Bent Valve?

[MinnBri]

Bent Valve? Here is the problem... I am trying to put in electronic ignition. I aligned the # 4 to TDC. And I noticed that the timing belt slipped from the marks. I hand turned the crank and the cams but it would suddenly stop, so I figured it was hitting a valve. Long story short, I have all the timing marks aligned, turns over great, but now no compression in # 4. With both intake and exhaust valves closed, I run air through the spark plug opening and it comes back through the carburetor. So I figure I bent the valve somehow. So what I’m asking is for a second opinion before I tear the head off to replace the valve. Any tricks to adjust or diagnosis the valve without ripping it all apart?

76 124 with pollution removed.

[Curly]

A bent valve will show up by checking cam to valve clearances. The bent valve won't shut fully, therefore the clearance at the cam will be greater.

[MinnBri]

thank you. I'll check that first. But I suppose that could mean some carbon or other crap got stuck between also.

[Kevin1]

Was this car running before you started the ignition swap?
Is it possible you have adjusted the timing marks to align when the crank pulley was one rotation off? The cam wheel marks only line up with the crank pulley marks every other rotation - the crank rotates twice for each rotation of the cams. Could it now be adjusted 180 degrees off?

[So Cal Mark]

76 was an interference year, so a slipped belt will bend valves. Carbon under a valve won't result in 0 compression. It would have to be a huge piece of carbon to drop pressure to 0. Checking clearance is the quickest way to verify, but if the other cylinders have compression it sounds like it's time to pull the head

[MinnBri]

Thanks for the help...it ran great before i did this oops... but anyhow...can you explain "76 was an interference year"

is it just the pollution control pump and etc.?
Sounds like time to take that head off.
Has anyone had good luck just replacing the vavle?
Seems to me everytime I did that in other engines, it would blow the rings or piston out.

[So Cal Mark]

"interference" means the engine won't freewheel. If the valve-to-piston timing isn't correct the valves will contact the pistons. Fiat enlarged the valve reliefs in 1977, lowering the compression ratio and allowing the engine to freewheel