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Question about valve lifters and camshaft break in.?

I am replacing the Camshaft, lifters, and timing chain on a SBC 350. The motor is still in the car and I have the valve covers and manifold removed (and other components). The camshaft break-in procedure recommends removing the inner valve springs and running engine at 2000-2500 rpm for 20-30 minutes.

MY QUESTION: I have the valve spring compressor tool to remove the springs. HOW do I prevent the valve from falling into the cylinder when I remove the spring? Can I conduct the break in without removing the inner valve springs?

5 Answers

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  • 1 decade ago
    Favorite Answer

    Clean lint-free Nylon rope. With the valves closed, stuff the rope in through the spark plug hole. Start with the piston a little before TDC on the compression stroke, then gently rotate the crank with a socket-breaker bar to compress the rope. A leak-down testing rig can also be used, but that can be tricky, as if you are just slightly off TDC, the piston will be forced down by the air pressure.

    It is best to break in with just the outter springs, as otherwise the extreme pressure of dual springs is liable to damage the cam lobe-lifter surfaces during break-in. Maybe you still have the old stock springs handy? They work real good because they're already softer than just the new outter ones.

    As far as when you adjust the rocker arms, there are these tools that you can clip on the rocker where the oil squirts out to deflect it, so it doesn't go all over the place.

    http://www.who-sells-it.com/r/rocker-arm-oil-defle...

    Or some people who do this a lot just cut down an old pair of valve covers.

    Source(s): ASE Certified Tech
  • 1 decade ago

    the reason they want you to remove the inner springs is so that there won't be too much valve spring pressure pressing down on the cam lobes. Too much valve spring pressure on a new cam will eat up the cam lobes. You can also find some weaker valves springs to run just during the break in and then swap them out for the correct springs you are going to run permanently.

    The easiest way to keep the valve from falling in the cylinder is to use a compression gauge hose. Remove the schraeder valve from the end of the hose that screws in the spark plug hole. Now you can connect an air hose with compressed are into the cylinder. that's how everyone I know has ever changed valve springs.

    Source(s): former ase master certified gm dealer service/diagnostics technician
  • Nap
    Lv 5
    1 decade ago

    I have worked on many a V8 Chevy engine-350 & 305. I have done too many camshafts and lifters BUT i have NEVER,EVER heard that. If you remove the valve springs and attempt to run the engine, yes, your pistons will swallow up those valves.No doubt. No support, there part of the piston head. No I would say that after installing the cam & lifters,etc you loosen up all the adjustable valves and let the engine start ( If It won't start and seems to chug-chug you have them too loose. So, in an orderly fashion loosen each and ever one maybe 2 clicks when the engine does start let run in this ragged fashion until ALL the valves are seated (You will know by the engine starting to get smooth) Then you tighten each one ( No order is necessary) Let the engine run for a good 25 to 30 minutes. The only problem here is the oil dripping or squirting onto the exhaust manifold.( This WILL start a fire) So, stay on top of It and flush them down every now and then. I used to, after I got the thing running in a orderly fashion, I put the valve covers back on loosely. Finger tight. Still watch It,though. But no, do NOT remove those inner valve springs.

    Source(s): 30 Years Auto Tech and Shop Owner-19 years DMV Investigator Auto Shop and dealer Bureau
  • Anonymous
    4 years ago

    What replaced into the reason they replaced the lifters? i believe those lifters are placed over the valve and spring assembly. because of the fact the cam lobe rides over the lifter face, the lifter will then act promptly on the valve and spring combination. If there replaced into an argument of wrong setting up, it could have manifested itself the minute the engine replaced into started. because of the fact it got here approximately some era after, it type of feels that there could have been underlying difficulty at artwork. Ruling out an oversped engine, another aspects could contain a valve keeper that had failed and allowed the valve to fall into the cylinder and hit the piston and reason substantial harm or a valve spring that breaks and motives the comparable factor. i know that this finished situation seems fairly coincedental, yet on occasion those issues take place and it in simple terms stinks.

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  • Anonymous
    1 decade ago

    Depending on the position of the plug holes relative to the valves you just might be able to fashion a piece of realy stiff, strong wire into a support for the valves whilst you remove the springs, but this would also depend on the spring compressor not needing to use the head on the valve to do the compressing.

    It is highly likely that with everything in your favour the above method will fail and you will be obliged to remove the head.

    I would simply remove the to take out the springs and then remove it again to replace them after running in.

    Source(s): 35 years of farting about with engines.
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