First off, let me tell you that I am a rank amateur at this stuff, so please use fairly small words when you respond.

I recently learned from what is considered a reputable mechanic that my B18 engine w/20 head has burnt valves in 1 and 4. I hope to do some of the work myself - this is a NEW hobby rather than a driver. Anyway, it can sit while I get to the job.

I have been offered a '75 B20 head with filled FI ports which appears to be in good condition for a reasonable figure. Claim is that the valves are unleaded ready and it is ready to go.

Is there any down side to using this head?

Better to simply take the old head in to a local mechanic than fool around with replacement?

Will my Volvo dealer be able to supply gaskets, head bolts, etc., etc.? What else do I need for a swap/renew job?

Do I torque the '75 head differently than one would an older one?

Will the old valve cover work?

How many more questions should I ask?

Thank you Lee B

I agree with Phil about the mismatch!

I think you should consider two questions.

First, is that truly the problem? If you describe the symptoms in some detail someone here should be able to support or question the diagnosis.

The other question is more major--what caused the valves to be bad?

--valve recession is caused by burning unleaded fuel (usually over a long period of time) without putting in hardened seats

--the valves could have been adjusted too tight, either because someone just screwed up or because they were trying to compensate for cam shaft lobes going bad

--misc. other causes.

The point is, you won't know what you can and cannot do until you get the head off the engine and take a look inside. If you are, as you say, a novice, tearing into an engine might be intimidating. Really, though, it is not that hard. You might want to look at www.vclassics.com, where you will find some great articles on engine rebuild.


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Tim--'72 ES, '90 240

Kind of a silly suggestion, but it really helps to have a spare engine on-hand.

I got a spare B18 with my 122, and I've completely disassembled it for a planned rebuild (which will be my 1st tme doing anything that major). Anyway, my point is that when you have a spare engine or component to look over, you start to feel more confident that you can tackle something like this. I think you ought to take that B20 head, just as a reference model, if not for any other reason.

As PhilS says, don't put a B20 head onto a stock B18 block. The article "How Not To Rebuild an Engine" over at VClassics.com should tell you why. That said, I'm not sure if that valves themselves would be different. If your valves are burnt and you just need some replacements, the B20 valves may work - especially if they have the "stealite" (?) coating. Check over at ipdusa.com for more info on that.

That said, anyway you look at it you'll probably end up pulling the head off and taking it to a machine shop. That won't cost you an arm or a leg, but it is very likely where you're going to end up so unless you need the car tomorrow, you ought to learn how to do it. Keep in mind that you'll need a new headgasket and likely new head bolts, so be prepared to go the distance before you start disassembling.

That is, unless you happen to have a spare engine... :)
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1967 P220 Amazon, 1972 145S, 1976 245 DL, 1983 245 DL, 1986 745 GLE, 1990 745 GL, 1995 945....
You mean to tell me that Volvo makes cars that are *NOT* Wagons?!?

I've put a B20 head on to a B18, it's no problem so long as you use the B20 head gasket. Compression will be down, but it will run fine on the cheapest petrol.

I've heard it said that You do not want to put large-diameter combustion chambers on narrower cylinder bores, but stock bore B20's have a larger diameter combustion chamber than the cylinder bore too.

If you have a healthy B18 bottom end needing head work, I would trash the B18 head & use an unleaded B20 head. Ideally, get a professionally ported head. It's a one time investment that lasts practically forever.

In Phil's "How Not To Rebuild an Engine", the problem is the opposite, a B18 head is fitted to a 2130cc engine. This would produce too much compression, thus making it very picky to tune. A quick fix would be to dump some compression by tightening up the intake lash.

Lee, I don't think it's at all efficient to use a B20 head of any sort on a B18 bottom end, unless the block has been overbored to B20 specs at some point (in which case it's a great idea). Do you know if yours ever was?

The engine was rebuilt, I know. I do not know, however, whether it was rebored. Could this, perhaps, explain the burnt valves??

Thanks

How much are we talking for Joe Average's machine shop to overbore my b18 to a b20 specification? Other than new pistons and rings what else would be needed to purchase?

I think you are talking hundreds of dollars. Plus you risk hitting a "void" which have been known to be in some B18 blocks, thus ruining your motor. B20 engines are rather common, so why bother boring a B18 out to a B20?
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1967 P220 Amazon, 1972 145S, 1976 245 DL, 1983 245 DL, 1986 745 GLE, 1990 745 GL, 1995 945....
You mean to tell me that Volvo makes cars that are *NOT* Wagons?!?