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Old 05-23-2013, 07:49 AM
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failed cam lobe

well it finally happend to me. i built a really cool marine engine two years ago it was a 355 flattop pistons 10-1 with a 214-218 110lsa reed cam. sounded great through the 8 inches of exhaust whene i was trying to break the freshly completly rebuilt engine in, the timing computer was messing up the distributor, it screwed with me for a while. in the back of my mind all the talk of cam falure was eating away at me. however after about 10 mins of screwing with it and finding the wireing problem, i did the traditional break in procedure. after that the boat hit the water and racked up almost 200 hours of run time on onieda lake and lake ontario and st. lawrence river in new york. after enjoying phenominal reliablility and forgetting about my breakin incident, whene i dusted her off earlyier this week i changed the oil and found some shavings in it. i didnt notice any difference in the exhaust note at all but i pulled the valve cover and #8 intake is not happy at all! how the heck did this thing run at 5000 rpms with 6000lbs of boat load sitting on the crank last 200 hours if i broke the camshaft in poorly? plus if anybody has an issue upon startup of a fresh rebuild, carb, electrical, lash setting, whatever, should you just throw your cam in the trash? i thought because my cam didint wipe out after 20 mins i was good to go. ive never had this happen to me before. that engine was my first complete rebuild and ran dang hard for 200 hours! i kinda want to stab a new cam in it but now the shavings got me runnin scared. now im just in the corner of the garage pukin my guts out wondering where im getting cash to rebuild this engine again along with finishing up my 305. so the porpose of this post is like all my other posts, im looking for advise on how to do it the cheap way. even though i know that the right way is to the tune of about 3 grand and a summer wrenching on my own boat while my friends and family are partying on there days off.

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Old 05-23-2013, 10:46 AM
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Originally Posted by s-10again! View Post
well it finally happend to me. i built a really cool marine engine two years ago it was a 355 flattop pistons 10-1 with a 214-218 110lsa reed cam. sounded great through the 8 inches of exhaust whene i was trying to break the freshly completly rebuilt engine in, the timing computer was messing up the distributor, it screwed with me for a while. in the back of my mind all the talk of cam falure was eating away at me. however after about 10 mins of screwing with it and finding the wireing problem, i did the traditional break in procedure. after that the boat hit the water and racked up almost 200 hours of run time on onieda lake and lake ontario and st. lawrence river in new york. after enjoying phenominal reliablility and forgetting about my breakin incident, whene i dusted her off earlyier this week i changed the oil and found some shavings in it. i didnt notice any difference in the exhaust note at all but i pulled the valve cover and #8 intake is not happy at all! how the heck did this thing run at 5000 rpms with 6000lbs of boat load sitting on the crank last 200 hours if i broke the camshaft in poorly? plus if anybody has an issue upon startup of a fresh rebuild, carb, electrical, lash setting, whatever, should you just throw your cam in the trash? i thought because my cam didint wipe out after 20 mins i was good to go. ive never had this happen to me before. that engine was my first complete rebuild and ran dang hard for 200 hours! i kinda want to stab a new cam in it but now the shavings got me runnin scared. now im just in the corner of the garage pukin my guts out wondering where im getting cash to rebuild this engine again along with finishing up my 305. so the porpose of this post is like all my other posts, im looking for advise on how to do it the cheap way. even though i know that the right way is to the tune of about 3 grand and a summer wrenching on my own boat while my friends and family are partying on there days off.
I'm going to torque a lot of guys that write in this form who believe that proper break in and gobs of aftermarket ZDDP additives are the solution to flat tappet cam and lifter wear.

The facts simply are that this has been a long term problem with Chevrolet and other brands of engines as well. It occurs mostly to those engines that do not use a thrust plate to constrain the cam in its bore, but not exclusively to those engines. GM had a class action suit against it about this problem way back in the 1970's so this is nothing new.

The reduction in ZDDP and other additives hasn't helped, but this problem way predates the EPA edict to get catalytic converter degrading contaminants out of fuels and oils by several years if not decades.

There are really only three solutions that take the playing of Russian Roulette with cam and lifter wear out of the equation:

1) That is the use of ceramic faced flat tappet, often referred to as "composite lifters" these are very expensive about 10 to 15 times the cost of a regular lifter set and are not always available.

2) Comp offers Parkerizing for 100 dollars, probably the best and lowest cost solution. GM used to Parkerize their cams but stopped the process when the EPA said they could no longer simply dispose of the remaining pot liquor into the nearest stream. So rather than pay the cost of environmental remediation they simply stopped doing it and we've been fighting cam and tappet wear problems ever since.

3) The other long term, but expensive, solution is to go with a roller cam. This was the OEMs final solution to cam and flat tappet wear to reduce, if not eliminate, their warranty exposure.

Ford back in 1958 originally released the FE with this idea used by GM that a slanted lobe and convex lifter and the distributor gear would keep the thrust load under control. After a year of production they introduced a thrust button, by 1963 production they abandoned the thrust button in favor of a thrust plate. I think that pretty well sums up the problem and the solution. I think the lifter has plenty to do without damping the herky/jerky fore and aft motions of the cam.

So any of these three choices pretty much eliminates the possibility that you’ll have to go back inside the engine again. I, also, do one other thing that as a group I’m sure the bloggers here feel is excessive and unnecessary for a flat tappet cam and that is to use the a cam button (made for fitting roller cams to pre roller blocks) to establish a thrust clearance rather than depend upon the lobe lifter interface and the distributor gear to carry the thrust loads. I only use the roller bearing style as these include a wear plate which takes that load off the timing cover which then stabilizes the set up dimension. Aluminum buttons riding on the timing case cover wear themselves and the cover slowly opening the clearance. Plastic buttons deform with heat and usage changing the clearance and actually finally crumbling when used in street engines that may not see inspection of internal maintenance for tens of thousands of miles.

Bogie

Last edited by oldbogie; 05-23-2013 at 10:53 AM.
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Old 05-23-2013, 12:31 PM
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2) Comp offers Parkerizing for 100 dollars, probably the best and lowest cost solution. GM used to Parkerize their cams but stopped the process when the EPA said they could no longer simply dispose of the remaining pot liquor into the nearest stream. So rather than pay the cost of environmental remediation they simply stopped doing it and we've been fighting cam and tappet wear problems ever since.
Does it do any good to parkerize the cam only and ignore the lifters? Shouldn't be parts be done?
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Old 05-23-2013, 01:05 PM
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And by parkerizing, I think we both mean nitriding.
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Old 05-23-2013, 05:11 PM
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Does it do any good to parkerize the cam only and ignore the lifters? Shouldn't be parts be done?
Most lifters have a hard wearing surface if you look closely you can see the demarcation line close to the foot. This is actually a material transformation rather than something applied to the lifter body that somewhat mimics nodular iron. The flat head Ford guys would know this as a chilled iron tappet but the modern process and material is different.

A big part of the problem is without specialized chemical or heat treatments you end up running a piece of cast iron against a piece of cast iron. Similar metals have trouble running against each other they want to fuse together. So running moly or ZDDP or whatever is a means to overcome that natural tendency of metals. Usually plenty of oil will let you push that somewhat, but the forces in this interface, the dimension of the parts, and the motion doesn't allow the typical hydro-dynamic wedge to form that you see isolating the moving parts in a bearing and journal situation. So over the lobe all you've got is the chemistry of the additives. Much of the time this works, some of the time it doesn't. That can be cam lobe profile dependent, older profiles that use a lot of ramp and milder spring pressures while not immune are more tolerant of the situation. Newer fast lifting cams have shorter faster ramps that require higher spring forces; these suffer greatly with this problem. Certainly over revving and floating the valve train is hard on this interface when you generate impact forces between lobe and lifter, as well as running a higher pressure springs. One also needs to consider that a boat engine is working harder most of the time in its duty cycle than a car engine and is cooled in quirky ways usually with whatever the water is surrounding the hull, so they take a greater beating than engines typically in ground vehicles with their lower overall power usage and well controlled cooling systems.

Bogie
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Old 05-23-2013, 06:37 PM
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And by parkerizing, I think we both mean nitriding.
Yes sorry, Parkerizing is not the same as nitriding but my pea brain keeps thinking one and the other is the same when they are not. Parkerizing is a chemical coating for infused dry lubrication on a part and nitriding is surface hardening treatment that changes the molecular structure a few mils deep to provide a hard wearing surface.

However, I will emphasize in relation to cams an over rev or anything else that causes the tappet to lose contact with the lobe then crash back will for sure start a failure mode; so guys really need to purchase the kit that cam makers furnish unless they have the facilities to test strange part brews. And the RPMs need to be monitored closely; cause once the lobe and lifter gets dinged, the damage is done.

Bogie
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Old 05-26-2013, 09:14 AM
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good talk bogie, you think i should tear this engine down? or prime/flush the oil galleys with new oil and stabb a cam in there and take some time setting up a thrust plate? i actually have a bunch of oem crap kicking around i might actually have a bunch of buttons and plates and stuff i should see how it cobbles together. i hate to tear fresh engine down but i spent alot of coin getting this thing speedin on the lake so the last thing i want is for it to go boom and have to start over. my old school dad is saying "oh itll be fine! put a cam and run it!" i have a different way of doing things than he does though. id rather side with him than my ideah but i dont like seeing shavings in my BRAND new engine. he sais "no biggie, been there done that". but he never built anything performance.
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Old 05-26-2013, 09:49 AM
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Originally Posted by s-10again! View Post
good talk bogie, you think i should tear this engine down? or prime/flush the oil galleys with new oil and stabb a cam in there and take some time setting up a thrust plate? i actually have a bunch of oem crap kicking around i might actually have a bunch of buttons and plates and stuff i should see how it cobbles together. i hate to tear fresh engine down but i spent alot of coin getting this thing speedin on the lake so the last thing i want is for it to go boom and have to start over. my old school dad is saying "oh itll be fine! put a cam and run it!" i have a different way of doing things than he does though. id rather side with him than my ideah but i dont like seeing shavings in my BRAND new engine. he sais "no biggie, been there done that". but he never built anything performance.
Wasted cam = tear down...... period.
There's really no way around it.
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Old 05-26-2013, 01:40 PM
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In 1973, the EPA forced GM to eliminate the "spit-holes" in the cam side of the rod cap. The EPA determined that the spit-holes threw too much oil up on the cylinder walls and created excessive emissions. The spit-hole's main function is to oil the cam lobes. That is when Chevrolet engines started having cam failures due to lack of lubrication. GM had to reduce valve spring pressure and engine performance. From 1986-1997 GM continued to use weak springs since the OE roller camshafts were relatively mild until the LS engines were introduced.

Break in rules for GM engines with flat tappet lifters:
1. Use stock rods with spit-holes.
2. If rods without spit-holes are used, increase rod side clearance an additional .010" and use a HV oil pump.
3. Use 250 lb. break in valve springs or remove the inner spring on double springs.
4. Do not fill hydraulic lifters with oil. Never set the valves on a running engine.
5. Set the timing and valves so the engine will start instantly and run up to 2000 RPM.
6. Use Joe Gibbs dyno and break in motor oil.
7. Use Valvoline VR1 "Not Street Legal" 30 wt. motor oil after break in .
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Old 05-30-2013, 08:30 AM
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ok...well the engine is out and up on a stand and the oil pan is off how do i clearance these rods .010 fore better oil throwing? i have a high volume oiling system in the engine already, i got my cam this morning its a good cam i think. might not make as much power at WOT but it should be good for tubing, its a lunati .213/219 @.050 256-262 adv. lift .454-.468 110 lobe center. its got a little less duration at .050 and a lot less advertised duration. the old cam was a Reed cams 214-218 265-272 advertised dur, and lift at .450-.464 also the lifter bore grooving tool has my attention has anybody tried this method? also on break in this time the engine will fire right up and run like hell for break in so there should be no issues on breakin this time. also the cam bearings look great...brand new. should i even replace them? the rod bearings ill be replacing if i decide to clearance the rods for better oiling.

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Old 05-30-2013, 08:40 AM
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the cam i took out had pitting and i knew as soon as i had the valve cover off it was a cam lobe becasue the rocker was loose as a goose after the valve closed.
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Old 05-30-2013, 08:44 AM
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as well forgot to mention that the lifter was very stuck in the bore. maybe becasue it was deformed after the failure or maybe it was not spinning because i didnt clearance the bores and polish the lifter enough. that is my hypothesis.
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Old 05-30-2013, 09:39 AM
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ok...well the engine is out and up on a stand and the oil pan is off how do i clearance these rods .010 fore better oil throwing? i have a high volume oiling system in the engine already, i got my cam this morning its a good cam i think. might not make as much power at WOT but it should be good for tubing, its a lunati .213/219 @.050 256-262 adv. lift .454-.468 110 lobe center. its got a little less duration at .050 and a lot less advertised duration. the old cam was a Reed cams 214-218 265-272 advertised dur, and lift at .450-.464 also the lifter bore grooving tool has my attention has anybody tried this method? also on break in this time the engine will fire right up and run like hell for break in so there should be no issues on breakin this time. also the cam bearings look great...brand new. should i even replace them? the rod bearings ill be replacing if i decide to clearance the rods for better oiling.
I haven't seen that grooving hydraulics nor face oiling solids offer any solution to the wear problem. We see all of them having failures regardless of break in proceedure and oils used. But it's quite random some engines experience problems many others don't. We have a customer right now that's loosing a lobe on a 350 with flat hydraulic tappets on a pretty hot street build. Since it's built on a roller block, my fix is going to be to convert it to a roller cam and be done with it. So much for saving money with a flat tappet cam, it only takes one of these excersions into cam replacement to pay for a roller up front and be done with the problem.

I've seen engines where the cam is tunneled so it runs in a flood of oil all the time and still the flat tappets give up, it's just a nature of the beast that as lifts and spring pressures go up so does the potential for lobe and lifter failure. I suspect at least in some cases where high spring pressures are involved we're actually looking at bending of the cam at least contributing to these failures. One needs to note the very large diameter increase to the cam shaft Chevy did on the Gen III LS engines, so it's important to realize that GM saw the small diameter of the Gen I and II cam as a problem.

Bogie
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Old 05-30-2013, 10:18 AM
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In order to increase the side clearance, the rods must be removed and parallel ground in a fixture. All rods should checked for twist and corrected by parallel grinding the faces of the big end. If the 1973 - up factory or aftermarket "no-spit hole" rods are to be used in high performance engines, that is the time to check each pair on the crankshaft and add side clearance. A total of .025" side clearance per pair is recommended along with a HV oil pump.

I am unsure about recommending grooved lifters or grooved lifter bores. You can use restricted push rods along with full roller rocker arms but never restrict the lifter galleries. I was able to use off the shelf Comp Cams 8305 restricted push rods that are 7.300" long otherwise I would have used custom length Smith Brothers restricted push rods.
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Old 05-30-2013, 11:57 AM
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bogie i did not know about the camshaft blank diameter growing to address an issue whene the ls engines debuted. perfectly sensible solution for gm. that brings a little light in on the subject as to say that there has ALWAYS been an issue with gen 1's. like ive said before on this forum about my own impractical ways of doing things, i am an ambitional optimist. i want overkill, weather it necessary or not. im going to try this again with this lunati cam and break her in with a vengance at 2000-2500 varying. because now the engine runs like an animal so she will fire right up with the q-jet and hit an exhaust note right at start up! if this cam fails again, after i puke my guts out again...im goin roller. it has the milled lifter bore tops and valley spider bosses drilled. ill be floggin this dam thing in about 9 hours labor. post back tomorow on this thread and thank you all for listening to my ranting and the insight. feels good to hear from experience. im the only cronie in my group doin sbc stuff. u guys are the only back i got other than costly machinist consulting. they charge money to ask questions around here in upstate ny....especially if your a do it yourselfer, even after you payed them to refurb your heads...
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