89 wellcraft 186 eclipse merc 4.3 alpha one

[unclebb]

jus signed up. so bare with me, i dont know how forums work. ..i have a question for someone who may have done the home work or a experienced person on the subject, can i add a 4 barrel to my v6? will it hurt anything, im getting mixed messages, i have a s.s 23p prop, im within 4400 - 4800 rpm wot. 2 people its great, i have to have people in the bow to plain with a load, i really dont wanna go to a 19p and loose alot of top end, im thinkin 4 barrel ? any thoughts? im open to trim tabs or other plaining devices??

 

[achris]

Thought about a ventilated prop, like a Laser II?

Chris..

 

[porscheguy]

I’ve got a ‘90 eclipse 196. It’s the same as yours with about a one foot extension in the back. I’ve got a thread in the prop section with my thoughts and data on several props I’ve tried out. My best performance top end was with a 23p laser2 at 52mph. I didn’t much care for the prop overall and it gave up a bit of acceleration. My preferred prop is a 21p mirage plus. I’ve had a bit of an issue all this year where I’m only hitting 4700rpm. Last year it would turn 4900. Not sure what’s going on.

Anyway, one caveat here. I’ve got a much newer 4.3 vortec engine in mine. It has the mercarb, so it’s rated at 190hp whereas yours is 165.

 

[Rick Stephens]

The extra 25 or 35 horse that would make a difference is more than just a carb update would accomplish. You might consider looking into what a set of Vortec heads, a Performa intake and an Edelbrock 1409 carburetor would set you back. That should accomplish getting you up around, probably over, the 200 HP mark and make a real difference. Rebuilt or new Vortec heads are not all that spendy. A 4 barrel Edelbrock Performa intake is the way to go for a freshwater boat. The 1409 carb is nice!

 

[Bondo]

Ayuh,..... Goin' to a 4bbl. will give ya an honest 20hp at top end,....

I suggest a Edlebrock 1409 which is an exact copy of the Oem Merc/ Weber/ AFB carb currently used, since the early '90s,....

If ya boat in the brine, a cast iron manifold, if in sweetwater, you can get by with an aluminum manifold,.....

 

[achris]

Change from 2 bbl to 4 bbl will give you 30hp (from 175hp to 205hp), but that's all at the top end, nothing 'new' low or midrange. Change to Vortec heads and you get another ~20hp at the top, and improved low and midrange as well.

Unless you need bow lift, and if you need to put people at the front to plane off, you DON'T, stay away from the Mirage props. Way too much bow lift for a small boat. When I had my 4.3LX (same engine as you, but with the 4bbl) I ended up running a 21" Laser II, and it was the perfect prop. Initially the dealer put a Mirage on, and I almost sold the boat because of it.

Chris........

 

[Rick Stephens]

You can get stern lift with trim tabs. I run Smart Tabs, they dropped my planing speed down to 13 or 14 MPH. I had them with a 3.0L engine. Probably way overkill with the 4.3L except the heavier motor made the boat too sensitive to trimming up. The Trim Tabs take a bunch of the porpoising out of the boat when trimming it out to scoot, and really soften how it behaves when crossing wakes. My wife loves them.

 

[unclebb]

what is a ventilated prop? if i change to vortec heads do i have to change the pistons? putting together the intel i received i come up with / 21p laser 11 prop (ventilated??) / vortec heads / 1409 carb / edelbrock intake / //////// TRIM TABS one guy said his wife loves them, well i guess after hearing what they do, my wife would too. i would like to be smoother going thru wake and kill some of the porpoising when trimmed up, if i do this beef up receipt the little top end i loose from the tabs i wont notice////// a friend had on his lower unit what he called a Dolphin, a plate bolted on just above the prop, anyone tried this doodad? whats it for? ive seen them on lower units///horsepower.....my 4.3 is only 165hp? doesnt seem like much for a 4.3 is this the engine hp or at the prop??

 

[achris]

It's prop horsepower. Crankshaft power is about 175hp. 4bbl carb and vortec heads will take that to about 220.

Avoid the plates/ wings/ fins that bolt onto the cav plate. Get proper trim tabs.

 

[Rick Stephens]

If you get serious about Vortec heads and intake, you can have a serious detailed conversation here on exactly what is needed. Vortec heads breathe a lot better than the older style heads. Chevy did a heck of an upgrade when they incorporated them into basically all their engines back in the mid 90's. While intake manifolds have to be changed with the heads, the exhaust stays the same.

One other thing of note, your '89 motor does not have a balance shaft in it. Balance shafts were added in 1992. While the balance shaft corrects for an unbalanced rotating assembly, smoothing out the vibrations, it also costs about 15 horsepower to spin. If you add Vortec heads and a quality intake carburetor combination, you will push past 220 horsepower fairly easily. Less costly than re-engining to a V8 for sure. Very straightforward upgrade of your motor while maintaining reliability.