engine block number

[hilsideser]

From what year GT6+ did the block number KD9492E come from?

 

[tomgt6]

My guess is it is a mk1 engine from what I can see at this site.
https://triumphspitfire.com/enginenumbers.html

 

[Andrew Mace]

Offhand, I'd agree. Easy way to tell "Mk1" engines from "Mk2/+" engines is by the head. If the head has exposed pushrod tubes, it's "Mk1"; otherwise, it's the later engine.

 

[3798j]

My GT6 is an April 1968 built Mk1 with early head. Its engine number is KD12463E.

 

[hilsideser]

Thanks guys. It's got the exposed tubes.

 

[hilsideser]

I went back and checked the vehicle again today and the COM # is KF34681. Small tag on tub, under bonnet, driver's side says 2478KF. Block says KD9492E and gear box says KC11614. There are push rod tubes on it.

 

[Andrew Mace]

Sorry, but I've lost track of what car we're talking about. But by the numbers you give (and I'm guessing the commission number is actually KF3468 L ?), you've got a Mk3 GT6, i.e., "squaretail" version, with a "Mk1" engine and gearbox.

 

[UmmYeahOk]

Odd... ...why on earth would someone do that? I thought the MKIII had more HP.

Also, mine has a KC. As with everything, KC is stamped everywhere. Why/when/for where was the KD manufactured? Is KC better than a KD?

 

[Andrew Mace]

With engines, the "KD" prefix refers mostly to "smog" engines for the US market, which had slightly less power than their nonsmogged counterparts. MkIII GT6 engines for the home market were pretty much continuations of the MkII/+ engine, and both were a bit more powerful than the original GT6 engine. In the US, the early MkIII engine was about on par with the GT6+ engine, but for 1972 and later a low-compression "smog" version for the US had dropped from roughly 95 hp to about 79 hp. Not absolutely horrible, but enough that it was noticeable (it was to me, having had both a '70 GT6+ and a '72 MkIII).

KD prefixes on differentials indicated (I think) the 3.89:1 ratio as often paired with an overdrive gearbox, as opposed to the 3.27:1 ratio with nonoverdrive gearboxes. It appears that the KD suffix was also used for body numbers on the MkII/+ GT6.