Posted this in engines with no response. Thought maybe someone here could help:

I have a '76 350 in my '71. Last weekend while sitting in 5mph traffic for over an hour, it starts running like s**t. Ran like that the rest of the 2 hour drive home. The next day when I started it up, the valves clatter like crazy for about 5 minutes then its almost back to normal.
So I decide to check the valve adjustment. Some of the valves were 2-3 full turns too tight! So now it runs nice and smooth, but under heavy acceleration I get lots of valve noise. At idle, or no load high RPMs it sound fine. The guy I bought the car from said it was rebuilt 4000 miles ago.

So now I am wondering, so I put an oil pressure gage into the idiot light sensor. I get 10-15lbs at idle, and 35lbs at highway cruise speed.

So, is this normal oil pressure or way low?
Would it cause the valve problems?
Could the valves have been adjusted too tight to compensate for low oil pressure?
Would a high volume pump help, and can i put one in without pulling the engine?

Thanks for any help.



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Mike Novak
'71 Chevelle convertible
red daily driver

Some of the more difficult questions can take ~a day to get a few answers.... I wish I could help more but I am not sure.... I would think that the stock idiot light sensor might not work the best with a gauge...Perhaps it simply has overheated - do you have a temp guage?

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Ron Cook TC Gold #1276 ___ ACES #5136
1969 300 Deluxe HTSS396 (http://www.chevelles.com/showroom/bow_tied4.jpg) The L35-325HP 396cid (http://www.chevelles.com/showroom/bow_tied3.jpg) 69 Memory Lane (http://www.chevelles.com/showroom/bow_tied.jpg) 1971 Malibu 2DR HT (http://www.chevelles.com/showroom/bow_tied_71Malibu.jpg)
CanAm Chevelle Club (http://www.canamchevelles.com)

That pressure does not seem outrageously low. 10lbs per 1000 rpm is not a bad guideline.

It's possible that your tight valves may have damaged something.

The next thing I would do is a compression test and see if any valves are leaking. This would be an indication that one or more are damaged.

Are you sure the valves are making noise, and not the lifters, cam, timing chain?

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Jameel Qazi
#'s 67 SS
65 TPI / 700R4 El Camino

novakm, i had the same prob, my friend over tightened my cam and ran fine but under heavy acceleration it would make a fast clatter noise so i tore down the engien to look at the cam one of the lobes where shot, he had the valve so tight there was no lobe on one section of the cam..

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72' Chevelle SS (Clone)
TC Member#1417

just to clarify, The valve system makes noise. ranges from tick tick tick to clack clack clack. When it's clacking, the exhaust sounds different too, like something is not right.

I tested compression 2 weeks ago. 137-140lbs in each cylinder. I will check it again saturday.

any way to check the cam without a tear down?

Thanks
Mike

I have a idiot light for temp, and I found today that there is no wire to the sensor. I can't even find the wire. looks like another saturday project.



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Mike Novak
'71 Chevelle convertible
red daily driver

only way i know w/o taking out the cam is to take off the intake manifold and look in the holes if ur block haas the cma holes to look doen mine didn't so i removed my cam.

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72' Chevelle SS (Clone)
TC Member#1417

well, low oil was caused by a bad bearing. I replaced the crank and bearings. oil pressure is now 50psi at idle, 75 when driving (hot). All the valve noise is gone and it runs great. While the crank was out, I checked lift on cam, and all lobes were OK.

Thanks for the help.

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Mike Novak
'71 Chevelle convertible
red daily driver

Be sure that your temp sensor is hooked up and operating this time. Suspect you damaged the engine from overheat.

FWIW when you turn you ign key to the run position all the engine idiot lights should come on. Its a lamp test for your benefit. If any one light fails to illuminate you need to investigate cause.


Glad you were able to find and repair problem successfully http://www.chevelles.com/forum/smile.gif

as an addition to charbilly's post; some of the warning lights only come on when the ignition is turned to the "start" position, such as the brake warning or the temp light.

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Leo Paugh
Maryland Chevelle Club #017
A.C.E.S.#3731
progress has little to do with speed, but lots to do with direction.
Maryland Chevelle Club (http://www.chevelles.net/mcc/mcc.htm)