brassfloat size
 

...are there differencies in brassfloat sizes on tripower 63-66 does center and endcarbs have the same float size...have a 64 center carb and the the center carb seems to have a bigger size then the end carbs. not shure if its the right float..... are there any clarification between the years.... thanks Robert

I believe the outer carbs are supposed to have bigger floats than the smaller center carbs.

There are only two sized floats for Pontiac Tri-Power carbs. The large carbs use a larger float and the small carbs use a smaller float. I believe Rochester carbs manufactured before 1968 all used brass floats. Since that date, the larger Nitrile (or plastic) floats were used--I don't think any small 2G carbs were manufactured after 1966 or '67.

Today, it's difficult, and expensive, to find quality brass floats, especially the larger ones. I began testing all brass floats for leakage by immersing in boiling water before using them. About one in 10 are leakers.

Since the smaller brass floats are readily available, I've wondered what the downside would be of using them in the larger carbs. The needle/sea assy. and function are identical to the larger carbs. There would be a slight difference in how much psi the carb could handle with a smaller float, but as long as the maximum is about 6 psi, no problem.

Nitrile floats are widely available, and do the job as well as brass floats did. I've heard horror stories of the Nitrile becoming saturated and causing flooding, but I've not seen that happen. Meanwhile, if you use any brass floats, test them before using them.

brassfloats
 

..thanks for response so th end carbs should have big floats and the center carbs assume small floats at least until 1965...so 66 centercarb would be interesting...

Maybe I didn't explain well enough. The '66 center carb uses the same float as the end carbs. The same rebuild kit is used in all three carbs in '66.

Unfortunately most current renew kits for the 1966 Tripower carbs contains the large inlet valve, .120", aimed for the center carb only.
The end carbs should have .086" inlet valves, larger valve seats may cause fuel level too high with flooding as a result.

The end carbs (at least 1964~1966) were released with fuel valve number 30-3.
The center carbs (1964~1965) were released with fuel valve number 30-9.
The center carbs (1966) were released with fuel valve number 30-13.

Sizes:

30-3 - 0.086
30-9 - 0.101
30-13 - 0.118

As Kenth stated, MOST of the renew kits DO contain generic valves; but not all of them do! Some do contain the correct parts.

Floats, and fuel valves combinations, were engineered to work with a specific fuel pressure and specific settings.

Guess what often happens if one does one's own engineering.

(Hint) there will be a discussion on one of these forums!

Jon.

.....thanks for all the useful Info...now all Info make everything clear for me...was also unshure which valve size is correct. Cause i saw different inletsize in my tmy tripower....