Volvo MD7 cylinder head

[Dart Eighteen]

I have a problem with the cylinder head on my MD7B.
Does anyone know if a head off an MD7A would fit?
If not, has anyone got a head for a 7B they would be happy to sell?

Thanks in advance.

Ian

 

[VicS]

Different part numbers but the differences are not immediately apparent from the parts diagrams. Worth investigating further I would say.

MD6

MB7B

 

[Dart Eighteen]

Thanks VicS,

I have spoken to a Volvo engine dealer and they said a similar thing.
We checked out the various specs of the engines and found that the bore and stroke were the same, but the MD7B had 17hp as opposed to 13hp for the A. We came to the conclusion that they must have made changes to the head to get the extra power.
Thanks for your help.

Ian

 

[VicS]

Different valves. Larger ports perhaps on the MD7B.

 

[DerrickHigton]

MD7B

The MD7B was run faster to generate more power and the gearbox ratio changed accordingly. Otherwise, I believe the A & B are identical.

 

[Bilgediver]

I have a problem with the cylinder head on my MD7B.
Does anyone know if a head off an MD7A would fit?
If not, has anyone got a head for a 7B they would be happy to sell?

Thanks in advance.

Ian

I think you will find the MD7 is the engine type and the ABC suffix
is the number of cylinders. ie MD7A is one cylinder MD7B two
and MD7C three. The components are identical and drilled and tapped so that they can be used as any head on any pot as different bits are attached to each head such as stop cable brackets and starter handle mechanism.

It is possible MD6 and MD7 can be interchanged but unlikely as Volvo messed around with the block/liner/head joint area on all these engines trying to get it right so most are different.

 

[VicS]

I think you will find the MD7 is the engine type and the ABC suffix
is the number of cylinders. ie MD7A is one cylinder MD7B two
and MD7C three

No
MD6A, 1971-1975, and MD6B, 1975-1976, were both 10hp, at 2400 rpm, 0.63 litres
MD7A 1976 - 1981 was 13.4 hp at 2600 rpm, 0.77 litres
MD7B 1981 - 1983 was 17.5 hp at 3000 rpm, 0.77 litres

All were 2 cylinder engines

 

[Dart Eighteen]

Thanks for your replys.
Would the extra speed of the MD7B account for the extra HP?

Ian

 

[D244]

I have got a MD7 with MS 2 Gearbox coming available in a couple of weeks
Probable head Gasket gone on one pot but running fine until a month or two ago.