TRExp

TR6 Tech Forum

TR6 cylinder head on a GT6

Moss Motors
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

GT6Mike Mike Hoffmann
Oakville, Ontario, Canada   CAN
Hey Gang,

I broke down and brought my GT6 to a shop as I could not iron out a heating issue I've had since getting the car. About 30 seconds after brining it to a reputable Triumph garage (JD Auto in Toronto), I was told that my cylinder head had been shaved too much. This was the reason behind overheating issues (boiling over in the overflow bottle, evaporating coolant, and just recently a little milky froth in the oil).

To try and get this done as economically as possible, we are going to use a TR6 head. After researching this I'm unclear if it is just the height of the cylinder head that is different, or if the combustion chamber is different as well.

Could someone confirm:

1. If the correct TR6 head is milled to appropriate specs, that this is a direct replacement and there are no bonnet clearance or water jacket issues?

2. Does anyone know how much to mill (I have a MK2 GT6) from the TR6 head? Ideally I would like to hit 10:1 compression as I'm running an engine that is .030 bored over and 280 duration cam.

Thanks in advance for any technical advice, I'm slowly learning this stuff and am a bit lost on the correct parts and math behind making this work.

- Mike

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
poolboy Avatar
poolboy Ken D
Sandy Hook, Mississippi, USA   USA
Do the GT6 manifolds fit that TR6 head ?

GT6Mike Mike Hoffmann
Oakville, Ontario, Canada   CAN
Yes.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
poolboy Avatar
poolboy Ken D
Sandy Hook, Mississippi, USA   USA
There were 2 different TR6 engine cylinder heads..the change happened in 72 with different intake port spacing.

GT6Mike Mike Hoffmann
Oakville, Ontario, Canada   CAN
To be clear - I know the manifolds will fit. My engine is '69 and I've had TR6 manifold mated up to it, as well as GT6 manifolds. The spacing is the same.

My question is about cylinder head height and it's impact on engine compression. I'd like to know how much to mill... it's my understanding that TR6 heads were simply milled down to make the GT6 heads.

poolboy Avatar
poolboy Ken D
Sandy Hook, Mississippi, USA   USA
Perdido Avatar
Perdido Gold Member Rut Rutledge
Tuscaloosa, Alabama, USA   USA
Mike,
I think Revington and others offer a thicker head gasket, iirc.
Rut

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
sixtynine Avatar
sixtynine mitch somethingorother
las vegas, nv, USA   USA
misread



Edited 2 time(s). Last edit at 2017-11-28 04:23 PM by sixtynine.

YankeeTR5 Dan M
Seattle, washington, USA   USA
The link below should help you figure out which is the correct deck height for your particular GT6. Looks like there were two thicknesses 3.3" and 3.4" (same as 2.5L PI cars) - with the thicker head also using domed pistons to get make up for compression loss from the thicker head I guess. Interesting side note here: Kas Kastner experimented with domed pistons as a way of boosting compression back in his racing days and found that shaving the head and sticking with flat pistons was best. YMMV. The info also provides some other useful specs like pushrod length, valve spring shim thickness etc.

Best of luck with solving your problem. I'd double check the deck height of the head you currently have and compare it to this chart. My first guess to resolving your sympton would not be too much compression, but I don't want to armchair quarterback your mechanic.

https://www.chriswitor.com/cw_technical/head_applications_chart.pdf

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
. Hide banner ads & support this website by becoming a > Gold Supporting Member <

To add your reply, or post your own questions

Members Sign In   or   Create an Account

Registration is FREE and takes less than a minute!


Having trouble posting or changing forum settings?
Read the Forum Help (FAQ) or contact the webmaster





Join The Club

Sign in to ask questions, share photos, and access all website features

Your Cars

1971 Triumph Spitfire MkIV

Text Size

Larger Smaller
Reset Save

Sponsor Links