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Tick in engine

1119 Views 6 Replies 2 Participants Last post by  scottyz
I just recently rebuilt my engine. It is a 383 small block. It has a comp XE274 flat tappet cam. After initial break in I noticed a slight tick or knock. It sounded most noticeable from the fuel pump. When you removed the pump you could not hear it. I put on a new pump. Tick was still there. I dont believe it is from a crank or rod bearing as I have good oil pressure and my specs during assembly are all good. The tick seems to be with every revolution of the cam. Today I pulled the valve covers to watch the valvetrain operation. I marked all the pushrods. One does not appear to be rotating. A few are slow like a full revolution is about every 25 seconds. I would imagine that the one pushrod that is not rotating means the lifter is also not rotating? The rest rotate at a good pace and rotate consistently. The one slow rotater happens to be closest to the fuel pump eccentric on the cam. Would this tick go down the fuel pump pushrod to the pump and make the noise greater? I have driven the vehicle about 200 miles so far and it runs great and strong but this noise cant be good so I am back to not driving it. What are your recommendations at this point?
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As long as all the intake & ex rockers are going up/down the same amount i would not be so inclined to think you have a bad cam YET.

But what could be happening is it's very easy to be a little off on the static valve adj and all you may need to do is re-adj your valves to approx 1/4-1/2 turn (MAX) down from ZERO lash for a high perf hyd cam. I would use 1/2-3/4 turn down from ZERO lash for a very mild to stock low rpm hyd cam that wont see over 4500-5k MAX rpms.

So if your experienced enough re-adjust the valtrain but if your not then have an experienced engine builder/mechanic do it.

If the valve adj quiets down the valetrain thats great and i hope it stays quiet. But if the tic returns soon after the valve adj i would check for a bad cam lobe/s or imaybe a rocker stud has come loose or one of the rocker nuts is worn and backed off both of which would need to be replaced if that were the case.


Lastly,if you adj the valves yourself and things are still not sounding good to you take it to a couple good reputable motor builders so they can listen to it 1st hand to give their experienced opions hoping they both have the opinion of the problem/s so you dont go barking up the wrong tree.

There are many things that can make this noice but the valvetrain is a goo place to start if you do in fact have a TIC and not a more of thud or knock sound.

You could also try placing a piece of 1x3 or a short broomhandle on the fuel pump with the motor running to see if thats in fact where the tic is comming from. You can also place it on the valve covers,timing cover,etc to try to locate the true origin of the noise which has helpe me track down some problems in the past just like a doctors stethiscope,the wood does really work good for this but be very carefull of the rotating parts like fan/alt/belts/pulleys/etc when doing this. Have someone available to help while doing this so they can work the throttle up & down or hald at a specific rpm that makes the most ticking noise so you can concentrate on what your doing and not accidentially get the woood caught up in any moving parts and get hurt.

Also get back to us here at that point to to run by us what you have done and what the motor builders opinions were too if you need to go that route.

Scott
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Yes,your right it could be a bad/defective lifter which a good motor builder could track down.

If you think it's tyr to narrow down which valve it is and then stop the motor.

Now try to push down on that pushrod and the others to see if that one or any others are mushy or easire to push down/collaps than theothers to locate any bad/cpllapsed lifter/s.

Then remove the intake and then all the lifters to inspect the cam lobes and lifter faces esp the lifter in question that might be making the noise.

If the lobes Lifter faces look good with no sign of damage then your cam should be ok but replace any mushy/questionable lifters at that point putting more moly cam lube on all new and used lifters for restart following new cam breakin all over again. Note,make sure to place all lifters that are not going to be replaced into the same lifter bore it came from or you can wipe out the cam.

Scott
Scottyz,yes you can see the lobes well enough to determine if they are ok.

You may need a very powerfull halogen flashlight and maybe even a small mirror But it can be done by turning the motor over a little bit at a time to insp each lobe along with the strong light & mirror.

As for your question how can you avoid this next time well if you did all things right when it came to cam/lifter install and breakin then some things are just out of your control and are not your fault which was likely what happened to you.

If the cam looks good post inspection then reinstall known good lifters into the lifter bore from which they came and replace any lifter/s that seem to be mushy when tested by pushing down on pushrods before you tear things apart or if they dont look good on the portion of the lifter/s that ride on the cam lobes. Dont forget to use moly cam lube on the used & new lifters and folow the breaking proceedure again as if it were a new cam again esp if you use any new lifters.

Scott
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