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The Engine that just won't behave !

Discussion in 'The Hokey Ass Message Board' started by Retro Jim, Sep 11, 2011.

  1. Loose wire or bad connection on one of the wires? Like from the switch to the coil etc?

    I know that sounds dumb but it is stupid shit like that, that always bites me in the ass.
     
  2. Smiliesafari
    Joined: Aug 11, 2011
    Posts: 15

    Smiliesafari
    Member

    Your compression numbers tell me the valves are OK. What you have are weak valve springs.
     
  3. lets try this again........I worked in a machine shop in the mid-70's and these 289-302- 300 i-6 engines all had the same problem.....random valve guide wear. The engines would pop and idle rough, and then at times run fine. As mentioned the distributor advance cam would also stick, make sure it moves freely and has no side to side movement.
     
  4. mrpowderkeg
    Joined: Mar 11, 2009
    Posts: 178

    mrpowderkeg
    Member

    yup sounds like vac leak somewhere. You could do a leakdown test to rule out bad cylinders, you'll be listening for air exiting through the crank case. Sounds like vac leak or valve guides, or timing gear issues. Seems like it's always the simple stuff though... One question I have to ask, since you are running points, are you running a solid core non resister wire, and non resister spark plugs?
     
  5. I think many are overlooking the fact that one side of the motor seems to be cold while the other is hot. I'd be seriously looking at an intake manifold that is not sealed on that side of the motor.
     
  6. mrpowderkeg had a good idea, how about putting air from your compressor (through a home made fitting) into a spark plug hole, spin the motor over untill that intake valve is open, with the throttle plates closed you may hear air comming from inside the block. If so could it be that intake gasket?
     
  7. herbet99
    Joined: Jan 16, 2009
    Posts: 194

    herbet99
    Member
    from Central NJ

    I'm not a mechanic.. but before I spend time making a spark plug fitting I would place a $10 vacuum gauge inline of an intake manifold vacuum port. That should tell you in about 30 seconds if you have an intake leak.
     
  8. mysteryman
    Joined: Apr 20, 2011
    Posts: 252

    mysteryman
    Member
    from atlanta

    is it possible something is in the intake keeping the gas from getting to a cylinder.or intake gasket installed wrong
     
  9. mrpowderkeg
    Joined: Mar 11, 2009
    Posts: 178

    mrpowderkeg
    Member

    Spark plug air fitting can be found at the auto parts store pretty cheap. A vacuum gauge should tell you if you have a loss in vacuum at whenever your issues pop up, problem is, is that you will have a loss in vacuum if it's missing when it backfires. Doesn't tell you where it is. Do you have a bad intake manifold, or a warped intake, or perhaps a vacuum fitting plug that is not there or cracked? How about the vacuum modulators for both vacuum advance and transmission, are they not leaking? A leakdown tester, or even just pressurizing the cylinder at TDC will tell you if you have bad valves, or worn rings, Air will either come out of the intake (bad intake valve), exhaust( bad exhaust valve) or crankcase (worn rings) I've even seen it bubble out of the coolant due to a cracked head :eek:

    Once again, are your wires and plugs non resistor, cause they need to be if you are running points. I had a situation where this turned out to be the case.
     
  10. rambler racer
    Joined: Sep 28, 2010
    Posts: 28

    rambler racer
    Member

    i would check with a vac gauge. but i wondering if there is a bad lifter that wont pump up at idle but will at higher rpms or a clogged lifter ports in the block . Or like my sbf the mechine shop didnt punch the oil plugs in the front of the motor and leaked down at idle. just my 2cent
     
  11. mrpowderkeg
    Joined: Mar 11, 2009
    Posts: 178

    mrpowderkeg
    Member

    Oh use a little spray bottle when the engine is idling and squirt the headers on both sides and tell us what cylinders are cold
     
  12. Retro Jim
    Joined: May 27, 2007
    Posts: 3,859

    Retro Jim
    Member

    OK Thanks for all the good questions and I will try to cover all of them .
    My vacuum gauge went up and had to buy a new one today and haven't had a chance to test the vacuum yet but will Thursday !
    I know nothing about the condition of the intake because the engine was assembled when I received it at my garage .
    Plugs wires are OK !
    When engine is idling , it might pop now and then but does pop mostly when I give it the throttle !
    There is NO open vacuum posts at all ! The ONLY vacuum hole is at the carb for the distributor !
    The engine is being used for a compressor ! No tans or anything attached to the engine !
    I have no camera to put video on You tube .
    The distributor advance plate moves fine and feels solid and not sloppy .
    I will have to make the plug for the pressure test to see if air is leaking from the Carb , Exhaust or oil fill in valve cover to rule out internal parts being worn out ! I will see if the Advance parts store has one if not I will weld one up !
    Wires are tight and secure . All wires are new with new terminals and gauges . NO solid wire was used , all are multi-strand wire .
    Could be some weak valve spring and the valves could be floating but don't think that is the problem . Weak valve spring will work OK at 1000 RPM's .
    If I start the engine it's OK 99% of the time but when I increase the throttle slowly the problem starts ! If I just hammer the throttle it's fine ! I can just keep hitting the throttle over and over and it runs great with plenty of power . Try to give it gas slowly and you have problems . Try to keep the throttle at a certain RPM and you have a problem .

    I hope I answered all the questions from today .
    I have just about had all I can take with this damn engine:mad: so I am just going to pull the damn intake and check the gaskets out ! I will also pull a couple lifters and check them as well as some cam lobes .
    That way I know what's going on at that point . I will put the intake back on and see what happens . I will post the results !

    Thanks for all the help and comments ! :D

    Retro Jim
     
  13. MeanGene427
    Joined: Dec 15, 2010
    Posts: 1,457

    MeanGene427
    Member
    from Napa

    Yep, I'd go through the valvetrain, might be as simple as a combination of the heads getting surfaced and valves sunk during a valve job and the stem height not being corrected during the valve job. One head might have been replaced and cut more or valves sunk more. Looks for the casting codes and date codes on the heads, casting codes should match, date codes within a few days of each other.
    One thing to consider, too, is that some engines with rotators & lash caps have two different length pushrods on intake & exhaust, might be mixed up
     
  14. BigChief
    Joined: Jan 14, 2003
    Posts: 2,077

    BigChief
    Member

  15. shock733
    Joined: Jan 19, 2009
    Posts: 199

    shock733
    Member
    from Florida

    I vote vacuum leak
     
  16. Retro Jim
    Joined: May 27, 2007
    Posts: 3,859

    Retro Jim
    Member


    Well that's what I am going with also !
    I contacted the owner over the weekend and he said to do the intake and see what happens . He ordered the parts for me since he lives 1.5 hours away in another state and paying for the parts used .
    When I get the gaskets I and get the intake installed , I will post and let everyone know what the out come is . I am really hoping this takes care of the problem !

    Retro Jim
     
  17. Rickybop
    Joined: May 23, 2008
    Posts: 6,584

    Rickybop
    Member
    from Michigan

    I repeat...

    Again...the main frustration with the diagnosis, is that the (assumed by me) intake leak is affecting only one side of the engine...so the good bank keeps the engine running and idleing ok. In other words, if you had an intake leak at the carb on an inline engine, which would certainly affect all cylinders, the symptoms would be more pronounced...it wouldn't want to idle...or hold constant rpms...and it'd be more obvious that there was a leak.

    The only other thing I can imagine, is if somehow only the cam-lobes for the intake-valves on the driver's side got wiped. But then I would expect some popping out the carb, and I don't think you would've gotten the decent compression readings. I doubt this is it.

    One other possibility...it wouldn't be the first time that a rag got left under the intake...:D

    Still think it's an intake leak. Of all the things you tried/checked/replaced, I didn't see that you sprayed carb-cleaner around. Maybe I missed it. That would've been the very first thing I did. It would tell you more than any post-disassembly visual inspection. After you remove the intake, it's too late to do that.

    Good luck. Let us know...I wanna claim my prize. Maybe a booby-prize, for being dead-wrong...lol.
     
    Last edited: Sep 19, 2011
  18. Retro Jim
    Joined: May 27, 2007
    Posts: 3,859

    Retro Jim
    Member

    Sorry but no prize for you ! BigChief said something about the intake leaking early in the post . :eek:
    Well I did get the intake pulled and what I saw was really scary ! Also 4 of the intake bolts were only hand tight ! :eek:
    Someone used new intake sides but the front and rear cork was re used and had about a 1/2 tube of silicon stuck on it ! Then on BOTH sides of the head side gaskets they used the other 1/2 tube of silicon up on the water passages ! What a damn mess !
    The next thing I did was pull some lifters to see what they looked like . Well someone has installed new lifter and maybe a cam but not sure . Problem is they didn't break the cam in right and the lifters have circles on the face already .
    The heads weren't done or they have more mileage on them than the rest of the engine . The valves have a good layer of carbon on the intake valves . The valve seals were replaced with good ones and not the cheap umbrella style you get in the kits . The valve covers have 2 different gaskets on them . :confused: One is rubber and the other is cork !
    So I guess I will find out what happens when I replace the intake gaskets and hope that cures the problem .
    I will let everyone know the outcome when I get it put back together this week !
    Thanks again for all the helpfull ideas ! :D

    Retro Jim
     
    Last edited: Sep 20, 2011
  19. George/Maine
    Joined: Jan 6, 2011
    Posts: 949

    George/Maine
    Member

    Seeing you have the dist out check and see if the shaft is loose causing it to float around points area. My guess.
     
  20. Retro Jim
    Joined: May 27, 2007
    Posts: 3,859

    Retro Jim
    Member

    That was one of the first things I checked when the engine arrived !

    Retro Jim
     
  21. Retro Jim
    Joined: May 27, 2007
    Posts: 3,859

    Retro Jim
    Member

    Well I finally found out what the major problem is with whole backfiring issue . Yes the intake was leaking but never knew this is why it leaked .

    The intake is badly warped ! Found out after I replaced the intake gasket with a new on then filled the radiator with water . Then all of a sudden the water started coming out the gasket in the front at the water jacket ! I pulled the intake back off and checked the head surface with a straight edge and the head surface is true . Did the same thing to the intake side , both were terribly warped and not true !
    Now I need to find a cheap or free sbf 2 bbbl intake !

    Retro Jim
    <!-- / message --><!-- sig -->
     
  22. nexxussian
    Joined: Mar 14, 2007
    Posts: 3,240

    nexxussian
    Member

    Good luck, with the price the recyclers have been paying there are alot of intakes that have been turned into chineese cars. :(
     
  23. voodoo1
    Joined: Jun 27, 2007
    Posts: 452

    voodoo1
    Member

    hit the Pick a part yards.
     
  24. Retro Jim
    Joined: May 27, 2007
    Posts: 3,859

    Retro Jim
    Member

    The salvage yards around here don't keep cars that old !
    Will check out the sorry on line auctions and C/L .

    Retro Jim
     
  25. BigChief
    Joined: Jan 14, 2003
    Posts: 2,077

    BigChief
    Member

    Glad you found the issue. Do you need a specific part number and date code for this motor? Hit up the Mustang and Falcon forums and do a search or a post. If the customer can stomach it, you may be time and money ahead with a cheap aluminum intake and a small 4 barrel.
     
  26. **** Uhh >>>>.
     
  27. theonlyiceman53
    Joined: Jun 1, 2009
    Posts: 1

    theonlyiceman53
    Member
    from Florida

    I had a old lemans with swapped plug wires and it ran poor and would only backfire occasionally. As simple as it was it took going through the whole setup of pulling valve covers, coils, etc. etc before stumbling on it. I thought that with swapped wires it would be obvious as it would backfire all the time. Not so.
    Bill
     

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