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.

"Popping" from exhaust on 454...

Discussion in 'The Garage' started by fortcollinsram, Aug 11, 2003.

  1. fortcollinsram

    fortcollinsram 1/2 ton status

    Joined:
    Nov 8, 2001
    Posts:
    2,261
    Likes Received:
    0
    Location:
    Fort Collins, CO
    \"Popping\" from exhaust on 454...

    Well my 454 runs like a raped ape...but there are still some things I am trying to work out...

    Well first off...it is a 1992 454 that is pretty much stock except for FT pistons, GMPP Truck Torque Cam, and Comp Magnum Roller TIP rockers...

    I know it is running a little rich and I *think it may have a very slight exhaust leak..But basically about 60% of the time, when I take it up to about 4000-4500rpm and then shift, it usually pops through the exhaust...It does it MAYBE 40 percent of the time if I do it in Neutral with no load on the engine (just revving it up)...

    I was told that it was probably an exhaust valve that is a little too tight. What are your ideas...I haven't set the valves since I put the heads on when it was on the stand. I just did the std. run to zero lash plus another 1/2 turn...So do you guys think I should run the valves or look else where...it runs great except for the popping...

    Oh timing is set at 4* BTDC, the factory spec...

    Chris
     
  2. BowtieRed

    BowtieRed 1/2 ton status Author

    Joined:
    Dec 31, 2002
    Posts:
    1,776
    Likes Received:
    0
    Location:
    Winston-Salem, NC
    Re: \"Popping\" from exhaust on 454...

    well whenever poppin occurs at high rpm's i always check timing first. my friend's camaro does it too, and i can almost guarantee it's his problem.
     
  3. fortcollinsram

    fortcollinsram 1/2 ton status

    Joined:
    Nov 8, 2001
    Posts:
    2,261
    Likes Received:
    0
    Location:
    Fort Collins, CO
    Re: \"Popping\" from exhaust on 454...

    Well I have checked and rechacked the timing...it is solid at 4*...

    I will also clarify that it pops ONLY when I let off the gas and let the rpms drop...I can sustain 4000rpm and it is smooth a a babies azz...it is on the slow down in revs that it pops..


    Oh and it is a TBI
     
  4. BowtieRed

    BowtieRed 1/2 ton status Author

    Joined:
    Dec 31, 2002
    Posts:
    1,776
    Likes Received:
    0
    Location:
    Winston-Salem, NC
    Re: \"Popping\" from exhaust on 454...

    what ya got for an exhaust? low backpressure can cause that as well. but i'd say check for an exhaust leak and lash next. but mine does it too- i reallythink it's normal. but mine is low BP, didn't do it before i took off the mufflers.
     
  5. k5blazerus

    k5blazerus 1/2 ton status

    Joined:
    Apr 22, 2001
    Posts:
    654
    Likes Received:
    0
    Location:
    Bend, OR
    Re: \"Popping\" from exhaust on 454...

    Maybe you need a exhaust crossover tube installed. Just a thought.
     
  6. BowtieRed

    BowtieRed 1/2 ton status Author

    Joined:
    Dec 31, 2002
    Posts:
    1,776
    Likes Received:
    0
    Location:
    Winston-Salem, NC
    Re: \"Popping\" from exhaust on 454...

    also if you screwed up the cam (not saying anything about you mechanical skills) the exhaust valve could still be open when the cylinder is firing. same principle as delayed timing except the problem is elsewhere.
     
  7. fortcollinsram

    fortcollinsram 1/2 ton status

    Joined:
    Nov 8, 2001
    Posts:
    2,261
    Likes Received:
    0
    Location:
    Fort Collins, CO
    Re: \"Popping\" from exhaust on 454...

    Thorley Tri-Y's with Dual 3" no cats, flowmaster 50s, exh. crossover before the muffler...I will change the header gaskets and collector gaskets and run the valves....hopefully it takes care of the problem...

    Chris
     
  8. 84_Chevy_K10

    84_Chevy_K10 Banned

    Joined:
    May 30, 2001
    Posts:
    17,669
    Likes Received:
    0
    Location:
    IL, USA
    Re: \"Popping\" from exhaust on 454...

    Sounds stupid, but check your plug wires closely. I had one driving me nuts for the longest and I could never figure out what the hell was going on. It didn't seem like I had a bad wire and it was very intermittant. It would pop out the exhaust only under heavy load under accelleration. I didn't suspect the wires at first because they were new, but one must have found the header.
     
  9. daimok

    daimok Registered Member

    Joined:
    Jul 18, 2002
    Posts:
    40
    Likes Received:
    0
    Location:
    north carolina
    Re: \"Popping\" from exhaust on 454...

    if it does it when you let of the gas it IS a exaust leak. My air cooled vw really pops when it get a exaust leak ( common ). more than likely its near the headers , its sucking oxygen in and reburning fuel.( and your running a bit rich /forums/images/graemlins/thinking.gif) Cant find the leak ? try this trick , pour some trans fluid down the carb - engine will smoke like a dog - i mean kill mosquitos for blocks. if you still dont see the leak while doing this , have friends plug the exaust pipes on and off , it will come out where it is leaking. will help lube your top insides at the same time.
     
  10. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

    Joined:
    Feb 17, 2000
    Posts:
    7,385
    Likes Received:
    0
    Location:
    Atlanta
    Re: \"Popping\" from exhaust on 454...

    [ QUOTE ]
    Well my 454 runs like a raped ape...but there are still some things I am trying to work out...

    Well first off...it is a 1992 454 that is pretty much stock except for FT pistons, GMPP Truck Torque Cam, and Comp Magnum Roller TIP rockers...

    I know it is running a little rich and I *think it may have a very slight exhaust leak..But basically about 60% of the time, when I take it up to about 4000-4500rpm and then shift, it usually pops through the exhaust...It does it MAYBE 40 percent of the time if I do it in Neutral with no load on the engine (just revving it up)...

    I was told that it was probably an exhaust valve that is a little too tight. What are your ideas...I haven't set the valves since I put the heads on when it was on the stand. I just did the std. run to zero lash plus another 1/2 turn...So do you guys think I should run the valves or look else where...it runs great except for the popping...

    Oh timing is set at 4* BTDC, the factory spec...

    Chris

    [/ QUOTE ]
    Ok so you got a stock block, crank and rods and nothing else.

    Going out on a limb here I would say it's the cam and it's exhaust duration. Was that cam cut for Fuel injection? The cut used on FI is different then the cut of a cam for a carb. It's proably also playing hell with the TBI. Start by checking your TPS and make sure it has the correct idle setting. If it tells the computer that you have any throttle then it may still be feeding gass on deceleration. That gas is still burning when it's hitting the exhaust.
     
  11. markd79ta

    markd79ta Newbie

    Joined:
    Aug 12, 2003
    Posts:
    1
    Likes Received:
    0
    Re: \"Popping\" from exhaust on 454...

    Does that motor have that crazy air injection on the manifolds with the air pump? Anyhow, there is a diverter valve that sometimes goes south. If this valve isn't operating properly, you will get that popping in your exhaust. Sometimes it can get really LOUD too. If you don't have this, go through your exhaust joints again especially before the cats like manifold gaskets, etc.
     
  12. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

    Joined:
    Mar 14, 2002
    Posts:
    7,324
    Likes Received:
    9
    Location:
    Grass Valley, CA
    Re: \"Popping\" from exhaust on 454...

    I don't think this is related to the popping noise, but ya might want to try bumping the timing to 8* BTDC. My BB ran alot better at 8* then it did at 4*. And remember that 4* spec is for a factory/stock motor. Your's isn't stock. /forums/images/graemlins/thumb.gif
     
  13. Sample

    Sample 1/2 ton status

    Joined:
    Oct 15, 2002
    Posts:
    536
    Likes Received:
    0
    Location:
    Apache Junction, AZ
    Re: \"Popping\" from exhaust on 454...

    It's the Flowmasters that you have on there. Every vehicle that I have ever seen with the 50 series has popped like that after reving and letting off the gas.
     
  14. fortcollinsram

    fortcollinsram 1/2 ton status

    Joined:
    Nov 8, 2001
    Posts:
    2,261
    Likes Received:
    0
    Location:
    Fort Collins, CO
    Re: \"Popping\" from exhaust on 454...

    Well it is stock block and crank, Eagle ESP rods and Hyper FT pistons with coated skirts.The cam is actually a mild version of the Crane 2030 which is the same cam GM specs for the 454ss which is a TBI motor. I will check the TPS (I have yet to do that...) and fix my exhuast leak and see how it does...

    Chris
     
  15. Don

    Don 1/2 ton status

    Joined:
    May 30, 2002
    Posts:
    1,778
    Likes Received:
    0
    Location:
    Spokane Washington
    Re: \"Popping\" from exhaust on 454...

    Grim Reaper already said this and I agree, too much overlap with the cam. A wee bit too much on the exhaust side. /forums/images/graemlins/eek.gif
     
  16. BowtieRed

    BowtieRed 1/2 ton status Author

    Joined:
    Dec 31, 2002
    Posts:
    1,776
    Likes Received:
    0
    Location:
    Winston-Salem, NC
    Re: \"Popping\" from exhaust on 454...

    yeah, i said that too. . . /forums/images/graemlins/grin.gif
     
  17. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

    Joined:
    Feb 17, 2000
    Posts:
    7,385
    Likes Received:
    0
    Location:
    Atlanta
    Re: \"Popping\" from exhaust on 454...

    [ QUOTE ]
    Well it is stock block and crank, Eagle ESP rods and Hyper FT pistons with coated skirts.The cam is actually a mild version of the Crane 2030 which is the same cam GM specs for the 454ss which is a TBI motor. I will check the TPS (I have yet to do that...) and fix my exhuast leak and see how it does...

    Chris

    [/ QUOTE ]
    BUT the E-Prom in the 454 SS was set for the cam that's in it.
     
  18. fortcollinsram

    fortcollinsram 1/2 ton status

    Joined:
    Nov 8, 2001
    Posts:
    2,261
    Likes Received:
    0
    Location:
    Fort Collins, CO
    Re: \"Popping\" from exhaust on 454...

    I have a 8747 ECM from a 1990 454ss...I know lots of guys wiht this samne cam in their 454ss with no ill effects, except more speeding tickets /forums/images/graemlins/eek.gif I ordered som decent header and collector gaskets..When they come in I will do those and run the valves and see what I come up with...

    Chris
     

Share This Page