Re: wiped out cam
Plenty of oil
Plenty of oil
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Re: wiped out cam
'65-'66 big blocks require a three hole rear cam bearing and a cam with a groove in the rear journal. If a later single hole rear bearing is used the lifters and top end won't get any oil. (Do an archive search as this subject has been discussed in great detail including photos.)
However, if as you say the top end was getting plenty of oil this may not be the cause, but it is something you should be aware of to verify when the engine is torn down.
I also suspect lobe hardness problems with some cam vendors. The ONLY cam vendors I currently trust without reservation are Crane and Federal Mogul (Sealed Power and Speed Pro brands).
DukeComment
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Re: wiped out cam
I know that Crane and FM cams are Parkerized, as were OE GM cams, and this aids the breakin process. I don't know who if any other vendors Parkerize their cams. Crane supplies cams to GMPP and Federal Mogul is a Tier 1 OE supplier, so this is assurance that their cams are manufacturer to the GM drawings, including lobe hardness and surface finish.
The entire camshaft is Parkerized, which leaves a mottled dark gray surface. Then the coating is polished off the journals (where it's not needed and possibly detrimental), which leaves them a satin silver, so a Parkerized cam is easy to identify.
DukeComment
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Re: wiped out cam
Sounds to me like you had solid lifter on hydraulic cam. The reasoning behind my statement is as follows. Hydraulic lobe profile wayyyy diff than solid. When you or you mechanic ran through initial valve set on engine stand he set valves with a 1/2 to 1 1/2 turns preload. This is done to set the plunger inside of hydraulic lifter to center it inside the housing . NOT to be confused with lifter bore inside block. A solid lifter is just that no plunger or spring inside. When you set the lash it is set with feeler gauges by thousandths. By setting the solid lifter like a hydraulicit would cause extreme valve to rocker and push rod to lifter pressures and geometry its self. This will cause notable engine eratic behavior. No idle, seems like it missing, back firing, sputtering, engine sounds like it will not claen up at any rpm. Just by trying to read through the lines this what it sounds like you went through. UNTIL CATOSTRAFIC FAILURE. It is not to bad of a job to fix. I would pull motor /.pressure check heads and check for any signs of valve spring binding"real shiney between spring coils" just for safety measures. Reason for press check heads complete is to rule out any valve damage. Check push rods for straightness and proper length. look real close at the ends and cup on rocker arms.Buy a cam and lifter matched set. Use lots of prelube and lubriplate.Change cam bearings make sure right ones for your block. find exact top dead center #1 cylinder. triple check your mechanical timing chain marks and crank timing gear key is good not sheared or smashed. There was a huge amount of pressure on valve train to bust a cam shaft. I believe the failure was assembly related . Very rarely the cam itself fails. I am in no way trying to be a know it all. small block chevys pull the vave studs out of the head like crazy with to aggressive cams with lots of lift you usually put screw in studs and push rod guide plates in for this reason. big chevys have them standard. Just take your time diassembling and look real close for clues. kevinComment
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Re: wiped out cam
" Other than that engine doing great. " Walter, your glass is definately half full.
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Re: wiped out cam
Using the wrong type of lifter for the cam should not wipe out the lobes, but using a mechanical lifter on a hydraulic cam and "preloading" them per the normal hydraulic lifter adjustment proceedure means the valves never fully close. Likely the engine will not start, and if it does it will barely run, and if run for more than a few minutes it will likely burn all the valves.
Using a hydraulic lifter on a mechanical lifter cam will result in the valve being slightly open on the clearance ramps rather than seating near the tops of the clearance ramps. This will also make the engine hard to start. It will will have very little power, and because the valves are off the seat much longer than they should be (on the order of 100-150 degrees more crankshaft duration), there will also be a tendency to burn valves if you drive the car.
DukeComment
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Re: wiped out cam
Here is some interesting reading. Keep in mind that the "original" series have bleed down rates which are faster than the "v-max" series.
I believe that nothing short of a gross mismatch someplace within the valve train must have caused such catastrophic damage to occur so quickly. The application of the ZDDP rich assembly lube should have negated the effect of low ZDDP levels in the Havoline.
I'm thinking that improper springs, or those, combined with incorrect installed spring heights, and/or valve stem lengths, and/or pushrod lengths probably contributed to coil bind. The fact that BBC use screw in rocker studs caused excessive loading of the entire valvetrain.Comment
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Re: wiped out cam
I'm too old. I would look silly crying about it.
Thanks.Comment
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Re: wiped out cam
I had the old cam taken out of the engine last year, as it hadn't been pitched out, it was holding a part of garage wall up, and it had a groove on the rear cam journal. The one in three pieces didn't which would lead me to suspect the culprit was insufficent lubrication to the cam although I definetly had good oil flow to the rocker arms. Will be researching in the next few days. One thing of note, the cam broke when one of my lifters came apart and dropped down siezing the cam and snapping it. There was an archived thread from July 2006 with this same issue.Comment
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Re: wiped out cam
Even with the correct three hole bearing, no groove in the rear camshaft journal means hardly an oil goes to the lifter galleries, which is also the source of the oil to the rockers. I'm surprised you said the rockers had plenty of oil. With correct parts the top end should be practically flooded with oil.
Search the archives to understand the differences in how oil is fed to the lifter galleries in pre-'67 and '67-up blocks.
Many early BB owners have been victimized by "engine builders" who don't understand this and install an improper cam and/or rear bearing.
It's okay to used a grooved rear journal cam in a '67-up block with the proper single hole bearing, but using a non-grooved cam in an early block means there is virtually no oil to the lifter galleries.
The groove in the cam is the oil transfer passage to the lifter galleries. One bearing hole is input from the main gallery, one hole oils the cam bearing, and the third hole is the exit to the lifter galleries.
'67 up blocks moved the oil transfer groove to the block around the outside of the bearing shell, so the oil transfer to the lifter galleries was around the outside of the cam bearing rather that between the bearing and camshaft.
DukeComment
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Re: wiped out cam
Duke no disrespect> the second senario you listed is exactly why the first will fail as well.Cam profiles meaning degrees of ramp lift and lobe seperation are like apples and oranges. I think the focus here is not the matter of lobes went flat. What kind of pressure do you think it would take to break a cam shaft in 3 pieces. This is why you have a shear pin key way on crank, I cant believe that didnt shear before cam shaft broke in 3 pieces. Ask yourself what does the cam shaft run? lifters to pushrods to rocker(which is a mechanical advantage lever" to valve stem. Any overload on an individual piece has a cause and effect. This is the reason I stated to check every part that I did so as you could fill in the smoking gun.He stated he could not get vehicle to run for any lenght of time. Ask yourself why if you have fuel/ air and fire it will detonate. Burning a valve at idle rpms with large amounts of cold raw fuel and excessive oils on wear mate surfaces(cylinder bores /valve guides and stems) definitely would reduce the odds of burning valve. Cold engine, choke closed ,fuel to air ratio and mixture rate on carb like a toilet bowl. There is something in the valve train. Also depending on lift and back fire coud have hit piston on valve head. He has not disclosed yet if he has appart, but if he knows cam broke in three places must be some disassembly. The breakage is the key not the lobe wearing flat. Again no disrespect!! Just trying to gain focus so that this man can enjoy his vette.Comment
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Re: wiped out cam
Opinion only...If the motor is apart AND the funds are avalible, Go roller. It eliminates many of the oil problems associated with oil formulation changes made over the years due to federal emissions rules and is easier on the valvetrain. BUT, don't think that "Roller" provides the freedom to go anywhere in the world of camshaft technology. Those choices are best left to the qualified engine builder that you choose to use; use a good one, their experience and knowlege is invaluable to an enthusiast that wants to build their own engine.Comment
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Re: wiped out cam
There's absolutely no reason to "go roller". OE camshafts and valve springs along with C-category oil are basically bulletproof as long as the engine is assembled to the same quality standards as OE, which seems to be beyond the skill level of some.
Most aftermarket roller cams have too much overlap, and I have yet to find an "engine builder" who actually understands how engines work at an engineering level, which is what is needed to re-system engineer an engine; and it's really tough to do a better job than the engineers who designed these engines 40-50 years ago.
DukeComment
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