Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

engine runs funny....something isnt right

Discussion in 'The Garage' started by bigbadchev84, May 2, 2006.

  1. bigbadchev84

    bigbadchev84 1/2 ton status

    Joined:
    May 17, 2004
    Posts:
    2,191
    Likes Received:
    0
    Location:
    Hermiston, Oregon
    im working on my project car and i just got the head back the valve guide was installed wrong and i kept breaking a rocker arm and bending pushrods on the same valve, the motor ran as smooth as glass even on 7cylinders before. fast forward to now, i get everything re-installed new plugs fire it up and it runs rough, it had 1/4 tank of old gas and i dumped 10gallons of new in, i swapped carbs to one i knew for sure was good and double checked valves and firing order still wants to spit a little through the carb, it will idle, but it idles rough, i noticed the the front intake gasket is pushed out a bit and the rear has a big gap, i was going to fix it but i wanted to make sure it was gonna run right before i wasted money on a new gasket, could this be part or all of my problem?
     
  2. bigbadchev84

    bigbadchev84 1/2 ton status

    Joined:
    May 17, 2004
    Posts:
    2,191
    Likes Received:
    0
    Location:
    Hermiston, Oregon
    anybody wanna take a stab at this?
     
  3. Boondocks

    Boondocks 1/2 ton status

    Joined:
    May 10, 2005
    Posts:
    129
    Likes Received:
    0
    Location:
    Massachusetts
    If I understand you correctly, you have a vacuum leak between the intake manifold and head?

    Use a vacuum gauge to check. Also, a little starting fluid sprayed at the suspected gap would cause a change in engine RPM is there is a leak there.
     
  4. 1985_K5_Silverado

    1985_K5_Silverado 1/2 ton status

    Joined:
    Dec 21, 2005
    Posts:
    984
    Likes Received:
    0
    Location:
    Corn Country
    Have you done a compression test on the cylinder that had the incorrectly installed valve guide, or at least (because it's easier) hooked up a vacuum gauge to see if the manifold vacuum reading is kind of "bouncy"? I'd just want to rule out any valve sealing problem on that cylinder (if it was me).
     
  5. bigbadchev84

    bigbadchev84 1/2 ton status

    Joined:
    May 17, 2004
    Posts:
    2,191
    Likes Received:
    0
    Location:
    Hermiston, Oregon
    this is a BRAND new motor 0 miles, i ave about $3500 into the thing and im getting dissappointed, the gasket on the front and back of the intake not the sides, i havent hooked a vacuume gauge up to it yet but i will, the cylinder is fine, it ran perfect on just 7 cylinders before and i have pulled the plug wire to that cylinder just to make sure, i have watched all the valves and they look fine, all moving the same, would those gaskets front and rear cause a vacuume leak? or just oil coming out? i dont have any oil coming out but thats what i was assuming,
     
  6. 1985_K5_Silverado

    1985_K5_Silverado 1/2 ton status

    Joined:
    Dec 21, 2005
    Posts:
    984
    Likes Received:
    0
    Location:
    Corn Country
    Sure, just hook up a vacuum gauge and see. Your PCV system won't evac properly unless those gaskets seal, and that sure could make the induction system suck air.

    Also (and no offense intended, since you probably would do this kind of half-assing, but just to mention it) avoid the temptation to just squeeze some rtv in there around those gaskets to try and seal it up the "easy" way.
     
  7. bigbadchev84

    bigbadchev84 1/2 ton status

    Joined:
    May 17, 2004
    Posts:
    2,191
    Likes Received:
    0
    Location:
    Hermiston, Oregon
    i have alot of money and time into this motor to be half assing anything, i didint see that the gaskets squeezed out at first, the motor is a REALLY tight fit so i didnt see it right away, just trying to not waste money on new gaskets if this wouldnt effect anything.
     
  8. bigbadchev84

    bigbadchev84 1/2 ton status

    Joined:
    May 17, 2004
    Posts:
    2,191
    Likes Received:
    0
    Location:
    Hermiston, Oregon
  9. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

    Joined:
    Jun 13, 2003
    Posts:
    29,622
    Likes Received:
    1,374
    Location:
    Jersey Shore
    redo the intake... ditch the end gaskets, seriously... I've probably done over a 100 intakes and I never use them... nice fat bead of the Right Stuff, Black RTV, etc is the way to go...

    If your block or heads where milled, those end gaskets could be keeping the intake runners off the heads, not good... I've seen it happen... could very well be a leaking intake port causing your prob...
     
  10. 1985_K5_Silverado

    1985_K5_Silverado 1/2 ton status

    Joined:
    Dec 21, 2005
    Posts:
    984
    Likes Received:
    0
    Location:
    Corn Country
    Did you try hooking up a vacuum gauge yet?
     
  11. bigbadchev84

    bigbadchev84 1/2 ton status

    Joined:
    May 17, 2004
    Posts:
    2,191
    Likes Received:
    0
    Location:
    Hermiston, Oregon
    ok put a new intake gasket on it, ditched the end seals for some rtv and torqued down the intake, fired it up and got it to idle.......very rough, hooked up a vacuum gauge and it was all over the place, checked firing order again, everything looked right, re-torqued all rocker arms down still running rough, sprayed carb cleaner all over carb, and down every part of the intake, nothing.....played with the timing and it is still rough, i pulled a couple plugs and the were drenched in gas, switched carbs again and nothing.....where do i go from here?
     
  12. projectcop

    projectcop Registered Member

    Joined:
    Jul 13, 2005
    Posts:
    10
    Likes Received:
    0
    Location:
    northern california
    bbc84;
    The suggestion of using the black rtv was a good one, but it must be done properly (not saying you didnt). The intake gaskets must be placed on the heads first, then an unbroken bead of the silicone placed where the end seals would have been. It should be allowed to "set up" for approximatelly ten to fifteen minutes before putting the manifold straight down on top of it. Then the bolts should be run down hand tight and then torqued to specs starting in the middle and working outward in a circular pattern. After tightening all the manifold bolts to speck; you should wait several hours before starting the motor for the first time. This will give the silicone a chance to "cure". If the motor is started before the curing process, there is a slight chance that the silicone could split, or move upon having pressure or vacuum put to it.
    If you are sure this has not happened; I was thinking since this is a brand new motor; the cam may not have broken in properly and you may have that one lobe on the cam going flat in the location of the one bad valve guide.
    BTW; how was the valve guide installed incorrectly enough to cause the original problem. I used to work in an automotive machine shop (10 years of machine work and building engines) and I'm wondering just how someone could get that wrong?
    George
     
  13. bigbadchev84

    bigbadchev84 1/2 ton status

    Joined:
    May 17, 2004
    Posts:
    2,191
    Likes Received:
    0
    Location:
    Hermiston, Oregon
    that is just what the machine shop told me, i bought the heads off of ebay about a year ago and it kept bending pushrods and broke 2 rocker arms, this is a 351w, i took the valve spring apart and had to pound the valve out with a punch, as far as the cam goes im not sure, i mean it ran awesome on just 7 cylinders as soon as that cylinder with the bad valve stopped working, i mean it ran so good i could have run it no prob but the last time it had a broken rocker, i replaced it and a pushrod, and when i started it it ran rough and like crap, i revved it a couple times heard a tink and it all smoothed out, i pulled the valve cover just to be sure and sure enough the pushrod was bent. i pulled it apart and it sat forever, finally got the head to the shop and then re-installed it and now having all these problems. i have a points style ignition i will try to make it out there today and maybe swap it out i have another one i could try and maybe some new plugs too. anything else i might check?
     
  14. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

    Joined:
    Jun 13, 2003
    Posts:
    29,622
    Likes Received:
    1,374
    Location:
    Jersey Shore
    Well, soaked plugs would lend you toward a carb issue obviously..

    But my suggestion would be to start over with some basic diagnostics.. pull the valve covers and plugs. run a compression test and check for proper valvetrain operation.. then go from there to ignition timing, fuel, etc...
     
  15. bigbadchev84

    bigbadchev84 1/2 ton status

    Joined:
    May 17, 2004
    Posts:
    2,191
    Likes Received:
    0
    Location:
    Hermiston, Oregon
    ok new plugs, and swapped dizzys no change, i had to use my torque wrench on some other crap today and noticed it dosent seem very consistant, i am starting to wonder if the head gasket wasnt torqued tight enough, would this cause these symtoms? i opened up the radiator to see if any bubbles came up and nothing super obvious, but it runs so rough that the water is jumping out of the neck with the cap off, i checked the oil and no frothing, i didnt dump the oil yet to check, i loaned out my compression gauge ill have to get it back tomorrow to double check before i tear it down again, but would the head gasket cause this posiibly? here are some pics of it, its got a 351w with 5lbs shaved of the crank to get it to rev quicker,( i know it kills the torque) 10:1 flat tops, 2.02/1.6 valves and closed chamber heads, nice cam, balanced and blueprinted all shoehorned into it with an auto and a 9" posi

    justin 031.jpg

    justin 032.jpg
     
  16. 78Suburban

    78Suburban 1/2 ton status

    Joined:
    Jul 4, 2005
    Posts:
    2,609
    Likes Received:
    0
    Location:
    Georgia
    wish i could help.. all I can say, is I know the feeling of frusteration.. good luck, my fingers are crossed for ya bud. :bow:
     
  17. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

    Joined:
    Jun 13, 2003
    Posts:
    29,622
    Likes Received:
    1,374
    Location:
    Jersey Shore
    Justin....

    yeah, I would get back to basics on it... cooling system pressure test will definitely let you know on the head gasket as will the compression test..

    This is another occasion for me to bring up what a great tool a cooling system tester is.. invaluable and should be right on everyones list right behind, but up there with a compression tester... ok, enough of that promotion... :wink1:

    If it blew between some cylinders on that bank you certainly could be getting the kind of issues you've described... Especially with 10:1's.. I would think it would be noticable between the 2 banks tho.. Where all the plugs the same?
     
  18. bigbadchev84

    bigbadchev84 1/2 ton status

    Joined:
    May 17, 2004
    Posts:
    2,191
    Likes Received:
    0
    Location:
    Hermiston, Oregon
    2 were dripping fuel, but the were spaced out, not next to each other? i dunno, i will try the compression test and a cooling test also
     
  19. bigbadchev84

    bigbadchev84 1/2 ton status

    Joined:
    May 17, 2004
    Posts:
    2,191
    Likes Received:
    0
    Location:
    Hermiston, Oregon
    ok well i rented a coolant tester and it had no directions, but i pumped it to 15 psi and it held for 10 min, so i compression checked the motor on the side i just replaced the head on, sure enough 2 dead cylinders on fords they are 1234 on the pass side front to back and 5678 on drivers side, well 2 and 4 had no compression? i pulled the head and sure enough those cylinders were filled with water, apparently they werent fuel fouled just wet lol i never thought to smell them, well i will be getting new gaskets tomorrow
     
  20. 78Suburban

    78Suburban 1/2 ton status

    Joined:
    Jul 4, 2005
    Posts:
    2,609
    Likes Received:
    0
    Location:
    Georgia
    glad to hear it was an easy fix... was there tons of water? it didn't hydralic it and bend a pushrod or anything did it?
     

Share This Page