Ferguson TO20: Z129 head on Z120?

[ironandsteel]

I am in need of a head for my '51 Fergie TO20 (continental Z120 engine). I'm having a hard time finding a Z120 head, but I think the Z129 heads are more available.

It seems that the head from a Z129 (from a TO30 I think) will fit, but the combustion chamber is smaller and the compression ratio would be raised.

If this is the case- what is the down side of more compression?
Harder to crank, I assume, but I'll be changing to 12v
Would it run hotter?

 

[Jerry/MT]

The Z129 head has a higher compression ratio, bigger intake valves. The higher compression ratio means a higher peak temperature and the bigger valves will have more airflow. You may need to re-jet the carb for the increased airflow but you might get by with just some enrichment on the existing power jet. TO-30 timing was a bit different but I am unsure of any cam differences.

 

[ironandsteel]

That sounds pretty good to me. I think I would just buy a TO30 carb. Thanks

 

[Steve@Advance]

No need to buy a different carb. The carb is sized to the engine displacement.

The main jet is adjustable, that will be all it needs.