QuestionQUESTION: Hello Scott,
I was planning on switching out my camshaft in the next few days and also doing the lifters. There usually is a service plate or hole in the top of lifters to get them out without having to remove the head. I don't see that this is the case with the GT6??? Is there a way to get them out without taking off the head?
Thanks,
Craig
ANSWER: I think not. Every triumph I've had requires the head be removed to access the lifters. Many times the head gasket is cut not for the lifters but for the pushrods and oil passage.
Same type of design oddity as tightening the head studs, you have to remove the valve train in order to tighten/check head studs.
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QUESTION: Scott,
Since I have the head off, what about shaving the head. It is a 72' GT6 so I think it has the 8:1 CR. How much could/should I take off the head if I wanted to bring it up to 9.25:1 or 9.5:1? I am thinking I could easily take off 0.045 or 0.050???
Thanks,
Craig
ANSWER: Another person asked about a TR6, here's the link, and I gave several web links to compression calculators and a table for compression vs. milling of a TR6 head. You would just have to change for the different stroke of a GT6
Yes, you could shave the head to raise the CR. As I suggested to the other person, measure your head and figure out what you have. Then use the calculator to determine how much to mill off the head to achieve the CR you want.
Be careful, however. milling the head will change the valve train geometry, and then you may have to shorten the pushrods, which means buy custom tube rods. They aren't that expensive, just be aware of the implications.
http://en.allexperts.com/q/Triumph-Repair-1459/2008/11/TR-6-cylinder-head-1.htm
Also, from http://www.geocities.com/hollywood/theater/3622/gt6-mod.htm
3.2.2 Increasing compression ratio
Below is excerpted a February 25, 1980 letter regarding the GT6, from Michael J. Barratt, Competition Manager East for Jaguar Rover Triumph (USA):
... compression ratios range all the way from 9.5:1 to 7.4:1 on later emission engines.
However, the datum point is the 8.5:1 compression ratio with a cylinder head of 3.460. The only modifications that were made to the engine on later models, to achieve a lower compression ratio, was to cut the head casting thickness. Therefore, regardless of the original thickness of your cylinder head, to achieve a compression ratio of 10.25:1, it is still necessary to mill for a final thickness of 3.375.
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QUESTION: Ok... now I have the cam in, the head on and put the timing chain/sprocket on. The problem came when I went to put the timing sprocket back on. I had research this a bit before hand and found that the sprocket and gear should have marks on them to line them up (like every other car). I didn't see that my sprocket had the marks that should have been there. There was one small dimple on it and I could see one on the gear. I put it back up as close as I could guess. The car starts and runs but doesn't seem to pull well over 3500 rpms??? Any advice you can give me?
Thanks,
Craig
AnswerI would suggest at this point getting a degree wheel and degreeing the cam, with a dial indicator. There's a process to go through to make sure you are at TDC, and then you can figure out what the centerline of the cam is, and set the correct timing.
You'll have take it all apart again (which you'll have to do to set/change the valve timing anyway) to the dimples lined up; the triumph books can explain the process better than I can in this format, but you can advance/retard the timing by flipping the gear around, which will get you 1/4 tooth increments to advance or retard. I would tend to say you have the cam timing retarded, but the only way you'll know for sure is to degree the cam, and see at what point the valve opens/closes
Sorry I couldn't help more..
