Landyacht
Active Member
Beware of Comp
Junkyard 360 performance build questions
- Thread starter Bart
- Start date
The Horvaths
Young man with a cowboy hat
There's the problem! You've got a flat lifter! Patch the hole up and put an inner tube in it.
65sporty
Old Man with a Hat
It's easy to blame the cam company but the installer has to do the break in correctly or that can happen to any manufactures lifters. Just my .02
Bart
Member
I have only ever lost one lifter, and it blew apart from the top. I have been using Comp cams for years. I know there are better race cams from other manufacturers, but they have always been good on the street for me. Sorry you had that problem.
70bigblockdodge
Old Man with a Hat
How long/miles did this take to happen?
Landyacht
Active Member
The car was driven daily during the summer months over the past 4 years . I haven't kept close track of the mileage during that period. My best guess would be that the cam has close to 7 or 8 thousand miles on it.
commando1
Old Man with a Hat
Sounds about right for a Comp Cam and/or lifters. And throw in the occasional crap Comp Cam pushrod to the mix.
Landyacht
Active Member
I ran it for 20 minutes at 2500 rpm and used the supplied assembly lube that came with the cam and ran a zinc additive with every oil change. I drove the car for 4 years and put several thousand miles on it before this happened.
70bigblockdodge
Old Man with a Hat
I use Sta-lube engine assembly lube on the cam, the black crap with the moly in it. Change the filter after the cam break in run because the moly plugs a filter solid. I am not a fan of zinc additives to regular oil because the detergent formula changed when the zinc levels went down, the new detergent treats high zzinc levels as contaminates rendering them non effective. This may be why yours took a while to wipe instead of fairly quickly. My .02 cents.
Landyacht
Active Member
The cam is an Extreme Energy series .507 lift @240 duration. Its also possible that a flat tappet cam can only handle so much lift at a short duration without compromising its strength and longevity.
70bigblockdodge
Old Man with a Hat
MP is 246@.050 with .509 IIRC and there are a few of them out there surviving. It may just be that your lifters were manufactured off shore in that time frame when flat tappets really became obsolete and the QA was crap. Either way I think that everyone has stepped up their game the QA is more on track and you need special oil that is not approved for the neighbors Honda, or go roller and get oil at wal-mart your choice.
commando1
Old Man with a Hat
If a cam won't last by using the recommended break in procedure, then they manufactured junk.
Period. End of story.
moper
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If it went 4000 miles that failure was not the cam. The symptom was the cam loss. It might have been that the engine sat for a bit too long, or didn't fire right up and the wear surfaces were compromised. Or something caused the lifter to bind in the bore and not turn, or a weaker valve spring that let the lifter hammer the lobe rather than following it. Stuff like that happened in the 70s and still does happen.
The vast majority of failures is not related to the cam, but to the engine assembling and first start. I've never lost a camshaft except once, when I ran a hydraulic flat tappet cam and factory hydraulic rollers on it in a block not designed for them. (ok - I was 17... Some of us learn by doing...lol) In any event I run a lot of Comp stuff, including custom grinds using lobes much faster than shelf grinds. In order to do this one has to verify everything: measure the lifter bore clearance for every lifter, remove the inner valve springs, make sure the break in lube stays on the cam ( I use Crane's paste and mix it with Crane's assembly lube), and make sure there is no reason the engine gets shut down until the break in is done. If you turn the engine over to get oil pressure rather than using a priming rod, you run a good chance of wiping the cam. If you turn the engine to use the fuel pump to prime the carb, or it doesn't start immediately - you run a very good chance of wiping the cam. That's because there is no pressurized oiling of the cam lobe. It is oiled by oil slinging UP off the crank and to a smaller degree oil draining back from the upper valvetrain. If you don't use the right oil you run a greater risk. Additives need special treatment to be throughly mixed prior to the oil going into the crank case. If you don't check for lifter rotation during assembly. If you don't have cooling capacity and it runs hot so you shut it down... etc etc etc.
The vast majority of failures is not related to the cam, but to the engine assembling and first start. I've never lost a camshaft except once, when I ran a hydraulic flat tappet cam and factory hydraulic rollers on it in a block not designed for them. (ok - I was 17... Some of us learn by doing...lol) In any event I run a lot of Comp stuff, including custom grinds using lobes much faster than shelf grinds. In order to do this one has to verify everything: measure the lifter bore clearance for every lifter, remove the inner valve springs, make sure the break in lube stays on the cam ( I use Crane's paste and mix it with Crane's assembly lube), and make sure there is no reason the engine gets shut down until the break in is done. If you turn the engine over to get oil pressure rather than using a priming rod, you run a good chance of wiping the cam. If you turn the engine to use the fuel pump to prime the carb, or it doesn't start immediately - you run a very good chance of wiping the cam. That's because there is no pressurized oiling of the cam lobe. It is oiled by oil slinging UP off the crank and to a smaller degree oil draining back from the upper valvetrain. If you don't use the right oil you run a greater risk. Additives need special treatment to be throughly mixed prior to the oil going into the crank case. If you don't check for lifter rotation during assembly. If you don't have cooling capacity and it runs hot so you shut it down... etc etc etc.
commando1
Old Man with a Hat
mopar: Your knowledge is very thorough, practical, combined with a good understanding of the physical process.
And I agree with you.
My argument is this. How could the factory pump out hundreds of thousands of BB's on the line with the crudest and the most minimal break-in (if any, actually), and have 98.6% go on and do a 100,000 miles in the general population.
The iron today is garbage compared to then, despite the advances in metallurgy.
And I agree with you.
My argument is this. How could the factory pump out hundreds of thousands of BB's on the line with the crudest and the most minimal break-in (if any, actually), and have 98.6% go on and do a 100,000 miles in the general population.
The iron today is garbage compared to then, despite the advances in metallurgy.
Landyacht
Active Member
One reason might be that the factory cams didn't have as much lift as the aftermarket cams and didn't need stiffer valve springs which in turn didn't assert as much pressure on the cam lobes. I think it comes down to reliability vs performance. If you want reliability and good street manners its best to go with the stock cam. If you want to go fast, go with a high performance after market cam but be aware of the possible consequences.
70bigblockdodge
Old Man with a Hat
Your cam was a failure not a consequence.
moper
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Here's some reasons - it's not metalurgy or "poor machining". It's the combining of different and sometimes unrelated elements that on their own would not be enough to cause catastrophic failure when occurring individually.
The cam lobes are very different in shape than a factory type camshaft. Which means in some cases (especially ones touted as "Mopar specific") the modern lobe is much more dependent on the correct lifter to lobe interface. Tip the lifter or the cam lobe a degree or two and they may not have the perfect conditions for long life - or any life in some extreme examples. This is what got Hughes in trouble some years ago with failures.
The valve spring pressures are significantly less on a factory engine than those used on a performance grind cam.
The lifter bores were new at the factory, not worn as they are now. That can significantly and negatively affect the tappet to lobe relationship. (see above on cam lobes)
The block has been seasoned after decades of use and temperature changes which means the cam bore may have shifted, changing the tappet to lobe relationship (again, negatively).
The oil was better suited for flat tappet camshafts.
The factory first start did not involve garage mechanics who crank the engine to get oil pressure, then crank it to get fuel up to the carb, then crank it more because the distributor's 180° out, then crank it slower because the starter and battery are hot, then when it does start, run it for 5 minutes until it starts to run hot and shuts it down...
The cam lobes are very different in shape than a factory type camshaft. Which means in some cases (especially ones touted as "Mopar specific") the modern lobe is much more dependent on the correct lifter to lobe interface. Tip the lifter or the cam lobe a degree or two and they may not have the perfect conditions for long life - or any life in some extreme examples. This is what got Hughes in trouble some years ago with failures.
The valve spring pressures are significantly less on a factory engine than those used on a performance grind cam.
The lifter bores were new at the factory, not worn as they are now. That can significantly and negatively affect the tappet to lobe relationship. (see above on cam lobes)
The block has been seasoned after decades of use and temperature changes which means the cam bore may have shifted, changing the tappet to lobe relationship (again, negatively).
The oil was better suited for flat tappet camshafts.
The factory first start did not involve garage mechanics who crank the engine to get oil pressure, then crank it to get fuel up to the carb, then crank it more because the distributor's 180° out, then crank it slower because the starter and battery are hot, then when it does start, run it for 5 minutes until it starts to run hot and shuts it down...
commando1
Old Man with a Hat
:laughing4::laughing4::laughing4::laughing4::laughing4::laughing4:
Priceless. Who has not done that.:busted:
not me, and not yet
rumpfox
Member
i built the same eng. with edl. intake , comp. 340, police h.p.cam. a street fighter convert. cheap headers 323 gear in a 71 chal. it was a very good street eng. all you'd want. cherp the tires in 2 gear shirts. gruze 100 mph all day long get 20 mpg. i took it out and put it in a 4 whl. drv. dodge truck. runs great and all the tq. to pull a traiolered race car 500 mls. without any worries
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