Cylinder Head Interchange --- 3 Cylinder Engines

[jimybud]

Could someone please provide details of interchangability of cylinder Heads?

Below is a partial list of three cylinder engines.

D650 D750 D850 D950 series

D722 D782

D1302 L275 D1802 L2402 L2002

one thread within the site mentioned that the D750 and D950 were compatible except the D950 valves would hit the side of the cylinder walls on the D750 block. Though not stated explicitly, I am assuming the D750 Head would work on the D950 Engine.

Any details or a web reference would be appreciated.

 

[bruceatlam]

I don't think you'll get a lot of response --- there are a lot of reasons why they aren't interchangeable. If you want to give a try, go ahead. Search and you shall find -------

 

[jimybud]

Please share what "reasons" you are aware of as this would be helpful for the members of this forum and potentially save them time and money.

 

[Bellinghamster]

I'm pretty sure that was me that mentioned the larger D950 valve interference.

I don't see any reason why a D750 or D850 head wouldn't work just fine on a D950.... just a hair down on power due to the smaller valves. I don't know about the D650, but only because I haven't seen one.

-Pete

 

[jimybud]

Could you help me understand the two holes between the cylinders? These holes do not Exist on the D950 head but are present on the D650 and D750 and maybe the D850. As the D950 cylinder and gasket will be larger, these holes will be exposed to the cylinder compression chamber.

 

[Kubota Newbie]

Small holes like those are commonly referred to a steam holes and are common on cylinder heads on blocks where the castings for the cylinders are so close, or are even siamesed, so that the water flow through the larger gasket holes will not prevent the formation of small steam pockets in the block and hot spots in the cylinder walls. There should be corresponding holes in the deck of the block.

 

[jimybud]

Does this mean that if the steam holes are within the cylinder area of the block the there will be leakage from/to the cylinder and head?

Or it is possible that the steam holes will be sealed by the head gasket.

 

[jimybud]

Is the head thick at the point of this steam holes so that I could thread them with a tap and plug them with a threaded plug?

 

[Kubota Newbie]

You should not try to install a head on a block where any of the casting holes would be potential sources of leakage. So if they overhang the cyl I would not go there. One little water leak and you'll be replacing a lot more than a head. You should get a new gasket and see what it covers. If the steam holes are completely outside the fire ring on the gasket then you'd likely be ok (maybe a little extra sealant there on installation). When crossing over heads on an OHV push-rod engine it is also important to make sure the push-rods align corectly between the lifter bores and the rocker arms.