Merc 420 Cyclone engines

[MILD THUNDER]

BTW, also, don't think that it can't hurt to just run it, and if it blows, it blows, no loss. For all we know, the cranks, rods, heads, etc, might all be in good condition, but things like bad valve springs, leaky exhaust, clogged fuel system, can destroy what could be a nice engine in about 5 minutes. So something that might cost 2,000 to go thru and check, might cost 5,000 or more because it greneded.

When i bought my first go fast boat, I had low oil pressure. Everyone kept telling me not to worry, since it was a new engine, and thats its just a bad gauge or sending unit. I didn't believe that. I had the engine pulled, and tore down. Turned out to be the main bearings were severly worn, and several other issues going on. If I had just "ran" it, i probably would have destroyed a 900.00 crank, a brand new Dart Big M block, and alot of other expensive pieces. So what cost me 5k, could have cost me 2-3 times that to fix/replace. Just trying to steer you in the right direction dude!

 

[old377guy]

It's great to see the guys come along side you on this project Brian. The drives, gimbals and transom assemblies really show no signs of corrosion. I continue to hold with the idea of removing every transportable part in the engine compartment and then inspecting, labeling, renewing and storing until such time as two reliable power plants are installed back in the boat. Once the items are removed and stored there will be more access in the compartment. Keep us posted.

 

[600sci]

I would go with Jim's advice..some nice 502's-509'sor 540's and all set. TAKE YOUR TIME !!!

also im with old guy...completley strip the engine compartment..check everythign and replace or fix whats needed..PUMPS..WIRES..and so on, sand and paint the bilge while empty..once u have saved some funds..and new motors go in ..u be happy u did so !

the 420 cyclons are a little different from HP420's and u should be able to sell them even in not running condition just for the parts..!

the boat would really be haulin ass with some mild 540's and the drives would easaly take that !

Go N/A...no electronic BS..some nice 1050 on a nice 540 and u should see 650-700 HP on a mild 93 octane set up.. NO NEED FOR BLOWERS ..just more to worry about !
Dont go for bling, go for reliabilaty !:USA:

 

[BDC1013]

Yep. The #3 propshaft tapers down right were it comes out of the lower housing. Similar to how a TRS or Bravo propshaft would. The 3A, like he says, has no taper. Just a straight big shaft.

I honestly wouldn't bother even trying to fire that other engine. Even if it does start and run, I wouldn't trust it for long. The seals are more than likely dried up, rings could be rusted, valvesprings weak, etc.

Now, not to say that its junk though. I would remove the engine, and tear it down. If the blocks are not toast from salt, or the heads, then I'd say just rebuild/freshen it. The 420HP Merc was a great engine, and also very easy to duplicate. You can find a older Mark IV 454 block, plenty of those around from hotrodders, old surburbans and pickups, etc. The crankshafts and dimple rods are good GM forged steel units. Also can be found for real cheap. The camshafts were crane, but alot of guys have used the cheaper "sealed Power" replacement cams. They offer some nice cams that are very comparable to the original 420HP crane cam, but about half the cost. The cylinder heads are GM rectangle port heads. These can also be found used/rebuilt for cheap. Same for the intake manifolds. Carb is your basic holley 800CFM double pumper.

What I am getting at, is that sure you can just order some 502 crate engines, probably have around 12-15k in them by the time you dress them with carbs, ignitions, accessories, etc. But I think it would be cool, and cost effective, to restore the boat with the original 454/420HP mills, GIL exhaust, and everything period correct. Granted it might only be a 60mph boat, but....still cool none the less. Now, If you really wanna get silly, you can while rebuilding the engines, build them with the intention of adding a supercharger down the road. Some good headgaskets, dished pistons, better rod bolts and head studs, and a cam ground on a 114LSA. Little things that dont cost that much more. Then once you get her running, a few years down the road, if you feel the need to go fast, you can bolt on some 250/256 blowers, and gain 10+mph!

I agree with restoring the boat with period correct stuff. I think it would be very cool too. There is no way i could afford 502's right now.

One thing about restoring the engine that is in there and building one identical is, in my past experience with having an engine rebuilt, it would have been way less off a hassle and maybe even cheaper than having it rebuilt, than if i would have just gone and got a crate. This experience was with a 69 LT1 small block that i had built to a 383. Mind you, small block car crate engines are a dime a dozen.

I am not worried about speed right now and if i were to spend money on go fast stuff it would probably have to include fuel injection with a whipple style supercharger because i wouldnt want to modify the rear hatches.

I could use some help finding all of this stuff to built these engines. If i could buy stuff one at a time over a period of time that would really help, and would probably be the best way for me to get this thing going.

BTW, also, don't think that it can't hurt to just run it, and if it blows, it blows, no loss. For all we know, the cranks, rods, heads, etc, might all be in good condition, but things like bad valve springs, leaky exhaust, clogged fuel system, can destroy what could be a nice engine in about 5 minutes. So something that might cost 2,000 to go thru and check, might cost 5,000 or more because it greneded.

When i bought my first go fast boat, I had low oil pressure. Everyone kept telling me not to worry, since it was a new engine, and thats its just a bad gauge or sending unit. I didn't believe that. I had the engine pulled, and tore down. Turned out to be the main bearings were severly worn, and several other issues going on. If I had just "ran" it, i probably would have destroyed a 900.00 crank, a brand new Dart Big M block, and alot of other expensive pieces. So what cost me 5k, could have cost me 2-3 times that to fix/replace. Just trying to steer you in the right direction dude!

now you've got me worried, haha. it might be safer to pull this engine out, tear it down and reuse what i have that can be reused, rather than blow the thing up and be at a loss.

I will check into those drives for you guys shortly, maybe snap some pictures if i can.

 

[BDC1013]

I would go with Jim's advice..some nice 502's-509'sor 540's and all set. TAKE YOUR TIME !!!

also im with old guy...completley strip the engine compartment..check everythign and replace or fix whats needed..PUMPS..WIRES..and so on, sand and paint the bilge while empty..once u have saved some funds..and new motors go in ..u be happy u did so !

the 420 cyclons are a little different from HP420's and u should be able to sell them even in not running condition just for the parts..!

the boat would really be haulin ass with some mild 540's and the drives would easaly take that !

Go N/A...no electronic BS..some nice 1050 on a nice 540 and u should see 650-700 HP on a mild 93 octane set up.. NO NEED FOR BLOWERS ..just more to worry about !
Dont go for bling, go for reliabilaty !:USA:

502's and 540's are so much more expensive than 454's.

Once i get everything out of the engine compartment i can definately sand and paint it all. There probably isnt much wiring compared to a car, and I could redo that on my own as well.

I agree with keeping it simple with carbs. I dont need bling, and all i want is reliability. I plan to keep this boat for a long time, if i restore it as close to period correct as i can now, it would be a lot easier to do it, than if i went another direction now and wanted to go back. If i get bored of my setup later on down the road, then i can see some 540's in my fuiture :driving:

 

[old377guy]

I would go with Jim's advice..some nice 502's-509'sor 540's and all set. TAKE YOUR TIME !!!

also im with old guy...completley strip the engine compartment..check everythign and replace or fix whats needed..PUMPS..WIRES..and so on, sand and paint the bilge while empty..once u have saved some funds..and new motors go in ..u be happy u did so !

the 420 cyclons are a little different from HP420's and u should be able to sell them even in not running condition just for the parts..!

the boat would really be haulin ass with some mild 540's and the drives would easaly take that !

Go N/A...no electronic BS..some nice 1050 on a nice 540 and u should see 650-700 HP on a mild 93 octane set up.. NO NEED FOR BLOWERS ..just more to worry about !
Dont go for bling, go for reliabilaty !:USA:

Exactly, it would not take anything fancy expensive or exotic to set up 502s(509s) to put out a reliable 500-550 hp and with great reliability.

 

[600sci]

502's and 540's are so much more expensive than 454's.

Once i get everything out of the engine compartment i can definately sand and paint it all. There probably isnt much wiring compared to a car, and I could redo that on my own as well.

I agree with keeping it simple with carbs. I dont need bling, and all i want is reliability. I plan to keep this boat for a long time, if i restore it as close to period correct as i can now, it would be a lot easier to do it, than if i went another direction now and wanted to go back. If i get bored of my setup later on down the road, then i can see some 540's in my fuiture :driving:

Just remember that tourqe is what moves a boat and not only HP...so 454's infront of #3's is really not efficient..gonna use more gas to push and also would not be that much fun since it would be slow. That boat is heavy and big for 454's.....back then 420's ( 454s ) where just used and a HUGE engine, in todays world its actually small !
And i dont agree on the price, do build a 454 with some BOOM u can build a mild 540. ( it does not have to be new parts on Block and such ! )

 

[BDC1013]

personally i do not have the knowledge of building engines nor do i have the knowledge of finding parts (right parts) for the right price. It may be real easy for some of you to build up a mild 540, but for me I would have no idea what I was doing. Finding something where i can install all the accessories, oil up, install and go is going to be my best bet. Now if i could find a couple 540 long blocks, i can install the rest on my own. Actaully i do not know this for a fact but i've assembled SBC long blocks and installed them in cars... so i ssume i'd be able to do the same once i got a pair of long blocks.

 

[Ratickle]

personally i do not have the knowledge of building engines nor do i have the knowledge of finding parts (right parts) for the right price. It may be real easy for some of you to build up a mild 540, but for me I would have no idea what I was doing. Finding something where i can install all the accessories, oil up, install and go is going to be my best bet. Now if i could find a couple 540 long blocks, i can install the rest on my own. Actaully i do not know this for a fact but i've assembled SBC long blocks and installed them in cars... so i ssume i'd be able to do the same once i got a pair of long blocks.

Pretty much correct. There are some things with remote oilers etc that can be installed backwards.

 

[PayCheck]

personally i do not have the knowledge of building engines nor do i have the knowledge of finding parts (right parts) for the right price. It may be real easy for some of you to build up a mild 540, but for me I would have no idea what I was doing. Finding something where i can install all the accessories, oil up, install and go is going to be my best bet. Now if i could find a couple 540 long blocks, i can install the rest on my own. Actaully i do not know this for a fact but i've assembled SBC long blocks and installed them in cars... so i ssume i'd be able to do the same once i got a pair of long blocks.

Hi -4 years ago I bought a complete boat without power and decided to piece together two 454s, I'm not a mechanic but have done more than my share of backyard wrenching, so thought I was well equipped for the job. I found out later it's called pay as you learn.

Unless you are a fanatic and need to know every detail of your marine engine assembly (like me), you will be much further ahead in today's market to buy complete and running mills. Maybe not as much fun, but miles ahead at the bank.

 

[MOBILEMERCMAN]

BDC Don't even haste your time thinking you are going to build your own engines.

 

[BDC1013]

thats why i think it would be cheaper to buy long blocks and assemble the rest on my own, rather than take this engine out and pay to have it rebuilt and pay to have another built just like it.

 

[BDC1013]

What do you all think?

Racingjunk.com

http://www.racingjunk.com/category/...06805/480-HP-454-s-fresh-fresh-water-run.html

I have two 450HP fresh/ new bore/piston's 7/16 rod's 0 hour 454's marine dressed big Merc in take's and ex. Head's are still in the bag ready to bolt on. motors are short block's with every thing with them Bravo hubs like new bell house water pumps / open so you can see what you are buying. will let the motors go at $3,000.each

 

[600sci]

What do you all think?

Racingjunk.com

http://www.racingjunk.com/category/...06805/480-HP-454-s-fresh-fresh-water-run.html

I have two 450HP fresh/ new bore/piston's 7/16 rod's 0 hour 454's marine dressed big Merc in take's and ex. Head's are still in the bag ready to bolt on. motors are short block's with every thing with them Bravo hubs like new bell house water pumps / open so you can see what you are buying. will let the motors go at $3,000.each

I think its cheap, if its in good shape and the combination is OK ..go for it !

 

[BDC1013]

found some others that are already assembled...

I have a pair of brand new GM Performance 454's. They were $5800 apiece at Summit Racing. They've been marinized by Falcione in Ohio. Stainless valves, Clay Smith cams (similar to Crane 741 but with a little more lift), Crane roller tip rockers, brass freeze plugs, felpro marine gaskets. They were run in on Falcione's dyno for 90 minutes.

They're at Shook Marine. $7500 plus shipping for the pair. I have almost double that in them with the mods and tax. Send an e-mail and I'll send you a pic.

What do you think?

 

[Ratickle]

There are some excellent deals out there currently on marine parts. Make your budget, don't be in a major hurry, and watch for exactly wnat you want within your budget.

 

[600sci]

no matter wich ones..make shure they have inconel exhaust valves !
and SS on the intake side

If u are not in a hurry i can get u some 540's NICE reliable for ~8-10 K each !

 

[old377guy]

Brian, ditto what Paul( ratickle) said. - Jeff

 

[old377guy]

any updates Brian?

 

[BDC1013]

no new updates... still "just looking" havent had a chance to go see the boat or do anything on it either. Been pretty busy plus im looking for a job right now.