Grose Jets

[T Broring]

Rich, as noted before the Grose Jest will only help if you are getting fuel starvation filling the bowls due to too small of needle and seat. You can measure the hole of the seat with a numbered drill bit (not the sharp end). The meetering needles are the thing that control your mixture. Occasionally you can open up the hole in jet that the needle goes into but this will change the mixture accross the range not just in certain areas like the needles.
The British 4cyls are pretty well known for what needle ranges to start with. With your V8 combination I would waste no time in contacting Joe Curto in NY or a specialist in England for needle recommendations. For the small cost of these parts you will be far ahead in taking someones starting recommendations. Few people know the TR8 carbs for racing in the US. One good fix is to get an adapter that allows you to use SU needles, for which there is a far better range of needles off the shelf.
Last, and you IT guys will love this, you can tune your carbs by using different oil in the damper. Many people would simply run carbs without oil because it takes a while to figure out. The oil works like an accelerator pump by raising vacuum (by slowing down piston rising). This draws more fuel for that brief high vacuum time. This allows you to run a leaner mixture and still get off the corners well.
FYI, years ago some people complained that the ball bearings in Gross Jets were falling out causing uncontrolled fuel flow. This could have been a sizing error or been from damage. Manty people stopped using them because of the rumered problem. New needle and seats with Viton tips are as good as you can get for SUs and Strombergs.

[Flyinglizard]

The TR 8 carbs need the float as high as you can get it . The fuel slosh from racing can starve the jet and the engine cuts out. My TVR did this and now has 2 in ,round bowl SU carbs.
RE Grosse jets might still be available from TWM . they were pretty good. Or Mark from British Auto in NY.
Re; high end. You can trim the mid range with a washer( weight) on top of the piston, under the spring. It takes a few tries . The WOT , on a dyno, read the fuel ratio or EGT and look into the carb, if the piston/needle is not opening all the way, reduce the weight, dont stretch the springs!!. Run it again and note the needle exposed, hand polish with 400 paper, over a flat file. a very small area of the needle, that is set in the jet at WOT. Use a flat file so that you can measure how much you have removed and dupe that figure to the other carb.Round or flat has not seemed to make any diff, just easier to measure.
It may take a few needles, go slow and careful.
Dont foreget that these jets can be pressed down into the carb and richen up the whole thing. Measure the jet height under the piston and balance both. Measure the needle up , etc.
If you dont know the basics, look around for the SU/ and stromberg book.

Run trans oil in the shox.
MM

[callard]

I visited Mr. Grose at his basement shop in the late '70s in Mass. We talked about his invention and why he came up with the idea. I had been experiencing fuel starvation in hard cornering with a Porsche and thought baffling was the answer. He explained that sometimes the centrifugal force was keeping the needle stuck closed in the seat and as the bowl emptied the main jets sucked air. The Grose jet has two balls in the cage, one to contact the float and push the smaller ball up to shut off fuel when the float level was correct. The Grose jet is not subject to the centrifugal force; the small ball uncovers the fuel opening in the seat. I found that setting the float level was extremely important (sometimes very thin fiber washers rather than what was supplied in the kits).
He manufactured many different versions of the jet depending on the carb in which it was to be installed. The two differences were the size of the opening for the small ball (flow rate into the bowl was determined by size but fuel pressure was usually low 2-4 lbs), and thickness of the seat/cage that screwed into the carb top.
I've used Grose jets in many different carb applications both in racing and on the street and never had a problem. But initial set up float height is critical.
Regards,
Chuck