I had my 088s gone through. Same head as the 934. Cleaned. Surfaced. Valve job. New springs on all 4. I spent about a grand.

and that's about right.. and if you needed to add new valves you'd easily add almost another grand cause if you're changing them, you'll likely go bigger, and that's my point, almost $2k in and you're near into mine!!

Great feedback thanks! I will post the numbers i research and some more details as they unfold. Thanks Tom.

I'm here to help if you need it

You can easily exceed the price of new heads rebuilding old ones. I won't do it anymore because when you do just about everything and it cost a good amount, and 2 years later someone thinks they have an issue and freaks out over the guides not being replaced. Add guides and valves and new heads are cheaper, even if you take them apart and verify

do you think you'll have to rebuild the new ones at the same interval

I use the finest parts available, Ferrea Valves, severe duty stainless steel intake and Super alloy (Inconel)exhaust, Pacalloy endurance (300 hr) valve springs, and hardened 10* retainers and locks, 4140 7/16" rocker studs and hardened 3/8" guide plates, these are custom build to suit per customer not sitting on a shelf waiting... so "drop on ready" is what you get with "My" heads!!!

What does the community recommend for valve spring replacement part number for stock hp500efi?

PAC?

Thanks. Tom.

a Pac endurance spring is what we use.. and they have a service life of 300+ hrs

heads were in good shape so stayed with existing castings - was about $600 plus I provided the springs/locks and retainers

ran into one issue in that most of the recommended springs had a installed height of 1.875" but my 2003 HP's which still had engine seals on them had installed heights of 1.950-2.030" without shims -- not sure if others have seen that with the 934 casting heads -
my original plan was to go with isky spring 8005-a after talking to Isky about the height they suggested the 8205-SP spring which would be about 135# seat pressure if installed at 1.95"

I am not adverse to going to PAC or other spring either just trying to stay in bounds with what others have had success with

Curious of your thoughts - thanks! Tom