I have some unknowns on my Hp500C. The previous owner said the springs were changed in 2012 along with the cam. He said less than 100 hours since freshening– but I didn’t receive copies of the receipts so I can’t be sure.

I’ve decided to pull the engine next weekend and go over everything over the winter. My plan is for compression / leakdown before any more teardown. Assuming all is good there, pull heads and replace:
Exhaust valves – Manley Inconel
Head Gasket – Cometic?
Head bolts – ARP (anyone know what the kit number is?)
Valve springs – Unknown at this point

I’m keeping my fingers crossed that my discovery of the exhaust manifold leak was external only (will pressure test this weekend) and no damage to cylinder or rings. I guess the compression and leak down will aid in that diagnosis.

Do I need new intake valves, lifters, rockers etc?

Our last run this year, nothing abnormal about operating conditions. All was well with exception of exhaust manifold.

Anything else to do while I’m there? I want reliability – turn it on and go.
Looking for suggestions.

Thanks,
Ryan

I have read a couple horror stories, along with my personal experience about lifters going bad. I would replace lifters if you are going to tear it down. Springs are a must if unsure of the brand.

My friend had a lifter go bad the end of summer on his 97' HP500 which ruined the cam lobe. The Merc. Mechanic we know said the HP500 carb engines used bad valve train parts from Crane.

Kinda getting the cart out front of the horse....is it running bad? did you have a specific issue with the engine? Merc OEM stuff is generally good, except their valve springs. Plan on a good valve job and new springs for sure. After that, if you've got a builder you trust, leave the rest up to him based on the intial evaluation.

If you want full peace of mind, call bob m, have him set you up with lifters and springs, possibly rockers. Fel pro gaskets are more than sufficient for your application. The arp head bolts are a nice upgrade.

It rus fine minus the cracked manifold. I have the engine out and in the garage. Within the next several weeks I'll start testing and tearing down.

My main goal is to have a reliable engine, if I need to replace springs, lifter etc for peace of mind I will. The season here is too short to mess around. But If I can reuse components, I can save $$ for gas.



Ryan