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Increasing Compression Ratio

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triple Webers will give more power and reliabilty than your current ZS setup

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The Webbers may be fancy looking but they are finicky to set up/keep in tune and they really don't work any better than a good set of well tuned ZS carbs for anything short of a full race motor.

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I disagree on both accounts. Once set, Webers stay in tune and don't go out (though triples, I'm sure, are a little bit harder to keep right than my twins). They are not atmospheric dependant like Strombergs are, so they'll run just as good on a humid, hot day as they will on a cold, dry day. Webers don't have floats either, so you don't have to crank the car until the floats fill up, putting strain on the battery and all moving parts, seeing as how they don't have oil pressure for those few seconds. They also give better power. Replacing my twin ZS setup with twin Webers will give me about 10 extra horses.
 
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Speaking of valves, a port and polish is good, and the valve stems can be reshaped to be more streamlined.

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Much of this information has come from Smokey Yunick who you may not have heard of.
D

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I've know about him. Didn't he write a book that explained a lot of stuff like this? I think I'm going to buy it.
 
Can any one tell me how to measure a TR6 head. I presume the late model (as well as early modle TR6) heads are measured from the milled rocker cover area to the milled part that attaches to the block. I need to know the correct measurement for an american '74 head. I know the head was milled before and I want to get to 9:1 or very near. I have heard the head should measure 90mm from rocker cover gasket area to block contact area. How many mm's should the head measure(with standard bore) to get the near 9:1 compression?
 
Vettedog, as mentioned earlier in this thread,

https://www.goodparts.com/tech_docs/TR6_Compression_Ratio.html
Give that a try.
And, from another thread regarding rebuilding a 2.5,

This is from a post awhile back, submitted by Piman.

There are various head thicknesses, UK TR6's had a 3.400" (nominal) head, stamped 516816, TR6 carb and 250 had a 3.535" head stamped 218227 and 5163233 respectiveley and replacement head for America were 3.560 stamped 219019.
The 3.4 head usually gives a 9.5:1 compression on a standard 2.5 engine.


BTW, it's the final combustion chamber volume that will determine the compression ratio, so any work done to the chambers will have to be accounted for.

Jeff
 
Thanks Luke, I all ready feel the force of this web site (even though I have not gotten the complete hang of it). I will have your much needed schedule at the machine shop, hopefully, tomorrow.

By the way, if it were not for the rope trick, the head would still be on the engine.
 
Here's a topic with some interest! Who doesn't want some more power?


the GT 6 head will give A LOT MORE COMPRESSION, even too much!
The TR6 has a 1/2 inch taller block than the GT6, and a correspondingly longer stroke. Pushing all that displacement into the GT6 head would probably not be possible unless you turn it into a diesel. I use to tignten down on the valve adjustment to a bit under the recommended gap, figuring it would open the valves sooner, wider and longer. Never ran a dyno on it to test the theory.
My mechanic advised putting a Crower cam in my GT6 for "track day" driving, and I did, but had nothing to compare it to. I think I'll consider balancing the pistons and rods, but do I have the fly wheel balanced with it? I'm guessing knife edging the crank would be very expensive. If you just want more performance, think of ways to lighten the whole car.
 
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