Technical Vacuum ports

I've always heard OEMs were using manifold vacuum almost exclusively up until emissions became a thing. I'm not denying what you said, but you're the first person I've seen say that. It's also possible it was a bit of both.

 

Lots of good advice......one other small point......even though you may disconnect the vacuum line from the EGR.....there could still be a problem with the EGR valve not fully seated or even a small piece of carbon or debris stuck in the seat which creates a vacuum leak even if you think the EGR is out of the picture because you have no vacuum signal to open it. Have fun........by the way , I LOVE the traditional paint and "factory" look of your engine.

 

Absolutely correct. Taking the EGR out could cause a pinging under cruise or light throttle under the right conditions. Richening the carb could help correct this.

 

Thanks again for all the replies, I’m off of work in a couple of weeks and I’m going to devote a bit of time to the car and start by doing the idle mixture and checking the accelerator pump although yesterday I picked up a used Edelbrock 2101 intake and gave it a coat of POR15 Chevy orange, so if I get fed up trying to sort out the old set up I can see me giving in and buying an Edelbrock carb and crossing my fingers that it solves the problem
Steve


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Put a q-jet on it ,the best all around street carb

 

@warbird1 is correct. Almost every manual I have, pre 72 ( factory or Motors ) shows ported vacuum to the distributor. Post 72, most went with manifold to the distributor with a temperature controlled vacuum tree in the hose. I have no idea who started this " fact ". ( Let the s@@t storm begin !! )

 

No matter what, lose the EGR valve. I wouldn't mess with the 2bbl carb. Use the 4bbl. manifold you have. Q jet is a good carb. but they have a couple of issues that can be addressed during a rebuild.

 

stylinesteve - have you figured out what year your motor is? - have you found factory type drawings showing where all lines go? - if not, someone here should be able to help provide that info - most Hot Rod motors used at one time had some smog equipment that was removed for better performance and looks.

 

Big cam------- snotty idle does better with full manifold vacuum.
About that carb.......Have you adjusted it like it should be?
Screw both of the air adjustment screws all the way in...then back them out 1 and 1/2 turns...both of them.
Crank the engine and warm it up.
Adjust the curb idle up JUST a little (to maybe 800-900 RPM)
Slowly turn the air adjustment screw IN until the engine JUST starts to change sound or starts to shudder just a little. Then back it out until it does the same thing........half way between these two points should be optimal.
Now do the other screw the same way.
Now slow the idle back down to 500 RPM (or so)
This should get you real close. A vacuum gauge (adjusted to the highest vacuum reading) is the best way...IF you have a vacuum gauge.
6sally6

 

Sorry man , but when you slow the rpm down 3-400 rpm , you've changed the emulsion requirements of the engine , further fuel/ air adjustments will be needed