dead as no spark at those cylinders?

 

possible intake and/or vacuum issue. end cyls and middle on other side.

 

Loosen all the Rockers to no action step. Remove all Spark Plugs. Do a Compression check and give results here. Al W.

 

Your valves showing change in setting that fast is a sign of the lobes going bad and grinding the bottom of the lifters off. One of you should check the valve lift and that will answer your question.

 

 

 

do a comp test,and with the valve covers off,crank over engine and look for rockers to move all the same

 

 

 

 

Another 'check the cam lobes' answer here. Hopefully you didn't damage the rest of the engine with metal debris and you can change out the cam and lifters and salvage it. Your compression, etc. looks fine. As a mechanic, I have very little faith in modern production flat tappet camshafts. I am very glad the camshafts in my old cars are decades old USA made stuff that was properly hardened and machined in the first place.

 

 

Yep. It's as simple as installing a hydraulic grind cam and hydraulic lifters. A drop-in deal with no mods needed.

 

 

Hello JHemp3,

I know everybody is heading towards blaming the camshaft but I have never heard of one loosing that many lobes (3,5 and 2,8) at one time. There is something else cooking here I believe. Even lifters fail one at a time, what is the likelihood of four separate lobes all being eaten/ground away? The odds are against that happening....

Those compression numbers look "great" for an older engine, they are sufficient to make a running engine if you have fuel and spark! Was the compression test done the old way (rotating the engine) cylinder by cylinder or did you follow the suggestion of one of the posters to loosen up your valves? Compression testing is useful but I prefer using a Leak Down testing rig, this gives you more information and pin points your problem, the bad side is it takes a lot more work than compression testing.

You said that you have "spark but no firing". That does not sound like a cam lobe but maybe something else weird. Are the plugs showing any fuel on them? If you hook everything up and try running the engine using some starting spray (Ether) and see if it fires on all eight or not. If it does then you have a fuel issue causing all this. You obviously have compression, you saw the spark so Fuel is all that is left on that list. How old is the distributor cap? Are there any markings inside of it? Try a black light of needed but if you had carbon tracking inside the distributor cap but that is not likely to "Progress" to four cylinders.

Before you start planning a rebuild get hold of a "Dial Indicator" and "measure" your actual valve movement, that will tell you if there is an issue there. The other thing to do is remove the current oil filter and cut it open and drain it out where you can see the oil. Then take a magnet and run it thru the mess to see if you are getting any metal into your oil. If there is no metal or very little metal in your oil that would eliminate the camshaft from being the cause.

How are you aware that the spark plugs are firing or not firing? What are you testing this with? I have seen wires that were going bad that would fire in the atmosphere but not under compression as that takes a stronger spark to ignite the mixture. Check your spark plug wires again and swap out a good set if they are available. How old are the spark plugs? I am sorry for asking questions but your issue is a very challenging one! The easiest way to check the wires is to run the engine in the dark, IF it is running.

I bought a magnet that attaches to your oil Filter and makes it collect any metal particles in the oil system. It is shaped to fit a particular size filter, once you install it make sure you remove the magnet prior to removing the oil filter from the engine, it is very hard to remove when the filter is off the car, it really holds onto the filter and the metal particles as well. It is called a FilterMAG and they are not cheap at all but they become priceless IF anything goes wrong inside your engine.

Again I apologize for the questions but we are trying to diagnose the issue "Long Distance". Whatever you find please post it so we can all learn what happened here! That is one of the things that makes this Forum so great, we ALL learn something!

 

When he says the lash is opening up fast that's a hint and not a great one.

 

If 3, 5, 2 and 8 are dead, especially at idle, I would look at your carburetor. It sounds like one side may not be flowing fuel. It just so happens that the cyl's that you mention are all fed from one side of the carburetor. Look at your intake manifold and note the runners are divided into upper and lower level and the cyl's that you mention are all on the same level of the manifold.
It would be the first thing I would look into and it's easy to diagnose.

A vacuum leak could also cause this if caused by something fed by one of those four cyl's.

 

 

makes the most sense to me.