525sc motors valve springs
 

I have a pair of 1998 454 cu. in. 525sc motors with 380 hours. What is the normal rebuild time or maybe just replacing the valve springs. Also what about rebuilding the superchargers at this time. I motors seem find with lots of power and no issues. But I am thinking of preventive maintence. Any opinions out there.

You are about due. I did mine at 340hrs. I would do a valve job, head gaskets and springs. A leak down test would tell you more as well. Most people have the blowers gone through as well in your hour range. I never had mine done, and it had almost 500hrs on it, but I changed the lube every 25 or so hours.

I agree with Griff. You are due for a top end. I just did the top end on a 525 sc about 2 months ago. They had right at 300 hours and the springs had lost over 20 psi. That is a substantial amount considering they are only about 140 on the seat. I didn't remove the heads. We did a leakdown and all seemed well so we just did the springs, 10* retainers, 10* locks, and new seals. I did remove the engines to do the work. It's a good thing that we did because we found several other problems (wiring had melted and was touching the exhaust from a previous overheat, water pumps were leaking and caused tons of rust, etc) This also allowed the owner to clean and paint the bilge.
The head gaskets are a really good idea. If you are going to pull the heads, then a valve job is a must.
As for the blower, if you can verify that the oil has been changed every 25 hours, then you are probably OK. If you are not sure about the service intervals, then you should probably have it freshened up. They have a tendancy for bearing failure do to gasoline contaminating the oil in the blower. Gas is a terrible lubricant and the bearings fail because of that. I would recommend Darrin Meyer in MI. It will run around 500-600 per blower for a complete rebuild.
Hope this helps. Give me a call if I can help.
Eddie