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Vacuum reading

Discussion in '"Stock" Alpine' started by mamoose124, Feb 13, 2020.

  1. mamoose124

    mamoose124 Diamond Level Sponsor

    Do any of you know what the normal vacuum reading should be for a 1725cc engine at idle? Or, where I could find this spec?
     
  2. Gordon Holsinger

    Gordon Holsinger Platinum Level Sponsor

    I was taught to tune for highest vacuum at idle. Check in the shop manual for specs on distributor. Make sure advance is working .
     
  3. Fergusonic

    Fergusonic Donation Time

    iaw what I see in my copied manual:
    5 Hg " @ 1/2* - 3*
    7 Hg" @ 3* - 5*
    8.25 Hg" @ 4* - 6*
     
  4. Mike O'D

    Mike O'D Gold Level Sponsor

    A quick internet search for generic engine vacuum indicates normal would be between 14" and 22" Hg. I asked the same question a while back and did not get a response with any actual numbers. I was hoping for " my engine runs great and I see a reading of X at idle". I feel I still need to do some tuning, but I was reading about 16" Hg.

    Fergusonic - where in the manual are those numbers from?

    Thanks.
     
  5. Fergusonic

    Fergusonic Donation Time

    workshop manual
    General Data Pg 17 bottom of page
     
  6. Barry

    Barry Platinum Level Sponsor



    First, that information is from WSM-124 which does not apply to a 1725 engine. Second, that information shows the degrees of vacuum advance that results from different levels of manifold vacuum; not the normal vacuum reading at various RPM's.
     
  7. Fergusonic

    Fergusonic Donation Time

    Sorry.....guess I should have ducked when that "dumbass stick" hit me.
     
  8. Barry

    Barry Platinum Level Sponsor


    I have been hit far too many times to count (or remember). As they say in the NBA, no harm, no foul.
     
  9. beamdream

    beamdream Gold Level Sponsor

    Typical reading for standard engines is around 22"

    20 - 22" is OK , a road test is recommended to see if there's any pinging; my own experience is that 22 will give you highest idle rpm but usually you'll be right on the edge of the pinging zone.
     

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