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Old 08-25-2012, 01:38 PM
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Vortec heads lift/clearance issues

In mocking the valve train up, my spring retainers are hitting the positive valve seals on my factory L31 heads.

I measured the clearance I could achieve from the ghetto grind (removing material from the bottom of the retainer), and I can remove about .065-.070" before I get into the retainers. So basically that won't work since I need .090" clearance between the retainer and seal. What are my options?

I can take them back to the head shop and have them grind the guides down. How far can the guides be cut before you run into problems with cracking or other issues?

I could try to do it myself with a hand drill using this tool, but I am not sure how easy this is and I don't want to risk botching the heads. Has anyone actually tried this?

I could ditch the positive seals and use something else. The Comp Cams K kit cam with some little o-rings. Could I just use those only? Will they leak too much oil or not last very long?

Is is possible to remove and reuse the positive seals that are on the heads now? They are brand new and never been installed on the engine. What is the trick to removing/installing them?

Thank you for any help!

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Old 08-25-2012, 03:40 PM
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If you want to use the tool. Get the correct arbor. Set two .060 valve spring shims in the spring pocket. Drive the cutter with a good drill. Cut till the cutter contacts the two stacked shims. Then repeat on next guide.

The seals will pop off the guide if you carefully get under the edge with a large pry/screwdriver. Gently nudge the seal upwards till it clears the boss.
The O-ring seals are not for modern valves. Which only have one groove at the top. Simply installing the O-ring on these valves is a waste of time. They don't seal off the retainer and oil runs right over them.

Be careful shortening the stock retainers as the 7 degree locks will pull thru under certain conditions. Saw a disasterous example just last week.
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Old 08-25-2012, 04:48 PM
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Thanks Bob! Excellent tip about doubling up the spacers! My preference is to do this right and I would rather not cut the retainers. If I do choose to do this at home I will definitely use the the arbor to guide the cutter.

I still have a couple of concerns:

Is there one diameter for all the seals? I can pop mine off and measure, but I don't know what the CompCams tool is.

How long will this take at home? Is this going to make me sweat and cuss for 8 hours just to do one head? What is the correct cutting speed? Slow and use cutting oil? Will Tap and Die cutting fluid work?

What is a good drill? I have a 120v 5.5amp Craftsman 3/8" drive drill. Will that suffice? I also have a table top drill press, but I think it will be tough to get the head under it and secured and lined up properly.
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Old 08-25-2012, 05:27 PM
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Seals are various diameters. Most aftermkt for 11/32 guide are .500 or .530. The tool you looked at is a .530.

Cut guides with slow to moderate speed.

Your drill is plenty power. You just let the tool do the cutting. My tooling at the shop has done hundreds of guides. So it needs a bit of down force help at times.. I cut all plain cast iron with DRY carbide, plenty of air to remove chips.. There are many theories nowdays. But I was taught to cut cast dry, 45 years ago, by an old master. Works great for me and cleans up quickly.
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Old 08-26-2012, 09:38 PM
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Quote:
Originally Posted by BOBCRMAN@aol.com View Post
Seals are various diameters. Most aftermkt for 11/32 guide are .500 or .530. The tool you looked at is a .530.
Strange. I measured the valve guide boss and it came out to .555". I found the receipt from the head shop and they only charged me $20 to clearance them when I had the heads done. So hopefully they will go back and make it right for free. Heck even if they don't and charge me $20, that is still cheaper than buying the tool and arbor. And then I don't have to worry about different diameters and buying new seals, etc.
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Old 08-26-2012, 10:56 PM
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>.550 is correct for stock seal. I thought we were talking aftermkt seal. $20.00 means they installed the seals. Not clearanced them. As you have already seen. I get way more to cut guides for seals..
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Old 09-08-2012, 02:57 PM
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Well I got the heads back from the head shop yesterday and I got a chance to mock everything up again just now. They said they took another .025" off the guides. I knew right away that wasn't going to be enough, but I didn't want to argue. I see another trip back to the shop soon.

When I put the heads on the block and physically check by rotating the crank on cyl #1....
  • The intake seems to have about .078" clearance
  • The exhaust has about .005" clearance

When I remove the springs so that just the retainer and keepers are installed, and I measure with my micrometer from retainer to seal...
  • The intake seems to have about .576" total distance (which calculates to .576"-.490" lift=.086" clearance which is similar to what I get when I mock the valve train)
  • The exhaust has about .520" total distance (which calculates to .520"-.490" lift=.030" clearance which is nowhere near my .005" clearance when I mock the valve train)

The cam is .327" lobe lift, which is .490" with 1.5:1 rockers (I am using full roller rockers)
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Old 09-08-2012, 02:59 PM
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Also what is the correct min. clearance for retainer to seal? Lunati says .090". Comp Says .045", another site I found says .060". I am guessing the more lift you have the more clearance you should have?
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