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TR4/4A SU's Again..."RH" needles H6 carbs in a 4A.

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K

karls59tr

Obi Wan
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I have a set of rebuilt H6 SU's that I would like to put on a stock 4A motor. I had a set of new "RH" needles and no stock needles so I installed them in the carbs. When I do the initial start up how far down should I turn the mixture nut seeing as how the needle is rich. Normally it's 10-12 flats down.
I can't actually try this because it's -30 here with the windchill and I don't have a heated garage so I'm kind of speculating about what will work when Spring comes. Also would I be further ahead to use a TR3 distributor in this setup because it would have a better match in terms of distributor advance. Or am I just looking for trouble trying this setup?:eagerness:
 
10-12 flats should be fine. Obviously you'll have to use some choke to start, and then refine the mixture setting with the engine warm, so the initial setting really doesn't matter at all.

I doubt that the TR3 distributor would be a better match; but most likely it will still work fine. You might lose a couple of horsepower, or a couple of mpg, but most people don't much care with these old cars. However, I think you'll take a substantial hit in fuel mileage from the RH needles. You might want to swap them out later, when you can get some SM needles.
 
As stated earlier in another thread, one subtle difference that I found between a TR3 and TR4 distributor is that the drive dog at the base of the distributor is reversed between the two units.
I use SM needles on my TR4's even with HS6 carbs.
Charley
 
charleyf said:
As stated earlier in another thread, one subtle difference that I found between a TR3 and TR4 distributor is that the drive dog at the base of the distributor is reversed between the two units.
Click to expand...
Don't you think it more likely that you found a unit that was assembled improperly?

Was the difference in the dog or in the shaft ?
 
TR3driver said:
Don't you think it more likely that you found a unit that was assembled improperly?

Was the difference in the dog or in the shaft ?
Click to expand...
I don't know the 40840 unit is the only one that I had and it was on the TR4 when I bought it. I then rebuilt the engine and later changed the distributor to a TR4 unit.. And that is when I found the reversed dog on the distributor.
Charley
 
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