[leylandauto]

So, I have a 650 Twin engine #KG 35314 that came with a 71 OIF frame. I have two heads with it

71-2358 which is a single carb head

E3663 which is a twin carb head.

It appeared due to cleanliness, it came from the above engine but I am not sure of anything right now. It would seem that the single carb head would perhaps be a better fit on the late 72 engine but then I have to figure out how to plumb it for an OIF frame. Is there a way to use the earlier head with too many problems.

OK, this was probably not my best purchase of old British iron but it's what I have so I have to make it work as best as I can.

 

[leylandauto]

Boy, I am going to owe a lot of beers here
E3663

71-2358

 

[RII]

I would say it depends upon what carbs you have. The single carb head appears to have an MAP intake on it. These were meant for use with Mikuni carbs and I'm not sure that the flange bolt carb mounting distance matches up with an Amal. If you have the corresponding carb it will be a pretty easy bolt up, and you get the simplicity of tuning only one. Also reduces expenses if you have to buy carbs period.

The dual carb head has the potential for greater flow/power and you can dial each cylinder in for best running. Again, do you have the matching carbs?

Second consideration is your airbox and how importnat it is for you to have it match up to the carbs. Pancake filters are readily available, but if you are trying to go for an original look, could lead you in a different direction.

Oil feed and return really aren't a factor as they are fed through the rocker boxes and gravity feed back to the sump through the pushrod tubes. Oil feed/return lines can be routed as needed based on your particular setup.

 

[Mr.Pete]

I answered this in the other thread.I don't see any problem using the T120 head.
Check the rocker box gasket surface and the depth of pushrod tube recess;I'm sure you'll find no difference or any problem.

You will need OIF rocker boxes.You will need 650 OIF inner 3/8" head bolts (4 off).Those bolts will not fit in earlier rocker boxes.You will also need large washers on those bolts (same part number as washers used on outer 3/8" head bolts).Original washers were too small at O.D. and crushed into the head,causing loss of bolt tension whenever the engine got hot.You need these parts for either head.