Nov 8, 2012

Fitting cylinder head

After 13 years and a last inspection of the pistons and bores it was time to fit the cylinder head of the B20B engine. First I fitted the new water pump. The pump came with two sets of rubber rings: 1 set with a height of 8.5 mm and the other one with a height of 9.5 mm. The 8.5 mm rings are for the B20B engine which has a thinner head gasket than the B18 engine.
I lubricated the new tappets inside and out with assembly oil and put them into the bores. Be careful not to drop them in the sump...

New tappets and original pushrods Volvo B20B engine
New tappets and original pushrods

Tappets fitted in their bores Volvo 122S
Tappets fitted in their bores

After the bores and pistons were also lubricated with an overdose of oil the gasket was alined with the bolt holes and the cylinder head was placed on top of it.

Cylinder head gasket alined with bolt holes Volvo 122S
Cylinder head gasket alined with bolt holes

"TOP" is on top of cylinder head gasket Volvo 122S B20
Make sure the word "TOP" is on top :-)

Before that I cleaned and checked all the cylinder bolt holes just by putting in the bolts and made sure they went in all the way.
The cylinder head bolts have to be tightened in a special sequence to the first torque of 39.5 Nm. There will be two more stages of thightening...

Old -  and new cylinder head bolt Volvo 122S
Old -  and new cylinder head bolt

Tightening sequence of cylinder head bolts Volvo 122S B20B
Tightening sequence of cylinder head bolts

Next thing to do is fitting the pushrods on top of the tappets. The rocker shaft and arms were already assembled so after good lubrication of the shaft I fitted it to the head with a torque of 33.5 Nm.

Lubricating the inside of the rocker shaft Volvo Amazon
Lubricating the inside of the rocker shaft
Turn the arms until you see the holes in the shaft underneath

Rocker shaft bolted to the cylinder head Volvo 122S
Rocker shaft bolted to the cylinder head
According to the manual you have to tighten the cylinder head bolts to a torque of 78.5 Nm after the rocker arm assembly has been refitted. But...... as you can see 5 of the 10 bolts are underneath the rocker arm.... There are special spanners/sockets for this but they are very rare and expensive so I did it the cheap way: taking off the rocker assembly in order to tighten all the cylinder head bolts.

Example of the special Cylinder head bolt spanner Volvo 122S
Example of the special spanner (thanks  for the pic Mr Popta)

After refitting the rocker arm assembly for the second time the valve clearances have to be adjusted. The valve clearance is the gap  between the cam/pushrod and the top of the valve. For a Volvo B20B engine the clearance is 0.50 - 0.55 mm (both inlet - and outlet valves).  

Cylinder 1 in TDC --> adjust cylinder 4 valves
Cylinder 2 in TDC --> adjust cylinder 3 valves
Cylinder 3 in TDC --> adjust cylinder 2 valves
Cylinder 4 in TDC --> adjust cylinder 1 valves

* TDC = Top Dead Centre - the point that both valves are completely closed


Valve clearance adjustment Volvo Amazon 1969
Valve clearance adjustment
Rocker cover fitted Volvo B20B
Rocker cover fitted





6 comments:

  1. I really liked the b20b engine, I've used it in my first car (Civic 1994), I change my b16b engine, with a b20b to get better acceleration. And my machine was very satisfying. nicee

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    Replies
    1. This step by step is for a Volvo b20 engine. Notice only 1 overhead cam on the exposed head. 🧐

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  2. Are the Honda B20 and B16 engines the same lower with different heads? Cand the heads from the Honda go on the Volvo Block? Please advise.

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  3. Japtuners please: This is a 1960's Volvo engine. It has nothing in common with a 90's Honda engine.

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  4. Is the rocker shaft torque the same for the B18B engine as for the B20?

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  5. Hi,
    We are in the process of restoring a Volvo 122S from 1965 and would appreciate any help finding out the correct colour of the engine block. Do you have a colour reference?
    Thank you in advance,
    Tiago

    ReplyDelete