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  #31 (permalink)  
Old 07-29-2013, 03:39 PM
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On the BBC a good alternative to decking the block to get a desirable net quench clearance is to us the
GM factory 454-450 HP -LS6 head gasket (.022" steel shim) apparently this LS6 BBC head gasket has been discontinued.

MR Gasket makes a similar one.. I believe Detroit gasket has one too. Do not go tighter than .038" net quench.

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  #32 (permalink)  
Old 07-29-2013, 09:24 PM
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Quote:
Originally Posted by F-BIRD'88 View Post
They asked for the spring specs, so I trusted them to ensure that the supplied parts would be OK.

you are assuming a lot and taking a lot on faith. If you are the guy turning the wrenches its up to you to check this stuff.
On a BBC when using anything more agreeive than the good old Factory BBC 454-450hp LS6 springs
it is nice to reduce the running spring pressure for the cam break in run.
Remove the inner spring coil on dual springs. Reinstall after it is all broke in.

I allow a full week of moderate street driving when beaking in a new enigine.
Do not allow the engine to idle slow for the first week. Turn the idle speed up 1000-1200 rpm.
Then when everything is friendly, reinstall the inner spring coil and set to height spec as required .
On a hyd cam you should not need more than 320PSI actual open spring pressure at max real valve lift.
The key is enough, but not excessive open spring pressure.
Yup the lifter bores need to be to size spec and no nicks or edge burrs that will prevent lifter rotation.
As I said, they assembled the engine the first time ... up to and including the valve lash adjustment.

The springs that I have been using are a single spring with a damper, and are highlighted in the chart above (90 / 291 lb seat pressure), and the parts catalog said that they were good to .600 lift.

When I replaced that Clevite cam with the XE284 ... I noted that .578 lift figure was getting close to that .600 figure, but thought I'd still be OK.

Everyone keeps talking about how steep the ramps are on the XE cams, which has me wondering whether these springs are stiff enough to keep those valves on the cam?

The other thing that has me thinking (you mentioned it somewhere, actually) was incorrect lash adjustment.

Hmmm ... this was just one lobe that was damaged ...
I tried to be careful, but I'll be the first to admit that I don't do this kind of work on a daily basis, and that perhaps I have "just enough knowledge to be dangerous".

I have a friend that suggested using a brake cylinder hone to de-burr that lifter bore. Is that crazy? I'm thinking I don't want to take any MORE chances.

Then again ... I suppose the worst case scenario would be another $200 flat-tappet cam and lifter set ... and I DO have the XE274 (one step down from that XE284) sitting on my work bench.
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Old 07-29-2013, 09:37 PM
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The spring should have been tame enough to not to need any any special break in proceedure. But a couple of thing do stand out. In the video the engine was idling around 1000 rpm that's too slow for a new cam. This is a long shot but you have lost 2 cams for some strange reason. I understand cell phone or camera audio is horrid but it sounds like a thrashing machine to me. Were the lifters on the base circle for each and every valve when they were adjusted?
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Old 07-29-2013, 10:35 PM
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Relatively new cam.

It had been broken in using the 2500-ish varied speed for 45 mins method.

I just like to run it once in a while, and usually keep the RPM down until it warms up ... as it has forged pistons an a loose fit when cold.

The reason I started it up this particular day was to test larger squirters in order to deal with a lean bog. Going from 131's to 135's seemed to do the trick. I also installed a quick-change kit for the secondaries, but left the black spring in. (One thing at a time, right?)

I've been reviewing pics tonight, and I had posted pics of all lobes earlier in this thread. I hadn't removed ALL of the lifters to inspect them only 3 or 4 near the front of the engine ... and they all looked fine. In retrospect, I wish I had looked at the one that I now know is bad.

However ... zooming in on that last pic, the edges of the lifter looked OK, not rough like they do now. So I'm thinking that something has gone wrong in just the last session that this engine had been run.

Yes, I HAD removed all of the rocker arms, re-installed, and re-lashed them all. I had just replaced the intake gasket, and had laid a peice of shop towel down in the lifter valley, in order to catch the old gasket debris fron the die-grinder / blue roloc disc.

So 2 possibilities ... either I screwed up on the lash adjustment, or perhaps dropped some dirt in on that lobe?

I doubt the dirt theory ... as I poured 2 quarts of motor oil through the oil return openings in the heads to make sure everything was well-flooded with oil just before firing it up again.

I dunno.
Going to sleep on this decision to try ONE MORE TIME with a flat-tappet cam or not. Third time's the charm?

One more thing. One of those Harland Sharp Rocker arms (#1 Intake, I think), was rubbing on the valve cover at one of the dimples for the valve cover bolts, to the point that it rubbed a very small hole right through.

Yes the audio was horrible ... accoustics inside the garage, etc ... but yeah, it did seem to have a bit of a rythym when you listen to it.??? Right around the 55 second mark ... That is the side with the bad lobe AND the rubbing rocker.

Last edited by 66GMC; 07-29-2013 at 10:47 PM.
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  #35 (permalink)  
Old 07-29-2013, 10:48 PM
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There still is the possiblility that you got a hold of 2 bad cams or lifter sets or 1 bad cam and 1 bad lifter set.
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Old 07-29-2013, 11:06 PM
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Quote:
Originally Posted by tresi View Post
There still is the possiblility that you got a hold of 2 bad cams or lifter sets or 1 bad cam and 1 bad lifter set.
Well I "owned up" to the first cam failure. My friend (a Ford mechanic) and I both made a lot of mistakes.

1.) He tried to prime cold 15w40 Rotella T using a cordless drill. As soon as the pump sucked up some oil, his drill stopped dead. "No worries, the engine will have oil pressure as soon as it fires up"

2.) I had washed the OLD original HEI up with varsol, which apparently was a bad idea. It would fire intermittently, but wouldn't run. We stopped trying after a couple of attempts, but ...

3.) Ordered an installed a reman HEI, and it fired right up. And then ... he started making curb idle adjustments, and ran to get his timing light. All the while at 600 rpm or so. He ignored my thumb-up gesture and verbal suggestion that we needed to get the RPM's up to 2500. When he went for his timing light, I actually did that myself, and he came back excitedly shaking his head. Keep in mind this was open headers, hard to converse.

4.) He killed the engine trying to move the distributor. That's when I told him about the 2500 RPM thing. He went into the "I've broken in many engines and have never heard of that, nor have I ever had a problem" story. We restarted and he continued to fiddle with it.

It wasn't until I got it back home to my newly-completed garage and put some mufflers on it that I heard the "ticking".
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  #37 (permalink)  
Old 07-29-2013, 11:18 PM
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Here's a link to the FIRST cam failure.
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  #38 (permalink)  
Old 07-30-2013, 03:56 AM
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Quote:
Originally Posted by 66GMC View Post

Then again ... I suppose the worst case scenario would be another $200 flat-tappet cam and lifter set ...

Wow. You're a brave guy. After two cams I wouldn't consider another FT.

Go roller as you stated you would do after the first one.
There's nothing like driving around with peace of mind.....ahhhhh....
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  #39 (permalink)  
Old 07-30-2013, 07:49 AM
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Go roller; or get off the XE platform and hold your breath. BBCs have enough inherent 'eccentricities'; lets not add more.

If you don't want to go roller; call one of the specialty companies like Chris Straub or Mike Jones. Chris has Morel lifters on his website. Chris also sells Clay Smith cams; he may have an off the shelf grind that works for you. For the 2 rebuilds you've done, a roller cam would have paid for itself. Your buddy obviously doesn't build flat tappet motors that use modern oils; please don't let him 'help' you with this, its costing you a fortune.
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Old 07-30-2013, 12:26 PM
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OK,OK ...

I've been looking at roller cams all morning and have decided that Comp's XR282HR (11-432-8) seems to fit my build to a "T"

Quote:
Hydraulic Roller-High performance for street cars with 2000+ stall, 9:1+ compression, headers. RPM Range: 2200-5800
230/236 dur, .510 lift, 110° LSA

I've also figured out that I need to use different pushrods (7815-16) and a cam button so I may as well go "all-out" and just pony up for the whole kit.


Yes, I also looked at Lunati and Crane ... but didn't find the specs I was looking for.

Yes, I know I could special-order a "custom grind".

No, I don't own shares in Comp.

edit: Actually ... it looks like those pushrods are not in the kit. Another $45.00
Oh well ...
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  #41 (permalink)  
Old 07-30-2013, 03:44 PM
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Well I "owned up" to the first cam failure. My friend (a Ford mechanic) and I both made a lot of mistakes.

1.) He tried to prime cold 15w40 Rotella T using a cordless drill. As soon as the pump sucked up some oil, his drill stopped dead. "No worries, the engine will have oil pressure as soon as it fires up"

2.) I had washed the OLD original HEI up with varsol, which apparently was a bad idea. It would fire intermittently, but wouldn't run. We stopped trying after a couple of attempts, but ...

3.) Ordered an installed a reman HEI, and it fired right up. And then ... he started making curb idle adjustments, and ran to get his timing light. All the while at 600 rpm or so. He ignored my thumb-up gesture and verbal suggestion that we needed to get the RPM's up to 2500. When he went for his timing light, I actually did that myself, and he came back excitedly shaking his head. Keep in mind this was open headers, hard to converse.

4.) He killed the engine trying to move the distributor. That's when I told him about the 2500 RPM thing. He went into the "I've broken in many engines and have never heard of that, nor have I ever had a problem" story. We restarted and he continued to fiddle with it.

It wasn't until I got it back home to my newly-completed garage and put some mufflers on it that I heard the "ticking"

-------------------------------------------------------------------------------------------------------
This very typical of the average hotrodder in his garage fresh engine start up cam break in scenario.

This is pure murder on a new flat tappet camshaft, and it don;t matter who made it, etc etc
This the whole purpose of the Moly paste on the cam lobes.

You cannot blame the flat tappet cam or the oil for this.


By the way this is also real hard on a new roller cam too, as well as the rest of the engine.
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  #42 (permalink)  
Old 07-30-2013, 05:03 PM
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Thanks,
I'll be sure to include that Moly paste in my shopping list.

Moroso 35000
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  #43 (permalink)  
Old 07-30-2013, 06:49 PM
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Keep the moly paste.Question??. What would be a sure bet not to have this problem????. Come on now you know the answer. You have been told by how many members here??. OK I'll give you a tip. A roller cam. I have reserved a place on the wall of my shop to bang my head against. It isn't a issue with BBC!!. It's you making the same poor choices over and over again. Oh well I(we) tried to help.....
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Old 07-30-2013, 07:02 PM
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Just want you to remember every oil change you do for the entire time you own this engine,to use oils like Gibbs oil and paying more for it.First time you don't stand a chance to flat spot a lobe.Syphilitics(sp)??. Forget that. It's the worst thing for flat tappet cams. So as you go in time paying more for the oil,your making payments that at one point or another will end up equaling the costs of a roller cam and never end up own it. Gook luck
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Old 07-30-2013, 07:35 PM
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Last edited by 66GMC; 07-30-2013 at 07:42 PM. Reason: Saving my breath
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