Technical Rebuilt 283 vacuum readings

The tri-carb setups usually only had idle mixture screws for the center carbs, and the other 2 sometimes had a small pin hole where the needles would have been. Those 4 small vacuum leaks are enough to cause this. Check to see if you have those pin holes!

 

You would think they would be 100% blocked off??? But good point.

 

Good plan.
However on #4 back off adjuster until the valve clatters Might be a 1/4 turn might be more. Then tighten adjuster until the valve quits clattering, then tighten another 1/4 turn.
Dan

 

They are blocked. 100%.

 

And this winner is @ClayMart . Moved the vacuum gauge to the carb throttle plate and the needle gave a steady reading. No fluctuations. If your ever down in Indy I'll buy you a beer. Thanks again, gentlemen!

 

Glad ya got sorted out.
Dan

 

Thanks for coming back and posting what you found. Too many times people neglect to report back to the group. Glad you found that. Now spend some time fine tuning the idle air mixture, and put some miles on it!

 

Just my observation....
218@050
224@050 duration
110* LSA
in a SBC 283 is pretty rowdy!! IMHO...(JUST THE WAY I LIKE'M!)
It's gonna requires some finesse in tuning (especially the ignition!)
BUT...to have the engine sucking through a 2 barrel carb !!!
"That's like trying-to-puke-with-a-rope-around-your-neck"
I just don't think you'll be able to get a decent idle/low speed performance with that set-up.
I would love to hear it idling though !
6sally6

 

Aw shucks . . . Glad to help out to some small degree. Not really famiiar with the tri-carb manifolds but imagined they maybe didn't have a large plenum area like a single carb setup. On a lot of I-6s there tends to be vacuum ports located in a runner or near an intake port. They work fine for a vacuum modulator or HVAC controls that don't need a steady vacuum signal.

May take you up on that free beer some day. Was just in Indy a couple months ago and met up with a couple old school chums and spent some time swapping lies at St. Joseph Brewery.

 

The ultimate goal is to get some miles on the car (once finished) and then use the Eldebrock X-1 intake with Holley 94s that is in my avatar photo. I figured a simple two barrel Rochester would be easy to learn to rebuild, break-in and tune the motor.

 

I am running about the same engine in my '63 Biscayne.
My Vacuum runs at ~15 steady whether idling or running down a level road, and runs just awesome.