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Topic Review (Newest First)
09-04-2009 08:32 AM
Originally Posted by Rufus_2
If I were to try the machining myself, how far down would I need to go?
If I understand your question, you're asking about machining the guides for seals, not cutting the seats to sink the valves.
Think of the seal as a coffee mug. Measure the inside depth of the mug from the edge to the bottom of the mug with the sliding depth function of your dial caliper. This, plus a couple of thousandths, will be the distance from the top of the guide boss to the finished cut on down the guide boss. Here's a set of Viton seals that fit the criteria needed....O.D. is 0.620"....
Here's a tool for installing Teflon seals that I have used. Not sure if it is the proper tool to install Viton seals because I have always used Teflon, but would think it would work. Call the techs at Edelbrock and make sure. Ask how they do it. I read recently that John Lingenfelter advises Viton over Teflon and that's good enough for me. Any future builds I do will include Viton seals.
The seals should include a clear plastic tube for protecting the seal as you slide it over the end of the valve stem, past the lock ring cuts. It looks like half of a pharmaceutical capsule. Be sure you use it to install the seals to prevent cutting the I.D. of the seal.
09-04-2009 06:27 AM
Valve stem seal needs

I went home last night and measured for the valve stem seal.

Valve Stem Diameter: 11/32"
Valve Stem Guide Diameter: 0.571"
Valve Stem Guide Height: 0.787"

Second Spring ID: 0.690"
09-03-2009 01:27 PM
Rufus_2 Bogie,

Here's the history of how I got to where I am with the motor.

When I orignally started working the motor. I wanted to build a mild street motor.

I had planned to go with the Edelbrock Performer intake and matching Cam.

When I took my motor to my engine shop they could not get the edelbrock cam with the rebuild kit they bought. He convinced me to go with a COMP Cam with similar numbers to the Edelbrock. This is where my problems started. I had done my research on the Edelbrock Cam and the upgrade was simple. I assumed the same with the COMP Cam and the engine shop never said anything about valve issues.

What I didn't know about this Cam is that Comp recommended the high pressure springs. I knew that I was going to need new springs and I started doing my reasearch. Comp recommends the double spring or their behive springs which cost twice as much. And of course, these new springs have driven me to new retainers, new locks, and now new oil seals. This is why you do research instead of taking others recommendations blindly, huh?

My install height problem has been fixed. Now all I need to do is figure out what to do with the valve seals.

I would go to a single spring, but I have not seen a spring with the stiffness COMP recommends. I am afraid to go softer for fear of valve float.

The root of my problems is I was very inexperienced when I started this project 3 years ago. I have since learned many things related to this hobby, and as in this case, sometimes the hardway.

I am tempted to take out the cam and go with the Edelbrock but I hate to throw away the money I have already put out.

So to summarize and answer questions, the valvetrain parts I'm using are not being used because I want to build a super stout motor they are being used because the COMP guys say I need them.
09-03-2009 12:26 PM
ap72 I should have added that sinking them on a mostly stockish street engine is usually not a good idea.

Sinking valves on the street ius usually bad- sinking them on the track can be good. Don't sink the valves unless you really know what you're doing (hint: you don't know enough about this to make it useful), to make up differences use shims and locks and if need be- different retainers.
09-03-2009 11:22 AM
Originally Posted by Rufus_2
If I were to try the machining myself, how far down would I need to go?
Whoa, don't do this. On stock street driven engines when they are repaired for aging the valves become sunk as the seats are reformed deeper into fresh material. This moves the valve into the pocket which reduces flow thru the valve and seat and weakens the spring tension unless it is shimmed. On a commuter motor this is of little consequence since the engine is seldom, if ever, operated at the limits of flow. But sinking the valves also adds volume to the combustion chamber, reducing compression. Again in simple service repair this is of little consequence. For a performance engine a compensation of some sort needs to be done to restore the lost compression ratio.

For an engine that is expected to deliver some performance, this procedure degrades upper end flow, thus power. It can be done successfully if you have a flow bench, sufficient experience, and some heads to waste figuring out how to best take advantage of sunken valves. This can be used to advantage in high end engines, but otherwise it just isn't something you want to do on purpose.

I think you need to get a hold of a Comp tech. These kits should go together without much fooling around. If you're building a full tilt race motor, the part selection can get you doing a lot of custom machining and parts selection. If this a street motor, you souldn't be facing these kinds of issues. If you are; it may be necessary to rethink the combination you're building.

Also, Installed Height does not include the retainer. The spring standing height is measured from its base coil resting on the head or shim to and including the coil resting against the bottom of the retainer. Now one can have clearance problems to the rocker with the thickness of the retainer, which is solved by relieving the rocker, replacing the retainer with a thinner part, extended stem length valves, or a stem cap; but this is a different issue from spring lengths.

The spring pocket can be milled but if this is not a race engine the .030 you're dealing with doesn't seem worth the effort. Milling the spring pocket does reduce its strength. For a suicide race engine, this can be a risk you decide to live with. For a street engine where a long life is expected from the engine, this isn't a place to compromise structural integrity of the engine.

I guess the first question we should have asked is what are doing with this engine. When I see cams with dual springs opposed to a spring or spring and damper, I have to wonder why? With where oils are going, a street driven engine with a cam that requires dual wound coils means a lot of pressure between the lobe and tappet. If this is a flat tappet cam, in today's lubrication environment it won't survive. The choice becomes a milder flat tappet or a roller cam to live in the 21st century on the street.

09-03-2009 06:22 AM
Rufus_2 The spring inner diameter is .690
09-03-2009 05:02 AM

Originally Posted by ap72
sinking the valves can have some bennefits if you match the chamber and cam to it properly

OH boy... DO-NOT do this to your heads....It will make zero difference in how the engine runs in your application.

Get the proper installed height with the correct locks, retainers, shims.

Do you know what the inside diameter of those springs are. I might be able to help out with a seal for you.

09-03-2009 03:04 AM
Rufus_2 If I were to try the machining myself, how far down would I need to go?
09-01-2009 11:48 AM
ap72 sinking the valves can have some bennefits if you match the chamber and cam to it properly
09-01-2009 11:14 AM
techinspector1 I never have cared for umbrellas. There's a reason Teflon and Viton positive seals are available and umbrellas are probably part of the reason. I'll give you an alternative to having the machine shop do the guide cutting. Here's the 0.530" cutter and 11/32" arbor to do them yourself. 50 bucks. Use a low-speed 1/2" drill motor with plenty of cutting oil applied by an assistant and a way to drain the excess into a pan so you can keep recycling it. Here also are Manley Viton 0.530" seals. Many manufacturers make them in both Teflon and Viton. I just happened to copy the Manley units. Measure the I.D. of the inner spring to make sure there is plenty of clearance for these 0.674" O.D. seals. There are seals available from others that are slightly smaller on the O.D.

Watch this video all the way through and you'll see why you want a little extra clearance between the seal and the spring....
09-01-2009 10:39 AM
ericnova72 If you can find one with the correct stem diameter that is small enough to go inside the spring, you can do it. You are not likely to find one that will fit inside a dual spring, however.
09-01-2009 10:34 AM
Rufus_2 I think I may have spoken too soon about machining. I forgot about my stem seal clearances. THe Comp Spring is a double spring. The stem seal I have is an umbrella that is to big for the inner spring ID. Comp recommends a positive stop Teflon which requires machining the stem guide.

Can I get away with a smaller OD umbrella?

Any other suggestions?

09-01-2009 08:39 AM
Rufus_2 Thanks for the mock-up suggestion. I bought the parts and mic'd the height. My install height was 1.820, which is 0.120 taller than needed. I was amazed at the thickness difference between the Comp Cams retainers and the factory retainers. It looks like I'm going to swap my retainer locks for -0.050 locks and add a 0.060 shim to make up for the distance. But atleast I don't have to machine anything. Thanks again for all the help.

08-31-2009 02:17 PM
Originally Posted by Rufus_2
Greetings All,

I have an Olds 455 that I have installed an Comp extreme cam. The valve spring they recommend requires an installed height of 1.700 the factory installed height is 1.670.

How is the best way to get there? I have seen one recommendation to mill the spring seat down 0.030 and I have had another recommendation to mill the mill down the valve seat during a valve job thus increasing the valve stem height.

My concern with the second option is that it would screw up the rocker geometry. The machine shop I talked to said machining the valve seat down 0.030 had the potential to hit water jackets.

Anyone out there got any suggestion?

I'm with 545C10 on this, .030 inch isn't worth sweating.

08-31-2009 11:49 AM
454C10 0.030" is close enough.
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