Duke - You called it. Two Broken valve springs

[Dan Pepper]

After reading Duke's reply to my inquiry RE a persistant miss, I took the vavle covers off to take a close look at the valve springs. Found two broken exhaust valve springs one #1 and #4. This also explains an earlier post I made inquiring why the rocker nut was so easy to turn when adjusting the valves on #1. Heh.

Now the fun part; fixen' it (even better yet, running on all 8 cyls!)

This is a '66 L36.

-Is this a job a greenhorn mechanic like me can do himself?
-What other components should I replace at the same time?
-What tools will I need?
-What do you recommended for replacement parts (GM or aftermarket)?

Advice welcome.

[Duke W.]

Re: Duke - You called it. Two Broken valve springs

I don't think I deserve the credit for suggesting the valvesprings, but they are not hard to change. The important thing to try and determine is "why did they break?" The BB valvetrain is not as reliable as the SB valvetrain, but I don't think broken springs on the L-36 are common. A question to ask is: Did someone install non-OEM springs or a non-OEM cam. A cam with too much lift or aggressive acceleration could overstress or bind the OEM springs or require a stiffer spring that may be more highly stressed and have a shorter life. Assuming the cam is OEM or equivalent, I would recommend OEM or equivalent valve springs.

To change the spring place that cylinder at TDC, remove the rockers and use an adapter in the spark plug hole so you can pressurize the cylinder with at least 80 psi from an air compressor. You'll need a valvespring compressor to compress and remove the spring. Prior to compressing the spring, place a suitably sized socket over the retainer and give it a tap or two with a medium sized hammer. This will break the retainer from the locks. As you begin to compress the spring, if the stem goes down with the retainer, give the retainer another tap or two to break it lose. Once loose, compress the spring enough to grab the locks with a magnetic finger. It's best to have your tools and parts properly staged so you can quickly change the spring.

I forget what kind of valve seals the BB uses, but if they are the O-ring seals similar to the BB you'll need new ones for each spring you change.

As with any other service operation, carefully read the appropriate shop manual before you progress with the work.

Duke

[Kevin #38315]

Re: Duke - You called it. Two Broken valve springs

Dan, if you're in SE Michigan and need some tools (like the valve spring compresser or the air compresser adapter) let me know. I have these and wouldn't mind loaning them so you can get back on the road.

Kevin

[Craig S.]

Re: Duke - You called it. Two Broken valve springs

Duke - they use umbrella seals...Craig

[Dan Pepper]

Re: Duke - You called it. Two Broken valve springs

Duke, Craig & Kevin,

Thanks for the info and offer of your tools. Kevin, I'm in Seattle, so I'll need to round up the appropriate tools here. But I'll buy you a nice salmon dinner on Elliot Bay if you don't mind flyin' em out and lending a hand!

Should I fix only the broken springs? Or replace all of them now to try to prevent others from failing down the road?

The engine is supposedly stock, with 52k miles. I have all the owner history and have talked to all the owners, so I do believe it's stock.

[Craig S.]

Re: Duke - You called it. Two Broken valve springs

Dan - I would change ALL of the springs. If they really are original GM springs, Joe L will come up with the right part and availability. I know the 66 427/425 springs are still available in sets from GM for a reasonable price, but I am not sure about the L36 springs. I fabricated a fairly elaborate valve spring tool using an RCBS Rock Chucker loading press handle, and a bunch of turned steel parts I made on my metal lathe. I would be willing to ship it to you and you could ship it back if you pay for the shipping costs...it is "tuned" for BB chevys and works great. I could take a picture and email it to you if you wish. There are a bunch of others out there though...Craig

[Dan Pepper]

Thanks, Craig...

I'd like to take you up on your offer for the use of your valve spring tool. I really appreciate it - I'll email you offline to arrange shipping, etc.

Best,
Dan