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TR6 Crankcase venting and general tuning advice?

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Alright. New development.

I went in the night before last to adjust valve lash to the above stated specs, and, curiously, the clearances had opened up profoundly on a smattering of the rocker arms across the head. Some were still tight but others has worked their way loose. I adjusted them within acceptable margins a la GP2 cam.

I have noticed that, though the plugs still manifest symptoms of an extremely lean mixture, the idle exhaust ansolutely stinks like gasoline and, in fact, once the motor is warm the idle wants to slowly drop like it's loading up with excess fuel.

Pinging under load is still detectable and run on is still a regular occurrence.

I drove to a local shop and went over this with the owner and he had a eureka moment. We looked at a TR6 head that his machinist misunderstood his intentions and shaved almost double the material off the mating surface. They calculated it provided about 11-1 compression. Inspecting the mating edge of that botched head and then looking at the one on my block, one notices that the small 'tabs' at the corners are very short compared to a stock head. The exhaust manifold is also quite close to the block; again, closer than the stock setups he has around.

We have come to suspect that the charlatain who put my motor together not only provided me with a slew of previous issues, but also had my head shaved too much or maybe accidentally twice.
 
I don't know if I am relieved or disappointed. I suspected and expected anything and everything...so I guess it just is what it is...

At least it can be remedied with a copper gasket/spacer once I figure out how short the head is, exactly.

There just isn't any other plausible explanation for the issues I'm having. Ignition, carbs, timing. It's all been adjusted and tried in every possible combination of settings. No dice.
 
I saw where you posted vacuum numbers but if you posted compression numbers, I have overlooked them. Before pulling the head, is there any way that you can get an accurate measurement of head thickness from the valve cover gasket surface to the bottom of the head (check in multiple spots)? Also, once you have everything properly adjusted, do a compression check. These two things will at least give you a guide as to what you have in hand. Then you can make the call on whether or not it's worth pulling the head for greater accuracy. Per Kastner a TR6 cylinder head that is 3.375" thick should yield a compression ratio of ~10.25:1 if the block is decked and ~10:1 if it is not. Take that head down to 3.290" thick abd the compression jumps to ~12.3:1 if the block is decked and ~12:1 if it is not. These are somewhat nominal as overbored cylinders does have some impact on the compression ratio.

The other way would be to pull the head to check and measure the deck clearance of the pistons relative to block surface at TDC as well as at the bottom of the stroke, then measure the bore to calculate the swept volume of the cylinder. Add any unswept volume if the deck was not zeroed. Then to "cc" the combustion chambers to determine their volume. Add 3.7cc for the volume of the compressed head gasket (~.226 cubic inch if you are into English units) to the completed volume measurements and you can calculate the compression ratio.
 
Thank you all for your continued advice and replies.

A gross measurement of my head thickness from the top of the gasket to the valve cover sealing surface is 3-3/8". This puts me in the realm of 10.30-1 according to charts I've seen.

I suppose as an experiment I could fill her up with 100 octane avgas from the small airport in town, but that would only further confirm this rather than fix it.
 
Alright. I had time to pull the head and check out all the ancillary components as well as use a caliper to get an exact head thickness.

It measures out to be almost 3.377.
Block is decked and pistons are flush with it at TDC. Cylinders are .060.

I found the rocker pads and pushrod faces to be unevenly and significantly worn. My thought is that with a higher lift cam and a shorter head, the pushrods should have been a little shorter than stock. Question now is, after I get a shim/gasket to bring the head a little farther up from the deck, will I be able to use stock rods...?
 
Updates on the compression ratio saga;

I had a long phone conversation with Mr.Good of Goodparts fame. He's a very knowledgeable and amicable man.

We went over the dimensions of my head and volumes of the combustion chambers as a result and as he has recently experienced on one of his cars, the resulting compression ratio makes it a bit tough to use as a street car.

Though I have found a copper gasket can be made to a thickness as to bring the ratio down to a more manageable 10-1 or so, it will have to be around .070 thick and cost almost $200.

I am thinking I need to find a new head and start over...shaving only enough to bring me up around 9.6-1 and not much more. If I can source one with the smaller intake ports, I can use my current valves.
 
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