hi-performance 320 EFI
 

hello new boat owner
Bought a liberator 211 with a merc 320 efi whit alpha drive . and last summer i only got 4200 rpm at wot. have 14.5X21 steel prop. Read that they should rev about 5000-5400 Wot. someone who has experience with this engine, and what can cause these kinds of problems?

:worthless_without_p Rare bird. I think Sprink has some experience with that motor.

I had to replace intake and exhaust valves for a guy, he over heating the engine, tulipping the valves. This was in a twin Donzi, outside of that he was every happy with the power.

Are you having any problems other than low rpm? Liberators are pretty heavy boats if I remember right, If no problems I would try a 17-19 pitch prop. a 19 should put you around 4600 a 17 should put you right around 5000 rpms. Just a thought, Randy

A 211 should be able to pull a 21 no problem, if it's a known good prop. Do you know the prop is good? My 87' 211 would turn a 21" prop to about 4600, and a 19" close to 5k, which was to high for my motor. This was all with the 350/260 about, 52-53mph. What is the ratio of that drive? That's a great motor and should put you on par with the 454/330.

211's Love the 21" ballistic prop.

Old age must be setting in, I forgot the alphas come in different ratios for 4-6-8 cyl engines. I believe it should be 1.47:1 for a V8 1.6something for a 6 & 1.8 for a 4. That would make a Big difference. Randy

Most of the 320EFI packkages that I've sen were fitted with 1.32:1 ratio Alpha drives, hence the 21p prop. Was probably fine for the day but the motor could be very tired by now.

I had an '86 272 LS Formula with twin 320 EFI's on Alpha SS drives...1.5 ratio. With 23" Cleavers RPM was in the 5800~6000 range!!! One of the fastest boats i ever had. I ran the bejeezus out of those motors and sold the boat with 300 + hours on it. It ran 75 the day I sold it....wish I still had it.

Wow, was that stock??? I have a co-worker with an 88 or 89 with 320's and he see's about 65, but no SS alpha's. It's a nice package, to bad it's cost killed it.

That's correct, my Lib had a 1.47 ratio behind the 350/260. I thought there was a lower ratio though as already noted above. If so, that's probably to much prop. Need to know what he has before anything get accomplished. I would expect the 320EFI to push that boat somewhere in the 55-58mph range'ish when propped correctly (very similar to the 454/330 speeds), though I've never actually seen one with a 320EFI.

It very well may be a tired old girl.

Just like Formula delivered it...I watched it go thru the old Miami plant and took delivery at the plant dock. I remember the Engine/Drive foreman remarked that the SS drives were shorter than the standard Alphas. Those motors made power all the way up to 6000 RPM. I ran that boat about 6~8 hours before I ran it over 50...after that I RAN it. I had a '88 'vette that had the same engine in it that was the same way...it just screamed. The only Pre Vortec Small Blocks I had any thing to do with that were stronger were 1970 LT-1's 350 Cu In/370 horse solid lifter motors that were wound to 7000 on several occasions. I drove Diego's sweet '89 272 SR-1 a few weeks ago with "massaged" 330 Horse 454's and it brought back memories of my '86. His 454's felt like a solid match on the "dig" for those 320's but his boat is done at 65...the EFI 320's just kept pulling all the way to 75.

Remember...1986...there weren't many Factory Boats that would run 75 MPH. I had a boating friend that had a '86 302 SR-1 with the cut down windshield and bolsters that couldn't get close to my 272 until the seas got to 3~5. I HAD to slow down to about 50 to survive and he could run past me at 65 no problem in the rough stuff with twin 400 horse 454's on TRS Drives. Honestly...those EFI 320's sounded like a Skill Saw cutting through 1/2" plywood at 5500 RPM. Those were the first marine engines I had where you could leave them for two weeks, walk out ,bump the starters and they would fire right up.

Twin 320 EFI's with Alpha SS drives were legendary performers. I'm like a kid at Christmas waiting to see how my old '79 255 Formula Liberator is going to compare with twin 400+ Horse Vortec Roller cam Motors on Bravo I's:evilb:

Awesome! Ss's, why don't we have them again?!

Mercury likes to exercise control. I have heard the guys at the upper end of this game discuss new projects from time to time and one recurring theme is to see how much you can accomplish without going to ANYTHING Merc.

Engine is renovated by the previous owner in 2008, and the drive gear ratio, I have no idea what is. can i find it somewhere on the drive? ordinary steel propeller that previous owner put on.
only problem is the rev problem and the speed im getting is 49 Mph(gps)

Poor mans way would be to mark the propshaft then turn the engine over with a socket 1 turn. Thepropshaft should turn approx. 1.5 turns or in sprinks boat it would be 1.3 then you will have an idea where its propped. Randy

do a compression test 1st...then go from there...

Determine drive ratio, if it is 1.32, then you need a 19" prop. 49 mph is not far off from typical 350/260, but that engine isn't making peak power at that rpm, a compression check wouldn't hurt either.

EDIT: and throw that aluminum prop in the garbage.