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"Carbs are different: the 120B

"Carbs are different: the 120B uses the Zenith Stromberg sidedraft, the AQ125A uses the Solex downdraft. Other than that, both engines are virtually identical: same block (B21), same head, same cam, same crank, same pistons, etc.

If you ever need to replace your engine, consider marinizing a 1976 to 1982 Volvo 242 car engine, which is exactly the same base engine as the AQ120B-AQ125A. I have explained in other posts how to do it."
 
"Thanks El , The Carbs are the

"Thanks El , The Carbs are the only difference I can see just looking at the engines . But you may have the Carbs reversed , The 120 has a Solex sidedraft . The 125 has a downdraft , but I haven't looked to see what make yet . someone could have changed the intake and put a downdraft Weber on it . I know I don't like the Solex ."
 
"Just for kicks, read my post

"Just for kicks, read my post # 2 in this thread "Differences in AQ125A & AQ125B heads" on the BOC.
http://www.baylinerownersclub.org/forum/showthread.php?t=29309

I'll admit that I don't do quite enough with these great little OHC 4's......, (mostly V-8 work).... so I asked this question of my friend, and well certified Volvo Penta mechanic, Marc...... and the above was his response after having years of experience on these.

I've personally seen the difference in the length of the camshafts from the early 120 cylinder head to the later cylinder head.
Apparently, the early cam is shorter and remains within the aluminum casting at the rear, whereas the later camshaft extends a bit longer, causing the need for different machining at the rear of the aluminum casting.

Now, I may be off base here since the question is; "What is the difference in a AQ120-B and a AQ125-A"

."
 
"Ricardo, the AQ125A is a B21

"Ricardo, the AQ125A is a B21 block, identical to the AQ120B and the AQ140A except for little details, but the head is not one of them: the heads are identical. Even the AQ120B and AQ125A have the same cam - an A cam (the AQ140 has a V cam). You can verify this by having a look at the part numbers in the link below.

http://www.volvopentastore.com/ENGINE_WITH_INSTALLATION_COMPONENTS_AQ120B/dm/car t_id.033702254--category_id.333009--session_id.149972796--store_id.366--view_id. 333009


Your post in the above link dealt with the differences between the heads of an AQ125A (B21 block) and an AQ125B (B230 block). The Aq125A and the AQ125B are two different engines (different block, size of pistons, heads, cams, etc).

Leo, you are correct: the carb in the AQ120B is a Solex sidedraft, my mistake."
 
"El Pescador, Thank you for th

"El Pescador, Thank you for the clarification. Like said, I just don't work on these often enough to be fully up to speed on this.

Marc showed me the difference between two of the OHC cylinder heads, but apparently I have them mixed up.
So for my understanding...., is it then correct that the AQ 125A cylinder head uses a shorter camshaft? If not, which one does?"
 
"Ricardo, the AQ120B, AQ125A a

"Ricardo, the AQ120B, AQ125A and AQ140A are all B21 blocks and all have the same head (part number 463630). The AQ125B, AQ131A, B, & D and AQ151 A, B and C are all B230 blocks and have the same head (part 1346408).

Meanwhile, the AQ120B, AQ125A, and all AQ131 share the same A camshaft (part 1336767); and the AQ140 and all AQ151 have a V camshaft (part 1344662/1219032).

http://www.jn-wassersport.de/advanced_search_result.php?keywords=1336767

http://www.jn-wassersport.de/product_info.php?info=p5473_CAMSHAFT.html

You can also verify the part numbers for heads and cams in the Volvopentastore site

http://www.volvopentastore.com/AQ/dm/cart_id.033702254--category_id.342808--sess ion_id.895578978--store_id.366--view_id.342808

As you may see, the cams are interchangeable between the different types of heads, and I have never heard of any machining required. I'm not sure what your friend Marc's point was, but I admit I have not measured the cams myself. Perhaps your friend Marc would be better suited than I to answer your question.
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"Meanwhile, the AQ120B, AQ125A

"Meanwhile, the AQ120B, AQ125A, <font color=""aa00aa"">AQ125B</font> and all AQ131 <font color=""aa00aa"">(A, B, C, D)</font> share the same A camshaft (part 1336767)......"
 
"El Pescador, I don't doub

"El Pescador, I don't doubt what you are saying here...... and I have yet to speak with Marc again, but I got to thinking about something;

I wonder if the early cylinder head casting is longer (than the later casting), therefore making the camshaft appear to be shorter in this cylinder head!!!!
I know that Marc was clear to me that with the one head (apparently the early head), the camshaft came short of the rear of the casting.......,
whereas with the later head, the camshaft nestled into the rear of the casting!

And of course, this is "if" I understood him correctly! I'll have to ask him again next time I see him.

."
 
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