I need a question answered and hopefully you guys can tell me. I have a B21 block from 1981 and a good head from a 1983 B230 at the machine shop. Will the head fit the block without any problems? It will be carburated so the sensor ports won't matter. Mostly concerned about interference, proper compression, parts fitting like head bolts and gaskets.

BTW this is a marine engine. The original head has bad corrosion on the #4 exhaust port. The machine shop is experienced with foreign engines but they don't have a final answer for this. They suggested coming here to see if anybody has actually done this. Thanks in advance.

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i'm pretty sure you can NOT use a b230 head on a older b21 engine or even a b23 engine.

 

Well now I'm really confused because someone just sent me this link about an hour ago and I gave the machine shop the go ahead.

What Are The Differences, B21, B23, B230? - Turbobricks Forums

Post #5 seems to say they are interchangeable. Are you 100% positive?

 

per that link, b21 has a different bore size than the b230 (92 v 96mm). that alone says no way.

b230F head



b230f block top




i dunno how a different bore head would fit on htat.

 

In other words you're guessing.

Using a headgasket to match the head, the only problem I see is lower compression. The deck is cast iron so no sleeve to try and match up to. The machine shop guy didn't seem to think it's a big deal either.

 

I guess. if the bolt patterns match, and teh coolant and oil ports match and the cam works, I suppose. but why not just put a b230 block in that car in the first place? they are available used all over the place in rotted out or wrecked volvos.

btw, I thought the b230f was new in 1985, either you got the year wrong on that head, or its a b23f head

 

Sorry I forgot to mention this is a marine motor actually in a boat. The gunnel is 6' off the ground in the driveway. The logistics of pulling a head vs pulling the entire engine is huge. The block is in great shape. The whole engine is in great shape except for the #4 exhaust port is corroded and leaking. It runs excellent but carbon monoxide is not something to mess with.

You're correct I don't know the year of the newer motor. All I know is the Volvo-Penta AQ125B is a B230 motor. I found a guy here in Seattle that knows these motors and he told me it all depends on the year of the B230 head. Early models should work, later models might not depending on the size of the combustion chamber. If the chamber size fits inside a B21 headgasket it should be fine. I told the machine shop to buy a gasket and check it out.

BTW I may have a good Marine B230 block available in the Pacific northwest if anybody wants it.