vacuum test on 340 with 292/501 comp cam

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75dust440

75dust340
Joined
Jan 2, 2007
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Location
plano, texas
I expected 8-10 psi. But was surprised when I got i steady 15 1/2 to 16 psi reading. The idle is at 1000-1100 right now (in park) and sounds incredible. I guess I cant complain, but seems like it should have read lower with that kind of cam.
 
why do you have it idling so high? A lower idle speed will drop the vacuum. I had the 292 magnum in a 10:1 440 before and I don't remember the numbers but it had good vacuum too. I was able to use power brakes with mine. A lot depends on where the cam was installed and compression.
 
The comp is close to 11.0-1. I dont see this car idleing at 600 in gear. Maybe 800 -900. I just got this motor running and I know I have some adjusting to do but it seems pretty happy where it is. I disconnected the advance and all the other vacuum inlets are plugged. I was reading on some of these bigger cams to not even run the advance. The motor fires instantaniously, and is violent sounding( it pops)open headers and tachs up with no hesitation. I think i"m at least heading in the right direction.
 
the motor in my duster at present is a 9.3:1 383 with a 284-.484 mopar cam. It idles in gear at 750. the lower the idle the nastier it sounds. It only pulls 9 in of vacuum in gear at idle.
 
9 inchs is what my purple 292 pulled on my 10-1 360. Idle was around 750 + a few at best rpm.
 
I have not installed a drive shaft yet so hopefully in the next month I will be able to see where she sets in gear.
 
i have a 284 /484/114 in my 360. it is 10.2 to 1 comp and pulls 6inch at 700+rpm in gear.
 
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