CRG Discussion Forum
Camaro Research Group Discussion => General Discussion => Topic started by: sixt9x33rs on September 29, 2013, 03:46:36 AM
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When is the right time to adjust valves on a 69 302? Every 5,000 miles or is there another metric?
Thanks,
Lawrence
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"when they need it"...? not sure what the manual says, but I'd guess it depends on what type of rocker nuts you are using (gm, old or new?), or 'lock nuts'? and it probably depends greatly on how you drive it. the only issue I've ever had was when I tried to use 'lock' nuts, because if the locking part looses, the rocker looses very quickly (bent a push rod in my case), and the same thing happened to my son in law when he used the after market 'locking' nuts'. So I prefer 'new' friction nuts from GM... and if they need adjustment, you won't break something, you'll just maybe get a little clatter which tells you 'time to adjust'...
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Like Gary says. I don't touch mine until I hear the odd rocker clatter sound. You kind of get use to hearing a certain sound when the adjustment is right and if one gets loose it's really easy to hear it. That's a good time to check all the clearances then. I think the book says around 12000 miles, but I'm not sure, this could be just average everyday driving without putting any stress on the engine though, I wouldn't think it would be that far out. Others here will probably add something to this, especially if they are diehard solid lifter fans. I know I am. Some people do it often because they are OCD too. I know a few local guys that do it just to do it, because they don't have anything else to do. LOL.
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Thanks guys.
I hear and odd sound but it does not sound like rocker chatter. It sounds more like an exhaust leak but I don't hear it through all the rpm ranges. This is why I was asking about adjusting the valves. I have tightened up the exhaust system to the manifolds and tightened up everything else around the exhaust system (air tubes) and the sound is still there. I will keep listening and poking around.
I don't think it is time to adjust the valves based on what ya'll have said. I am not sure what type of nuts are on the studs. The car has been driven 6000 miles since last adjustment.
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use "PAL" nuts on top of the stock ones as a lock nut. the concave area goes against the adjustment nut
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What type of rockers? Do you know? The factory rockers will have a distinct clack sound where roller tips and maybe full rollers will have a click/tap sound I think. A good thing to do is to take a rather long screw driver, or if you have an automotive type stethoscope, and put one end on the valve cover over the rockers and the other end to your ear and listen for any noises. Works pretty good. If you have a tick sound, put it on the fuel pump as well. There is a small spring on the plunger in the pump body that can break. This spring takes up the slack at the plunger and when it breaks the plunger kind of gets some clearance between the end of it and the lobe it rides on the camshaft. Something I learned about back when I was a kid in the 60's. Definately 2 areas you can rule out if you have a ticking noise. I have found too that exhaust leaks are hard to find in most cases. If you have headers and you hear it around the engine it most likely is a gasket at the head. Check to see if you don't have a bad spark plug boot. I have had arching even with new spark plug wires.
These are just a few things you can look at rather quickly to see what you have going on.
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the original spec for 346 cam was .025/.025 but GM changed it to .030/.030 because the FI corvette engine did not like the closer lash setting lowering the idle vacuum. I would not use the .025/.025 on your Z/28 unless you have a 4.10 rear gear or deeper.
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the original spec for 346 cam was .025/.025 but GM changed it to .030/.030 because the FI corvette engine did not like the closer lash setting lowering the idle vacuum. I would not use the .025/.025 on your Z/28 unless you have a 4.10 rear gear or deeper.
Just curious, what do the rear gears have to do with the rocker clearance? I was using 4.10's and have true 1.50 roller tip rocker and have made adjustments of .027 and .030 and didn't realize any differences between the two. I have 3.73's back in now and still don't realize any difference except the car doesn't pull as quick with the 3.73's as it did with the 4.10's. Can you clarify a little on this Clem? Thanks.
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the tighter lash will hurt your bottom end power and with a close ratio trans starting out from dead stop could be a PIA with a taller gear. 302 are not loaded with a excess amount of torque
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What type of rockers? Do you know? The factory rockers will have a distinct clack sound where roller tips and maybe full rollers will have a click/tap sound I think. A good thing to do is to take a rather long screw driver, or if you have an automotive type stethoscope, and put one end on the valve cover over the rockers and the other end to your ear and listen for any noises. Works pretty good. If you have a tick sound, put it on the fuel pump as well. There is a small spring on the plunger in the pump body that can break. This spring takes up the slack at the plunger and when it breaks the plunger kind of gets some clearance between the end of it and the lobe it rides on the camshaft. Something I learned about back when I was a kid in the 60's. Definately 2 areas you can rule out if you have a ticking noise. I have found too that exhaust leaks are hard to find in most cases. If you have headers and you hear it around the engine it most likely is a gasket at the head. Check to see if you don't have a bad spark plug boot. I have had arching even with new spark plug wires.
These are just a few things you can look at rather quickly to see what you have going on.
will check it out thanks.
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Thanks guys.
I hear and odd sound but it does not sound like rocker chatter. It sounds more like an exhaust leak but I don't hear it through all the rpm ranges. This is why I was asking about adjusting the valves. I have tightened up the exhaust system to the manifolds and tightened up everything else around the exhaust system (air tubes) and the sound is still there. I will keep listening and poking around.
I don't think it is time to adjust the valves based on what ya'll have said. I am not sure what type of nuts are on the studs. The car has been driven 6000 miles since last adjustment.
use a wooden dowel or wooden broom handle on the rocker cover with the other end in you ear and listen for a different sound. same for the fuel pump. you can check the fuel pump by just removing the bolts,pull the pump away from the block and with the fuel in the carb the engine will keep running but the pump will not be working. my new 70 454 450HP chevelle had a knocking fuel pump the first couple of weeks i had it and that is how i found it.
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Motorman; my uncle many years ago taught me the "broom handle" method. It's never failed me yet!
Jim
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Broom handle idea is great. Will check it out thanks again.
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Even a long screwdriver works well. I recently bought a Harbor Freight automotive stethoscope and I was stunned how better that works for picking up faint sounds that not even the 'old school' methods can detect. It's much safer to use near rotating mass and you can look like a Dr. without the medical school expense ;)
Mike
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a few years ago i was at a stop over point for the interstate battery great race. those are the real old cars that do a road rally. there was a 29 chevy there with a noisy engine so i told the guys get me a broom handle and start the engine. i used the broom handle on each cylinder and the noise was coming from #1. so i told them shut off the engine and remove the spark plug and give me a rag. they restarted the engine while i held a rag over the spark plug hole and out came a piece of metal. put the spark plug back in and they were on their way to finish the race. i got a nice write up in the rallys magazine later that year.
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a very nice story clem.... :)
Did you use the same broom handle that they used to hold up their hood? :)
J/K..
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a very nice story clem.... :)
Did you use the same broom handle that they used to hold up their hood? :)
J/K..
if what I did had not worked they may have used the broom handle on me.