QuestionThe GT6+ needles are a good suggestion, I should be able to find out what type they were easy enough. I do want to remain fairly "Triumph" loyal also so I won't be going to a different drive train. Do you know where I might be able to find out about the difference on the compression ratios and how much I could take off the head if that is the case. That should be a fairly cost effective way of helping it out. Thanks for the help.
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Hello Richard. I recently bought at 72 GT6 that I am looking to modify slightly to get more HP. Do you have any recommendations for needle selection for the stock ZS carbs? If not, what other carb choices are there or what about shaving the head to increase the CR? I know that they orginally had a 9.5:1 compression that decrease to 8.5:1 compression by the time the Mark III came out (my model). Any help would be appreciated.
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Hi Craig, Jim here.
I don't have a recommendation for "upgrades" to the stock needle. I guess one idea would be to use the needle from the GT6+.
As to other changes, I guess the two questions are 1) how close to "Triumph" do you want to stay and 2) how large is the bank account?
At the most basic level you can consider either replacing your current drivetrain with a GT6+ setup, or rebuild yours to match the + specs. Sidedraft Webers are a popular upgrade, although converting to SU HS6s might be a better choice for a street car.
I've even seen a GT6 with the TR6 2.5 liter engine. That took a bit of creative engineering to make it all fit within the bonnet.
Cheers,
Jim
AnswerCraig,
I personally haven't tinkered with any of the GT6's I've had, so I'm not the best source of information.
There are several really good sources of information on the web these days.
One really good source is the North American Spitfire Squadron (NASS... www.nasshq.org), it's a national group dedicated to the Spitfire and GT6. It's worth joining up on the free email list to check it out... and if you like the group it's worth the membership fee to be a full fledged member.
Also, it's worth looking to see if there's a local Triumph club in your area. You can see a list of local clubs at www.vtr.org under "Chapter information".
In the early '70s Triumph "rationallized" some of the production to take advantage of economies of scale, so the late GT6s wound up with the same head castings as the TR6. At the same time the factory was trying to keep ahead of the US emissions laws... not always easy to do for a company with limited resources.
Cheers,
Jim
