1974 455 Oldsmobile jetboat engine

I know of no reason why not. I've seen it done on the old Chevy 420s big blocks.

 

OK thanks I'm just totally out of my element - I sail hydrofoil moths and the 455 is the support boat.

My only concerns are how standard the mounting brackets are to hold the exchanger (the ones I've seen mount on longer bolts at the water pump) and whether the manifold plumbing is highly variable, but none of this stuff is rocket science so I'll just forge ahead.

Any recommendations on who makes the best fresh water cooling kits? I have not found one specific to the 455 so I was planning to order one for an older 454.

Karl in LA

 

look at crusade 454 exchangers. there are a lot of suppliers you an google for heat exchangers.http://www.oscomotors.com/catalog/catalog43.asp

 

Looks good thanks for the tips. Will post some photos when it comes together.

 

nas-t

hi i have some experience with 455 olds as i have hade more then one failure
there are three things i can tell u

cracked block
head or head gasket
intake manifold or gasket

also when u had ur motor done did u have instaled a water line from ur pump threw ur oil pan to cool ur oil ???? if not then u should if so then make sure its not leaking !!!!!!!!!!!

i hope this helps

MR NAS-T

 

Also Where Ur Heads Pressure Tested And Resurfaced

 

Since 1974 I have had the problems of water in oil on 455 olds jet boat. I have spent more money then my boat is worth trying to fix this problem. I had determined to fix this problem or die trying,and have finally found the answer, after rebuilding my engine once again for the umtinth time . First of all,my inline hose connects to a simple shut off valve so that I will never turn water on before starting engine at home.Biggest problem is when you do this you get water back up in your risers and into your oil pan before you even go to the lake. Any way, from there it connects to an inline water pressure regulator set at 15 lbs.,with the over flow released out the back of boat thru hull.Now for the great secret.At the back of my high rise intake manifold, there are ports on each side that have been plugged off . I could not remove the plugs after all these years becaue they are alluminum,so I drilled them out with a 1/4 in. hole with 1/4 in.fittings and put 2 1/4 in plastic hoses that release the pressure off the heads. These also exit thru the hull. I could not believe that when I tested this on my first trip out,that I had only2 lbs.of pressure in this set up. First I thought that my pressure gage was not working,but after rechecking I found it OK. The follwing are tips to insure this set up and keep water from your oil.
1. When starting engine at home,always start egine first and then turn on water. Most jet boaters don`t know it but if you start water first, it will flow thru engine and when it runs up your riser it will backflow into your exaust ports. You will have already put water into you engine and don`t even know it intill you get to the lake and start mixing it with oil and then comes the problems. Make sure you turn off water before turning of engine.(this is a must}
2. Never forget to connect inline hose back to the pump when finished running at home.
3. Always start your engine while someone backs you in to lake.This prevents water from being forced back thru risers ,just in case your flappers are bad.
I have not had any problems for over a year ,now and I run my boat at least 3 times a week.
4. Make sure after your back home again, that if you not going to be useing your boat for a while,to cover you outside overfows with a piece of tape to keep insects like muddobbers and wasps from clogging hoses.
I hope my experience with these problems have help you and will cure your frustration.

 

Wet Logs

I HAVE AN EXTRA SET IF YOU ARE INTERESTED THEY ARE hARDIN MARINE ALSO HAVE A SET OF 460 IF ANYONE IS INTERESTED

 

water in oil

If you do not take out the thermistat. water will pass by the intake gaskits and you will get water in the oil.

 

Fresh water getting into oilpan . Modify stuff - mate. Run semi - synthetic oil if you can .
Pressurise the oilpan , old motors will do this by themselves . Try a condenser system - Try to install a remote oil filter arrangement . Race shops have these. Try an oversized pan ( race pan ). Oil heated to engine operating temperature will steam off water. It
turns to steam when your engine gets up to operating temp , and burns off . What you can do is this : Install a home made oil vapour condenser . Something ( like a can ) that will evaporate out your crankcase overflow vapour , and separate the oil from the water vapour.

 

I am having a prob wit my 76' 455,I'm buildin too much press and blowin the back of the intake manifold gasket...where and how do I vent this pressure????

 

When you skim heads too many times on a V8 the inlet manifold needs machining to match the gaskets and head bolt holes or they dont line up. This will leak internaly into the crank case.

Krusty -you mean crankcase pressure is building up? This should be released from the rocker cover, it will have a pipe that goes to the air filter. Remove rocker cover and clean the outlet

 

yes and it is blowing out the rubber gaskets on the front and back of the intake manifold,ok so this may be plugged???anything else i should be lookin for???

 

Nope thats where the crank case relief is, from there it releases pressure for the whole engine ,--both banks.
You might have a breather on both rocker boxes ?

 

Metals DO AGE.

I wonder why you guys do not use a raw water pump ?

210 PSI is a lot. That kind of pressure WILL CAUSE thermal shock to engine parts. The sudden rpm jump is GOING to pump a HUGE amount of lake water temperature into a warm / hot block.
Anybody using a 130 degree thermostat ? It does stop a lot of thermal shock / warping.

210 PSI????? Serious instantanios temperature warping of thinner surfaces.
Use a seperate raw water pickup & pump. Call me in the morning.