Typical vacuum for 308

50C8DAN50C8DAN Senior Contributor
in HUDSON Posts: 1,514
Anyone know the typical vacuum at idle for a 308?

Comments

  • dougsondougson Senior Contributor
    Posts: 673
    I am running a PCV valve which makes a bit of difference, but I routinely run at 18-20" at idle (one caveat, not all vac gauges are equal, I try to go with a higher quality).
    Doug Smith - "Toby Knoll Garage"

    1951 Muntz Jet
    1953 Woodill Wildfire/Dodge
    1954 Hudson Hornet coupe/Grand National Tribute car
    1955 Studebaker Speedster/Cadillac - "Studillac"
    1956 Corvette SR Replica


  • 50C8DAN50C8DAN Senior Contributor
    Posts: 1,514
    I am swapping out my tredlevac for a modern vacuum booster that typically needs 18 in min.  So wondering if I need to add an aux. vac. pump.
  • dougsondougson Senior Contributor
    Posts: 673
    I would. I have a treadlevac and it works fine now but I know they can be troublesome.
    Doug Smith - "Toby Knoll Garage"

    1951 Muntz Jet
    1953 Woodill Wildfire/Dodge
    1954 Hudson Hornet coupe/Grand National Tribute car
    1955 Studebaker Speedster/Cadillac - "Studillac"
    1956 Corvette SR Replica


  • RichardDRichardD Member
    edited April 13 Posts: 470
    Dan, just installed a PBR VH40 booster on my '53 {1450 psi @ 20"hg}. You will not believe how good the brakes are. EXTREMELY strong--in a heartbeat !! Check your messages.
  • RichardDRichardD Member
    Posts: 470
    attached VH40 & 44 data

    PRB data_20170411_153256.jpg
    5052 x 6552 - 4M
  • KdancyKdancy Senior Contributor
    Posts: 2,104
    Richard, just wondering, have you checked your vacuum with a reliable boost guage?
    I checked a fairly new 308 with only a few miles on it and was getting 17 lbs, but the guage is many years old. I assume that as that 308 breaks in, the vacuum will increase.
    53 Super Wasp Coupe ready for restoration
    53 Studebaker Coupe Custom
    64 Champ pickup
    Wellborn, Fl
  • RichardDRichardD Member
    edited April 14 Posts: 470
    No, Kerry, just stating what the attachment has on it at max. Think 16" would be good.  Thanks, now I am curious.
    Would need to be the vacuum when the brakes are applied. But I am glad stopping is not better than it is now. Not sure that the 18" above is a minimum; would be an unworkable system. That is why I attached the graph for 'typical' hydrovacs.
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