How much should one expect to pay to freshen a pair of 420HP mercs? They have good compression, and run good, but Id still like to go thru them and get new rings, bearings, timing chains, valve jobs, gaskets, and then have the carbs dialed in. The only reason i would like to do this is because I dont really know the history of these motors.

Then dont touch them
If you take to a motor guy with a dyno by the time you are done you would be very lucky to be at 5k a motor but prob more

10k to freshen a pair of stock mercs? I can see if I needed cranks, pistons, rods, etc. I'd be better off buyin some crate 502's for 10g.

Are they high hours?

I had my 502 done over here in South Bend by a reliable race shop for 3600.00. I had him do it for the same reason that you want it done. He found all kinds of problems. Glad I did it. He did everything you posted and put it on his dyno.

2500/pc

I Would Say 2200 To 2500 A Motor.

One motor is a crate merc 454/425, and the other is a 400 cylone that someone supposedly rebuilt to 425 specs. The hours are unknown. The crate merc motor runs real strong, it will pull to 5200. The rebuilt cylcone runs good, but only pulls to 4500, which makes me think valve springs are weak. Either way, Id like to have them gone thru, and set up on a dyno.

These babies are out right now and the bill is currently up to $6000.00 each. That doesn't include taking them out of the boat and installing back in.....


And to give you an idea of estimates, I was originially quoted $2900. per motor to rebuild. Now $6000. All unforseen extras.....

Any questions??