The B20B head in my shed does NOT have this larger bolt hole below and near the thermostat orifice.
Is that hole on a pipe coming out of the front of the head? If so, the car head has two welsh plugs at the front of it, and this pipe might be fitted there instead of welsh plugs.

The B20B head in my shed has a cover plate over this orifice. It's used on FI cars.

PS: May be of interest - https://forum.cgoamn.com/index.php?topic=8810.0

PPS: Shop manual available here - https://www.manualslib.com/manual/1003752/Volvo-Penta-Aq105a.html#product-AQ130C

    DinoBru huh I'm surprised by that, the Volvo crowd pick up Penta motors for their crankshafts etc. I'll ask around some more.

        jamesinc Thanks jamesinc coz pretty soon the block will be cactus it's got salt water in it that I can only crank over by hand. To get it all out.

          Major Ledfoot that is a pipe hole for a stainless tube that's incorporated in the thermo housing. I have the tube it's removable. It's a ten bolt, pushrod type. A photo of yours will tell me if it can be adapted. Cheers

              DinoBru Here are the pics of my B20B head.

              This is the area near the thermostat housing. Note there isn't any hole for a sender, but there appears to be a flat which could carefully be drilled.

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              This is the RH side of the head, where there's a cover plate fitted to B20A and B20B engines (carb).

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              This is the casting number.
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              This is the front of the head, where there's a pair of welsh plugs. The bolt on the LH of pic is for an accessory bracket.
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                  That plate can be drilled for pipe and cover plate is where my temp switch goes. There is curves in the orifice between two and three intake pipes.

                  Major Ledfoot Yes !!!! They seem to be a head machinist told me that can be done. That's awesome Major Ledfoot now the 2 most important questions what state do you live in, and are you prepared to part with it.

                    DinoBru Sorry, I'm not selling any of my B20 heads. The one I photographed for comparison porpoises is about to head off to the machine shop for the engine rebuild of my 144, once all my new parts finish arriving from Sweden, Germany, and Only Gawd Knows Where.

                    @paul0075 in CBA might have a spare B20 head. @1971_144GL (also in LST like me) might have a spare he wants to get rid of. In Melbourne, try VolDat. And SA / WA / NT / QLD? No idea who might have old Volvo bits.

                    PS: Ideally, you'll want a late B20B head, which will already have the 44mm inlet valves like the Penta. B20E heads will have holes drilled for FI; B20A heads might only have the 42mm inlet valves, but have the advantage of more meat on them if they need resurfacing but the 44mm inlets can be made to fit. You will need to get the longer Penta manifold studs.

                        I have a B20B head, where are you located?

                          Rob I'm located in Adelaide, is it for sale, if so maybe send some pics that would be great. Rob.

                            I have a complete 1972 B20A in my workshop in Mt Gambier that is available.

                              Roinik great, was it running I'd have to see pics of the head while on it to see if it's compatible thanks Roinik.

                                I have to dig a bit to get to it. The head is the same as the B20B photos above, but with lower compression. It does have small valves and a 6-bolt crank, being a 72. I haven't seen it run, but I've been told it was running before it was parked. I did turn it over with a screwdriver when I pulled it about 2019. From memory it had about 130,000 country miles on the clock.

                                  Roinik as long as it's a 10 bolt and pushrod type. When you get around to pics that'll be fine. My pics are a B18 Volvo Penta it ran fine with it.

                                    Huh? You're obviously new to the marque. There's a 6-bolt crank (6x bolts in the flywheel) that is all Imperial and wider journal's, or there's the later 74+ crossover metric + Imperial 8-bolt crank. The latter can take the B21 pistons. The 6-bolt is more common, but reputedly suffered from the very remote chance of cracking a gudgeon pin. I suspect that failure was due to uncontrolled detonation.

                                    Either one will do what you want. Either one has the potential, with a lot of head porting, to make decent power numbers.

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