General TR SU HS6 Carb Question

[KVH]

I just rebuilt my carbs. New jets, shafts, bushings, butterflies. Now, my rear carb is doing all the work, sucking air way stronger than the front carb. Even if I adjust the throttle screws way down, the rear carb is stronger by far. My timing and point gap are good. Strange to me. I also have new needles

This doesn't sound like a float issue to me. Is there possibly a vacuum leak somewhere that could cause this. I have a Race distributor with no vacuum advance and the port on the front carb is plugged. My Unisyn shows a much weaker front carb suction.

I'd value any thoughts.

Thanks all.

 

[charleyf]

I just rebuilt my carbs. New jets, shafts, bushings, butterflies. Now, my rear carb is doing all the work, sucking air way stronger than the front carb. Even if I adjust the throttle screws way down, the rear carb is stronger by far. My timing and point gap are good. Strange to me. I also have new needles

This doesn't sound like a float issue to me. Is there possibly a vacuum leak somewhere that could cause this. I have a Race distributor with no vacuum advance and the port on the front carb is plugged. My Unisyn shows a much weaker front carb suction.

I'd value any thoughts.

Thanks all.

My first thought is that you may have not put the butterfly in correctly on the rear carb. It is easy to get it on backwards. The butterfly has a bevel that needs to be put on correct. If on correctly you should be able to close the air flow down completely.
Charley

 

[KVH]

I'll check. I think I was pretty careful on that score, but no harm in checking again.

 

[poolboy]

Are you checking the carbs for balance with the throttle shafts un coupled and independent ?

 

[charleyf]

My first thought is that you may have not put the butterfly in correctly on the rear carb. It is easy to get it on backwards. The butterfly has a bevel that needs to be put on correct. If on correctly you should be able to close the air flow down completely.
Charley

A good way to check to see if the butterfly closes all the way is--.
With the carb off the car place a small flashlight in the front of the intake, raise the piston and needle so the light shines all of the way through. Do this in a dark room. Look at the rear of the carb for how much light or where any light is getting through. Then adjust the butterfly as necessary.
Charley

 

[bookertmg]

I'll check. I think I was pretty careful on that score, but no harm in checking again.

I’m not sure what your car is, but I had the same problem with my 59 AH. What I found was that the intake manifold has a drip line that was missing on the front of the manifold. Huge vacuum leak. The 2 openings on the manifold were there for “wet” manifold condition. I believe they are really not needed as others have stated.

So I put a Teflon taped bolt in both ( the rear is really a bitch) to eliminate the vacuum leak. Corrected the problem and balancing the carbs was easy peasy. This may not be your problem but just a thought. Good luck.

 

[KVH]

Thanks guys. Great input. It’s fixed. Charley nailed it. My butterflies were in correctly, but in that rear one that was running too strong I somehow had it lodged a bit sloppy and had too much daylight at the bottom.

Luckily, I had extra butterfly screws, and I was able to remove the ones I had installed and replace with new.

Frankly, the process was tedious because there seemed no way to have perfect alignment with no gap. I was able to see slight daylight top and bottom, paper thin but still there.

But now I’m balanced and idling smooth at 900 rpms. And, yes, I set the speed and balance independently.

Thanks again.