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  #46 (permalink)  
Old 07-31-2013, 11:00 AM
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Caustic soda, or lye, is water soluble. If there are fats in contact w/it, the sresult is soap, or something resembling it). So if the material seen in the coolant passage is lye reacted w/a fat (or presumably grease), in theory it should also be water soluble.

But either way, I don't see it having anything to do w/a failed cam break in. Sometimes these things just happen for no apparent reason.
  • The same lifter bore wasn't involved in both failed cams, so it could be presumed the bores are OK- or they're tight and you just got "lucky" that only one lifter/lobe failed. Measure them and compare the diameter of the bores to the lifter diameter. You want at least 0.002" clearance. There are tools to groove the lifter bore to add lubrication at the cam/lifter interface. For solid lifter cams there are EDM lifters to add lube to the interface as well.
  • It's unlikely the lifters were from a bad lot, else more than one would have failed. Don't use "white box" no-name lifters!
  • Also unlikely the cam heat treat/surface treatment/metallurgy was faulty or more than one lobe would have been affected. Stick w/known brands w/good reputation for not going flat.
  • Endplay can be eliminated as a cause IMO, else more than just one lifter/lobe would have been effected and it was a different lobe each time. That said, using a cam button is a viable option.

This narrows it down to incorrect valve adjustment, the break in lube and/or the break in procedure used. Couple questions:
  1. Was the cam washed clean of the rust preventive it shipped with?
  2. Was the break in lube physically rubbed into the porous surface of the cam lobes?
  3. Was the lube thin and runny or thick, black grease?
  4. It did contain molybdenum, right? Brand?
  5. Absolutely NO IDLING for the first 15-20 minutes, right?
  6. Did the engine start right away?
  7. Valve train clearances all checked beforehand?
  8. Valve adjustment correct? IIRC there were issues w/this.
  9. Was the oiling system primed before initial start-up? (This is important but as long as the oil pressure came up immediately on starting the engine and there was moly grease on the cam and lifters, this shouldn't have caused an immediate failure.)

Looking at the page on cam break in, do you see anything obvious that could have caused the cam to take a dump?

My bottom line is there's just no good reason a flat tappet cam cannot work in this engine. That's not to say a roller set up wouldn't be killer and all, but sometimes that's just not in the cards. And it's not like there aren't more FT cams running in BB Chevy-powered street machines than roller cams.

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  #47 (permalink)  
Old 07-31-2013, 11:30 AM
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Originally Posted by AutoGear View Post
Were the lifter bores machined?
Yes, when the engine was originally overhauled.
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  #48 (permalink)  
Old 07-31-2013, 11:43 AM
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Were the lifter bores bushed? If so, correcting/getting the angles right can be a daunting task for the uninitiated, hope whoever did the work was well versed on the procedure. If the bores were honed, they still should be checked to be sure.
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  #49 (permalink)  
Old 07-31-2013, 12:12 PM
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This narrows it down to incorrect valve adjustment, the break in lube and/or the break in procedure used. Couple questions:
  1. Was the cam washed clean of the rust preventive it shipped with?
    No. I didn't see that in Comp's instruction sheet.
  2. Was the break in lube physically rubbed into the porous surface of the cam lobes?
    Rubbed? No. "smeared* would be a better description.
  3. Was the lube thin and runny or thick, black grease?
    Runny-ish
  4. It did contain molybdenum, right? Brand?
    Lucas Assembly Lube #10153
  5. Absolutely NO IDLING for the first 15-20 minutes, right?
    Not the second time. I did it all myself.
  6. Did the engine start right away?
    Yes
  7. Valve train clearances all checked beforehand?
    Nothing done here, other than just lash adjustment.
  8. Valve adjustment correct? IIRC there were issues w/this.
    I believe that I did it the "one cylinder at a time way", and that I actually DID have a successful break-in. I truly believe that the latest damage is VERY recent ... after re-sealing the intake.
  9. Was the oiling system primed before initial start-up? (This is important but as long as the oil pressure came up immediately on starting the engine and there was moly grease on the cam and lifters, this shouldn't have caused an immediate failure.)
    Yes, to the point that oil was coming out of every rocker arm, and draining back into the lifter valley.

Looking at the page on cam break in, do you see anything obvious that could have caused the cam to take a dump?

I'll have to read that a bit later. I'm at work right now.

My bottom line is there's just no good reason a flat tappet cam cannot work in this engine. That's not to say a roller set up wouldn't be killer and all, but sometimes that's just not in the cards. And it's not like there aren't more FT cams running in BB Chevy-powered street machines than roller cams.[/QUOTE]

Thanks. I appreciate the fact that you have taken the trouble to do this detective work, and will definitely do everything on this list "the next time". (if there is one)
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  #50 (permalink)  
Old 07-31-2013, 12:15 PM
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You can trust in my next first gen BBC for myself is going to be a roller.BBC's leakiest link is the valve train. You see I do put my money where my mouth is.
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  #51 (permalink)  
Old 07-31-2013, 03:05 PM
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Is that coolant leaking into the valley around #7 intake/exhaust lifters ?
Could be your problem right there...



Duke
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  #52 (permalink)  
Old 07-31-2013, 03:33 PM
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Quote:
Originally Posted by cobalt327 View Post
Were the lifter bores bushed? If so, correcting/getting the angles right can be a daunting task for the uninitiated, hope whoever did the work was well versed on the procedure. If the bores were honed, they still should be checked to be sure.
Not bushed. Honed.
This engine came out of a 79 GMC 2500 with around 80,000 miles on it, and the PO said that it had never been touched. It was also LPG fuel, and surprisingly clean inside.

When I took the block in for the original inspection (hot tank, magnaflux, and cylinder bore taper, etc) the machinist said it had about .006 taper which would clean up well with a .010 overbore.

At that point, knowing I had a GOOD core, I instructed him to proceed with a complete overhaul, including align honing and freshening of all critical tolerences. I supplied the Clevite (Probe) forged flat-tops, and advised him that there was a possibility of a supercharger upgrade in the future. I had purchased some reconditioned 781 cylinder heads from a different machine shop and had them shipped to me ... and I instructed my machinist to dismantle and inspect to make sure I wasn't going to have any problems with them. He re-assembled them with those Clevite springs that I also supplied. (Most of the components that I supplied were Clevite items because that is what our store sold at the time.)

The crank was replaced with a Scat 9000, as the threads were stripped on the balancer bolt ... so it wasn't going to cost much more than grinding and repairing the stock one.

I also supplied a new (Dorman) balancer and flex-plate, and the rotating assembly was then balanced.

The engine was then fully assembled to the long-block stage and spun up.
I painted the block and installed all of the tinware. The first start-up occured a couple of months later. (I know ... another , but it couldn't be helped. I just so happened to be changing jobs during this time frame.)
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  #53 (permalink)  
Old 07-31-2013, 03:37 PM
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Originally Posted by thinwhiteduke View Post



Is that coolant leaking into the valley around #7 intake/exhaust lifters ?
Could be your problem right there...



Duke

Yup, but I'm not entirely sure whether the coolant you see there was an old leak or freshly deposited when I took the intake off.
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  #54 (permalink)  
Old 07-31-2013, 03:44 PM
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Quote:
Originally Posted by 66GMC View Post
Yup, but I'm not entirely sure whether the coolant you see there was an old leak or freshly deposited when I took the intake off.
Just thought I'd mention it because that photo looks exactly like what happen to a mate of mine, but the coolant was leaking into the valley during operation and fragged the lobe nearest to the leak..... Just a thought.



Duke
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  #55 (permalink)  
Old 08-01-2013, 10:08 AM
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Comp Cam's e-mail response ...

I had CC'd COMP cams a fairly detailed message, outlining most of what has been discussed here. (Actually included a link to this thread.)

This was their response ... in it's entirety.

Thaaaaaanks

Yup, now looking at alternates ... including the one you PM'd me AutoGear. Thanks!
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  #56 (permalink)  
Old 08-02-2013, 02:27 AM
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Be sure to investigate the possible coolant leak! Else you you may be doing it thrice !
Duke
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  #57 (permalink)  
Old 08-02-2013, 07:09 AM
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when I was at machingshop talking over cost on machining my block. he was adment on bushings for the lifter bores..
he didn't care that I was going to run a roller..
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  #58 (permalink)  
Old 08-02-2013, 10:23 AM
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Quote:
Originally Posted by thinwhiteduke View Post
Be sure to investigate the possible coolant leak! Else you you may be doing it thrice !
Duke
Yes, I'll be re-checking the torque on those intake bolts several times after warm-up etc. It was dry this last time, and zero oil leaks from the rear china wall either.

FWIW, my machinist is taking the entire month of August off, so I'll have plenty of time for R & R, too. (reading and research)
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  #59 (permalink)  
Old 08-02-2013, 10:26 AM
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Originally Posted by gearheadslife View Post
when I was at machingshop talking over cost on machining my block. he was adment on bushings for the lifter bores..
he didn't care that I was going to run a roller..
Was there a specific reason?
Were your lifter bores worn past specs?

I'm thinking of have the bores notched for better lubrication ... will ask the machinist what he thinks.
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  #60 (permalink)  
Old 08-03-2013, 12:53 PM
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Hell man on our brand new aftermarket block 565 we went round and round with a solid roller and valve train damages until we finally fixed it ourselfs with the proper lifter bore clearances.Now we know better and with the next two a 632 and now the 605 we set it and forget it.
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