Cylinder Heads - What is the difference between Models?

[jnnngs]

Hi,

I have just bought a '79 Z model, and believe it has had the cylinder head replaced at some point.

I am trying to find out what head it has, and to understand any differences / implications. So, what are the differences between the Z / A / B / C models? Are they all compatible across the various models?

I believe the B / C models have different carb connector / rubbers - is this a difference with the head and/or the carbs?

The head I have is stamped:

20150826_184135.jpg

Any idea what model it is off?

Similar question on the cam cover - the only difference I am aware of is with the bolts/rubbers which clamp it to the head, how can you tell which cover you have?

Thanks,

Paul.

[daves79x]

'79 and '80 heads are the same. '81 and '82 heads had larger stud holes for the center 4 studs, but reportedly still seal OK with the early smaller studs. So any will fit early models, might be tight on the center 4 or need drilled out to use the early one on the late. Those numbers you show might mean something, but have nothing I know to do with what you're asking.

Carb angle is only due to intake rubber differences.

'79 cam covers are unique with small grommet sealing surfaces and all '80-'82 covers had the larger flat sealing surfaces for the larger grommet rubbers. Bolts have different part numbers but any set will work. Any cover will work on any year with the right grommets.

Dave

[jnnngs]

Dave - Thanks.

On the carb rubbers, not sure I understand. So can you use the later rubbers on the earlier models (or vice versa)? Any benefit in doing so?

On the head, can't tell for certain externally whether it has the larger holes for the centre studs, but think it does. I compared it with a Z model, and externally the only visible difference I could see was above the intake ports - the ribbing above them is different.

The "unknown" head:

20150827_123251.jpg

A Z head:

20150827_123309.jpg

(The Z model head is stamped HF-1 versus HF2)

Anyway, my real concern is that if it is a B/C model, then once I get it vapour blasted to clean it up what the finish will be like given that it would have been sprayed black originally (you can see a difference in the quality of the casting in places). Hopefully it will be OK.

Paul.

[jnnngs]

Hi,

Took the head off and confirmed I have a later B/C head. As far as I can tell the differences are:
- stud holes around cam tunnel are for 10mm studs rather than 8mm
- ribbing on inlet side at top of head is different (exhaust side is the same)
- fins on side of head are thicker / squared off - head was black, with polished fins on the sides.
- B/C head is stamped HF2, the Z's are stamped HF-1, not sure about the A

Paul.