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Technical **Update** Holley 8150-3, 650 CFM Replacement

Discussion in 'The Hokey Ass Message Board' started by LowCountry Mike, Dec 2, 2019.

  1. Hello gang,
    I'm still plugging along on the T-Bucket project, and I'm having an issue keeping the car running (Ford 302, 1st gen). Since I've had it, I've removed the rear needle to reset it. I did that because of a back fire through the carb, and the subsequent spitting of fuel while running. There is no longer spitting fuel, but she won' t stay running. The last time I started it, I ran it for a good while with no issue. Now, it's a b!tch to get started, and will only stay running if I feather the throttle.

    I also recently changed plugs and wires. I did them one at a time, triple checked the gap on the plugs. No chance that I got them out of order.

    Humbly awaiting your guidance, lectures, accusations, and criticism.

    RS
    Mike Holley 8150_3.jpg
     
  2. Boneyard51
    Joined: Dec 10, 2017
    Posts: 5,191

    Boneyard51
    Member

    Back fire? Check your power valve! If your carb doesn’t have a power valve saver valve, buy the kit to put one in. But even with the saver kit, you can rupture a power valve diaphragm. When that happens you have a very rich idle condition, to the point it won’t idle with out some throttle.
    Looking at that carbs throat, it looks like it’s seen it’s share of backfires.















    Bones
     
    Gangrene likes this.
  3. onetrickpony
    Joined: Sep 21, 2010
    Posts: 529

    onetrickpony
    Member
    from Texas

    Valve or timing issues, probably. You need to start basic diagnostics, like compression checks and such.
     
  4. I should have mentioned that I did do a compression check. . Compression check was done dry, and not warmed up. From what I've read, as long as the there isn't a range greater than 15% between the high and low, I'm good. (?)

    1 = 132
    2 = 120
    3 = 122
    4 = 128
    5 = 130
    6 = 135
    7 = 131
    8 = 130

    RS
    Mike
     

  5. Boneyard51
    Joined: Dec 10, 2017
    Posts: 5,191

    Boneyard51
    Member

    Your figures look ok for a dry engine. Compression test figures depend on a lot of things.
    Did you block your throttle plate in the wide open position? Did you have a battery charger on your battery while checking the compression? Did you take all the plugs out to do the check? What is your compression ratio. Is your starter in good shape? These are a few of the things that effect the compression test figures.






    Bones
     
    Truck64 likes this.
  6. bantam
    Joined: Oct 16, 2006
    Posts: 327

    bantam
    Member

    As said earlier, check power valve following the backfire (blew out mine on a backfire on my SBF last year), add fresh fuel and check timing.
     
  7. Boneyard51,
    Didn't block throttle, no battery charger, all plugs were out, no clue how to calculate the ratio (will search in a sec) and starter and solenoid are brand new.

    All,
    I will check the power valve when I get home this afternoon. Thanks for the advice.

    RS
    Mike
     
    Boneyard51 likes this.
  8. Truck64
    Joined: Oct 18, 2015
    Posts: 5,101

    Truck64
    Member
    from Ioway

    Holley incorporated power valve protection in every carburetor since 1992, check the date code.
     
  9. onetrickpony
    Joined: Sep 21, 2010
    Posts: 529

    onetrickpony
    Member
    from Texas

    A backfire can sure blow a power valve but something caused the backfire first. The carb top looks like it has caught fire a few times, too. What kind of distributor are you running? Those Chinese knock-offs do stuff like this all the time, especially the ones using the GM HEI module and coil.
     
  10. Tickety Boo
    Joined: Feb 2, 2015
    Posts: 1,404

    Tickety Boo
    Member
    from Wisconsin

    Can't see from the angle of the picture but there should be a cap plug or hose over the 3/8 vacuum port on the rear of the base plate, I have had them blow off in a backfire if the cap was in bad shape :oops:
     
  11. raven
    Joined: Aug 19, 2002
    Posts: 4,624

    raven
    Member

    Backfire through the carb usually indicates timing too advanced. Start there. If it did backfire through the carb, your next step is probably to change out the power valve, then check timing before you try again.
    There are so many variables...
    r


    Sent from my iPhone using H.A.M.B.
     
  12. All,
    After looking at some other issues with the carb, I have decided to just replace it. Holley recommended the Slayer Series Carburetor 450CFM as a good replacement for mine. Also going to use it with the Weiand Street Warrior Intake that I have on order. Thoughts?

    My question is, wouldn't that effect the performance?
     
  13. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 3,525

    2OLD2FAST
    Member
    from illinois

    You can send that 650 to me ! I need another one ...
     
  14. Boneyard51
    Joined: Dec 10, 2017
    Posts: 5,191

    Boneyard51
    Member

    You can never go wrong with a new carb, but 98% of all carbs are fixable. You may have to tune the new carb, so why not just fix the old carb. If it ran right once, there a real good chance it will run good again, with just a little work. The 650 may be a little large for a stock 302, but properly tuned it would work just fine.


    Bones
     

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