I need to ajust the valves on a 70-402, I would rather not do this with the engine running to avoid the mess, can this be done with feeler gages and if so what would the specs be for intake and exhaust.should it be done hot or cold. Thanks Don
Valve ajustment 70-402
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Then feeler gauges arn't used.
Do a search for valve adjustment as there's a few ways to do it.
Here's some posts:
http://www.chevelles.com/forums/showthread.php?t=280316&highlight=valve+adjusting
http://www.chevelles.com/forums/showthread.php?t=279596&highlight=valve+adjusting
FYI ,I do them hot/running.
Do a search for valve adjustment as there's a few ways to do it.
Here's some posts:
http://www.chevelles.com/forums/showthread.php?t=280316&highlight=valve+adjusting
http://www.chevelles.com/forums/showthread.php?t=279596&highlight=valve+adjusting
FYI ,I do them hot/running.
There is not much to adjusting Hydraulic Lifters on a working Engine that is one which is not being assembled.
Take off the Valve Covers, Start the engine let it heat up to temp and let it Idle then simply back off each lifter one at a time with the engine running until it clacks (Note: Let it clack to ensure the Lifter has fully pumped up - that is if it stops clacking back it off some more) then tighten it 1/4 or say 1/2 turn for all lifters. I prefer 1/8th turn. The reason being if something is amiss with the Valve Train I will hear it, eg: Worn Rocker Nuts that slacken off.
Cutting the top of an old valve cover will save an oily mess.
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Setting Up Hydraulic Lifters during assembly for a first time start up is an entirely different matter where you ensure the lifter is sitting on the Base Circle of the cam and tighten the Rocker Nut until the Push Rod barely makes contact with the Petal Valve then turn it another 1/4 turn. Here again I prefer 1/8th turn as you will hear a tappet noise if you wipe a lobe while breaking in a cam.
Take off the Valve Covers, Start the engine let it heat up to temp and let it Idle then simply back off each lifter one at a time with the engine running until it clacks (Note: Let it clack to ensure the Lifter has fully pumped up - that is if it stops clacking back it off some more) then tighten it 1/4 or say 1/2 turn for all lifters. I prefer 1/8th turn. The reason being if something is amiss with the Valve Train I will hear it, eg: Worn Rocker Nuts that slacken off.
Cutting the top of an old valve cover will save an oily mess.
Setting Up Hydraulic Lifters during assembly for a first time start up is an entirely different matter where you ensure the lifter is sitting on the Base Circle of the cam and tighten the Rocker Nut until the Push Rod barely makes contact with the Petal Valve then turn it another 1/4 turn. Here again I prefer 1/8th turn as you will hear a tappet noise if you wipe a lobe while breaking in a cam.
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Why do people turn down one, two or three quarters, after clatter stops, when factory manual instructs a full turn? (71 350...not sure what manual describes for 70 402)
you dont always get a real accurate preload by listening to the rockers tapping, but it will work for ballpark adj.
if you pull all the sparkplugs(makes it easier to turn over) then use the old deal when the intake starts to close, adj. the ex.-when the ex. starts to open, adj. the int.
you want to crank down the rocker arm to just "zero" preload, then 1/2-3/4 turn for preload
a good way to know when you are at "zero" preload is to use a thin feeler gauge, maybe
.002 or so, make it a firm slip fit, but not tight enough to move the lifter plunger-this will get you close enough to zero, i only rec. this if your unsure of being able to get the right feel for zero preload, then do your adjustment
if your curious, you can also use the feeler gauge to determine how many thousands a 1/2 or 1 full turn is, simply by turning the adj. nut and meas. the diff with the feeler gauges
hope that helps
sup. you can rev a little higher with a lighter preload, but might pickup a valve tap now and then, prob a min. of 3/4 is good for a street car
if you pull all the sparkplugs(makes it easier to turn over) then use the old deal when the intake starts to close, adj. the ex.-when the ex. starts to open, adj. the int.
you want to crank down the rocker arm to just "zero" preload, then 1/2-3/4 turn for preload
a good way to know when you are at "zero" preload is to use a thin feeler gauge, maybe
.002 or so, make it a firm slip fit, but not tight enough to move the lifter plunger-this will get you close enough to zero, i only rec. this if your unsure of being able to get the right feel for zero preload, then do your adjustment
if your curious, you can also use the feeler gauge to determine how many thousands a 1/2 or 1 full turn is, simply by turning the adj. nut and meas. the diff with the feeler gauges
hope that helps
sup. you can rev a little higher with a lighter preload, but might pickup a valve tap now and then, prob a min. of 3/4 is good for a street car
Thanks for the replys, I know how to ajust with the motor running, but it seems no matter what oil stoppers I use in the rockers I end up with a mess all over the engine and inner fenders from oil spray, I was just looking for a cleaner way of doing it. Thanks
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