68 Newport Carb Question

[66Newyorker]

You can make the 650 thunder work with some work. Still check the fuel pump push rod. Remember that the Edelbrock carburetors are just a Carter design. Performer is an AFB and Thunder is an AVS.

http://www.amazon.com/Super-Tuning-...1420039504&sr=1-1&keywords=carter+carburetors

Check out this book it has a lot of good info.

I have the Street Demon 625 on my 440. Uses the same metering rod and air valve secondary, has taken some time, but I'm slowly getting it where it needs to be.

 

[mrzods13]

Great thanks I will be buying this book

 

[70bigblockdodge]

Would the thunder series 800 be too much.

Loosening the spring tension will allow it to "come on " quicker, not sure of the technical term wken you go too far it will bog "big flat spot " or even cough or stall if really bad. The beauty of the thunder series is they really can't be too big, but if the primary side is same size as secondary like the thunder series the tip in off idle can suffer a bit, I have this problem on my 70 Challenger with a 750 holley I masked the problem by increasing the shooter size, not the best fix and when I put a 800 thermoquad on it it actually drove better and may go back to it.

 

[moper]

The way the secondaries work on the Carters and therefore the Edelbrocks (either type) is the air door is closed either by the weights in the AFB, or the spring tension on the AVS/Thunder/Thermoquad/BG Demon. The throttle plates under the air door is linked to the primaries. So when you floor it, the throttle plates open. The issue is the fuel flow because the fuel will only flow when the air in the secondaries moves. What happens in a few hundreths of a second is this: you floor it - the secondary throttle plates open. There is a momentary low pressure spot that develops directly below the air door. That pulls the air door open slightly. That allows air to move through the venturi and boosters, which in turn pulls fuel through. As rpm rises so does the pressure drop, so the door opens further. This all should happen smoothly, and the air door timing is key. If you have a bog when you floor it, chances are the air door is opening, then shutting, which stops fuel flow giving the bog. Tighten the spring adjustment and it should go away. Once it does, it's a tuning game of secondary jet and loosening air door adjustment until it's fast and smooth.
I normally remove a small amount from the air door weights on the AFBs when I rebuild them because they are conservative. The others you just adjust.