T and D rockers coming loose?

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by Neil Morley, Jan 10, 2019.

  1. Neil Morley

    Neil Morley Member

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    im running a conventional headed bbc with T and D shaft rockers and have had great success up to this point but attended and won a no prep race New Year’s Day but had 3 intake rocker nuts come loose and fall into the motor so far I’ve found 2 and 1 is somewhere still in the motor but I found a piece of it in the pan, also I use the Recomender LSM torque wrench for the rocker jam nuts? Any ideas on why they possibly came loose? Possibly valve float even though I didn’t rev it over 8100 rpm which is the usual rpm I turn it unless the springs are going away? I run a Manley severe duty valves with 340 lbs on the seat and around 880 on the nose with just over .800” lift! Also I’ve got 60% leak down on number 7 cylinder and it’s going past both the intake and exhaust valves like I may have tuliped the valves which number 7 is one of the intake valves that came loose? And number 7 wasn’t burning any cad off the plug like it was rich so I don’t know how it would tulip the valves??? Any ideas would be greatly appreciated ! Also I had the blower slowed way down and plenty of fuel for the conditions! Anyhow thanks for your
     
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  2. promodracer

    promodracer Member

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    Seat material. good video from matt at MBE on this. Good Luck
     
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  3. TAFC577

    TAFC577 New Member

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    also replace the studs and the cross shaft on the rockers that came loose or you will be repairing it again !
     
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  4. jay70cuda

    jay70cuda Member

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    Do you have a pic of your rocker setup. I know how mine was fixed and all the issues went away
     
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  5. Mike Canter

    Mike Canter Top Dragster

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    Tuliped valves and loose adjuster nuts is a real good indication of detonation. What did the spark plug look like out of that hole. I know you said the fuel was ok but how did you know that and how was your max timing advance?
     
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  6. Neil Morley

    Neil Morley Member

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    Hi mike and sorry it to me so long for a response, the reason I believe my fuel curve was ok is I’ve been running this combo successfully for awhile and it’s a conventional headed 555 ci bbc with a static compression of 10.5 with a max advance of 28 degrees and a HH 14/71 OD @ 14% and a enderle 990 pump with a105 main and a 65 high speed the blower at 8000 rpm makes about 32-33psi but the spark plug on number 7 cylinder which is the one that the valves are leaking looks like it just came out of the box, in fact only 3 of the 8 plugs are burning about 40% of the cad around the plug so I think my tuneup is pretty safe?
     
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  7. Mike Canter

    Mike Canter Top Dragster

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    Do you adjust the main jet for changes in Density Altitude? That sure is a lot of indicators on cylinder7 for detonation. Have you checked the port nozzle jet for blockage? Tulips go for a valve is normally caused by too much heat in the cylinder.
     
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  8. Neil Morley

    Neil Morley Member

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    If I were lean or detonating wouldn’t you see some heat on the plugs?
     
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  9. Mike Canter

    Mike Canter Top Dragster

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    It can happen earlier in the run at the top of a gear and since you completed the run the run it may just show the end run coloring.
     
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  10. Neil Morley

    Neil Morley Member

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    If that’s the case how do you tune that if your not getting a reading off the plugs and nothing looks alarming on the data logger??
     
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  11. jay70cuda

    jay70cuda Member

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    How old is all this stuff. Age and fatigue play a major part in t&d stuff. Been there done that.
     
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  12. Mike Canter

    Mike Canter Top Dragster

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    The plug only colors towards the end of the run because that is when it gets hot enough. They will not tell you what is going on at the beginning of the run. Abort a run early and look at your plugs and see there is no color of burn on them.
     
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  13. Neil Morley

    Neil Morley Member

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    Well I should mention that my rockers are almost 9 years old with a lot of runs and a lot of street driving on them and I will admit that I meant to pull the valve covers and check the lash after the first run but didn’t because typically they don’t move but even though they show no signs of wear and the trunion and roller tip still feel tight and smooth maybe it’s just time to replace them? Let me ask this question what spring pressure do you think is necessary for this combo? 55 mm large base circle cam with .904 lifter specs lift .819 int .810 ex. Dur@ .050 280int 290ex 114 LSA 2.30” stainless int valve 8200 rpm with 40-43lbs boost???
     
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  14. Neil Morley

    Neil Morley Member

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    I forgot to mention that those lift numbers are with a 1.8 rocker ratio!
     
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