Hello
I am restoring a 73 d200 club cab with a 440 auto
Engine
1971 440, new mopar electronic distributor with orange box, new 8.5 wires, new lifters ( don’t know what cam is in it) new intake with a fresh rebuilt 650 dbl pumper, shorty headers, new exhaust, new oil pump, completely rebuilt 727. Holley electric fuel pump delivering a solid 7 to 9 psi.

This motor starts great holds 20 in of vacuum at idle, runs cool at 180, 75 psi oil pressure

first the timing,
I was having all sorts of issues with the vacuum advance, I would get it perfect but when accelerating would knock. I read a thread where they ran the 440 without it so I tried it and it solved everything.
here is the Issue, when feathering the throttle the truck is perfect, lots of torque (410 gear) and accelerates smooth but when I floor it ( full throttle) either from a stop or on the road it bogs and after a couple of seconds takes off.
I thought is might be the carb so I tried 2 other carbs that I had rebuilt ( a center squirted and a 850 dp) but they had the same results.

thoughts.!

 

Try a 750 Vacuum Secondary and see if the issue goes away.

 

70 =

You're running a top end single plane intake manifold - typically not good for low end.
The 650 is good for low end, not so good for top end.

What power valve(s) are you using?
What size jets, squirters?

Yes, a 750cfm vacuum secondary (#3110) out of the box might solve the problem, but there shouldn't be any reason the 650 DP should bog.

Also, the cam determines air/fuel requirements and timing, so tracking down that info might help.

Archer

 

Thanks Archer
The cam was my next step, thank you

 

IF you cant find a 750 Vacuum secondary to try..... Give the 650 less secondary pump shot and see if that helps your bogging issue...

If these dont help, you have some work ahead of you.... Its hard to tune around the dead velocity spot in the engines requirement.