They were proprietary springs that PAC made for Mercury, so specs are not published as far as I know. Seat pressure with stock springs is pretty low around 110-120#. As far as I know, the ideal range for the 525 is 140-150 on the seat and 380 - 400 over the nose. Stock springs installed height is between 1.800 and 1.810; too low for a good replacement spring. You need to switch to 10 degree retainers and locks and then you can get more installed height for a good spring. I have installed the 8005A's at 1.850 which puts the spring pressures right where I indicated above.

A spring with 500# rate is going to put you over 400# for sure.

The need for stronger springs is debatable. I went with stock spec springs. Pac # TVS-1631 125 #s seated. 435 #s open. Never a problem.

For what you were quoting, including pulling the engines out, removing the heads, rebuild the heads, put them back together, install the engines and test run it will run less than 3K per engine, complete. So, about $5500 or so for the entire job. That includes surfacing the heads, new ARP head bolts, Cometic head gaskets,pressure testing the headers,etc.This is for freshening the top end. That alone will not increase the power. Reprogramming is an additional $800 per engine. It will add a little power up top but will give a pretty good jump in midrange punch.

In order to raise the power to 625 hp, you would need to completely rebuild the engine. You would need an increase in cubic inches, a decent jump in compression, larger throttle body, etc. That price would depend on exactly what we do, but you should plan for 12-15k easily, per engine.

Give me a shout if you have any questions or need any assistance.
Eddie

In my mind, there is no debate. There is no reason under the sun that a 550 hp engine should need springs after 200-250 hrs. The stock springs are not stiff enough to go 500+ hours on an engine that is ran like it should be. If it spends it's life at idle to 3000 rpm, then maybe. But if it is run like a lot of people run them, those springs will cause other issues, like rocker arm failures, beat up valve seats, etc. I'm not trying to argue with you or be an a$$hole, but if that were an engine that we built, it would be good to go for 450-500 hrs without an valve train issues. There is no reason that Mercury couldn't use a spring that is better suited for that application so that they don't need to be changed so soon.

Let me put it another way.....why did you change your springs and how many hours did they have?
Eddie

Yep. Thinking of buying a used Cig w 250 hours but I cant afford to drop more money for engine repairs!

I have 2004 525's in fresh water use with 510 hours on them. I test the headers twice a year and change oil every 40 hours. The boat still runs as fast as it did new. I do plan to pull the heads this winter just to be safe. I have most of my engine time at 4000 RPM and a good bit at WOT. They have been great engines.

Don't take this the wrong way, but....I would re-evaluate whether you can truly afford the boat. This stuff is just part of the game.

Dave M, very good point. Comfortable w the purchase but all the potential repairs on motors w 250 hours give me pause. I can turn the key but cant turn a wrench. Lol. Headers have been replaced this year, which is good.

The initial purchase price is the cheapest part of boat ownership!

On the 525/600/700 it is not considered repairs, it's maintenance and it must be done. Not all the time, but many boats with these engines end up for sale at the 250-300 hr mark. Just in time for the next owner to foot the bill. Use it as a purchasing tool, any responsible owner knows the maintenance requirements of Merc Race engines and if price is not adjusted in consideration of lack of maintenance, look for another boat.