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Need help with 1973 b20 aq151c

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Junkinmike

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So I bought this 1973 boat with a b20 aq151c it has no prop. What size do I get and what hardware do I need to install it?? I’m trying to upload pictures but cannot get it to work.
 
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Junkinmike said:
So I bought this 1973 boat with a b20 aq151c it has no prop. What size do I get and what hardware do I need to install it?? I’m trying to upload pictures but cannot get it to work.
Click to expand...

The 151 was not available in 1973, so I guess the boat has had a new motor. Equally important to know is what drive you have. If it is still the original 1973 drive, props will be different. If you have a 290single prop drive, that the 151 usually came with, you need a short hub prop. The size will be difficult to guage without knowing a bit more about the boat. Mine 151 is in a 19 ft cruisier that weighs about 1400kg and is fitted with a 14x17 left handed prop.

the 151 is a B230 engine BTW. It's a 2.5 litre version of the B230 2.3 litre engine that Volvo used in cars. The B20 is a 2.0 litre unit.
 
Yes..... J25ELCI is correct. The 151 engine was not available for marine use in 1973. Someone has changed it and the Flywheel Cover.

In 1973, the OEM stern drive would have been a 250.
The 250 has a small diameter main drive gear male yoke shaft, is has bevel cut lower unit gears...... but is plenty stout for the 151.
Use ONLY 30 W Engine oil in the stern drive!

Correct again..... this lower gear unit will not correctly accept the long hub propeller due to the position of the 250 exhaust outlet housing and the spinner arrangement. (you may do a special SS Safety wire spinner keeper arrangement...... but the exhaust outlet would need to be replaced)
However, it will accept any of the other OEM short hub propellers.... either in LH or RH.
LH prop works best with the smaller 250 Tim Fin/Torque Tab!

volvo penta 280 vs 250.jpg

Along with a propeller, you will also need a "short" spacer/line cutter, a SS locking washer and a 1 pc spinner (cone nut).


Volvo Penta short spacer line cutter .jpgVolvo Penta early locking tab washer .jpgVolvo Penta early spinner .jpg



As with any boat, prop selection is typically "trial-and-error".
You will want to test an array of propellers until you achieve the correct OEM WOT RPM and with the hull loaded as you normally would.
In other words....... with the Engine in full tune, and with the hull loaded as you normally would........., the correct prop diameter and pitch will allow the Engine to reach the WOT RPM. This is a TEST RPM only, and should not be sustained for any duration.

See your OEM specs for the WOT test RPM.


Good luck.
 
The block is stamped b20 and has aq151c on it at well. The drive has 270 on it. I’m new to all this just thought the boat looked really cool and would be fun to restore. It’s a Glastron gt150 like the boat used in the old James Bond movie but I am going to need all the advice I can get. Wish I could figure out how to post pics
 
I’m looking at a prop on eBay that has the nose cone as well. The guy says it came off of a 270 so I guess I’m going to start with that?
 
Save the "named" photos to a file folder on your PC.
When back at MarineEngine.com, place your cursor in the text field where you would like the photo to appear.
Click on the "insert image" icon.
Next, invoke the tab labeled "from computer".
Click on "chose file".
Locate the image file and click on it.
Next..... click on "upload file".

The image should appear within the text field.

The system will let you post one image at a time.

Once the image appears, you can go back and add text above or below it.



OK..... the 250, 270, 275, 280, 285 and first gen 290 rear covers will interchange. So, it is not the best method to determine which drive you have.
Pictures of the engine and stern drive would help!


.
 
...re photos on this site.. They are size limited. If too big theywon't upload. You'll need to use a program like "paint" to resize them.
 
If it says B20 on the block, then that's what you have. It will be the 2.0 litre model. Does it have twin carbs? If so, it may be an AQ115 or an AQ130 with an AQ151 top cover. Or have you simply got your numbers muddled and it says AQ115 rather than 151?
 
Yes it has twin carbs. I will go check the number again I had my son read them off to me because I’m half blind I still cannot get pictures to load
 
Its hard to say what prop would work good on your setup. Is the engine running close to 100%. How much does the boat weigh with fuel, gear and bodies? You will need all the parts Rick showed. I’m gonna guess 14X17L with a healthy maybe 14X19L short hub only!
 
Junkinmike said:
250 stern drive?
Click to expand...


From what I can see in the photo, yes.

The 250 will:
..... have metal inserts at each side of the main suspension fork (for the reverse latch anti-rotation pins).
..... have an oil cavity drain plug in the Intermediate housing just below the shift mechanism cover.
..... be absent an oil fill port at 1:30 O'clock position above the eccentric piston area (transmission area).
..... be absent the female threads in the prop shaft for the spinner locking bolt.
..... have an exhaust outlet housing that does not protrude past the lower unit housing.
..... use the small rubber bumper on the transom shield.
..... use the small collar steering fork vertical shaft.

What the photo does not show would be the smaller universal shaft's male yoke, nor does it show the bevel cut gears of the lower unit.


While it may be older and have the items listed above, is still a good drive and should not give you any trouble behind a smaller engine.


.
 
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