69 L71 Valve Spring / Retainer Recommendation

[Joe L.]

Re: 69 L71 Valve Spring / Retainer Recommendation

In any case, 30 years later I am still happy.

Richard------


In the final analysis, that's the important thing.

[Chris H.]

Re: 69 L71 Valve Spring / Retainer Recommendation

Ok, time for full disclosure. I ordered and installed the VS708 dual springs and used the original single spring retainers with the Felpro nylon umbrella seals last week. I decided to do this job as I knew the springs and seals were original and it would be a good thing to replace them.

During removal of original springs I found a broken one! (4 intake) and one that had already been replaced (6 intake) by a previous owner. The replacement spring was a dual spring and dual style retainer. I feel fortunate that that broken spring didn't result in greater damage (charmed life indeed Joe!). The spring damper was holding it together.

After install the car ran smoother and pulled harder and I was very happy. But the more I researched retainers the more uncomfy I was becoming with idea of using a single spring retainer with a dual spring. So that's why I ordered the Crane Cam single spring / retainer kit. I also order some Felpro OEM rubber style umbrella seals to go with the single spring setup.

Parts should show up any day and I hope to complete the job next week. Thanks for all comments / advice.

[Patrick B.]

Re: 69 L71 Valve Spring / Retainer Recommendation

Chris-- I wasn't sure Crane was in business before reading your post. I have an old Crane catalog and it is very informative regarding valve retainers. They give dimensions of many valve spring caps they sell with 3/8" valve stems, 7 degree locks and steps for dual springs. In fact, all of the 3/8" valve stem retainers seemed to have steps for dual springs. I will measure a GM 627 retainer and see how it compares to the Crane retainer dimensions. Although you have decided how to replace your springs, I think there is still general interest in finding a way to use the VS708 springs in a way that replicates the GM 627 spring, seal and cap. I also found it interesting that you were able to attach the Fel-Pro umbrella seals to the single spring GM caps, supporting the idea that they will fit any 3/8" stem, 7 degree cap.

The Crane copy of the L-71 cam is 969961, and they recommend two valve springs for it. Both are dual springs (99893 and 99890), and the the first spring is much heavier than the GM 627 spring. I am curious about what single spring they recommended for your L-71.

[Chris H.]

Re: 69 L71 Valve Spring / Retainer Recommendation

Patrick, The Crane spring I selected was from their Website. It's a generic spring / retainer kit they recommend for all non truck big blocks. The nylon guide seal I pushed on to the bottom of the valve stem and is not mounted to the retainer.

[Chris H.]

Re: 69 L71 Valve Spring / Retainer Recommendation

Ok, finished my valve spring odyssey. In the photo going left to right, are the various combinations I looked at. First is the original (broken) single spring with umbrella seal and retainer. 2nd is a replacement spring (dual) with a special retainer and nylon seal that I found on #6 exhaust. Based on how brittle the nylon seal was, I believe that repair was done a long time ago. 3rd is the VS708 Sealed Power spring that I used with the nylon seal and original style single spring retainer. 4th is the final arrangement, the Crane Cam single spring with matching retainer kit, used with a Sealed Power umbrella rubber seal.

The 2nd spring and retainer appear to be GM parts. Would love to have had 15 more of those retainers as they fit perfectly with the VS708 spring. Oh well, I'm comfortable with solution I chose.

I also created an air tool fitting out of an old spark plug which worked great holding the valves closed. I also experimented with rope method.

[Joe L.]

Re: 69 L71 Valve Spring / Retainer Recommendation

All------


I'm home now and I dug out the big block valve spring caps (retainers). There were three caps used on 1965-72 Corvette big blocks (except L-88). Cap GM #3864900 was used for 1965 L-78. Cap GM #3859909 was used for 1966-E69 427. Cap GM #3964264 was used for L1969-72 427/454. The latter also replaced all earlier valve caps for SERVICE when used with the dual valve spring.

The dimensional specs on the caps are as follow:

GM #3864900

OD-------------------------1.408"
first step OD---------------0.972"
ID (at bottom)-------------0.436"
thickness (at outer OD)---0.112"

GM #3859909

OD---------------------------1.407"
first step OD----------------0.970"
ID (at bottom)--------------0.440"
thickness (at outer OD)----0.110"

GM #3964264

OD---------------------------1.401"
OD at first step--------------1.081"
ID (at bottom)---------------0.417"
thickness (at outer OD)-----0.115"

The GM #3864900 is identified by a an "O"
The GM #3859909 is identified by a "T"
The GM #3864264 is identified by a "U"

You will note from the above dimensions that the ID of the 3864900 and 3859909 measured at the bottom is slightly larger than the 3964264. It's not much but it makes a big difference. I tried fitting the Fel-Pro umbrella seal to these caps and the neck fit so loosely that it would not be retained by the cap. I would not even consider installing the cap and seal with the seal not firmly retained by the cap as it is with the 3964264.

Also, you will note that the first step OD of the 3864900 and 3859909 is different than the 3964264. So, as I mentioned several days ago, the early retainers would not properly center the inner valve spring of the dual spring assembly.

Some photos of the valve caps are shown below:

[Joe L.]

Re: 69 L71 Valve Spring / Retainer Recommendation

More------

[Joe R.]

Re: 69 L71 Valve Spring / Retainer Recommendation

Hi Joe,

That's great info!!! Thanks for providing it!!!

Joe

[Chris H.]

Re: 69 L71 Valve Spring / Retainer Recommendation

Thanks Joe, the dimensions you provided will assist folks who want a retainer for the VS708 spring. Comps Cams and others publish retainer dimensions so perhaps there is a match out there. Here's a photo of my "T" retainer and "U" retainer. The "T"'s were on the single spring (including the broken one), while the "U" had the dual spring and nylon umbrella seal (on the valve stem, not integral with the retainer).