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Thread: 4.2 stroker issues

  1. #1
    Join Date
    Nov 2020
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    3

    4.2 stroker issues

    first off if this has been covered i apologize. So I installed a
    4.2 crank and rods and pistons in my 1994 thunderbird sc. It runs great with the small issue of lifting the intake. Now there is now set amount of throttle i have to give it. When it goes it goes could be cruising at 10mph or going down the strip a wot just as likely for the intake to lift. Any one have any ideas what could be causing this or how to remedy it?

  2. #2
    Join Date
    Jul 2005
    Posts
    492
    Good evening


    Explain "Lift" and the aftermath.


    Noise "rattle"?

    Leaking oil. Intake and or Exhaust manifold?

    Leaking coolant. Intake or Exhaust manifold?

    Did you purchase a rotating kit (crankshaft, rods, pistons (dished) and bearings) for a supercharged 3.8L?

    What was the final torque on intake manifold bolts?

    Where the heads milled at the machine shop?

    Is the stock static timing correct? Is the engine modified example injectors, MAFs?

    Is a tune required in its current configuration?

    Contact/ Post question in this forum to Dave Dalke or facebook @ Dave xr7 to get best answer for this issue.

  3. #3
    Join Date
    Nov 2020
    Posts
    3

    sam jones

    Thank you for getting back to me. And by lift I mean when I take the lower intake off it is like the gasket was crumpled like an acordian. The heads where surfaced and have been ported and polished. Final torque was 17ft pounds. It has complete magnum power sports top end. With 10% pullies. And no it only a new crank new crank rods and dished pistons for a 03 f150. And it currently does have a tune from Dave on a quarter horse chip. The guy I bought it from had it done. May need re tuned not sure. And yes it is set to factory static timing specs

  4. #4
    Join Date
    Nov 2020
    Posts
    3
    Oh 42 lbs injectors with matching maf and sample tube. And a high flow fuel pump forget the flow rate.

  5. #5
    Join Date
    Jul 2005
    Posts
    492
    Good evening


    I would think unless your car has the identical configurations to previous "donor," the tune chip would be invalid.

    Below is an excellent discussion on the intake manifold bolts. Note the intake manifold bolts coming loose after heat cycles requiring retorque.

    http://www.sccoa.com/forums/showthre...ld-bolt-sealer

    Is the current tune for a 3.8 or the new 4.2? If not contact Dave XR7 on chip advice options. Hopefully others in the forum with tuning experience will "chime in".

  6. #6
    Join Date
    Jan 2003
    Location
    Woodbridge, VA
    Posts
    5,283
    Are the heads, SC heads or the F150 heads? The F150 heads should have less and smaller bolts. And it could be stretching them with the kinda boost I guess you are making. 42lb injectors are probably close to done too.

    How much boost does it make?
    ~Chris
    SCCoA Member #1826
    Bettie Riding jack stands
    SCARlit on drag duty now

  7. #7
    Join Date
    Apr 2002
    Location
    St. Charles, MO
    Posts
    21,173
    Quote Originally Posted by rfp View Post
    Thank you for getting back to me. And by lift I mean when I take the lower intake off it is like the gasket was crumpled like an acordian. The heads where surfaced and have been ported and polished. Final torque was 17ft pounds. It has complete magnum power sports top end. With 10% pullies. And no it only a new crank new crank rods and dished pistons for a 03 f150. And it currently does have a tune from Dave on a quarter horse chip. The guy I bought it from had it done. May need re tuned not sure. And yes it is set to factory static timing specs
    I would try using a light coat of gasket sealer or cooper spray on the intake manifold gaskets, a small blob of high temp silicone in all four corners, then torque manifold bolts to a final of 24 ft lbs. I would also recommend using a sealer on all the manifold bolts because some intersect with coolant ports.

    David
    Last edited by David Neibert; 11-11-2020 at 06:21 PM.
    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat.............10.597 @ 135.78

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