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Penta Faq

box car racer said:
So what is the "super marine block"? Do all 90+ blocks have big rods and mains? At what point and why did they switch to the 250 and 251? does a 90+ 250A have small rods and mains?
Click to expand...
All Penta engines manufactured after -89 based at the B-230 block have the late style crank,the same size of mains but a different placing of the radialbearing (in the rear instead of the middle at early version). The rods are also the better ones (with a thicker cast)
 
I think that, just like the car motors, the crank changes showed up in 1987. I have a Penta AQ171 on the engine stand in the barn. It has an 87 block stamp date. The crank has the thrust bearing on No. 5 and has the 63 mm bearings. It does have the skinny rods. The block is stamped K on the driver's side, in the middle, near the deck.

Dick Prince is using an 87 block in his race car, www.ovlov.net because he had one and it had the crank improvements.

Philip Bradley
 
pbonsalb said:
I think that, just like the car motors, the crank changes showed up in 1987. I have a Penta AQ171 on the engine stand in the barn. It has an 87 block stamp date. The crank has the thrust bearing on No. 5 and has the 63 mm bearings. It does have the skinny rods. The block is stamped K on the driver's side, in the middle, near the deck.

Dick Prince is using an 87 block in his race car, www.ovlov.net because he had one and it had the crank improvements.

Philip Bradley
Click to expand...
is it a a or c? the spec i posted on which models had the big mains is straight out of the volvo greenbook for penta.
 
I called a boat yard that deals in engines and asked about purchasing a 2.5L Penta crank. It said his supplier needs the crankshaft forging number. Wondering if this is the same as the part number? If not what would it be for a late 2.5L penta?
 
yama said:
I called a boat yard that deals in engines and asked about purchasing a 2.5L Penta crank. It said his supplier needs the crankshaft forging number. Wondering if this is the same as the part number? If not what would it be for a late 2.5L penta?
Click to expand...
early = 855482-6
late = 3514121-7
 
AQ151's only come with 531 heads? Is there a 160 head? Where are the numbers? What about head with casting numbers 1000160 , 463360 , 6770 and 850/4. Sounds like a 160 head?<TABLE cellSpacing=0 cellPadding=0 width="100%" border=0><TBODY><TR><TD>
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n xntrx volvo said:
Stoker/ crank info
​
The aq151 and aq171 had a 86mm stoke crank. This compares to normal Volvo Auto 80mm, giving them a 2.5 liter displacement. These crankshaft are direct replacements for b230's.
The letters after the Penta number are important. Stay away from the A. It had small mains and was based on the 9mm rods. Early Penta motors, just like early B230s, had less desirable bearings and bearing location, and rods. Blocks produced before 1988 used small mains and 9mm rods, 1988+ = 63mm mains and big rods.
All penta cranks are forged. They will have a thick parting line on the counter weights.
Breakdown by model
- Small
AQ131A, AQ131B
AQ151A, AQ151B
AQ171A, AQ171B
-Large
AQ131C, AQ131D
AQ151C, AQ151D
AQ171C, AQ171D
sp 230 (all)
sp 250 (all)
sp 251 DOHC (all)

Rod / Piston interchange
​
Click to expand...


Are you, ah, sure about that last line in the paragraph?
 
I might go pick up a non-crossflow, pushrod, ohv AQ120 this weekend. It's complete from carbs to pan with a box of new and used spares for $99. I hoping it's only seen freshwater. I realize the carbs are garbage.

I'm mainly interested in the exhaust manifold as a possible starting point for a log turbo manifold for my 122s.
aq120%204.jpg


Any information on these motors?

6 or 8 bolt crank?

I've only seen what's available here:
http://www.volvo.com/volvopenta/na/en-us/marineengines/outofproductionengines/gasengine/sterndrive/

thanks,
curtis
 
undrtw said:
I'm mainly interested in the exhaust manifold as a possible starting point for a log turbo manifold for my 122s.
Click to expand...

note the Freeze plugs in the mani this because all the boat engines have a water jacket around the primary's
 
ravennexus said:
note the Freeze plugs in the mani this because all the boat engines have a water jacket around the primary's
Click to expand...

Thanks, i didn't realize that's why it was so fat. I'm not really a boat guy, so i didn't even consider that.

much respect,

curtis
 
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