GT6 bore dimensions

[Johno]

G'day

So I'm getting different bore dimensions from different locations with regard the gt6 engine. Apparently they all had the same bore.

Can anyone confirm the trusted bore dimensions and crank main, and crank piston dimensions? 

Also ..😊😊. Is there a dimension where one should step up to the next piston or shell size? This removing ambiguity.

Thanks

Johno

[johny]

Best to use the free to download workshop manual👍

[Johno]

So where might I find that?

[johny]

You know theres a search function on here? There also things called search engines to look for internet stuff... Anyway once again the manuals are at vitessesteve.co.uk

[Pete Lewis]

Triumph Car Service manuals - Vitessesteve

pete

[JohnD]

Johno,

You're "getting different bore dimensions from different locations"  .  Is this cylinder bores?  How are you measuring them?   The 'proper' instrument is a bore-micrometer, a very expensive item!   Another way is to put a naked piston ring in the bore, push it down with an upside-down piston to level it, and measure the gap.    This won't tell you the absolute bore diameter, but allows you to compare different bores and by positioning the ring at different heights in the same bore, to tell if there is wear in the bore wall.     Rebores, and the pistons to fit in them come in +10thou increments.

The crank journal diameters on the main and big ends can be measured with a Vernier caliper (very cheap!) to a tenth of a millimeter (4 thou), but best is to buy a micrometer, 1-2" range which will measure to less than a thousandth of an inch.  Lots for sale on eBay for less than a tenner.  Since even a precision instrument may go off, look for a gauge block in the same range.    Micrometers may be adjusted but its probably easier to know that yours is +5%, or whatever.

But even a Vernier will let you compare journals.  Then, regrinds and the oversized bearing shells to fit them, also come in +10 thou increments.      Another way (I like 'other ways'!) is to use "Plastigauge", strips of soft plastic that to assemble into the bearing, then take it apart to measure how wide the plastic has been spread. It's a surprisingly accurate way to measure clearance!

John

[Johno]

Thanks for all the helpfully info. Different as in Haynes manual etc. Too prize goes to Peter for a succinct answer and the relevant info. Thanks pete. Oh and search engines .... Fancy that!!

[Graham C]

Oooh JohnO I would have given JohnD the prize for a most comprehensive answer, considering the shortness of your question?

😀 😂😂😂

Graham

[johny]

Thing is I think JohnO meant hes found different figures for GT6 engine dimensions being quoted by various sources😁

[Pete Lewis]

haynes just copy data , we have a local village "Haynes"   and thats best where they stay

nice pub ,they do /did  a summer event where we all drive round the village and wave at locals 

more fun than the manuals  ...they are a compromise  over the original triumph ones 

Pete