New engine has loss of compression

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DartVadar

DartVadar

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So my 360 has about 3k miles on it now and I stared it the other day, it wasn't started for a while so it took a bit of cranking. I started listening to the starter and noticed it ever so slightly sped up as It was cranking in one spot, which from what I understand shouldn't happen, it should be even.

The motor is a .30 over 360, eddy RPM heads, comp 268 cam, weiand intake, holly carb etc, not that anything besides the pistons and heads matter really. I installed the pistons, and they were gapped properly. The car doesn't burn a drop of oil or smoke, and being so new I highly doubt that I have a ring failure. It also runs really strong (So I think anyways). But I think I know where the problem is...the eddy heads. For some stupid reason I just took them out of the box, looked them over for obvious defects and ran them...I understand that ootb they can have some issues. I just wanted to hear the damn car start, my mistake really.

So is it common for these heads to have valves that don't seal sometimes? I know my grandpa bought a car with eddy heads that the guy just threw on, and my machine shop told us that all of those heads need a valve job right away for them to perform well. And what is the best way to test, compression test, leakdown test? I have no issue taking the heads off and take them in for a valve job as the car is sitting in my garage for the winter.



[ame="http://s72.photobucket.com/user/kellyb43/media/IMG_2736_zpswb6lvosz.mp4.html?sort=3&o=0"]IMG_2736_zpswb6lvosz.mp4 Video by kellyb43 | Photobucket@@AMEPARAM@@http://i72.photobucket.com/albums/i189/kellyb43/bth_IMG_2736_zpswb6lvosz.mp4@@AMEPARAM@@72.photobucket.com/albums/i189/kellyb43/bth_IMG_2736_zpswb6lvosz.mp4[/ame]

This is what it sounds like trying to start it, it may be hard to hear but its not an even sound, hopefully it works.
 
An overly tight valve guide can do this. (and comon OOTB for those heads)
Might just pull the covers and have a look to be sure the valves are all closing all the way. (turned over carefully by hand of course)
If you comp test it first, what happens if a valve hangs open far enough for a piston to hit it?
 
I will check for that. Either way those go would it be a good idea to take the heads off and get them checked out?

And it's been running fine for all this time, how would a valve hit?

And I see that the video isn't working, I'll fix that when I get home.
 
DartVadar said:
I will check for that. Either way those go would it be a good idea to take the heads off and get them checked out?

And it's been running fine for all this time, how would a valve hit?

And I see that the video isn't working, I'll fix that when I get home.
Click to expand...

That depends, as I would find out if I had a hanging valve first and then make the decision to have them done or not.

As to the second question, what if it is a valve sticking open and due to sitting it sticks open farther?
 
Yeah those eddy's OOTB aren't ready to run, my machine guy always tears them down and checks them really good before he bolts them on a customers engine, he actually tries to steer them to better heads that aren't mass produced by machines and not humans. He finds some crazy stuff wrong with them but the most common problem he finds is bad valve jobs, bent valves and cracked seats not to mention different spring pressures and the list goes on so be careful could suck a valve and damage your bottom end!
Sorry forgot to mention I have never owned or ever will own a set but this is what I hear when bench racing at the shop lol.
 
dragondan64 said:
Yeah those eddy's OOTB aren't ready to run, my machine guy always tears them down and checks them really good before he bolts them on a customers engine, he actually tries to steer them to better heads that aren't mass produced by machines and not humans. He finds some crazy stuff wrong with them but the most common problem he finds is bad valve jobs, bent valves and cracked seats not to mention different spring pressures and the list goes on so be careful could suck a valve and damage your bottom end!
Sorry forgot to mention I have never owned or ever will own a set but this is what I hear when bench racing at the shop lol.
Click to expand...

I have a set , have seen many on the bench , have not seen the horror stories heard on the net , then again , I'm nit selling a service or have some agenda . Shop I know has sold hundreds if not thousands and they have had no complaints , maybe they are just lucky , or honest ?
 
I took a set OOTB eddies..drove around with them for two years...took them off...replaced the valve seals..which were junk...and put them on a bracket car and ran 11s with them....

if you are checking for tight guides..make sure you remove the valve seal first...
 
According to this guy they are garbage , well I took a pair apart just to check , guy is f o s, or he bought counterfeit heads , that or the pair I looked at were the one good set out there . skip first 15 minutes . Heads had the spring cups , no gap with straight edge , and did not lose 4cc of liquid on the cc test . Fuckin eh . Think he sells pro comp , that need no work ootb
[ame="http://www.youtube.com/watch?feature=player_embedded&v=GoGAgggy874"]340 mopar rebuild n dyno.edelbrock heads caponeauto - YouTube[/ame]
 
So, you are diagnosing a "compression loss" without a compression test? Novel idea, but that will net you the wrong results.
 
RustyRatRod said:
So, you are diagnosing a "compression loss" without a compression test? Novel idea, but that will net you the wrong results.
Click to expand...

Well currently I am judging it off the way the starter speeds up every revolution, and the fact that I didn't get the heads checked before I put them on. I am going to do a compression test when I get home today, so I will have some actual results to judge by.
 
DartVadar said:
Well currently I am judging it off the way the starter speeds up every revolution, and the fact that I didn't get the heads checked before I put them on. I am going to do a compression test when I get home today, so I will have some actual results to judge by.
Click to expand...

A compression check will show compression and my hid a leaky valve(or rings for that matter) but a leak down tester will point to a valve or rings do to were the air is leaving the motor.

If you don't have a leak down tester i would still start with a compression check.
 
I will do a compression test first to see if the compression is in fact down. I will update with what I find.
 
No need for a fancy leak down tester. They are nice, but if you don't have the tester, you're out of luck. All you have to do is remove the valve cover, turn the engine until both valves on the suspect cylinder are closed, remove the plug on that cylinder and apply air to it.

Air exiting the carburetor = burned or not seating intake valve.

Air exiting the tail pipe = burned or bad seating exhaust valve.

Air exiting the cylinder head in the valve cover area = bad rings or a hole in a piston.

Leakdown testers are nice, but people get hung up on the latest and greatest tools highlighted in all the magazines, when you really don't need them.

If you have a points race car or something you are actually competing with, that's another story.
 
rustyratrod said:
no need for a fancy leak down tester. They are nice, but if you don't have the tester, you're out of luck. All you have to do is remove the valve cover, turn the engine until both valves on the suspect cylinder are closed, remove the plug on that cylinder and apply air to it.

Air exiting the carburetor = burned or not seating intake valve.

Air exiting the tail pipe = burned or bad seating exhaust valve.

Air exiting the cylinder head in the valve cover area = bad rings or a hole in a piston.

Leakdown testers are nice, but people get hung up on the latest and greatest tools highlighted in all the magazines, when you really don't need them.

If you have a points race car or something you are actually competing with, that's another story.
Click to expand...
+1
 
I would not take anything from the starter speed varying as said. The starter teeth could be binding a tad more or less on some section of the flywheel than other sections and cause this. Do a proper compression test.
 
Well I just finished doing the compression test and like I thought, I have a lame cylinder :(

1- 135 PSI
2- 134 PSI
3- 134 PSI
4- 99 PSI! I squirted some oil in and it went up a bit to 112 PSI
5- 133 PSI
6- 139 PSI
7- 131 PSI
8- 131 PSI

Number 4 is the issue here. Now because the PSI went up a bit does that mean its the piston ring? I assume its normal for a bit of blowby to occur. I will try to get a leakdown tester to see what is leaking though.
 
DartVadar said:
Well I just finished doing the compression test and like I thought, I have a lame cylinder :(

1- 135 PSI
2- 134 PSI
3- 134 PSI
4- 99 PSI! I squirted some oil in and it went up a bit to 112 PSI
5- 133 PSI
6- 139 PSI
7- 131 PSI
8- 131 PSI

Number 4 is the issue here. Now because the PSI went up a bit does that mean its the piston ring? I assume its normal for a bit of blowby to occur. I will try to get a leakdown tester to see what is leaking though.
Click to expand...
What was the compression 3000 miles ago ? Does 135 sound low or is that in the normal range for a 360 ?
 
jerry6 said:
What was the compression 3000 miles ago ? Does 135 sound low or is that in the normal range for a 360 ?
Click to expand...

I kinda thought that too, but all the numbers but 4 were consistent. The motor only has 3k miles on it, I never did a compression test on it when I first got it running (Never thought there was an issue). The cam is a good size so I assume that is having an effect on the lower (or maybe not??) readings. I hope it is normal anyways.
 
At this point i would be pulling that cyl head and poring some water into the combustion chamber and see if it runs threw the valve in to the port.

If it does, it the valve bent(valve to piston contact?) if not i would see how many more cyl leak water. if it leaks water it is NOT sealing. pull both heads and have a reputable shop fix them.
 
Yea I will pull them soon and see how they hold water. I'm doubting they will.

Also about the compression numbers, when I did the compression test I took each spark plug out individually and ran the test for 4 revolutions, also I didn't have the throttle open, the air cleaner was also still on. Could that have effected the readings? And is the 135 in fact low. My engine "should" be over 10:1 compression ratio. But if those numbers are consistent I assume that is a good thing?
 
Pull all plugs, hold throttle Wide open, turn over until the gauge stops.
 
How far are your pistons in the hole, cc's on piston valve reliefs, cc's on your heads, head gasket thickness? I bet you're more like 8.5 / 9 to 1 range. You should be around 165+ for 10 to 1
 
russhal said:
How far are your pistons in the hole, cc's on piston valve reliefs, cc's on your heads, head gasket thickness? I bet you're more like 8.5 / 9 to 1 range. You should be around 165+ for 10 to 1
Click to expand...

The Pistons are zero deck, and they are KB 107s, with I think 5cc valve reliefs. The heads are closed chamber 63cc heads with a 0.039 head gasket. Something doesn't quite seem right here... I know similar combos run mid 10:1s.
 
Your numbers look to be low to me, that thing should have more cylinder pressure with 10-1. I would say well above 150 psi is were it should be. You might try a different compression tester to see if your numbers come up.
 
TrailBeast said:
An overly tight valve guide can do this. (and comon OOTB for those heads)
Might just pull the covers and have a look to be sure the valves are all closing all the way. (turned over carefully by hand of course)
If you comp test it first, what happens if a valve hangs open far enough for a piston to hit it?
Click to expand...

I know that feeling first hand ! New heads complete 'unchecked ' valve grabbed,The blocks a coffee table now!!!
 
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