Triumph ITB Balancing Question

[KMoore68]

Hi,

I have installed a set of Triumph ITBs on my 1977 911 S. The car is running ok but I have an odd problem with balancing the ITBs.

With the linkage disconnected, I balance all the ITBs to 6 kg/hr. I reconnect the linkage and I double check the same balance for all ITBs.

After I drive the car for a bit when I return home, ITBS 1, 2, 3 and 6 are still balanced at 6 kg/hr but 4 is at 8 kg/hr and 5 is at 10 kg/hr.

I'm a bit stumped and was hoping for some ideas what might be wrong.

[shamrok]

I have the Triumphs as well and find the entire linkage pretty finicky and temperamental. One thing to check is that all the butterfly nuts aren't overly tight. Also, make sure all the springs and adjustment screws are in good order. There's a slew of places that things can stick, but I'd check those nuts first. Pretty much everything from the bellcrank to the center linkage to the individual butterflies should rotate freely without even a little binding. It's okay if things are looser than you think they should be in my experience, the neglible slop is better than the inconsistency that came with having things tighter.

For me, it eventually came down to me taking them out, pulling them completely apart, replacing nearly every piece of hardware with new stainless hardware, some well placed grease, and they're now at a point that I'm not fiddling with them very often.

[KMoore68]

Originally Posted by shamrok

I have the Triumphs as well and find the entire linkage pretty finicky and temperamental. One thing to check is that all the butterfly nuts aren't overly tight. Also, make sure all the springs and adjustment screws are in good order. There's a slew of places that things can stick, but I'd check those nuts first. Pretty much everything from the bellcrank to the center linkage to the individual butterflies should rotate freely without even a little binding. It's okay if things are looser than you think they should be in my experience, the neglible slop is better than the inconsistency that came with having things tighter.

For me, it eventually came down to me taking them out, pulling them completely apart, replacing nearly every piece of hardware with new stainless hardware, some well placed grease, and they're now at a point that I'm not fiddling with them very often.

Thanks for the ideas!