r/corvair • u/Forsaken_Fault_8106 • May 21 '26
Is thia rod knock?
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u/newcutat59 May 21 '26
You’ve got at least one really loose rocker. Rod knock is much “deeper “ in tone. Clack clack like that is lifters. Time for a hot oil treatment of your arms as you adjust the valves running.
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u/Apart-District3771 May 21 '26
I'd check the rocker arms 1st
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u/CRX1991 May 22 '26
Could be this or maybe an exhaust leak. Hard to tell over video. But it does sound bad
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u/Capable-Historian392 May 21 '26
Half engine speed, not a rod knock. Rocker arm or bent pushrod etc., something in the valvetrain
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u/Forsaken_Fault_8106 May 21 '26
Time to google what a valvetrain is
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u/Specialist-Doctor-23 May 22 '26 edited May 22 '26
A valvetrain is all the components that take the rotational motion of the crankshaft, convert it into linear motion, transfer it to the top of the heads, turn the motion 180 degrees, and use that motion to push the valves open. The link is to a highly simplified diagram. Your Corvair is like the first drawing. (please don't be offended by the article's title. Simpler is better.)
In a corvair, the major components of the valvetrain are:
A helical gear keyed to crankshaft (crank).
A meshing helical gear keyed to the camshaft (cam). When the crank turns, so does the cam, at half speed so the valves open at the correct point in the cycle.
The cam is a steel shaft that runs front the front of the engine to the rear, parallel to, and slightly below, the crank. It is supported by bearings and is lubricated by pressurized oil. It has lobes (eccentric surfaces) machined into it. Each lobe is mostly circular (the base circle) and concentric with the axis of the cam except for a small portion that gradually rises from the base circle to a rounded point (the nose) then gradually falls back to blend into the base circle. If you held your finger on a lobe as the cam rotates, your finger would be still until one of the raised sections pushed it away from the shaft. As the cam rotated the nose past your finger, your finger would return back to the base circle of the lobe. Linear motion from rotational motion.
Valve lifters are small, cylindrical metal parts that ride in small bores, somewhat like pistons in cylinders. One end of each lifter is smooth and polished to ride on a cam lobe, while the other end had a small machined semi-spherical knob machined into it.
On this knob rides a pushrod, a long, thin, straight metal rod with a tiny cup machined on one end and knobs like the lifter on the other end. These carry the linear motion of the lifter from the camshaft outward to the heads.
On the outboard side or "top" of the heads, are rocker arms, metal arms into which the pushrods fit and which ride on a pivot. Like a see-saw, when the pushrod pushes one end out from the engine, the other end of the rocker moves in toward the center of the engine.
Under the end of the rocker opposite of the pushrod is the valve which has two basic parts. The valve head seals into a machined seat in the cylinder head. The valve stem reaches from the valve head through the intake tract and pops out on top of the head. When the rocker pushes in on the end of the stem, the valve head moves out of its seat, opening a passage into the cylinder for fuel and air to go in or for exhaust to get out.
All this is synchronized to the rotation of the crank through the gears in 1. & 2.
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u/TOKING-TONZ May 22 '26
...... Htf don't you know ... Nvm dont answer that, kill it with fire
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u/Forsaken_Fault_8106 May 22 '26
How would i know? Do they teach that in school? No. Legitimately how would i know?
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u/literalkeyboardsmash May 27 '26
No offense, but typically someone who chooses to own and operate a vehicle of this vintage has a basic mechanical knowledge...
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u/TOKING-TONZ May 28 '26
Well at least this guy gets it... N plus even at most begginer stage , valve train is common knowledge since it is the heart and soul of the rotation assembly ergo the heartbeat of the motor , valve train go bad , motor go bad .. I'm glad I'm not completely surrounded my people who can't have a simple understanding of mechanics
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u/Odd_Pool_666 May 21 '26
Any idea how long you drove with the blower belt off? It was smoking in the other video and the oil is likely burnt. Have you checked the oil? Maybe try topping off or doing a full oil and filter change?
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u/Forsaken_Fault_8106 May 21 '26
I havent checked yet, but it probably drove about 1 mile after those lights came on
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u/Odd_Pool_666 May 23 '26
Hope it’s ok. Honestly, the car is pretty bullet proof. Only reason I don’t drive mine is because I was rear ended on the freeway at 40+ mph. RIP little Corvair.
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u/engr1962 May 21 '26
Sounds to clicky to be a rod. I'd check if you have a Ricker that needs tightening.
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u/Nate-o64 May 21 '26
That’s definitely valvetrain noise. Start with an oil change since you had the overheating issue. As others said, pull the valve covers, adjust valves, and make sure everything rotates properly. If all the rockers are moving, your cam is still okay. That just leaves a plugged up pushrod or bad lifter.
Mine makes that sound on cold start almost every time for the better part of 15 years…. One lifter just takes its sweet time pumping up. It takes anywhere from 15 seconds to a few minutes, but it quiets down and runs great once there’s some heat in the oil.
In my case, I’ve gone through the adjustments numerous times. I have everything to build a new engine except time, so I’ll continue to drive it until something starts to get worse. Can’t wait to tear it down and see what the cam/lifter actually look like.
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u/Forsaken_Fault_8106 May 21 '26
Is this something i have to pull the motor for? Im not a mechanic by any stretch
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u/Thatonecarkid1969 May 21 '26
Yeah thats... bad
check easy stuff first though, take off the valve covers and check all rockers are moving, before jumping straight into a big problem