470 CID fairly new build

Discussion in 'Race 400/430/455' started by Ol blue, Jul 28, 2021.

  1. Ol blue

    Ol blue 70 GS 455

    Running a hydraulic roller cam. Set valves/rockers 1/2 turn preload. Just went 3/4 turn past and it sure sounds different. What is the recommended pre load.

    243/249 cam@ 570 lift both sides. TA st1 TE ported heads. Iā€™m dropping 4-500 rpm when I shift in gear. Put in an MSD AFR sensor. Bought new carb and played with power valves and jets with 0 success. Figured maybe I was light on pre load ( set cold ). Have a 9.5ā€ 2509-3000 stall in my t-400 trans. Thinking maybe my old 10ā€ TCI 3800 stall might cure my issues. Any input is welcome. The car idles good and when above 3000rpm runs steady and solid.
    Thanks
     
  2. race0

    race0 Active Member

    My Morel hydraulic roller lifters say .030-.035" for aluminum heads and cast iron block. Depending on the thread pitch of the adjuster nut, 3/4 of a turn after you determine zero lash should get you in the ballpark.. Timmy
     
  3. TrunkMonkey

    TrunkMonkey Well-Known Member

    I had problem with my 430 and TA 413 roller. It was breaking up at WOT and popping I the exhaust on moderate accel and holding it at moderate load/RPM.

    I had followed TA's instructions on the roller rockers, but exchanged my Morel lifters for Johnsons (before I assembled the engine) and set them at 7/8 turn preload. (not realizing the Johnson's did not like that much preload)

    Backed them all off and reset them to exactly 1/2 turn and it was like flipping a switch.
    The car woke up a tremendous amount.

    I think the exhaust valves were starting to barely unseat once the car had about 800 miles after break in, as the problem started and then the popping got more pronounced over the next 200 miles of troubleshooting.

    I also had an injector intermittently hanging open, and never caught it in the chocks, only acted up when driving, and since it was a new build, I was working on eliminating variables and pulling my hair out because one change, the car acted a little better, then started acting bad again, over and over, then the injector hard failed and I finally solved the overall problem, but the popping in the exhaust was a thing that valve adjustment fixed.

    I realize this may be long and slightly a drift, but hope it might help someone with similar symptoms and comes across this thread in a search.)

    Posting for anyone who might have an odd engine misfire, stumbling at WOT (like a manual choke left on) or other weirdness you cannot eliminate. It does not take long to adjust. Pull all plugs, set any one cylinder to TDC, set preload, then follow firing order from that hole on, and you will be done in under an hour. FWIW, I let the engine set overnight and did it cold.

    Since the car ran fine during 500 mile break in (for ring and pinion heat/cool cycles) but I only romped on it a few times after the 500 mile point to seat rings, and it ran strong, then I did light drive for longer distances, and encountered a transmission failure from a damaged torque converter that was damaged in shipping, and rebuilt it (again). After I started driving it again, is when it started acting up, (and ultimately was the bad injector causing the major problem)

    I did not suspect the valve adjustment, until after I eliminated everything else.
     
    Last edited: Jul 29, 2021
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    So the problem is you are dropping 4-500 RPM when you shift from Park to Drive? What is your initial timing? That cam will like about 20* or more initial. If you can, lock out the mechanical advance and run constant timing, that is what I did, and I have less cam than you do. You will need a start retard to avoid starter kick back and hot crank issues. My drop is only 150-200 RPM. I run constant 35* timing. My MSD Digital 6 has a 20* start retard that you can turn on and off. Runs at 35*, cranks at 15*.


    My 470 was initially set up with 3/4 turn past 0 lash. That was with the TA supplied Morel lifters. Aluminum heads grow more when hot lessening preload. When I swapped in the Johnson lifters, I set them up at 1/2 turn as per recommendations. Those lifters run with less preload. If you go too far with preload, you will see it on a vacuum gauge.

    If I understand your main problem, your ignition timing is what you should concentrate on first. Running more timing at idle will lessen the RPM drop when you put it in gear.

    If your distributor is set up with very light springs, you may have a substantial amount of mechanical advance in at idle speeds. This can be exacerbated as you increase the idle speed in Park, in an attempt to make the idle in gear better. When you put it in gear, it drags the RPM down, AND you lose mechanical ignition timing, dropping the RPM further.

    If you want to experiment, put the heaviest weight springs you have in. Then with the engine fully warm, advance the timing up to 34*, and set the idle speed at 1000 RPM or so. Put it in gear and see how much it drops.
     
    Last edited: Jul 29, 2021

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