Mercruiser 5.7 260hp

[cvx16cvx]

I have a 1987 enchnater with a Merc 260hp 5.7 I/O. Boat runs great up to 4800rpm with a 23' mirage I am at 65mph. With an Alpha 1.
I want to go 70 mph.. Was thinking of going with an Edelbrock RPM Performer set of aluminum heads with the macthing intake carb and cam .. All Edelbrock, also was going to upgrade the ignition to all MSD.
With a $2000 budget I plan on buying off Ebay used heads and intake. I will buy the carb new.
Has anyone done an upgrade to their 5.7 260hp motor.
I would love to turn 5500- 5800 rpm all day! Any suggestions???
Should I buy a complete 7.4. 454 set up?
I just bought a new NOS Alpha SS lower unit case. Thanks cvx16cvx

[Boston Predictor]

when you do your cam you should do the timing chain and rockers too. get a double roller timingchain, and get some roller rockers. as for the intake manifold i would suggest the edelbrock victor jr air gap with a edelbrock650. that should bive you a substantial gain and alot more torque at all rpms...especialy high rpms.

[cvx16cvx]

Should i go with a B&M Blower set up??

[boatman4021]

cvx, just an idea. you should try the land and sea set back kit. it's a bolt on kit that should put you where you want to be or maybe more without giving up you stock engine. my friend has a 22' baja with the same engine and runs 66mph gps. the land and sea kit gave 7mph and his fuel economy is great. boatman

[happy]

i don't think that flat tappet engine is going to turn 5500 reliable. (all day long) it may if you convert it to a roller motor, but that can get expensive at the machine shop.. you may consider talking to your local merc dealer about a non current engine package.. you get the whole nine yards, engine , drive, shield , trim pump, and warranty to boot.. it'l be above your 2k limit.. but well worth it in the long run.

[vinny p.]

I have a 454 Magnum MPI that I dont need anymore if you are looking for 385 reliable horsepower.

[cvx16cvx]

Vinny P. how many hours?? How much do you need for it?? Do you have the harness?? Thanks Chris

[Eriktheviking]

You don't have room for a big block in that thing.Also you mentioned that you bought an S/S lower unit.Not sure if that S/S lower will work with that upper. I had one and I believe the upper case was different too.An Alpha s/s would probably work great on that boat.All that engine work is great but without good exhaust you won't reap the full benifits of it.Your current exhaust(if it's stock) is only 3".Those risers are very restrictive.

[bakedgoods222]

I'm not to sure about them land n sea setback plates they look goofy and Mercury has a bulletin saying not to use these. I'm sure they work but what is the cost in the long run? Stick to old fashion Horsepower for top end results. http://www.checkmate-boats.com/graemlins/thumb.gif

[vinny p.]

The major components are there. When I built my 540, I took the exhaust, pulleys and accessories, p.s. and oil cooler, motor mounts and bellhousing from the 454. The rest is there including all the wiring. The motor has never been raw water cooled, always closed cooling. I am looking for about $4k for it.

[daren34]

id try roller rockers at 1.65 to one and maybe a tempest plus

good luck
daren

[happy]

whats that new merc package??? i think its a 383, and i think the hp #s are above 340.. i havn't read all the specs on it.. but our shop is getting one to install.. should be here this week.. its a stroked 350.. and when i see it, and install it.. i'll let you know.. its supposed to be one rocking lil engine..

[daren34]

6.2 377 cid
320 horse

looks like bravo only

daren

[happy]

nope its a 383.. says so right across the cowling.. the merc site has very little about it yet.. i'm not sure what the hp is.. its either 340 or 360.. we expect to recieve this engine early next week.. and it is a bravo package .. will keep you updated

[cvx16cvx]

okay I am going to stay with a small block! Also keep the alpha set up with adding the SS lower unit. I was thinking og today taking a LS1 motor and marine spec ing it out.
Should I just do up the 5.7 260hp I have.. Going with some headers and Aluminum heads intake and hot cam???
I want to keep it reasonably priced. Are the 496 engines big blocks?/ Thanks Chris

[bakedgoods222]

Yes the 496 is a 8.1 liter Big Block

[daren34]

i would not go aluminum unless you are willing to go to fresh water cooling!!!


even lake water will ruin aluminum heads

i would go with better iron heads like dart

then 1.65 roller rockers you might make enough
horsepower to get over 70 without major work

maybe change cams while you have everything apart

you are already at 9.0 to one compression

good luck daren

i think you would be suprised at just the rocker arm change maybe try that before you spend the big bucks

daren

[happy]

wow.. we went from a 2k budgett.. to way off the wall.. what do you want.. and how much you wanna spend..

[cvx16cvx]

http://checkmate-boats.com/graemlins/devil.gif Okay so the budget has changed http://www.checkmate-boats.com/infopop/emoticons/icon_biggrin.gif but I want to stay low$$ Small Block. Maybe I will go with some dart heads or rework mine. Will Aluminum heads really be ruined by pond water??
What about the intake??
I found a clean set of used Edelbrock Performer rpm heads 64cc with the same manifold. Should I go this route?? Should I buy a crat 383 450hp set up? I can get one under $5K.
Cmon give it to me straight plan on pulling the engine next month...Thanks Chris

[happy]

chris..

the 383 is a small block.. same footprint.. and a nice package!!

daren... pm me if you'd like to see the pics..

[persuaderkurt]

Where do you get a crat 383 450hp for under $5k. Walmart? http://checkmate-boats.com/graemlins/Eyecrazy.gif

[SneakyPete]

Check Scoggin Dicky, you can buy a set of their high lift iron vortec heads with an edelbrock air-gap intake for $1,009. The heads can handle up tp .525 of cam lift. http://www.sdpc2000.com/catalog/2172/SDPC-Vortec-Cylind...ds-and-Head-Kits.htm (http://www.sdpc2000.com/catalog/2172/SDPC-Vortec-Cylinder-Heads-and-Head-Kits.htm)
Check either high performance chevy magazine, hot rod, or car craft as they did a vortec head build up and got 400 something horse for cheap money.
Vortec heads are great bang for the buck, I am going to go that route if my 2 bolt main targetmaster ever lets go.

[SneakyPete]

440 Budget Vortec Build - I know its a car engine, but it can give you ideas for the top end
http://www.carcraft.com/techarticles/81998/index.html

[bakedgoods222]

Check With Davison's Metro Power Center In Michigan they have long blocks of all sizes crazy cheap!! 1-(866)-593-8100 http://checkmate-boats.com/graemlins/Eyecrazy.gif

[persuaderkurt]

http://www.checkmate-boats.com/infopop/emoticons/icon_smile.gifI have heard of and am aware of the terms small block and big block, but what is a long block?

bakedgoods222 thanks for the info. I have a 5.7LX carbed and have been thinking of putting on a procharger. After all is said and done I am estimating the cost to be around $5k. $3.7 for procharger plus a new carb and prop should put me close to $5k. I will have to give Davison's a call. Maybe a new engine would be a better option. I can always sell mine to offset the cost of a new one.

I have always been very happy with my engine....just would like a few more ponies. http://www.checkmate-boats.com/infopop/emoticons/icon_wink.gif

[vinny p.]

The term "long block" refers to an incomplete engine that consists of only the block, heads and internal components. Sometimes it can come with the "tin", which means oil pan, timing and valve covers.

[jrumon]

cvx16cvx...
You can get some big HP numbers out of s mall block Chevy! Just for giggles, I had an "A-Class" Eliminator 23' cat offshore running a Merc speedmaster III and a very stout (nascar grade) 355ci small block on pump gas (93 octane) turning 108+mph for hours!

If you can scare up a newer style Vortec 350 or 383 from a competition ski-boat (300-340hp range), it is an EASY bolt-in and BIG difference for your performance goals (plus it's going to be reliable)!

If you decide to build your own, make sure its being built to MARINE SPECS with the highest quality parts (correct VALVES, PISTONS, RINGS, BEARINGS and SET-UP-SPECS are an absolute must)! Go to Amazon.com and order the book on "Building a Marine Performance Small Block Chevy"... I think it's by Peterson Publishing or S&A books? It has EVERYTHING you need to know for under $20.

[cvx16cvx]

Okay Well I am getting some great thoughts! The ski boat motor deal is the cheapest but i believe they dont run over 5000rpm.
Did I mention my goal is to beat my buddy.
He is running a 1971 Tahiti 18ft flat bottom with a 455 Olds Torker intake MSD set up with a berkley jet drive and a jetovater trim. It kills me that he is just a little faster....
In any kind of chop, lake chop that is.., I crush him. Well the engine is coming out onto a stand this week so please keep up the suggestions..Thanks Chris

[jrumon]

Chris... The ski boat motors are very stout and they have tons of torque... just what you need to turn that bigger prop!

Get yours out and look at it... You should be considering something fairly "heavy duty"... like 4-bolt mains, steel crank, good rods and rod bolts, good pistons, really good valves, etc. Some of the merc stuff is nice, some is just your basic truck 350. Put together someting strong, and again, to MARINE SPEC's! Some of the old HOT-ROD stuff works, but not always in a marine application... Jim.

[CheckmateFever]

I would love to upgrade my engine some day too. I like the ski-boat engine idea, where do you find them?? About how much are the going for?

Cvx, i'm looking foward to seeing what kinda results you get, it'll give me a good idea of what to do with mine eventually!!

[jrumon]

FYI guys... Want a quick 50+HP on your 260 merc for under $2000?

Performer RPM intake
Holley 750 marine carb
Competition Cam MARINE GRIND hyd. cam (comp kit)
Stainless marine performance small block manifolds & risers

Stock heads, stock shortblock, stock ignition. We did a "bolt-on build" to a 250 hour Merc 260 and pulled 315hp @ 5000 rpm on the dyno.

[Chris E]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by vinny p.:
The term "long block" refers to an incomplete engine that consists of only the block, heads and internal components. Sometimes it can come with the "tin", which means oil pan, timing and valve covers. </div></BLOCKQUOTE>

If your talking a Mercruiser engine, from the factory, their idea of a long block includes everything but ignition, fuel and exhaust manifolds - just to make things more confusing.

[happy]

i asked our machinist guy how to get a flat tappet 350 to roll in a marine version at 5500 rpm all day.. his response is.. why is nascar gonna run them?? how much money do you have??

[jrumon]

happy...
most of the new motors (vortec's) are hydrolic roller cams. They make tons more torque and very durable compared to the old standard flat-tappet ones. Sounds like your engine guy is too "old-school" or doesn't know enough at building a MARINE motor??? You don't have to build a "NASCAR" motor to turn 5500rpm!

Again, building a STOUT HEAVY DUTY motor is the same for performance whether in a car, truck, or boat... The marine motors are usually set up to a different set of specs to deal with the continuous full-load running & internal heat for long periods of time... That's why correct severe-duty VALVES are a must, along with proper piston & ring clearences, heavy duty bearings, using good oil & oiling system, etc.

[SneakyPete]

Is there machine-work required to put a hydraulic cam into a flat tappet motor? I thought it was just a matter of changing the cam, lifters, and pushrods...

[jrumon]

There are KITS for everything...

A flat-tappet referes to the cam & lifter design. The bottom of the lifter is "flat" and basically glides around the cam lobe. It can have either solid or hydrolic lifters (can is cut differently for type of lifter).

A roller cam set-up uses a lifter with a roller-bearing on the bottom and a special cam designed to have that roller on it. The advantage is less friction and more radical cam profiles to boost torque or horsepower. Sometimes they also require special valve springs and pushrods depending on the use and application. Roller lifters can be solid or hydrolic as well, and the roller can is designed for type of roller being used.

Hope that helps... Roller is a bit more expensive, but worth the effort! Sometimes you can use later-model factory "roller motor" parts at a good price! Jim.

[happy]

ok.. j.. show me 1 flat tappet small block chevy series engine thats in a boat that runns reliable 5500 rpm all day long.. now make it affordable.. aint happening.. the all day long 502's 500's 525's spinning 5200.. a dragster runs up high rpms and they gotta go thru them (engines) all the time.

&lt;&lt;&lt; an no j.. aint old school.. just trying to get people up to speed.. i hate people spending money on bad ideas.. and a small block running 5500 rpm all day long.. is wrong.. the approach to the whole idea of getting more speed needs to be addressed differntly in this situation. thats all..

there is new stuff out there that will get him the speed he wants.. and ultimatly.. at less cost.. but thats not what he wants to hear.. so

there it be..

and my machinist says... c'mon... meet us in the keys this time next year.. then we'll speak.

[vinny p.]

I am not a Nascar engine builder so maybe I dont know the rules. BUT, I thought that Nascar rules state they have to run flat tappet cams. Rollers would be a rules violation. I would bet the house that if they were allowed to run rollers, they would.

[cvx16cvx]

WHOA! Okay stop the bickering..I just want to go fast as cheaply as possible..Was thinking of doing a 383 kit to my Merc 5.7 260hp..I have not thought of running the Enchanter on the NASCAR circuit..I just want reliable HP with a higher rpm than 4800...
Yes I have seen automotive crate 383 motors for $3k..There is a dozen of them on EBay.
I might just go thru my engine and stroke it it go with Dart heads and make it a roller set up..Whew! http://www.checkmate-boats.com/infopop/emoticons/icon_biggrin.gif

[happy]

now your talking... up grade your crank to steel, roller set up on the top half.. nice carb, and exhaust.. you'll be doing fine.. and remember this.. horsepower is to prop diameter, as torque is to pitch.. thus you can utilize your horsepower to swing a larger diameter prop.. and increase your pitch for your increased torque.... what you'll find is you don't need to run 5500 rpm...

ps... nascar isn't running 20 yr old chevys.. heheheh my point was to make it spin that high all day long is expensive and crazy.. he's on the right track now stroke it and put some good stuff on the lower half to handle whatever upgrades he wants.. &lt;&lt;&lt; at the keys.. got work to do.. go luck with your project...

[boatman4021]

Remember what I said before. The lAND AND Sea stern jack will make you faster than your friend's jet boat with out giving up your stock, reliable motor or your fuel economy. If any thing, it will help out an gas consumption. So what if Mercury says not to use them. They also tell you to use only Mercury oil filters and gear lube! My friend has been running one for about 8 years without any problems at all. It's an easy 6-8 mph on your boat without pulling the engine or even removing the valve covers! boatman

[cvx16cvx]

I will definitley do a Land & Sea stern jack plus I am adding the Mercruiser SS lower unit with a high water pickup. Do you belive this combo will give 5-8 mph??? I still want to up my horsepower from 260hp to at least 300...
Will the out drive mods be the cheapest way to go?? Still have not found a stern jack anywhere but from Land & Sea there was one on Ebay but was sold before I got it! Anyone out there with a used one I am ready to buy Thanks Chris cvx16cvx@yahoo.com

[boatman4021]

The stern jack should give 6-8 mph with ease. You may have to change prop's. In most case's, you can run one size bigger when using a stern jack. I will be on the lookout for one. If I have any luck, I'll let you know. boatman

[daren34]

i thought they quit making the stern-jack for the alpha

daren

going to roller fulcrum roller tip rocker arms stepping up from 1.5 ratio to 1.65 ratio will almost get you the added hp you want

this will make you cam have more lift !!
and you have a lot less friction on top
this is probably the cheapest and easiest hp you can get

daren

[vinny p.]

Sorry to disagree, simply adding roller rockers, even ones with a larger offset, wont net you any noticable change.

[boatman4021]

I agee! Opening the valves just a small amount with a stock cam doesn't mean anything. A larger cam, different intake and carb, and a good ignition system might get you 25 to 30 extra hp.Even with small gains you increase rpm's and decrease reliability. To make large hp gains, you need to change heads or have port work done on yours. It all comes down to what you want. Just remember, the more you want to play, the more you gotta pay! boatman

[cvx16cvx]

Okay so I am going to stroke it out to a 383. I am choosing heads. I run 99.5% of the time in fresh water.. Still I am unsure if I should go Aluminum heads...Edelbrock, Trick Flow, Ar or go with some DART iron heads.
They all make marine spec heads.
I still want to keep a idle 500rpm to a redline 5500rpm.
I am definetly going with an Aluminum Intake. Probably a Sea Demon Carb. Maybe Edelbrock matching Carb and intake..
Sp any Ideas am I thinking straight??
Is 375hp to 400 hp too much for an Alpha SS drive matched to a 21' Enchanter hull??

[Big Dave]

Good choice to keep the rpm's down. Merc recommends keeping the propshaft speed down to 3750rpm's.
I am watching closely to see what to do with the 305 in the diplomat!!!!
Can you see a 383 in a 17ft boat????
Why would increasing valve lift from @480 to @512 not increase horsepower and rpm range?
not to mention the reduction in rotating friction??????

[boatman4021]

A small increase in valve lift without a change in valve timing(duration) just makes to hole a little bigger while still being fed by the same carb, same ports and same or less compression. While it may increase hp, the gain would be so small you would never notice. As for roller rocker's, they would help some, but again not enough to notice. Reducing friction is always a good thing, but it doesn't show up until you get into the higher rpm range. Back in my drag strip days, one of my racing buddy's had a machine shop and a dyno. He took a 350 Chevy that hit the dyno at 388hp with conventional 40 weight motor oil and switched to synthetic, hp was the same below 4000rpm's. At 6000 rpm's, 8 more hp. Synthetic oil will make more difference than just roller rocker's because it reduces friction in the whole engine. boatman

[boatman4021]

By the way, a great choice in heads for what you are wanting to build and keep the rpm's down would be the newer vortec cast iron heads. You can buy them ready to bolt on fairly cheap. boatman

[cvx16cvx]

Are there any Marine Spec Aluminum Heads out there?/ Is anyone manufacturing these for small blocks?? Any recomendations. Is aluminum a mistake? I am in fresh water 99.5% of the time.Remember this is going to be a 383 stroker idle at 500 rpm redline 5000-5500 Looking for 375hp..Single carb,MSD marine distributor, spark box, etc. etc.
<pre class="ip-ubbcode-code-pre"> </pre>Still havent found an affordable header set up!!

[boatman4021]

You can use the Edlebrock heads. I don't know of any difference in heads for marine or auto. Some of the ads that you see for crate motors say not for marine use. The reason for that is the gaskets. I checked into this for myself a few years ago. Everyone I called said that the metal on the head gaskets were not designed to withstand the corrosion that is seen in a marine engine. But don't just take my word for it, look in your hot boat magazine's and get some toll free number's and start calling. See if you get the same answer's that I did. The gm vortec head will give the performance that you are looking for. GM offers a 350 crate motor with these heads(or they did) that I think was rated at 375hp. I built my own copy of that same engine with a brand new set of vortec heads and it ran great. Only problem was, I put it in a baja. One of my weaker moments! boatman

[boatman4021]

I was wrong, the 350 h.o. crate motor is 330hp at 5000rpm. It's on sale right now for $3425.95 complete from carb to oil pan. http://www.crateenginedepot.com. They also have the vortec heads ready to bolt on for $268.71 each. You can see all of the spec's and part numbers for that motor on the above site. My guess is that you could build the 383 stroker from the 350 h.o. spec's and maybe a little more cam and reach your goal! Check out the crate engine depot web-site. boatman

[cvx16cvx]

Wow now I am really getting some good ideas.. Thank you everyone..This forum is great! Well motor is out and on a stand..It is incredibly clean for a 1987 Always a fresh water motor! I may just keep it as a spare and buy a 383 short block and go from there! http://www.checkmate-boats.com/infopop/emoticons/icon_biggrin.gif

[cvx16cvx]

Hey what about a crateengine.com circle track 350 with 400hp...It pushes 400hp at 500rpm and redlines at 5800rpm. Under $5K
Just thinking???

[daren34]

wow
probably still need to change the head gaskets
the marine one's use a stainless shim and fire ring

what about that reman 383?
any dealers here make you a deal?

daren

[boatman4021]

It would be my guess, that come spring, cvx16's friend with the jet boat, may be looking for someone else to pick on! boatman

[Big Dave]

Main other marine difference-
BRASS freeze plugs!!!!!
regular freeze plugs will not last a year

[happy]

we just ran that 383 today... in a 30 yoa 24' sea ray... ran a mirage plus 19 @56mph gps.. a typhoon 19 4 blade @ 52mph gps... its a runner.. hell of a package with all the bells and whistles... drop by daren.. and see it its way cool

[happy]

aint seen an alpha drive yet hold up over 300 hp.. &lt;&lt;&lt; just my opinion... i've seen bravo 1s hold up with a professional driver as much as 800 hp.. and also seen the xr's crater at 400 hp.. w/o a pro driver.. just food for thought..

[jrumon]

Alpha drive is a "weak link", but it CAN SURVIVE if you run it right. Merc used the Alpha with the hot 350/300HP Tempest (actually closer to 350hp), they also used it in 1986-1987 with the 454 mag (330hp) until the Bravo was finally released in 1988.

The keys to the Alpha surviving with more HP & Torque:
&gt;running GOOD synthitic fluid in it...
&gt;&gt;run a drive shower to cool the upper gear set...
&gt;&gt;&gt;making sure the outdrive is set up to proper specs (on the tight side to reduce gear lash)...
&gt;&gt;&gt;&gt;most importantly, not FREE-WHEELING it under full load (prop coming out of water and re-entering under full throttle load)... the Alpha tends to explode under harse load-unload-load conditions you can get in running a hot motor in a performance application.

[boatman4021]

Hey cvx16, you need to contact me asap for the deal of a life time! My buddy asked me to help him sell his 383 stroker motor. This motor would make your boat scream! I just posted it in the part's dept for $2000. He also has a set of vortec heads complete with rocker arms and Edelbrock intake for $500. These heads are like new and ready to bolt on! you can call me at 304-619-5185