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 Post Posted: Tue Jun 22, 2010 10:14 am 
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I put a set of these on my 18* SBC when it was built 3 years ago. Originally I was running much lower spring pressure than what they called for on the box and the result of that was a broken exhaust rocker arm. After that I shimmed those springs up to what they say to do and have run them like that since.

Well, a couple of weeks ago I broke another rocker arm and my first thought was that the springs might be shot. Yesterday I pulled the spring off where the rocker arm broke and this morning I ran it over to Kowalsky's to have him check it. Manley spec on that spring is 800 lbs @ 1.150. My 3 year old springs checked 805 lbs at 1.150 so those springs are still good as new.

After talking with Don we came to the conclusion that when the first rocker broke from not enough spring pressure that this one might have been fatigued enough that it broke over time, which means that others may do the same thing. Don also suggested that I shim those springs more as the Manley spec on coil bind is .020 longer than actual coil bind of the spring that is on my engine. So looks like I'll be adding .020 to the intake springs just to be on the safe side.

Anywho, a phone call to Manley Tech Support confirmed that the spring was not the problem and they said that an additional .020 shim on that intake spring wouldn't hurt the spring itself but would add to open spring pressure. Although I have no concrete numbers on this I'm guessing that open pressure will be in the 815 lb range since they are presently .012 over that .1.150 dimension number @ 1.162 and put out 790 lbs open.

Oh the never ending saga of these "high spirited", "hand fitted", PITA 18* engines! I guess I know now why Rick360 didn't build another one for his Dragster!!! This one will be my last also!

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 Post Posted: Tue Jun 22, 2010 1:21 pm 
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Ken0069 wrote:
Oh the never ending saga of these "high spirited", "hand fitted", PITA 18* engines! I guess I know now why Rick360 didn't build another one for his Dragster!!! This one will be my last also!


Try a 9.5" deck SB2.2... ](*,) ](*,) ](*,) ](*,)


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 Post Posted: Tue Jun 22, 2010 1:25 pm 
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I didn't build another 18º engine because I wanted a CHEAP engine to build AND operate. I was concerned about cylinder pressures with a really good flowing head running pump gas as well as the rpm range needed with a high flowing head. I am contemplating HOW to build a pump gas engine using my 18º heads after I get some time with the dragster to decide if I want it quicker.

Back to the original topic ... I NEVER set up a spring to be close to coil bind. I read about it all the time, but IMO if you aren't spinning it up past 8k, a spring is happier with less shim (more installed height). My 383 had EXTRA height and those springs lasted me 5 yrs and the guy I sold the Camaro to ran them 2 more yrs and decided to change them and after replacing them he told me they were the same pressure as the new ones. This is a lower rpm engine. My 414 hasn't had enough laps yet to know the results, but the springs were setup the same way ... tall.

The 18º engine I had titanium 11/32" valves w/ Jesel rockers and .760" net lift. I ran USED Pacaloy springs that were given to me cause they were down on pressure. I tested them and picked the best ones for the intake and the rest were exhaust. I didn't want 300+ psi spring pressures so I set them ~270# and some of the EX were ~250#. I set them all with the same shims and were at least .100" from bind, but probably more. Never had a problem.

With all that said, I don't think the coil bind clearance had anything to do with either of your broken rockers. IMO your rpm is not high enough for that to be a problem. On a high end high rpm engine I think there may be some benefit to tight bind clearance. On my stuff I set them up tall so the springs last longer.

Feel free to do your own thing, cause I know you will anyway. =;

Rick


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 Post Posted: Wed Jun 23, 2010 8:01 am 
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rick360 wrote:

Feel free to do your own thing, cause I know you will anyway. =;

Rick


After running this board for 4 years I've found that most of us do just that. ;-)

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 Post Posted: Wed Jun 23, 2010 8:47 am 
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Ran a leak down on this thing yesterday while I had the air hose hooked to it and there's good news and bad news. Here are the readings I got with actual cranking compression only read on the right bank after I got the low leak down numbers. #6 has not been done yet because I still don't have that rocker arm that I ordered Monday of LAST week?

#1=6% #2=12% 240 lbs
#3=6% #4=25% 235 lbs
#5=9% #6=3% 245 lbs
#7=5% #8=11% 235 lbs

I've been planning to do an overhaul this coming winter and looks like it might be time to do just that.

*EDITED

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 Post Posted: Wed Jun 23, 2010 9:09 am 
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If 790 LBs isn't enough pressure to control the valve train, and is causing broken rockers, I can't see 815 LBs making the valve train perfectly happy, something else is the problem.
What does the intake valve weigh, peak lift, and max rpm?

I don't go along with every engine needing shimmed to .050" coil bind either. When a valve spring gets near coil bind the spring rate goes up, and when the coils start to stack the rate goes way up. I think this shimming close to coil bind started when lofting started to be a planned valve event instead of an accident.

I have an engine with .695" peak lift using 1.65 rocker, and 119 gram valve, it sees 8000 rpm on the shift (sometimes in the burn out), and 7300 at the finish line in the 1/8 mile, and well past 8000 at the finish line 1/4 mile, with around 220 on the seat, and a little over 500 over the nose. It has around 500 1/8 mile passes, and 6-7 1/4 mile passes, 17 dyno pulls to 8000 rpm, and a few passes down main street.
It got used crane gold rockers that someone had clearenced for the springs, with an unknown amount of time on them before this engine, and none have broken yet.

This winter I did the oposite, I took .015" shim out of the intake.

If you have enough spring pressure, how is more better?

I say set the right bank up to .050" of coil bind, and the left bank at 150", and run it, and see which side has the most rocker trouble. :-k

But like you said Ken, we're probably all going to do what we had planned anyway. =;

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 Post Posted: Wed Jun 23, 2010 10:00 pm 
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Randy first let me say that I consider both you and Rick to be real assets to this forum! Quite contrary to what both of you might think, I do take to heart ANYTHING you post on questions I have. That being said, I also have others that do not belong here that I respect and listen too as well.

FYI, the intake valves are titanium and the exhaust valves are SS.

When I broke that first exhaust rocker Crower Tech Support told me it broke because there was not enough spring pressure. Don Kowalsky, who is a championship winning engine builder who builds and leases Hooters Pro Cup engines told me the same thing. Kowalsky maintains that he has NEVER had a Crower rocker arm fail! Manley Tech Support told me that these springs were designed to operate at .080 from coil bind or I could have "harmonics" issues with the spring, which is what Crower and Kowalsky say kills rocker arms.

Both you and Rick say you ran engines with much lower spring pressures without any problems so that has worked for you. To date I've tried running them with less than recommended pressure, which they say broke the first one and now I've had a second one fail that Kowalsky is saying was probably the result of running them with weak spring pressure before. Either way I've got 3 people telling me that I SHOULD run them up at 800+ lbs on the nose.

Whether the previous run with low pressure caused this intake rocker to fail remains to be seen. If low pressure early on caused it, then I'm likely to see more of it in the future. If I have another one fail then someone else will own them!

And on another note, is there a chance that those Jesel ALUMINUM rockers are a little more forgiving where spring harmonics are involved? :-k Kinda like aluminum rods in blown engine instead of forged steel?? :-k

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 Post Posted: Thu Jun 24, 2010 5:31 am 
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Ken, I suppose you are talking shaft rockers? I remember a couple of years ago,one of our local dirt trackers who runs high dollar store bought engines was breaking Crower shaft rockers.He finally took the engine back to the builder & they put a whole new set on & they are fine. He said Crower told his builder they had a bad batch & made them good.I wonder if you're luck is as good as mine..........


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 Post Posted: Thu Jun 24, 2010 7:53 am 
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BarryW wrote:
Ken, I suppose you are talking shaft rockers? I remember a couple of years ago,one of our local dirt trackers who runs high dollar store bought engines was breaking Crower shaft rockers.He finally took the engine back to the builder & they put a whole new set on & they are fine. He said Crower told his builder they had a bad batch & made them good. I wonder if you're luck is as good as mine..........


BarryW this set was purchased back in the spring of 2007? Does that time frame match the incident you are speaking of?

I've got a set of their stud mounts on my 23* engine that were bought back in 1991 and they are still in use today, which along with Kowalsky's experience is the reason I went with them again.

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 Post Posted: Thu Jun 24, 2010 11:21 am 
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Got that rocker arm and checked #6 cranking compression and it was 245 lbs? So cranking compression was only 10 lbs different from 25% to 3% leakdown? I would have thought it should have been more than that? :-k Hummmmmm?

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 Post Posted: Thu Jun 24, 2010 5:51 pm 
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Nah leakdown and comp test have nothin to do with one another. You cant tell leak from a comp test unless its really really bad. Leak is such a small flow.
Hey have a look at the break with a mag glass and see if its got beach lines in the fracture. If its started long time ago at the low spring runs then it should have beach marks, lots of them.


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 Post Posted: Thu Jun 24, 2010 5:56 pm 
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shrinker wrote:
Hey have a look at the break with a mag glass and see if its got beach lines in the fracture.


OK I'll bite, so WTF are "beach lines" anyway? O:)

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 Post Posted: Thu Jun 24, 2010 6:11 pm 
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Ken0069 wrote:
shrinker wrote:
Hey have a look at the break with a mag glass and see if its got beach lines in the fracture.


OK I'll bite, so WTF are "beach lines" anyway? O:)


Never mind, Google is your friend! =; I'll go look at it now that I know what to look for. ;-)

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 Post Posted: Thu Jun 24, 2010 6:25 pm 
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YUP, got "some" beach lines (like 6 or 8) on it near the push rod area about a half inch wide, which I'm assuming is where it started. The rest of it just shows jagged edges.

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 Post Posted: Thu Jun 24, 2010 6:39 pm 
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With that many beach lines it likely it failed over time, so toss the whole lot out.


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