ET: Engine (Twin) Torque Plates and Cylinder Honing

[Bill Thomas]

I have another type of piston for my project, I was given with a barrel, Looks good,
I bought it from a well known Vin' Man, I thought it was a Specialloid, Till I got home, It was cheap !.
But I keep saying to myself , Don't use it,
But it's a long way off yet.

 

[greg brillus]

The modern world of too much information, that's the problem full stop these days, with computers it's all so easy to look up things and then get sidetracked as usual. You can easily spend so much time looking up how to perfect everything that in the end you might have a great bike........but you are too old to enjoy it. It's taken me near 7 months to rebuild my racer, that started off as just an engine change........with so many other changes to it now and the cost has become substantial, I just want it finished and back ready for the track.

 

[Cyborg]

A wise sage once said, perfection is the enemy of good enough (I learned that on a motorcycle forum). Personally I don’t spend a whole lot of time on the internet seeking out the latest and greatest technical information. I do spend way too much time on the two motorcycle forums I frequent when I should be finishing my Comet project. Unfortunately it has dragged on for more than 7 months, so I feel your pain. The main reason I hang out on these 2 forums is to learn and thanks to folks like you, David, MM, and others, I have learned a lot about Vincents.

In my situation, (due to some unfortunate circumstances) I have the ability to bore some cylinders and do head work in-house. I don’t do work for others because I’m still on the wrong side of the learning curve when it comes to lathes and mills and that means I’m just budgeting my own time and money.

I found MM’s numbers (before and after torque plates) very surprising. It is certainly something I need to understand and be aware of when boring/honing cylinders. If I’m struggling to get perfection with my 2 stone, 2 wiper, POS (semi) rigid hone, then I should be aware of how much the use of torque plates can effect the outcome. My Vincent cylinder holding jig also serves as torque plates, but haven’t measured a finished bore with and without the plates. Once I do that, then I can decide what’s good enough.

We could discuss the use of torque plates on cylinder heads when cutting valve seats and how much of a difference they make. However, that would be considered another high jack and might cause some of the “good enough” tribe to go into some form of vapour lock.

 

[Magnetoman]

I find the older I get, and the more knowledge I accumulate, I find myself overthinking things I never gave a second thought to years ago. ... just my view (after nearly 60 years of engine rebuilding)

My view after also nearly 60 years of engine rebuilding is a bit different. There's a rule of thumb that's relevant to this, that says we typically can't perceive differences in various phenomena that are less than ~10%. If you drive two automobiles that are otherwise identical, but one has 8% more h.p. you won't be able to discern that, or differentiate between the brightness of two otherwise identical headlamps, one of which is 8% bright than the other.

As a motorcycle example, fifty years ago I could adjust a carburetor so that a bike would run fine. However, recently I assembled an onboard data logging system for air fuel ratio (AFR). A year ago I used it to modify a 1036 Concentric from the two-stroke configuration all of their bodies were made with, to four-stroke for use on a Gold Star.

I can't feel the difference in performance of having tuned the carburetor with this data logging system, so does that mean I'm overthinking things? I would say, no, because the data doesn't lie. There is a measurable difference. But, someone else might say, yes, I'm overthinking things because the performance "feels" the same with a carburetor tuned the old fashioned way.

Vincent didn't "need" torque plates, or torque wrenches, or digital voltmeters, or ... when they built these machines back then and they ran "just fine," but does that mean we can't do better if we use these tools now? No, I don't think so. Personally, I prefer to use the knowledge I've accumulated to improve how I build and tune motorcycles, even though they certainly would be "good enough" if I only had the knowledge I had a half-century ago.

 

[Vincent Brake]

Boiis, the devil is in the detail.

 

[LoneStar]

I can't feel the difference in performance of having tuned the carburetor with this data logging system, so does that mean I'm overthinking things? I would say, no, because the data doesn't lie. There is a measurable difference. But, someone else might say, yes, I'm overthinking things because the performance "feels" the same with a carburetor tuned the old fashioned way.

Man is the measure of all things...