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TR2/3/3A Vacuum lin

javfla

Freshman Member
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I just purchased a pair of H6 carburetors and found that there is no threaded port for the vacuum line in either one. So wondering if anyone has tried going directly into the air intake manifold, as there is 1/4 threaded port in the center and top of it? Or is that a bad idea.
 

TR3driver

Great Pumpkin - R.I.P
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Are you sure you have a pair? Sounds like you might have gotten two rear carbs. The vacuum port is on the bottom of the front carb (at least for the TR3 version), somewhat easy to miss.

Anyway, if you use manifold vacuum, you'll want some way to block it off at idle. A friend of mine did that with Webers, by setting up a microswitch triggered by the throttle linkage and a vacuum solenoid from some emissions setup. He reported that it worked well, and lowered fuel consumption by about 10% (compared to no advance). I don't recall where he got his solenoid, but the wife's 89 Dodge Caravan with 2.5L turbo had one that would work, I think. Ditto for Dad's 73 Buick Estate with 455.
 

doc50

Jedi Trainee
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I wonder if you couldn't just drill and tap the bottom of one of the carbs?
I think they are identical but for that one feature.

Thom
1959 TR3
#34909L(O)
 
OP
J

javfla

Freshman Member
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I think you are right about getting two rear carbs. The supplier is checking on that now. Sounds like going into the manifold might involve more than I want to do right now. Appreciate your help.
 
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J

javfla

Freshman Member
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Yes they do appear to be just alike. If I don't get good news from the supplier I will probably go with your idea. I am not sure what type thread is on that end of the 1/8 vac line, as I spent all day yesterday looking for 1/8 fittings in Wichita with no results.
Thanks for the help.
john
 

CJD

Yoda
Country flag
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Look in the instrument section at oreillys or autozone. They sell a universal oil pressure kit which includes 1/8" copper tube with ferrules and fittings that fit my H6 carbs and distributor perfectly.
 
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J

javfla

Freshman Member
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Thanks for the info CJD. Will check that out tomorrow. I am sure anxious to get this garage queen on the road and enjoy some spring open air.
 

TuffTR250

Jedi Warrior
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I had a similar situation about a year ago. I discussed with Joe Curto and he recommend against trying to drill and tap out the bottom of one of the carbs. He told me that it is very critical to get the tiny venturi hole through the carb in the exact right spot or the vacuum won't work correctly.
Regards,
Bob
 

TR3driver

Great Pumpkin - R.I.P
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I've never figured out what the threads in the carb for that port are, but they are not common SAE or metric. Might be BSW though. They may even be different for different carbs, as ISTR some use the union (as my car does) and some don't.
 

TuffTR250

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I swapped out one of the back carb bodies for a front carb body with a guy locally. I was lucky he had one and was willing to swap. Good luck!
Regards,
Bob
 
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J

javfla

Freshman Member
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I swapped out one of the back carb bodies for a front carb body with a guy locally. I was lucky he had one and was willing to swap. Good luck!
Regards,
Bob


Wow Bob you were lucky. Good for you. I just got word from my supplier and they agreed they had shipped two rear carbs and are replacing the set. They are coming from S. U. in England, so hope to have them in a couple weeks. Thanks to everyone for their posts.

John
 

GTP1960

Jedi Knight
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Look in the instrument section at oreillys or autozone. They sell a universal oil pressure kit which includes 1/8" copper tube with ferrules and fittings that fit my H6 carbs and distributor perfectly.

Hey CJD,

Do you know which oil pressure kit you used? They have a few to choose from on their websites.
also, did you run the 1/8" copper tubing from the #1 carb. All the way to the distributor? Or do you use a flex tube to join the copper.

my vacuum tubing has two problems:
1) it's kinked
2) it appears to only be 1/16"
(is 1/8" standard?)

thanks


Guy
 

TR3driver

Great Pumpkin - R.I.P
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Have to be a little careful; the advance tube is sized by outside diameter (1/8"). The inside diameter is probably close to 1/16".
 
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