Manifold and vaccum plumbing

[prg machine]

are there any pictures someone could post,,,, or a diagram of the manifold plumbing/vaccuum and breather stuff????

[prg machine]

ttt ANYONE?????

[wedgemon]

Maybe this'll help. This is a bare bones vacuum set up.

- Dave

[prg machine]

looks about right..... thanks.......ported vaccuum for advance?? meaning above the throttle plates?

[cruiserman]

Only if you want. Some of us use manifold vacuum .

[prg machine]

now the engine guru who set me up with my 383 stuff says to block off the vaccuum advance on the MSD distributor... I will see

[WorkinLonghorn]

If it's a street machine and you want good mileage,you'll want the added advance that the vac adv provides during cruise/light throttle.

[prg machine]

Originally Posted by WorkinLonghorn

If it's a street machine and you want good mileage,you'll want the added advance that the vac adv provides during cruise/light throttle.

okay,, so how should i set my timing up to get the 34* total??? and run the advance from vaccuum... I agree with you cause the guys that did this motor are racing heads.

[WorkinLonghorn]

The 34 total doesn't include vacuum advance.That(total advance) is what you get with initial (say,10 degrees) plus max centrifugal advance (perhaps 24 degrees). 10+24 would be 34 total advance at high engine RPMs.They sometime specify that you plug off the vacuum line while checking these figures.
BUT for every-day driving which includes part throttle and cruise conditions,the engine can take much more advance and will reward you with better performance and much better economy.Thus the Vac Advance which is only a factor during PART throttle.
Think about it this way; when you are cruising along at 1/8 throttle,only a small amount of air/fuel is entering the cylinders and so the "compression ratio" is very low,maybe 4-1 or something.Therefore if you start the spark earlier,the slow-burning,low compression charge will produce it's power at the optimal point in the cycle.