Broken valve spring

[shadango]

A bent valve will bend below the stem so it will still slide up& down Ok but yes the compressed air will leak past the gaps in the rings & bleed out so you should be Ok

Thanks...

I honestly do not know if the leakdown is caused by a leak at the fitting itself or internal....when I listen to the air leaking out, I think it sounds like internal.....which would be bad....but......praying its not.

When I did the compression test on the other cylinders, there was no leakdown like this........

I guess I will know for sure when I put the new spring on and check compression. Crossing my fingers that the dampener was holding the valve up high enough to avoid colliding with the piston.

[tommyg29]

slightly unrelated, but does anyone know of a calculator that can tell me where each piston is in its cycle at a given time.
Example, I can see the #3 and #6 intake valves are open. Where would the #8 piston be sitting? TDC, bottom, or somewhere in between, on its way up, or down. I know impossible to tell exactly but just curious.

[Strawdawg]

Thanks...

I honestly do not know if the leakdown is caused by a leak at the fitting itself or internal....when I listen to the air leaking out, I think it sounds like internal.....which would be bad....but......praying its not.

When I did the compression test on the other cylinders, there was no leakdown like this........

I guess I will know for sure when I put the new spring on and check compression. Crossing my fingers that the dampener was holding the valve up high enough to avoid colliding with the piston.

Put the springs on, spray some carb cleaner into the port...if it comes running out into the cylinder, the valve is bent

[tommyg29]

fingers crossed 

[Chryco Psycho]

simple if 1 is at TDC then 6 is also , then 8 & 5 is 1/2 way up the cylinder 4 & 7  is at BDC & 3 & 2 is 1/2 way down , same as the firing order

[shadango]

Well, replaced the spring and did a compression test on the cylinder (hot engine).....

As a means of comparison, I looked back at some pf my postings here from 3-4 years ago.......

Back then, my readings, cold, carb closed, back in 09 were

1  starts at 75...pumps to 125  (in just 2 or 3 rotations)
2  starts at 75...pumps to 125
3  starts at 75...pumpls to 125
4  starts at 80 or so....pumps to 140
5  starts at 75...pumps to 130
6 starts at  75...pumps to 123 or 124
7 starts at 75....pumps to 123 or 124
8 starts at 100...pumps to 136



A year later, I posted that "all cylinders read 145-150 when warm" (not sure carb open or closed)....unless I had mis-spoken.......


My compression readings this time around were (warm, carb closed)

cyl 1 -133
cyl 2 - 127
cyl3 - dead
cyl 4- 140
cyl 5 -138
cyl 6 - 141
cyl 7 - 130
cyl 8 - 144

After the new spring, cylinder three reads only 115 as a best reading --- 110-112 other readings.  Warm, carb open.

So there is something up with that cylinder.  But I took it for a ride and honestly cannot feel anything wrong...it runs fine....seems normal.

The old FSM says for specs that 100 psi is the minimum spec.....no "normal" range.....and a "maximum variation" of 40 psi.  So going by the book, and my seat of the pants, I guess it is OK even considering my engine is not stock.....j heads.

Still, I know what folks say here and I may have issues in the valves or rings I guess.......

Gonna drive it a few times and see how things go.  Do not want to put brand new springs all the way round if I will need head work soon anyways.

[72cudamaan]

If the spring was fatigued before it broke then you may have a slight carbon deposit on the valve. If so
then hopefully it would burn off. I agree, run it for a bit and see if the reading improves. If no improvement
then you haven't lost anything as the head would have to be pulled anyway. And I can't see you making it any
worse than it is now. By the way, you're within 10% of all cylinders and that is the standard normally used.

[shadango]

If the spring was fatigued before it broke then you may have a slight carbon deposit on the valve. If so
then hopefully it would burn off. I agree, run it for a bit and see if the reading improves. If no improvement
then you haven't lost anything as the head would have to be pulled anyway. And I can't see you making it any
worse than it is now. By the way, you're within 10% of all cylinders and that is the standard normally used.

Thanks for the advice.........how does one figure that 10%?

Some of mine are at 140.....and the lowest is at 115.....

I was shocked that the FSM says 100 is the minimum pressure and that no "average" pressure was listed.....

[Strawdawg]

if both valves are closed and you introduce some air pressure into that cylinder, you should be able to hear it coming out the tail pipe if the valve is bent and not sealing well..

Or, a vacuum gauge should bounce around a bit if the valve is bent much

[72cudamaan]

Thanks for the advice.........how does one figure that 10%?

Some of mine are at 140.....and the lowest is at 115.....

I was shocked that the FSM says 100 is the minimum pressure and that no "average" pressure was listed.....

It's measured comparing the highest to lowest reading. I guess I obviously didn't look at your numbers correctly since
you have more than a 10% variation. I still say drive it for a while and check it again. If the valve just has debris on it, it
may clean itself off. The other choice is to run the engine at a high idle and dribble water down the carb. That
will steam clean the valves and might help. Can't hurt (as long as you don't flood the engine).

[shadango]

So I have driven the car a couple/three hundred miles........did a compression test again (warm/WOT)

1- 140
2- 134
3-120
4-142
5-141
6-143
7-133
8-150

Then added 3 squirts of oil from my old fashioned oiler into 4 of the 8 cylinders to check again:

3- 140
4- 158
7- 150
8 -167

The compression #3 DID come up some...from 110-115. But not a huge amount.

So, looks like I have not only a valve issue at #3 (about 15% less than the average of the rest, and 20% less than cylinder ,  my rings also are worn I guess.   

When I got the car originally, I was told the whole engine was gone over with stock lower end.  Either they didnt touch the lower end or...well, yeah I guess thats it.  I was hoping the lower compression numbers were due to the J heads....but I guess not.   Unless 3 squirts of oil was TOO much and tainted the readings?

Gonna change the oil and add "Restore" to it and see how that affects the overall compression.  I know it wont fix the valve issue, but I am curious to see what it does for the rings, if anything.   I saw a lot of threads elsewhere on that topic so I figured this would be a good test.  I will report back the findings.  My old man used it in his 56 Merc some 30 years ago and swore that it worked then.....so we will see. 

Long term, I guess drive it till it gets worse or breaks or I become flush with $$$$$$.    LOL

[72cudamaan]

Lots of ring wear, that's for sure. You're running over 10% increase with oil added. Not so good. Try
the tune up in a can as you're right, you probably can't make it worse. Just don't be surprised if you don't see an improvement.

Good luck with it.

[cudabob496]

slightly unrelated, but does anyone know of a calculator that can tell me where each piston is in its cycle at a given time.
Example, I can see the #3 and #6 intake valves are open. Where would the #8 piston be sitting? TDC, bottom, or somewhere in between, on its way up, or down. I know impossible to tell exactly but just curious.

There's a graph at bottom of article that discusses piston position.

http://en.wikipedia.org/wiki/Piston_motion_equations

[shadango]

Thanks for the good luck wish.......

I always try to win the giveaway motor at Carlise......was hoping THIS year would be the one!  LOL   But probably not going this year......so........

[shadango]

Soooooooooo.......another development.

Just driving along easy to day and I broke another spring ----same cylinder (cyl 3) but this time the intake spring.

I had bought 16 springs but after running it a bit and feeling OK, I decided to hold off on the other springs since the rings are worn , etc etc...why put new springs on when I will need work later. So I returned all but 1 extra spring plus the one I installed.

Well, looks like for whatever reason these springs are all ready to go......runs fine with the new spring....I do hear a air leak in my exhaust so I know the exhaust valve is not sealing 100% too.....but cant get major work done right now so I am gambling that replacing the rest of the springs will get me thru the summer. I hope.

AND OF COURSE I just shipped the 14 new springs I decided to not use back to summit.....lol...on the phone with them now to get them sent back to me.

My guess now is that my motor was not freshened up like I was told when I bought it.

Anyways, I just did an oil change and added restore last week........Took some new compression reads after the new spring:

1- 149  (up from 140)        2- 135 (up from 134)
3- 125 (up from 120)         4- 140 (down from 142)
5- 152 (up from 141)         6- 154 (up from 143)
7- 146 (up from 133)         8- 146 (down from 150)

So between the new oil and the Restore my compression overall is up.....

Hoping that swapping the rest of the springs out will get me thru the summer........I should have just done them all to begin with...but figured that after I made it through a few hundred miles of driving with the one spring , all was well.....