Thunder Struck

What are my '89 420's worth on a trade in from a shop willing to sell me fresh 502's 540hp? One runs, one makes noise - 850+ hours on them.

Audiofn

I guess it depends on what the problem with the one motor is. I would think that if you can get 3 grand or so I would take the money and run.

Jon

Audiofn

I am assuming that they are not salty dogs,

Pantera1

420's are good base motors, lots of forged parts etc

Thunder Struck

Ok, I'll lay my cards on the table.

No salt, Ontario motors.
Overheated one... #6 or #8 or both have valve train noise and there is a squeak from the rear of the block (most likely a bearing). It runs smooth though. The other runs fine. He will take as is to be rebuilt and resold by him.

Offer is currently, $6,000 for my motors, in return I will get rebuilt 502's out to 510/540hp. Performance built, well known builder up here, balanced, blueprinted, fully rollered etc. $26,000 for the pair re&re included with a one year warranty. So in the end it's 20k Canadian. The motors are complete except the exhaust. Will my Gil manifolds work with these motors as there is no exhaust included?

rdoactive

Yep the Gils will fit.
But for half of what you're planning on spending, you could probably freshen your existing motors. If you didn't completely waste something in them. Now just ask yourself if the extra 3-5mph is worth the cost.
My $0.02
Gary

Thunder Struck

Oh yes, I have been flipping on just this question. Problem is two HP marine engine buildes will not touch them for under $9500 + 2k to do the re&re. Thats 21k.

I have found a guy that will do them to stock (not rollered)/ balanced / with full valve train overhaul for $6,000 each plus 2k re&re for at total price of $14,000. Both of the other guys say they do not know how he is doing it for this. One of these fellas is the guy with the 502's offer.

Apparently the 420's have expensive parts or so I am told.
So now I am at a 6k difference with more up to date motors, rollered, more CID and a 240hp increase. Will I only get 2-3 mph with the increased hp?

Is it best to leave the old girl stock or beef her up a little?

StraightJacket

I'm doing a set right now and I plan on the same H.P. for nowhere near that money . We just got them torn down and doing a comparative to see just whats there , someone jacked these up to sell the boat. For 26 grand we could make some 540's probaly , deffinitly 509's well in the 650-700 H.P. range.

tomcat

It is against the law to reinstall stock engines.

I would really need to know the parts in the 502s before I could decide. This will tell you if 540 HP is realistic (what heads and cam). A true 120 HP gain is worth 7-8 mph in your boat and that's huge.

Give me a call, I'd be happy to provide free advice since I've been down this exact road.

Griff

There is nothing in the 420's that should be that expensive. Just good basic parts.

All the prices/$$$ you are talking are Canadian, right??????

Take off, what??? 25%???? of the $ amounts to a get a US dollar comparison????? If thats about right, then none of the prices sound out of line.