5.0 and 5.0 LX engines

[Rick Craig]

I had to replace my 5.0 LX engine this year due to cracked block and head. I found a good 5.0L. The LX was a 4 B carb and the 5.0 was a 2B carb. I put the 4 B carb on the 5.0 and the boat runs great. Does anyone know of any other difference's in these engine. Cam, Heads, etc. Or should I just leave well enough alone. Running a 17 pitch prop. Alpha 1 second gen out drive. 21 ft Crownline 210 ccr 1992 model. RPM range if I'm to belive the dash is 5500 most of the time. Speed is 45 -48 MPH.. Any help would be great as I can't find anything on the differences.

 

[Bondo]

Does anyone know of any other difference's in these engine. Cam, Heads, etc.

Ayuh,..... Welcome Aboard,.... The differences are the intake, carb, 'n decals,.... Ya done Good, be happy, 'n Go Boatin',.....

 

[flipbro]

If your RPM is correct your a little high and suggest bumping up to a 19 pitch!

 

[Bondo]

If your RPM is correct your a little high and suggest bumping up to a 19 pitch!

Ayuh,.... Good catch, I completely missed it,... gotta prop it up to hold 4800 rpms,.....

Probably gain abit of top-end too,....

 

[Fun Times]

Hi there, welcome to iboats!

If you bought an engine model/block similar to your 1992 year range than the main difference between the 5.0 L and LX is the intake manifold design and the size/model of the carburetor and in some cases (not yours) the ignition module may have a different timing advance range. You would have had to put your original intake manifold on your new block?

5.0L (2 BBL.) GM 305 V-8 1988-1995
5.0LX (4 BBL.) GM 305 V-8 1988-1995

 

[alldodge]

RPM range if I'm to belive the dash is 5500 most of the time

Get a hand held tach to make sure your rpm's are that high. At 5500 rpm your engine might be coming apart if held there, it should only be doing 4800 as others mention. Your 21 footer speed sounds about right around 45 mph (if this is GPS). You might be set up just right, just need to make sure before you start changing things

 

[Rick Craig]

I would like to thank everyone for you help. I got more solid advice here than from any dealer in town and Mercruiser put together. I do plan on putting a hand held tach on her this weekend. And the speed is GPS speed checked against the speedo. Speedo is about 2 MPH faster than GPS. But I have also found this to be the case in my truck. Truck is always 2 MPH faster. I have thought about changing the prop as this boat is 3900 pounds and struggles to get on plain with 6 persons on board. Thank god for trim tabs. 19 pitch is what I was thinking. But haven't gotten that far yet. I picked this boat up last fall and spent the season working out the bugs. Now getting about time to do some updates. I really like this boat might even restore her..

Thanks again for all your help.
Happy to be aboard...!

 

[Alumarine]

All things being equal if it struggles with a 17 pitch prop it's going to have more trouble with a 19.
Are you sure the trim tabs are going down enough for getting out of the hole?
Is the drive trimmed in all the way?

 

[harleyman1975]

I agree if 17 is struggling to get you up but possibly over reving maybe a 4 or 5 blade prop is in your future. I have a 20' Regal with a 5.0 2bbl and am fine tuning its holeshot. Switched from a 14 1/4x21 3 blade to a 14x19 4 blade and the boat liked that a lot! Little more top end RPM, better out of the hole, speed stayed about the same Top end RPM before was 4350 with 4 ppl and now its 4650 with 4 adults and full tank of gas (4800-5000 with just me) .

 

[thumpar]

Check the switch on the tach. Most have a selection for different number of cylinder engines. It could be set to the wrong selection.

 

[Rick Craig]

I checked the RPM's this weekend with my OTC meter. 4380 WOT. Me and the wife aboard. As far as Trim Tabs going down, They do on the trailer. I come from a large family. Most go over 200 pounds. I'm at about 1100 pound with 6 people. Then add coolers and regular gear aboard and a full tank of gas 60 gallons. Might just be the weight. as far as 4 blade props. I have thought about it. Any Ideas on pitch and size. I will check the Tach there maybe a switch on the back.

 

[alldodge]

I checked the RPM's this weekend with my OTC meter. 4380 WOT. Me and the wife aboard. As far as Trim Tabs going down, They do on the trailer. I come from a large family. Most go over 200 pounds. I'm at about 1100 pound with 6 people. Then add coolers and regular gear aboard and a full tank of gas 60 gallons. Might just be the weight. as far as 4 blade props. I have thought about it. Any Ideas on pitch and size. I will check the Tach there maybe a switch on the back.

Turning 4380 with a 19 3-blade and the weight your carrying your not doing bad. Going to a 17 3-blade should bring you up around 4600, so maybe a 15 4-blade will put you in about the same spot. This is just guessing but if you can find a place to let you try some. Now if your speed of 45 to 48 mph was gps, your not doing bad at all.

Now if you run with less weight you will need to watch for over revving.

 

[Bondo]

4380 WOT. as far as 4 blade props. I have thought about it. Any Ideas on pitch and size.

Ayuh,.... An inch or two, Less pitch than what's on there now,... maybe two, or 3,.... 4800 rpms at Wot, is Ideal,....

The pitch/ size might be under the prop nut,....

Diameter will be determined by the Engineers that designed the prop in the 1st place,....

 

[Rick Craig]

Pitch is 17 now. Can't remember the size, And your right I have to remove the prop to see the size numbers. Most of the time I have 2 to 4 people on board. No problems with plane or speed. I think there might be a place at the lake that has some used props that they will let me test. I know I have some wiggle room in the RPM range. And the speed is GPS when water was like glass little to no wind.

 

[Bondo]

Pitch is 17 now. Can't remember the size, And your right I have to remove the prop to see the size numbers. Most of the time I have 2 to 4 people on board. No problems with plane or speed. I think there might be a place at the lake that has some used props that they will let me test. I know I have some wiggle room in the RPM range. And the speed is GPS when water was like glass little to no wind.

Ayuh,.... You may want to take this conversation up to the Prop forum, 'n start a new thread in there,.....

There's a few folks in there, that don't often venture down to this forum,.....

Maybe link this thread in yer new Prop thread,... for the Info above,...