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Old 07-02-2019, 10:22 PM   #1
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Join Date: Oct 2018
Default B21 Head on B230(?) engine?

Hi guys,

I'm very much a Volvo novice but I'm in a bit of a predicament getting my 1978 245 back up and running. The problem is that the B21 Kjet engine has developed some rod knock. However, a friend of a friend has set me up with a new engine, however it's a later engine out of an 84 car (which makes it a B230 I think?).

The real issue is that I need to get the car running in 2 days, and the fuel rail on the "new" motor has been damaged along with some of the wiring harness deteriorating. What I was wondering if it would be possible to put the old B21 Kjet head onto the new block to make a Frankenstein of sorts. I know the Kjet worked but I don't know enough to be sure that the two will work together. I don't need the engine to be perfect I just need to get it running again.

Thoughts? Criticisms?
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Old 07-02-2019, 10:44 PM   #2
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Join Date: May 2007
Location: PDX

It's a B23. Either way you will be fine.

Herr Harlard am Erstens

1979 242 DL

Originally Posted by t8fanning View Post
My knob has a big chunk of steel on it
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Old 07-03-2019, 12:17 AM   #3
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Join Date: Aug 2014
Location: Boulder CO

See this post for nice measurements and pictures of head gaskets and head combustion chamber sizes:

You should be fine with a KJet head on a B21/B23/B230 block, just be very careful not to damage any of the aging KJet pieces when you swap them over. You want the head gasket to match the cylinder size -- the head combustion chambers are all smaller and will work with with either smaller or large cylinders.

How bad is the rod knock? Maybe leave it as-is until you have a bit more time for it to be down.
'85 245glt b21ft aw71 k-jet -> lh2.4
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Old 07-03-2019, 01:12 PM   #4
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The rod knock is pretty bad, the car fortunately still runs but I don't want to tempt fate and drive it around. The car is parked at a friend's house so I'll see if he is okay with it being parked there for a bit longer
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Old 07-03-2019, 01:46 PM   #5
Ronald Culberbone III
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Join Date: Feb 2010
Location: Portland, OR

You will be fine running the b21 k-jet head on b23 or b230 block, just use a b23/b230 head gasket.
Cult Person. Pissing in your Kool-Aid.
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Old 07-04-2019, 06:18 PM   #6
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Join Date: Jun 2002
Location: S NJ, a suburb of Phila.

A B23 which your 84 engine should be will directly swap in. A B230 needs to have some type of adjustment for the a/c belt setup or use the newer accessory setup.
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