vac issue ???

[jonk00000]

i have my idle set at 850. my vac is at 11 ish i think it should be a lil higher. no boost leaks.
i have comp cams 259 intake 258 exhaust

any suggestions on why my vac is so low ????

 

[95blackGsTurbo]

any suggestions on why my vac is so low ????

i have comp cams 259 intake 258 exhaust

Answer. Upgraded cams cause a lot more overlap that stock cams therefor you don't get as much vacuum as you would with stock cams. But that still seems rather low. I would run a compression check. I can pull 15in Hg with 272's.

 

[andymoraitis]

It all depends on how the cams are degreed as well. My Comp 200's pulled 15-16 in/hg with the idle at 750-800. With the intake cam advanced, I see 9 in/hg at 950-1000 RPM. Keep in mind that even on the same type of cam, there can be some minor variance in the grind that will make one run slightly higher or lower vacuum.

Run a check for vacuum leaks by spraying carb and choke cleaner around the vacuum lines with the motor at idle. If the idle changes, you have a leak and the line needs to be replaced. Keep in mind that differences in altitude will make a difference. Higher elevation means less vacuum while the reverse is true as you approach sea level.

Your vacuum readings don't sound that far off to me. Keep us posted,

Andy