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Valvetrain issues

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  #1  
Old 03-19-2018, 10:52 PM
Kyle Wood
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Valvetrain issues

Im lost here, I just rebuilt my 400ci with a bunch of go fast goodies. Well i herd some valve train noise so i decided to take off the valve covers only yo find some of my pushrods have slop in them. Roughly .05" max to .02 min of slop. Most of the ones with slop are the intake valves, however some are perfectly snug and how they should be.

What could be the cause?
i have 300 miles on fresh engine. Ive done 2 oil changes and always addef ZDDP additive (hydraulic flat tappet). I thought my pushrods might be too short, but if this was true id think they all would be affected. All the rockers when the engine is hand turned over seem to have the same amount of movement between them, so i dont think a lobe has failed.
Im thinking of ordering 9.575" pushrods to see if this fixes the issue but id want to be sure it isnt somethinf else before i drop 100 dollars on pushrods.

i have an adjustable pushrod however i must be doing something wrong. I turn the engine to comp stroke, insert the adjustable pushrod to a smidge bigger than what i currently have (9.5"), finger tighten the rocker to zero lash, then torque to 20ft/lbs. However when i go to torque my rockers it ends up pushing the valve down.
 
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Old 03-20-2018, 09:57 AM
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Probably be better to take it back apart to see, before spending any money.
 
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Old 03-20-2018, 03:25 PM
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Youre definately doing something wrong here if your valve is being pushed down (open) on the compression stroke. Im not familiar with the modified engines but are you using the stock style non-adjustable rocker arms? If you havent changed to aftermarket heads and or rockers you should be just torquing down with stock length rods.

the fact that its onpy some of the valves is a concern. Id recommend atleast removing intake and valvetrain/lifters to start over here. Its only an afternoons work for some peace of mind
 
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Old 03-20-2018, 04:37 PM
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If the valve is getting pushed down when tightening the stock rocker to spec, it tells me the pushrod is too long or the base circle on the camshaft is wonky. Ford Performance makes pedestal shims to correct this:

https://www.summitracing.com/parts/fms-m-6529-a302

If too much slack as you have described on some valves you can remove material off the bottom of the pedestal to bring it into spec. Go careful to preserve and maintain the preload.
 
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Old 03-20-2018, 04:38 PM
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If the valve is getting pushed down when tightening the stock rocker to spec, it tells me the pushrod is too long or the base circle on the camshaft is off.. Ford Performance makes pedestal shims to correct this:

https://www.summitracing.com/parts/fms-m-6529-a302

If too much slack as you have described on some valves you can remove material off the bottom of the pedestal to bring it into spec. Go careful to preserve and maintain the preload.
 
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Old 03-20-2018, 06:22 PM
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Shimming should only be done to fine tune. Too much shim will destroy valve train geometry and could lead to big trouble. Did you check to make sure all the valve tip heights were the same ? They need to all be within .005, that is very important in a nonadjustable valve train. If they are all different heights then you would need a different length push rod for every rocker, not practicle.
Put #1 on tdc, Remove the valve spring and put a light "checking" spring on & a marking compound on the valve tip. Put adjustable push rod in and adjust rocker to zero lash. Turn crank through a cycle all the while watching the lifter plunger, you do not want it to compress. Remove rocker and see what the sweep looks like on the valve tip. If pattern is not centered adjust the push rod accordingly and try again. Once the pattern is centered measure the push rod and add the preload figure to it ( I use .030) and that's your new length.
 
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Old 03-20-2018, 09:30 PM
Kyle Wood
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What worries me too, is that i have o ly a few pushrods that are loose. Iy seems like it would be an all or nothing. Or maybe ine or 2 if i had bad lifters. I have stock heads with non adjustable rockers. I ordered myself some 9.56 inch PR. After doing some reading and talking with a few ford people, ive herd some 400s take 9.56. Hopefully this will fix my issue. Only 40 dollars.

if this does fix my issue, how do i decompress the lifters since probably a few are completely pumped up due to the slop in the rods? If possible, id like to not take off the intake since ive check it with propane and it is 100% sealed. Thanks all!
 
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Old 03-20-2018, 09:45 PM
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did you replace the head gaskets? thicker or thinner gaskets will affect to pushrod length. or mill the heads?
 
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Old 03-21-2018, 12:00 AM
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Rotate the engine over, and see if those same pushrods are still loose.
 
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Old 03-21-2018, 08:27 AM
Kyle Wood
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I rebuilt the engine, so fresh head gaskets (felpro) so in not sure how thick they are. I am waiting on .060" longer and i think it may fix my issue. However can i just torque these down and it will bleed the lifter out to where it needs to be? Or do i have to pull them and somehow bleed them down?
 
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Old 03-21-2018, 10:54 AM
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Originally Posted by Kyle Wood View Post
What worries me too, is that i have o ly a few pushrods that are loose. Iy seems like it would be an all or nothing. Or maybe ine or 2 if i had bad lifters. I have stock heads with non adjustable rockers. I ordered myself some 9.56 inch <acronym title="Page Ranking">PR</acronym>. After doing some reading and talking with a few ford people, ive herd some 400s take 9.56. Hopefully this will fix my issue. Only 40 dollars.

if this does fix my issue, how do i decompress the lifters since probably a few are completely pumped up due to the slop in the rods? If possible, id like to not take off the intake since ive check it with propane and it is 100% sealed. Thanks all!
Don't take anybodys word for anything, they are not doing the work on it. As far as a stock length, who cares ? That's all changed now. Don't be throwing good money after bad by just throwing parts at it. You are moving in the wrong direction here and setting yourself up for disaster. Go back, start over. Check all cam lobes, make sure they are not going bad. Check all the stem heights, make sure they are within .005. then find push rod length, the right way. The lifters being pumped up will work to your advantage finding length because you don't want the plunger to move while checking for length. Good luck.
 
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Old 03-21-2018, 11:37 AM
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Kyle,

You need to start over with your valvetrain.

In reading your posts of how you think it should be setup, I don't think any of it is correct...if so, it was luck.

Bolt down, non adjustable rockers, for a hyd. flat tappet cam :...(I am assuming that is what you have)

1.) I agree to check valve tops to be within 0.005 or so. Put a straight edge across them and feeler gauges in gaps to see what's going on.
2.) If 1 is ok, then put #1 TDC on comp stroke..cam is on base circle both I/E.
3.) Bolt down rocker without pushrod in place
4.) install adjustable pushrod and lengthen until until you remove any up and down slop, and provide just enough length that you can twist the pushrod but feel a little bit of drag. Make sure you are not depressing the plunger in teh lifter.
5.) back off rocker, measure pushrod, add 0.030" to that number and that is your final pushrod length
6.) do steps 1-5 for the other valve for that cylinder, and then buy your pushrods.

Most likley for a stock rebuild from a competent machine shop, you will be able to utilize the same PR length for both I/E.

The lifter plungers should never be depressed during this exercise.


Double check the two valves that are loose...if those two need a longer pushrod beyond the 0.005" you established in step 1, then the cam and lifter is wiped for those valves.
 
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Old 03-21-2018, 01:37 PM
Kyle Wood
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I will have to try that. Thank you for writing a good step by step guide. I already ordered the PR so they will be here friday. However i am going to try to use the adj PR again since i had been using this slightly wrong.

Without pulling the intake or cam, is there a way to check the lobes? Could i pull the lifter on the lifter in the worst cylinder with a magnet and look at the riding surface to see if it is scuffed and make a decision based on that?
 
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Old 03-21-2018, 01:57 PM
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I'm curious as to what your noise sounds like, who -what, when. I too have had an unusual noise after my 400 was rebuilt about 8000 miles ago. On accel at certain speeds, it has what I think is a rocker/pushrod type tapping sound that is very throttle sensitive. I can barely back off the gas a little and it stops. Mine sounds like a sewing machine tap-not heavy harsh or as deep as a lifter that has collapsed-almost like a vibrating noise. Seems most prevalent at steady cruising speeds. I have a hill in my neighborhood and it doesn't even make the sound when accelerating up the hill under moderate load.
 
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Old 03-22-2018, 09:56 AM
Kyle Wood
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My valve train sound "normal" just a tad louder than what i thought it should be. I opened the valve covers to see what wad going on and if everything was normal, which it wasnt. Once i tried tightening everything and taking out the pushrods and reinstalling, it sounded like a noisy lifter (because of the extra lash) more lash now than before for some reason. Slightly longer Pushrods should be here today so hopefully that will fix my issue.

pop off your valve covers and see if you notice anythinf wrong.
 
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