Triumph T120r, 1960’s To 70’s Head Rebuild

Forum Colleagues,

I am relatively new to the forum and to Triumph engine rebuilding. My comments here are about rebuilding Triumph 650 head(s), I have a 1969 T120R that I am in the process of disassembling in order to rebuild, not necessarily restore. The motor I have has a Routt 750 cylinder that I will be needing to replace as it’s been rebored a few times before.

So to the head . . . I have been looking on all the forums and more, like YouTube videos, etc. I had thought I would try to rebuild the head myself, and saw many videos that seemed to reflect that this was possible for a “novice.” However I also read much that seemed to indicate this should be left to experts with the proper tools and experience. I contacted our friends at Lowbrow Customs and asked why their Triumph 650 engine rebuild videos did not have a section on rebuilding the head. They responded with the advice that this was best left to experts and that the head in the video was sent out for rebuilding.

From what I read and see online, one can both remove and install new guides either by heating and driving or heating and pulling or pushing. Since the guides have shoulders it seems they can be replaced properly once the shoulder is flush with the head. Once the new guides are in place it is a matter of reaming with a reamer consistent with the diameter of the valves to be used. So measuring the clearances and checking the clearances physically at this juncture allows a proper fit. Then there is the cutting (if necessary) of new valve seats with the appropriate cutters. It seems that the most critical part of the job is the cutting (if necessary) of new valve seats. This is the most difficult part of getting the whole job correct. I’m here assuming that the choosing of and installation of valve springs is a matter of choosing the springs appropriate for a street, race or other engine. I am also thinking that on occasion a new valve seat does not need to cut, but only re-lapped.

I certainly don’t want to go through an entire re-build and then have it come apart due to my “novice” head rebuild. So what am I missing in my estimation of my ability to re-build the head myself? I do not have a problem with sending the head out for a professional head re-build. However if this is something I can do myself, even if I need some additional tools, I believe it would be more personally satisfying. I wonder if there is a lot more to fitting the valve springs or any other aspect of the re-build.

I’m sure this has been discussed in detail previously, however I have not been able to put it together in a way that discourages me from trying, apart from the advice to leave this to the experts/professionals. I know these engines were designed and manufactured before the advent of precision, computer-driven machining.

Thank you for any comments, and if this is the case, forgive me for resurrecting an old discussion!

Brian

 

OK Joe, thanks. This seems to be the message I am getting from others - and it is helpful in my decision making. I suppose this is a case of not knowing the things I don’t know, and leaving this up to those who know what I don’t know is the good advice. Thanks and Cheers!

 

Got it, thanks!