I have a set of 415hp 502's. They have over 500 hours on them now. Still running good, good compression, good oil pressure. They seen to be noisey on the upper part og engine. Clicking and rattle sound. Should I freshen up the top end? If so what should be done? The motors are coming out anyway to do some painting and rigging in the engine room, so now would be a good time if needed. These engines are not used that hard. Rarely run at full throttle, mostly long distance cruise at around 3800 RPM. Any words would be appreciated.

Thanks,

Steve Hixson

For my cruisers running at 3200rpm most of the time 500hrs was always my valve job/exhaust service point. On a performance engine running 3800rpm and intermittant WOT I would cut that to about 300hrs max. to error on the safe side. That would consist of:

Valve job
guides checked
new springs
new seals
deck heads
inspect all parts
muratic acid exhuast manifold if cast iron
pressure test heads, intake and exhaust would be wise.
Replace ignition perishables
rebuild carb
new tstat

BT

Thanks blue thunder
That's what I thought. Exhaust was replaced last year, carb was gone thru and stats replaced at same time. Do you think I will get another 500 hrs before the lower half needs attention?

Steve Hixson

As long as you change oil/filter regularly and the oil temps are never going above 220-230f, the bottom end will last much longer than 1000hrs.

BT

Don't have oil temp gauges. So I don't know. I do have room in dash for a couple more gauges if needed. The engines have oil coolers, so I assume I am O.K. Or is assuming not a good thing on engines that are ran at this RPM?

Steve Hixson

Chances are you would have had a prob by now if there were an issue with oil temps. I personally would spend the small amount of money and install them though so you can be 100% sure. Marine engines are very hard on motor oil.

BT

I will add that to my to do list when the engines are out. Where would the best place to install a temp sender?


Steve Hixson

Mine are installed in the remote oil filter pad in the oil stream ahead of the cooler. That way you are reading the hottest temps (or close to) that the oil is experiencing.

BT

Mine has two filters per engine. I think that there is a threaded fitting on the filter housing with a pug in it. That should work good for sender local.

thanks for the help.

Steve Hixson

If interested I have 2 sets of heads off my 500 hp's, Also carbs,intake, ingtion, and old cams and lifters, I would guess the have 100 hours (max) since inovative when through and resealed these motors just before I bought the boat.