Reboring a B18 to 2L

Steve121 · Jan 11th, 2005, 19:08

Hi all, I have a 1968 121 with a B18A engine which needs a rebuild, got the head off to check bore conditions after suspected broken piston rings proved true, the bores are a bit damaged and would need reboring. I was thinking of taking it out to 2 litres and except from needing a B20 head and new pistons, was wondering if you guys know if anything else is needed or if indeed this is possible? would I need a B20 crank or are B18 and B20 cranks the same?
Any thoughts would be appreciated!

cheers

TomTom · Jan 12th, 2005, 16:19

I think that the crank and the flywheel are different for B18 vs B20. The conversion has been going on for ages, so go for it, but no more than B20.

It may be worth speaking to a Volvo expert to check that the work you're attempting is worth it (I mean rather than just buying a spare B20, if you can find one).

Tom

mike gilbert · Jan 12th, 2005, 17:39

I would advise looking for a decent B20 and using that. It may need new rings if its tired but it's unlikely to need new pistons and everything else you will have to get to uprate your B18. It will be much cheaper, quicker and easier. Also if you can get a B20E from a fuel injected car it will have bigger valves in the head for more efficient breathing but can be used with carburettors using very simple modifications.
If you do want to go down that route I may have a B20 arriving soon in a car that was to be restored but is apparently past it. If so it will be broken.
Mike Gilbert, 1800 Register.

Mike Arnold · Jan 12th, 2005, 22:45

When I restored my 1800cc 122 I considered rebuilding the engine but opted to buy a pre-built exchange from Tony Barrett (the "old Volvo man"). I opted for the 2 litre and it has been powerful. The differences between the B18 and B20 were exhaust manifold and crank breather.

classicswede · Mar 4th, 2005, 23:05

hi, my advice would be go for it. This is a very simple conversion to do, all you need is a set of B20 pistons and rings. you could also fit late B20 big vales by machining the valve seats and fitting ipd guides which are essential for running unleaded/lpg. if you would like more info you can call me on 01407 830 851 or 01407 832290. good luck

Jan 11th, 2005, 19:08	#1
Steve121 complete member Last Online: Apr 25th, 2024 13:56 Join Date: Dec 2004 Location: Wootton, Bedfordshire	Reboring a B18 to 2L Hi all, I have a 1968 121 with a B18A engine which needs a rebuild, got the head off to check bore conditions after suspected broken piston rings proved true, the bores are a bit damaged and would need reboring. I was thinking of taking it out to 2 litres and except from needing a B20 head and new pistons, was wondering if you guys know if anything else is needed or if indeed this is possible? would I need a B20 crank or are B18 and B20 cranks the same? Any thoughts would be appreciated! cheers

Jan 12th, 2005, 16:19	#2
TomTom Master Member Last Online: Jun 3rd, 2021 16:03 Join Date: Dec 2002 Location: London	RE: Reboring a B18 to 2L I think that the crank and the flywheel are different for B18 vs B20. The conversion has been going on for ages, so go for it, but no more than B20. It may be worth speaking to a Volvo expert to check that the work you're attempting is worth it (I mean rather than just buying a spare B20, if you can find one). Tom

Jan 12th, 2005, 17:39	#3
mike gilbert Master Member Last Online: Jun 3rd, 2024 13:52 Join Date: Dec 2003 Location: Peterborough View Photos By: mike gilbert	RE: Reboring a B18 to 2L I would advise looking for a decent B20 and using that. It may need new rings if its tired but it's unlikely to need new pistons and everything else you will have to get to uprate your B18. It will be much cheaper, quicker and easier. Also if you can get a B20E from a fuel injected car it will have bigger valves in the head for more efficient breathing but can be used with carburettors using very simple modifications. If you do want to go down that route I may have a B20 arriving soon in a car that was to be restored but is apparently past it. If so it will be broken. Mike Gilbert, 1800 Register.

Jan 12th, 2005, 22:45	#4
Mike Arnold Master Member Last Online: Today 09:05 Join Date: Dec 2001 Location: Stockport, Gtr Manchester View Photos By: Mike Arnold	RE: Reboring a B18 to 2L When I restored my 1800cc 122 I considered rebuilding the engine but opted to buy a pre-built exchange from Tony Barrett (the "old Volvo man"). I opted for the 2 litre and it has been powerful. The differences between the B18 and B20 were exhaust manifold and crank breather. __________________ Mike Arnold. 1966 122S

Mar 4th, 2005, 23:05	#5
classicswede Trader Volvo in my veins Last Online: Today 13:18 Join Date: Dec 2004 Location: Anglesey	RE: Reboring a B18 to 2L hi, my advice would be go for it. This is a very simple conversion to do, all you need is a set of B20 pistons and rings. you could also fit late B20 big vales by machining the valve seats and fitting ipd guides which are essential for running unleaded/lpg. if you would like more info you can call me on 01407 830 851 or 01407 832290. good luck

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