Dennis Moore, Blown 1500, Bobby Daniels, & anyone else.

I have a pair of 1999 HP 500s that I am getting ready to replace the old style valve springs and retainers on and upgrade them to the current and correct setup.

My question is, as it has come up in preperation for this project, how many hours can one reasonably expect to get out of stock HP 500s before it would be necessary to pull the heads and do a valve job?

I was planning on just replaceing the springs etc. without having to remove the heads or pull the engines. If I need the valve job it will obviously change the whole scope of project and open many other avenues as one can imagine.

Any info and advice will be appreciated and considered in my final decision as which way I go.


Need answers fairly fast as I need to move on this quickly.


Thanks in advance,
Mark

Mark ,do a cyl. leak test on motor to decide if you need a valve job .It would help to do a good 3 angle job and pocket port the heads or at least have somone cut the seats with a serti valve machine ,
Its hard to say when you would need a valve job as it depends if springs were good and controling valves or broken and not controling them ,,ect. good springs 350 hrs should be o.k.
This is just my opinion
we could do this for you quickly and at special oso cost (Cheap)

P.M. me if I can help any more

I know that on my motor, the valves and the rings both went out at a point just over 500 hours. If the lower end is going to go at the same time as the valves, I would have to question the value of doing a valve job at this time.

It depends on how the engine is run (full speed all of the time, partial throttle most of the time or excessive idling). Oil change intervals and quality of the oil, type of weather (water condensation collects over the winter or in highly humid locations), type of boat (heavy boat or light boat?), quality of fuel (some engine detonation?), backpressure on the exhaust (water reversion?), engine temps (ever overheated?) etc.

Just keep an eye on the oil pressure and do an occasional compression test. Note the amount of oil used between oil changes. Buy an oil filter cutter and inspect the filter after every oil change. Every once in a while pull off the valve covers and check the adjustments on the rocker arms and inspect the valve springs. Look at the color of the plugs carefully when you change them.

A double pumper, mechanical secondary carburetor will shoot an excess amount of raw fuel into the cylinders everytime the throttle is pushed ahead. This will wash some of the oil off of the cylinder walls and lead to premature cylinder/ring wear. The raw fuel will also get past the rings, into the crankcase and dilute the oil hurting the lubrication properties of the oil (the reason for vacuum secondary carbs). This will wear out the engine a little faster especially if oil changes are not done more frequently.

Sincerely
Dennis Moore

Anyone else want to throw in an opinion or response on this one. It is getting down to decision time.

Mark

Mark
My boat is in Jacksonville now having the same thing done except we ran into problems. The thing you want to make sure of is your exhaust and risers. My engine has short risers on them so it let water come back through and rust the valve springs among other things. Give me a call if you like and I will let you know what all the mechs told me
David
704-634-9004

vagrant,

I am lucky in respect to the riser issues. Mine have the higher rise design. Also from looking thru the oil fill caps (have not pulled the valve covers yet) there is not any signs of rust and have never seen any signs of any reversion. Have had that problem on another boat so I am familiar with what to look for.

Also there has not been any indication that there is any problem to this point. With all the discussion about the spring issues I was doing it more precautionary to start with. Don't know what I will actually find once I start tearing into it. Do not want to go more in depth than absolutely necessary at this time however I do want to make the best decision that I can. If things look bad once inside I guess I will not have a choice at that point.

Thanks,
Mark

Vagrant/David ---------- water coming in the risers cannot get to valve springs ,,,,,,,unless the rings are beyond terrible. They are not connected 99% of time its from condensation ,,oil to cold ,ect.
I'll be happy to help you with the problem ! But please don't believe its from water coming in exhaust

Vagrant... do you know what your oil temp was running? I'd go back to the mechanic and ask exactly how he thinks reversion would cause rust on valve springs. Please let us know what you find out. I am curious about that topic.

Thanks,

BT

i would think water contaminats oil, oil lubercates everything, water in oil, water and steel rust , simple as that. reversion sucks water into engine through exhaust valve into cylinders, mixes with oil on cylinder walls mixes with oil in oil pan and is pumped to every internal part in the engine
later