this a good area for the unit or am I missing somewhere else where I could put this???

That is almost exactly how I did mine on my Pontiac except I have a 90* fitting at the top so the sender will clear the distributor. Mine works just fine.

**TIMINATOR** · 09-08-2009, 02:30 AM

Extension is no problem unless you use too much teflon tape, in that case you will have no ground and an inoperative gauge. We had a guy install one with 8" of plastic tubing from a direct reading mechanical gauge kit and he couldn't understand why he gauge didn't read..... 1TIMINATOR

**lILREDROCKET** · 09-21-2009, 10:20 PM

hey where can I get that sending unit? I bought a boat with a piece of crap motor from kingjames, and im replacing everything, including the motor. I have a punched out 350 olds as well, 10.5 :1 Comp. fat cam, reworked heads. and im curious about the cooling system hose routing. I bought a pressure bypass valve, and a put it out the transom, but im still worried about excess pressure...... Where can I find a diagram? And whats the best way to get Hardin aluminum wet logs to seal correctly?should I use a steel backing plate as a washer to distribute the load ? and is copper the right choice gasket? This jerk had solid silicone on the logs. ( which are at the machine shop right now.)

running out of money and patience please help. Is there a friggen book on jet boats or what?

75 Tahiti 19ft
Berkley jet, w place diverter
350 olds
hardin wet logs

**mschei2** · 09-22-2009, 02:30 PM

hey lilredrocket,i have an olds 455 with hardin logs and gaskets keep blowing out.my friend has same set up and took a long board and sanded the logs so there was no warpage,then installed with high temp silicone and hasn't leaked in 4 yrs.i am going to do the same to mine over the winter.just my .02

**Last Mohican** · 09-22-2009, 04:43 PM

Originally Posted by lILREDROCKET

hey where can I get that sending unit? I bought a boat with a piece of crap motor from kingjames, and im replacing everything, including the motor. I have a punched out 350 olds as well, 10.5 :1 Comp. fat cam, reworked heads. and im curious about the cooling system hose routing. I bought a pressure bypass valve, and a put it out the transom, but im still worried about excess pressure...... Where can I find a diagram? And whats the best way to get Hardin aluminum wet logs to seal correctly?should I use a steel backing plate as a washer to distribute the load ? and is copper the right choice gasket? This jerk had solid silicone on the logs. ( which are at the machine shop right now.)

running out of money and patience please help. Is there a friggen book on jet boats or what?

75 Tahiti 19ft
Berkley jet, w place diverter
350 olds
hardin wet logs

You wil not have a pressure issue with logs. You do not need a bypass. See the attached image for the plumbing. Go from the pump to the bottom of the logs, out the top of the logs to the front of the block, out of the intake manifold to the snails.

Check this thread over at PB.
http://www.performanceboats.com/html...741#post702741