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TR2/3/3A Can porting a TR3 Cylinder head be a DIY job?

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I have done some porting on both my TR3 and the 250. I did most of the "porting" with a drill motor and different grinding stones. Look on you tube, not hard to do but very time consuming. After I did what I could I would take the head to the machinist and let him finish it up. You can save some money by doing the grunt work.
 
Use a die grinder (15k rpm or better) and a good selection of ball grinding points. Mark the old guides with a scratch tool where they protrude into the gas flow venturi, press them out, cut them off at the line and then press them back into the holes they came out of (we had a set just for the purpose in the shop I worked in). Make a gauge ring out of coat hanger wire, less is always more, consistency of diameter is the desired result. Singular most important trick. Buy a long (3/16) drill bit, cut off the drill with a dremel then if your reasonably good with the dremel cut a slot on one end long enough to accept a strip of roll type abrasive cloth and have at it. 120 grit will polish it out nicely in no time. Careful not to pull out the abrasive cloth out while polishing. And I recommend doing this outside and even then using a dust mask and definitely eye protection.
 
It really depends on your definition of porting. If you mean matching the manifolds to the head, and a general clean-up of casting imperfections, then that is not difficult to do yourself. You can also match the combustion chamber cc's.

If you mean increasing the flow substantially, that takes a flow bench and some knowledge of what works best, so my answer would be no.

I agree with Tom's recommendation of using a die grinder with carbide burs to do actual work. You can find the burs with long shanks to reach deep inside the ports.
 
"Singular most important trick. Buy a long (3/16) drill bit, cut off the drill with a dremel then if your reasonably good with the dremel cut a slot on one end long enough to accept a strip of roll type abrasive cloth and have at it. 120 grit will polish it out nicely in no time. Careful not to pull out the abrasive cloth out while polishing. And I recommend doing this outside and even then using a dust mask and definitely eye protection."

I found that an old brass carb throttle rod works well for polishing with abrasive cloth. Just cut off part of the rod on one end and you can reach all the way into the port. I still use the one I made 50 years ago.
 
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