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Thread: Heat difference left and right header

  1. #1
    Member Bullitt's Avatar
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    Heat difference left and right header

    I used an IR heat scanner and measured the left and right collector on the headers on my uk club stainless exhaust. There was a difference of 110 degrees celsius, around 230 farenheit. Any reason for this? Engine is overhauled with new pistons and camshafts etc. I know the valves need some adjustment.
    Svein Apeland

    1981 DMC DeLorean DMC-12, VIN: 01598. Gas flap hood, manual transmission, black interior, wide stripe, galvanized frame, Spax and UK club exhaust.
    x1979 Pontiac Firebird Trans Am
    x1975 Chevrolet El Camino
    x1974 Plymouth Satellite Sebring
    x1966 Lincoln Continental
    x1983 Porsche 944
    x1982 Porsche 944

  2. #2
    Senior Member Nuclearbacon's Avatar
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    It could be fuel delivery. A leaner mixture is going to cause the engine to run hotter. A slight difference in the internals of the intake manifold might cause that mixture difference and thus the increased temperature. Of course that is assuming everything else is in good shape and equal. Carbon buildup on the Pistons on one bank would cause higher compression thus hotter combustion temperatures (but new internals would rule that out). But possibly less airflow on the left than on the right causing higher exhaust temps on one side.
    -Luigi-
    Thank you ALL for your patience and your tremendous help!

    1982 VIN#10588 Build Date Dec '81

  3. #3
    Member Bullitt's Avatar
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    Quote Originally Posted by Nuclearbacon View Post
    It could be fuel delivery. A leaner mixture is going to cause the engine to run hotter. A slight difference in the internals of the intake manifold might cause that mixture difference and thus the increased temperature. Of course that is assuming everything else is in good shape and equal. Carbon buildup on the Pistons on one bank would cause higher compression thus hotter combustion temperatures (but new internals would rule that out). But possibly less airflow on the left than on the right causing higher exhaust temps on one side.
    Could this be adjusted with the mixture screws on the intake? The ones you are not supposed to touch... ! 😊
    Svein Apeland

    1981 DMC DeLorean DMC-12, VIN: 01598. Gas flap hood, manual transmission, black interior, wide stripe, galvanized frame, Spax and UK club exhaust.
    x1979 Pontiac Firebird Trans Am
    x1975 Chevrolet El Camino
    x1974 Plymouth Satellite Sebring
    x1966 Lincoln Continental
    x1983 Porsche 944
    x1982 Porsche 944

  4. #4
    Senior Member Rich's Avatar
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    Quote Originally Posted by Bullitt View Post
    I used an IR heat scanner and measured the left and right collector on the headers on my uk club stainless exhaust. There was a difference of 110 degrees celsius, around 230 farenheit. Any reason for this? Engine is overhauled with new pistons and camshafts etc. I know the valves need some adjustment.
    Can you tell us which side was hotter? Will guess right side. Yes?

    Also whether the test was performed with engine idling or at higher speed and for how long before readings were taken? Just curious. Seems like a non-trivial difference between left and right....
    March '81, 5-speed, black interior

  5. #5
    Member Bullitt's Avatar
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    Quote Originally Posted by Rich View Post
    Can you tell us which side was hotter? Will guess right side. Yes?

    Also whether the test was performed with engine idling or at higher speed and for how long before readings were taken? Just curious. Seems like a non-trivial difference between left and right....
    Right side was hottest. Engine idling. Temperature was around 180 degrees, had been running for 15 to 20 minutes.
    Svein Apeland

    1981 DMC DeLorean DMC-12, VIN: 01598. Gas flap hood, manual transmission, black interior, wide stripe, galvanized frame, Spax and UK club exhaust.
    x1979 Pontiac Firebird Trans Am
    x1975 Chevrolet El Camino
    x1974 Plymouth Satellite Sebring
    x1966 Lincoln Continental
    x1983 Porsche 944
    x1982 Porsche 944

  6. #6
    Senior Member vwdmc16's Avatar
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    Overhauled with new cams you say? It's very possible that you have one of the cams retarded one tooth. That is happened to me about a year ago when I rebuilt my motor, I quadruple checked the cam to crank timing butI still got it off one tooth and had to do it again. The car ran just fine but it was seriously lacking power and compression. I'd say start with a compression test and expect lower numbers on the side that is cold.

  7. #7
    Senior Member vwdmc16's Avatar
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    It's also possible that you have 1 cylinder does not firing consistently or even a tall is it at least running smoothly?

    Quickly Getting back to my incorrect cam timing which I suspect may be your issue as well, I was able to change the timing on my driver side Bank while the engine was still in the car and without removing the valve covers. I only had to remove the bumper, muffler, belts, crank pulley and timing cover. It actually wasn't that difficult. Don't even need to open the cooling system, it would even run just fine with that cover off. but spray oil everywhere obviously.

  8. #8
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    How long have you had the exhaust on the car? A mixture adjustment should have been performed when the exhaust was fitted.

    And if you're anal, a fuel pressure test to confirm the CPR is operating within spec and that the primary pressure is correct. More often than not the primary pressure refulator will require shimming to put it back to factory spec (5.3 bar or 76 psi) Although for the UK club exhaust we recommend increasing this slightly to 5.4 bar or 78 psi, as well as resetting the base fuel mixture of you want to get the best performance out of the exhaust.
    DeLorean Club

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  9. #9
    Member Bullitt's Avatar
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    Quote Originally Posted by vwdmc16 View Post
    Overhauled with new cams you say? It's very possible that you have one of the cams retarded one tooth. That is happened to me about a year ago when I rebuilt my motor, I quadruple checked the cam to crank timing butI still got it off one tooth and had to do it again. The car ran just fine but it was seriously lacking power and compression. I'd say start with a compression test and expect lower numbers on the side that is cold.
    Well that would suck. I had a well known company do it. They told me the timing chain was a pain in the ass.
    Svein Apeland

    1981 DMC DeLorean DMC-12, VIN: 01598. Gas flap hood, manual transmission, black interior, wide stripe, galvanized frame, Spax and UK club exhaust.
    x1979 Pontiac Firebird Trans Am
    x1975 Chevrolet El Camino
    x1974 Plymouth Satellite Sebring
    x1966 Lincoln Continental
    x1983 Porsche 944
    x1982 Porsche 944

  10. #10
    Senior Member vwdmc16's Avatar
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    Find any culprits for the issues?

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