What valve springs should I use ??
 

I need to replace the stock valve springs in a pair of 2000 model year 500 EFI blue motors. They have 360 hrs on them. What do you guys recommend??

Thanks,
Smitty

Isky Tool Room 9905 should work!

Dave

Wow 360 hrs on the originals? I heard you were supposed to change them at 200 hours.

That spring would give waaaaay too much pressure for that stock EFI. Unless your stepping up to a soild roller with +.700 lift! At 300 hours, and being your changing valve springs, your best bet is to have the heads checked for the right spring height after the valve job. We usually end up setting the springs at 1.900 inst. height on those engines. We use an Isky spring, 1.530 dia. dual with damper, p/n 8005. It gives a spring pressure of 130-135 at the seat.

Isky 8005 Sp :d

I put Comp 929-16's on my old boat,
and did the same with a friends boat.

At 360 hours, you may want to check the
lifters too.

The EFI's have different springs than the carb engines and are not as prone too failure.

The carb motors used a Crane spring, the EFI's the Comp 929's. Both were marginal in quality, and prone to failure if run beyound 200-250 hrs. That's where Merc recomends they be "checked", which is Merc Speak for changed.

The Isky SP series are the ticket here, much higher quality, as with anything you get what you pay for. At your hours the roller lifters and rocker arms are up for replacing as well.

what lifters are in the 500hps and what lifters should they be replaced with ?

later

The Isky 8005-SP have a seat pressure of 150 lbs. @ 1.875 and 435lbs @ 1.225 Max net lift .650 coil bind at 1.160

The Isky 9905 have a seat pressure of 165 lbs. @ 1.900 and 450lbs. open at 1.300. Max net lift of .600 coil bind @1.160

The Compcams 929 have a seat pressure of 148 @1.880 and 432 @ 1.230 coil bind at 1.160

I don't see why these wouldn't work. Merc is using the Comp929's as far as I know. These are are perfect mate, and a much better spring. No pizzing contest, just a fact.

Dave