Carlos Murphy
Well-known member
How dose this retired BMW tech adjust the valves on his Chevy 350?
I aint never werked on a over head valved motor afore...
I aint never werked on a over head valved motor afore...
valve adj ?
- Thread starter Carlos Murphy
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2muchtorque
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Need more info
Carlos, there are a lot of good people here to help myself included, need more info to correctly assist, like are the lifters hydraulic or solid, is this a new engine build, a new cam and lifter swap or just a maintanence adj. on a running engine. Need to know this b4 proceedure can be recommended. If I cant get back with you I know someone will, good luck buddy.
Carlos, there are a lot of good people here to help myself included, need more info to correctly assist, like are the lifters hydraulic or solid, is this a new engine build, a new cam and lifter swap or just a maintanence adj. on a running engine. Need to know this b4 proceedure can be recommended. If I cant get back with you I know someone will, good luck buddy.
You're going to get two sets of reply's-do them hot or do them cold. I've never seen any reason to mess with doing them hot-total waste of a bunch of paper towels and a hell of a mess.
I do it cold. For a stock-type motor & cam w/ hydraulic lifters, this is how I do it:
*Note motor spins clockwise, looking from front to back. #1,3,5,7 on driver side, 2,4,6,8 on pass. side. Firing order is 18436572.
*With plugs out, put a 1/2" drive ratchet & socket on the crank bolt and turn the motor over clockwise. At the same time, have a finger over the #1 spark plug hole (or have a helper). When it starts to blow air past your finger, you are coming up on TDC on compression stroke. Continue turning until it just quits blowing past your finger-now the piston is at the top (and more importantly-lifters are on base circle of cam) & you can adjust both valves on that cylinder. This way eliminates the possibility of adjusting the valves @ TDC on overlap instead of compression, as well as it makes having to try and see the timing marks unnecessary.
*Back off the rocker arm nut until pushrod is slightly loose. Now retighten the nut, while spinning the pushrod between your fingers. When you can't spin the pushrod anymore, all the slack is out. Now tighten another half turn to preload the lifter. REmember to adjust both valves @ this time.
*Now you can follow the firing order-doing the same procedure to get each piston @ TDC on compression stroke (for reference, each cylinder fires @ 90 degrees rotation from the previous). When you get through all eight cylinders, you are done and won't have to mess with them anymore (especially hot).
I do it cold. For a stock-type motor & cam w/ hydraulic lifters, this is how I do it:
*Note motor spins clockwise, looking from front to back. #1,3,5,7 on driver side, 2,4,6,8 on pass. side. Firing order is 18436572.
*With plugs out, put a 1/2" drive ratchet & socket on the crank bolt and turn the motor over clockwise. At the same time, have a finger over the #1 spark plug hole (or have a helper). When it starts to blow air past your finger, you are coming up on TDC on compression stroke. Continue turning until it just quits blowing past your finger-now the piston is at the top (and more importantly-lifters are on base circle of cam) & you can adjust both valves on that cylinder. This way eliminates the possibility of adjusting the valves @ TDC on overlap instead of compression, as well as it makes having to try and see the timing marks unnecessary.
*Back off the rocker arm nut until pushrod is slightly loose. Now retighten the nut, while spinning the pushrod between your fingers. When you can't spin the pushrod anymore, all the slack is out. Now tighten another half turn to preload the lifter. REmember to adjust both valves @ this time.
*Now you can follow the firing order-doing the same procedure to get each piston @ TDC on compression stroke (for reference, each cylinder fires @ 90 degrees rotation from the previous). When you get through all eight cylinders, you are done and won't have to mess with them anymore (especially hot).
2muchtorque
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- Jul 23, 2009
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Remember this phrase
" Exhaust valve starts to open- you adjust the intake valve, the Intake valve just before it fully closes- you adjust the Exhaust valve". This ensures you wil be on the heel or base circle of the cam as Adam correctly stated. Heres a tip I would always teach to someone starting out, keep a felt tip marker handy, and put a mark on each rocker arm AFTER you have adjusted that valve, might need to whipe a spot with some laquer thinner so mark will show, and be sure to turn the engine over in DIRECTION OF ROTATION that it runs. Learn that method and you can not fail, BUT you still need to know if you have solid or hydraulic lifters. If you have a solid cam and you want to adjust the valves with a hydraulic method, because it sounds like a squirrel orgy under your valve covers, you are in for a very expensive education. Squirrel orgy, thats funny right?
" Exhaust valve starts to open- you adjust the intake valve, the Intake valve just before it fully closes- you adjust the Exhaust valve". This ensures you wil be on the heel or base circle of the cam as Adam correctly stated. Heres a tip I would always teach to someone starting out, keep a felt tip marker handy, and put a mark on each rocker arm AFTER you have adjusted that valve, might need to whipe a spot with some laquer thinner so mark will show, and be sure to turn the engine over in DIRECTION OF ROTATION that it runs. Learn that method and you can not fail, BUT you still need to know if you have solid or hydraulic lifters. If you have a solid cam and you want to adjust the valves with a hydraulic method, because it sounds like a squirrel orgy under your valve covers, you are in for a very expensive education. Squirrel orgy, thats funny right?
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" Exhaust valve starts to open- you adjust the intake valve, the Intake valve just before it fully closes- you adjust the Exhaust valve". I have been building and dyno tuning race engines for 30 years, from 5" stroke Harley drag engines to 638" small? "mountain motors", learn that method and you can not fail, BUT you still need to know if you have solid or hydraulic lifters. If you have a solid cam and you want to adjust the valves with a hydraulic method, because it sounds like a squirrel orgy under your valve covers, you are in for a very expensive education. Squirrel orgy, thats funny right?
I agree completely-that's how I do my race motors (sprint cars). But- for a mild or stock cam, it's not necessary. It's so much easier to explain and easier to learn (if you're doing it for the first time) to do them both @ TDC. People have been adjusting valves like this on stock motors forever-it works just fine.
