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.