Anyone replaced a throttle body shaft? (UPDATED WITH PICS)

todds112 · Post by **todds112** » Sun Sep 14, 2008 6:50 pm

My back carb has the brass shaft with plenty of play in it. Pretty sure this is why I could never get them synched up very well. Ordered the replacement steel one. Went ahead and ordered new screws for the throttle plates. They have a weird end on them that makes it look like they are not re-usable.

Should I lock tight them? If so what kind? Any other pointers?

Jim LaGuardia · Post by **Jim LaGuardia** » Mon Sep 15, 2008 12:50 am

Changing the shaft is pretty straight forward, remember to use new shaft seals (if your bases are machined for them).

todds112 · Post by **todds112** » Mon Sep 15, 2008 2:37 pm

No seals on this one. That will be the next carb upgrade, have both bases machined to accept the seals. For now I hope just the steel shaft tightens things up. Apparently one base is version I, the other is version II.

Also I was told how the throttle plate screws work (thanks Dennis). The weirds ends on them are meant to be staked or flared after they are tightened, no lock tight should be used.

todds112 · Post by **todds112** » Mon Sep 15, 2008 7:30 pm

Here is the base assembly removed and mostly dissassembled. As mentioned this is the version I base, note the brass shaft.

Here is the shaft, you can clearly see the wear. This allowed the whole shaft to wiggle.

These are the throttle plates. There are little punch marks on them to indicate the top, upper side.

Finally, here are the screws. The end it what is designed to be flared after they are installed to prevent them from falling out into the intake.

Probably could have re-used them, but I ordered 4 new ones, no sense taking a chance for only $12.00.

I will update the post when I get the parts and put it all back together.

todds112 · Post by **todds112** » Fri Sep 19, 2008 11:58 am

Got both carbs back together, just need to install them and get them adjusted.

Re-assembly was very easy. The shaft went right in. Did away with almost any play. Had one oops. The upper top of the throttle plates go on the same side of the body as the cut off valves. Luckily I figured that out before I staked the little screws. Slid in the plates, then closed them. This got them to align correctly and fit the bores. Then snugged the screws and staked them.

Visually both throttle bodies look the same now, amount of travel, clearances, etc. Replaced all the idle adjustment screws. Old ones were visibly deformed.

I have both carbs set to the base setting: idle screws out 2 turns. The main idle(s) adjusted to just where the plates start to open.

I am hoping these repairs will make a noticable difference in tunability. I'm thinking I might see an improvement in fuel economy too.

todds112 · Post by **todds112** » Sat Sep 20, 2008 6:03 pm

DONE! Man, what a difference. Very little to no gas smell. Runs much smoother. Carbs were almost exactly synched at the "zeroed" settings. Hopefully the repair lasts for a while.

If you have a carb with the brass throttle shaft in it. I would highly recommend replacing it.