I installed new valvesprings a couple weeks ago in prep for a hotcam I want to install later in life. The springs were lunati part #73943. Seat pressure 108lbs, open press 339lbs, max lift .630".

I had some heartache lashing the stock rockers, and I figured if I'm gonna open up the engine again and play with the rockers, I might as well install some 1.6RR's. I bought a set of proform 1.6 self aligning rockers.

Once I had those properly lashed, I drove the car 50 miles, and two valvesprings broke. The springs were recommended to me by a reputable speed shop here in town. THey guy told me he puts them on LT1's all the time. If they were good to .630 lift, I don't see HOW they are breaking with a stock cam and 1.6RR's.

I took the car to a professional and had him relash the rockers and replace the two broken springs. 50 miles later, ANOTHER spring broke.

Are these lunati springs just total garbage?
Do proform rockers have some wierd geometry that breaks springs?
Was I correct in using 7.200" stock length pushrods?
If I put my stock springs back in, can they handle a stock cam + 1.6RR's?

Please tell me that there is some secret to this combo that I missed. I can't believe how hard it's been to do a simple, bolt on valvetrain upgrade.

 

http://lunaticams.com/Product.aspx?id=452&gid=189

IF they are set up at 1.750" you have 108 lbs of seat pressure and that is barely enough for a stock cam.

IF they are set up any higher due to valve job, valve length difference if you changed valves, different retainers, etc, etc, you have even less pressure and that could be the problem. FWIW, stock set up ht is 1.780" so even if he reused all stock valves, retainers, etc, it is only 1.780".

This would be the first thing to look at.

If you broke 4 valve springs and have not dropped a valve, I would consider yourself lucky and the next spring that breaks could drop a valve and destroy the engine.

I would make sure the rockers are adjusted properly (1 cylinder at a time while that piston is at TDC on compression stroke.

I would also make sure you have Non Self Aligning rockers and guide plates or if running Sels Aligning rockers, make sure the rocker is not hitting the retainer/locks instead iof the valve.

Lloyd

 

I would also get ahold of Lunati and send a couple of the broken springs too them for inspection.

 

What is the part# and the install height you used?


I highly doubt its a spring problem.


If that spring has .630 lift I bet it coil binding with a 1.78 install but if you tell us you install and part# someone should be able to help.

 

I'm gonna replace my busted spring today, and I'll measure the installed height. As far as I know, the engine is a rock stock IRON head LT1. It should have stock unmodified valve. WHen I installed the springs, I re-used the stock locks and retainers. Maybe that is giving them the overly tall install height. EVen so, it seem's to me like that would make life easier on the springs, not harder. Plus, wasn't the stock seat pressure 88lbs or something like that?

lunati part #73943

single w/damper 1.266 108@1.750 339@1.250

^^^^^^
There is the part # and the info off of thier website. I'll mic the springs today and check the install height.

 

Are they well seated in the pocket?
Where are they breaking?

What did you do about getting the dampers to fit? Not aware of any dampened spring that fits the iron heads, some folks pull the dampers with varying results.

Unless you are using taller locks or retainers I bet it is close to a 1.700 installed.

 

well, I just put the motor back together, AGAIN.

The height from the bottom of the valvespring to the top of the retainer is 1.903".

The height from the bottom of the valvespring to the top of the valvespring is 1.780"

The previous spring that had broken had done so right in the middle of the spring. NOT at the top or bottom.

The problem this time happened to be a broken rocker arm. I'll post pics later, but the roller pivot part had cracked in half. THe valve was permanently closed. It was a new proform 1.6. I had previously overtightened it, so perhaps metal fatigue caught up. It had approx. 350 miles on it.

I put on a stock replacement stamped 1.5 arm. It now has 15 1.6RR's and one stocker. It's a bastard.

I'm beginning to think now that I don't have a fundamental problem, but rather a series of skill based errors that evolved into really bad luck and parts failures.

 

I would not drive the car like that; I'd also change valve springs out. Something is not right!

 

where does the spring coil bind?

 

uhhhhh......

I had a catalog which had that data, but I threw it out. I wanna say they binded at 1.250", but that can't be right, since they are good to .630.

 

That might be correct if they're installed at their correct install height. Again, you need the actual specs on the springs to be able to set them up correctly.

On another note - From what I've been reading on the forums, Proform does not have a good reputation for durability.

 

IMO take it all out and put back to stock
until such time that you can gather what
you need according to the cam you'll run.

 

I've been reading that too lately. I've used these exact same 1.6 self aligning rockers on an old vortec 355 of mine though, and they were fine. I'm gonna give them a second chance.

 

Well, good luck then.