Welcome to Club Hot Rod!  The premier site for everything to do with Hot Rod, Customs, Low Riders, Rat Rods, and more. 

  •  » Members from all over the US and the world!
  •  » Help from all over the world for your questions
  •  » Build logs for you and all members
  •  » Blogs
  •  » Image Gallery
  •  » Many thousands of members and hundreds of thousands of posts! 

YES! I want to register an account for free right now!  p.s.: For registered members this ad will NOT show

 
Like Tree1Likes

Thread: can a motor backfire if you overwind it???
          
   
   

Reply To Thread
Page 1 of 2 1 2 LastLast
Results 1 to 15 of 16
  1. #1
    billlsbird is offline CHR Member Visit my Photo Gallery
    Join Date
    Sep 2004
    Location
    Pahrump
    Car Year, Make, Model: '32 Ford 3 Window Coupe w/ 392 Hemi
    Posts
    916

    can a motor backfire if you overwind it???

     



    Hello everyone, Can a motor backfire if you overwind it? I have blown 392 hemi in a '32 ford & it's been backfiring. I just found out today that I've been overwinding it.... Thanks! Bill

  2. #2
    Mike P's Avatar
    Mike P is offline CHR Member Visit my Photo Gallery
    Join Date
    Mar 2003
    Location
    SW Arizona
    Car Year, Make, Model: 57 Plymouth, 37 Dodge PU, 83 El Camino
    Posts
    3,351

    Yes it can. It's usually caused by the valves floating or the mixture leaning out because the fuel system can't keep up with demand (in the old days point float could also be a problem).

    If it startsd backfiring all the time at lower RPM after it's been over reved chances are you have bent a valve or pushrod.
    I've NEVER seen a car come from the factory that couldn't be improved.....

  3. #3
    shoprat's Avatar
    shoprat is offline CHR Member Visit my Photo Gallery
    Join Date
    Apr 2006
    Location
    Orange
    Car Year, Make, Model: 57 RANCHERO
    Posts
    261

    A blown mtr will also backfire when too lean
    A Ranchero is NOT an El Camino

  4. #4
    pro70z28's Avatar
    pro70z28 is offline CHR Member Visit my Photo Gallery
    Join Date
    Aug 2003
    Location
    CC
    Car Year, Make, Model: 70 Camaro Z-28 Now/40 Chevy Back Then
    Posts
    4,306

    Backfiring with a blower is a bad combination.
    "PLAN" your life like you will live to 120.
    "LIVE" your life like you could die tomorrow.

    John 3:16
    >>>>>>

  5. #5
    jerry clayton's Avatar
    jerry clayton is offline CHR Member Visit my Photo Gallery
    Join Date
    Feb 2006
    Location
    Bartlett
    Posts
    6,739

    They usually only do it ONCE!!!!!!!

    I think I still hold the altitude record for a 6:71

  6. #6
    pat mccarthy's Avatar
    pat mccarthy is offline CHR Member/Contributor Visit my Photo Gallery
    Join Date
    Apr 2005
    Location
    bay city
    Posts
    10,546

    when i over rev my 548 past 7000rpm it,s on the rev chip cuts out the cylinders and then i get off it.it will un seat the pop off valve on intake and pop then i put my foot back in it
    Irish Diplomacy ..the ability to tell someone to go to Hell ,,So that they will look forward to to the trip

  7. #7
    gassersrule_196's Avatar
    gassersrule_196 is offline CHR Member Visit my Photo Gallery
    Join Date
    Mar 2004
    Location
    spokane
    Car Year, Make, Model: 65 corvair corsa
    Posts
    3,250

    Quote Originally Posted by jerry clayton View Post
    They usually only do it ONCE!!!!!!!

    I think I still hold the altitude record for a 6:71

    i remember reading about a somebody who had a brand new pink blower and backfired it thru the O in the champion sparkplug sign on the top end i belive it was riverside?

  8. #8
    billlsbird is offline CHR Member Visit my Photo Gallery
    Join Date
    Sep 2004
    Location
    Pahrump
    Car Year, Make, Model: '32 Ford 3 Window Coupe w/ 392 Hemi
    Posts
    916

    Thank you Mike, Shoprat, Pro70, Jerry, Pat & Gassersrule, Then I think this is why my motor is backfiring at high RPM's. I've been overwinding it. I looked at the paperwork that came with my motor & redline is 6000 RPM. I've been winding it over 6000. I'm sending away tonight for a 6000 chip for my rev-limiter. I don't think it's running too lean cuz the motor was professionally built & tunned. And the guy who put the motor in set the fuel pressure regulator at what he said was the right pressure {6 pounds?}. It also backfires when I'm turning it over to start it but not once it's running {at lower RPM's}. So maybe the timming is also off? In fact, I think I read where blower motors should start in an instant. Why does mine turn over & over? Thanks again! Bill

  9. #9
    R Pope is offline CHR Member Visit my Photo Gallery
    Join Date
    Jun 2005
    Location
    Eston
    Posts
    2,270

    Check the intake valve springs. If they are ok, do a comp. test, may have a bent intake valve. Backfire when cranking means something is allowing combustion into the intake. Not good with a blower!

  10. #10
    dem45133 is offline CHR Member Visit my Photo Gallery
    Join Date
    Jan 2006
    Location
    Hillsboro
    Posts
    11

    Interesting... but not surprised... I'm not an expert in racing designs by any means... but by the time ones takes a big block and strokes it out another 100 plus CI or so... its getting a bit long in the stroke.... 7k is pushing it... isn't it?

  11. #11
    jerry clayton's Avatar
    jerry clayton is offline CHR Member Visit my Photo Gallery
    Join Date
    Feb 2006
    Location
    Bartlett
    Posts
    6,739

    No----------------

  12. #12
    stovens's Avatar
    stovens is offline CHR Member Visit my Photo Gallery
    Join Date
    Oct 2007
    Location
    Petaluma
    Car Year, Make, Model: 48 Ford F1
    Posts
    9,505

    My Harley will do that especially at elevation! Scares the bejsus out of the people your trying to pass!
    " "No matter where you go, there you are!" Steve.

  13. #13
    Dave Severson is offline CHR Member/Contributor Visit my Photo Gallery
    Join Date
    Jul 2003
    Location
    Madison
    Car Year, Make, Model: '67 Ranchero, '57 Chevy, '82 Camaro,
    Posts
    20,801

    Dem, and others, the OP started this thread in 2010 and has made a lot of progress on the car since then........
    Yesterday is history, tomorrow is a mystery, Live for Today!
    Carroll Shelby

    Learning must be difficult for those who already know it all!!!!

  14. #14
    pat mccarthy's Avatar
    pat mccarthy is offline CHR Member/Contributor Visit my Photo Gallery
    Join Date
    Apr 2005
    Location
    bay city
    Posts
    10,546

    Quote Originally Posted by dem45133 View Post
    Interesting... but not surprised... I'm not an expert in racing designs by any means... but by the time ones takes a big block and strokes it out another 100 plus CI or so... its getting a bit long in the stroke.... 7k is pushing it... isn't it?
    your kidding right ? i have 548.565.589s 632.s running past 7000 .valve train is key
    Irish Diplomacy ..the ability to tell someone to go to Hell ,,So that they will look forward to to the trip

  15. #15
    dem45133 is offline CHR Member Visit my Photo Gallery
    Join Date
    Jan 2006
    Location
    Hillsboro
    Posts
    11

    No I wasn't kidding... I was asking. But then its been 30+ years since I gave any real thought to high perf... but then that's what this forum is for (I thought anyway). 30-45 years ago in the Muscle car heyday... 7-8 k was a good way to pull rods apart, suck valves, and otherwise ask for general mahem when it flew apart in your average Joe affordable toy. But its changed a lot since then, I'll give you that. In my day it started with the 273, 318, 340, 360, 383, 413, 426, and 440s in the Mopars. Never been a big fan of GM although the Buicks and Pontiacs had some serious BBs in the 60s. Ford too... my wife had several Ford/Mercury products... her little Couger w/ a 302 was a nice runner... got me in trouble... pegged up under the 0 pin... they frown on that. I never saw her 429 T-bird (before me). But I am partial to Mopar... sorry, so shoot me if you have to.

    So re-educate me. When I build my rod... I'm thinking stroked Mopar big block... likely decked. Maybe a paxton? or other supercharger. Not a fan of turbos per say... don't like the lag. My 5.9 Cummins has a terrible lag here at 7300 ft ASL. Want I want is what the old muscle cars had... instant torque... NOW. Not waiting on some computer to think about letting it run due to EPA... no waiting on a spool up on a turbo... NOW. Only way I know anyway to do that is CI... the more the better. Am I wrong? Remember...on the road... hp at 120+ mph doesn't matter... can't drive there ... at least very long anyway before your explaining to the judge.

    And NO, I can't stand anti lock brakes and computer controlled drive lines... all that is in my feet! Yea I'm old school... and now a 61 year old kid... again.

    I could get a ticket on a skateboard... I swear it!. My wife could pass em doing 30 over and they would do nothing... Humpt!

    So where is a good place to start studying on building up a streetable 700+ hp Mopar BB?

    Dave
    Last edited by dem45133; 07-25-2014 at 08:18 PM.

Reply To Thread
Page 1 of 2 1 2 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
Links monetized by VigLink