Just wiped a lobe. Wanna try a non-thumpr now. Any suggestions so I don't lose power? - Page 2 - Hot Rod Forum : Hotrodders Bulletin Board
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Old 02-21-2013, 04:54 PM
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Quote:
Originally Posted by Zerocyde View Post
I had the cam for 3 years before the lobe wiped. I thought cam break-ins were only like 200 miles...
It never really ends anymore because the chemistry of oil has changed greatly and the old levels of ZDDP just aren't there to protect the flat tappet style cam and lifters. This is one reason (and a big one) the OEMs started to replace the flat tappet cam with rollers back in 1985. Others are reduced oil pressure and viscosity, elimination of indexed streams from the rods to pressure lube the cylinder walls and the cam, less drain-back and throw-off from lower pressures and tighter clearances, the use of a windage tray which cuts the mist flying around with the crank assembly. This combines in a hot rod engine with a more aggressive modern cam profile which is to cut back on long ramps that ease the tappet into motion and the use of higher lifts, cams like the Thumper, Extreme Energy, Voodoo, etc. get right too it with short fast acting ramps. This adds a lot of power and makes better use of compression ratios with unleaded fuels and high overall gearing but it's hell on the valve train parts.

Certainly nitriding or Parkerizing the cam will put a permanent hard wearing surface on it but to be safe it would continue to be a good idea to use a ZDDP booster. ZDDP forms a sacrificial coating on the cam and lifters similar to the chemical/heat hard overlay surfaces which by the way GM used for many years before ZDDP became popular in oils. But the ZDDP has to be constantly renewed as it gets used up between oil changes. GM had a lot of flat tappet cam and lifter wear problems when they stopped Parkerizing the cams and lifters of production vehicles back in the 1970's.

I have never been enamored with Chevy's idea of using the angle of the lobe and convex surface of the lifter that is there to cause the lifter to spin on its axis as also a method to preload a thrust force on the cam to stop it from longitudinally travelling in its bearing bores. I have forever build the Chevy with a roller cam thrust button to pick up that load as I figure the lobes and lifters have plenty enough to do without keeping the thrust load against the cam's movements.

Bogie

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  #17 (permalink)  
Old 02-21-2013, 05:09 PM
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You need to do more than replace the cam. All that ground up metal is now in your oil passages. It needs to be somehow cleaned out or you will be doing bearings next
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Old 02-22-2013, 03:49 AM
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Originally Posted by oldbogie View Post
It never really ends anymore because the chemistry of oil has changed greatly and the old levels of ZDDP just aren't there to protect the flat tappet style cam and lifters. This is one reason (and a big one) the OEMs started to replace the flat tappet cam with rollers back in 1985. Others are reduced oil pressure and viscosity, elimination of indexed streams from the rods to pressure lube the cylinder walls and the cam, less drain-back and throw-off from lower pressures and tighter clearances, the use of a windage tray which cuts the mist flying around with the crank assembly. This combines in a hot rod engine with a more aggressive modern cam profile which is to cut back on long ramps that ease the tappet into motion and the use of higher lifts, cams like the Thumper, Extreme Energy, Voodoo, etc. get right too it with short fast acting ramps. This adds a lot of power and makes better use of compression ratios with unleaded fuels and high overall gearing but it's hell on the valve train parts.

Certainly nitriding or Parkerizing the cam will put a permanent hard wearing surface on it but to be safe it would continue to be a good idea to use a ZDDP booster. ZDDP forms a sacrificial coating on the cam and lifters similar to the chemical/heat hard overlay surfaces which by the way GM used for many years before ZDDP became popular in oils. But the ZDDP has to be constantly renewed as it gets used up between oil changes. GM had a lot of flat tappet cam and lifter wear problems when they stopped Parkerizing the cams and lifters of production vehicles back in the 1970's.

I have never been enamored with Chevy's idea of using the angle of the lobe and convex surface of the lifter that is there to cause the lifter to spin on its axis as also a method to preload a thrust force on the cam to stop it from longitudinally travelling in its bearing bores. I have forever build the Chevy with a roller cam thrust button to pick up that load as I figure the lobes and lifters have plenty enough to do without keeping the thrust load against the cam's movements.

Bogie

There are many shops,ours included,that refuse to build anything but a roller engine,hydro or solid.

We too have seen cam failures many miles after break-in.With oil change intervals being at 2500 miles and the added costs of a Joe Gibbs racing oil adding to that oil change each one,your ending up paying for the roller conversion alittle at a time.It doesn't seem like alot,but it adds up.All that aside from putting the engine at risk for major damages.

It is true now that you have metal in the oil passages,it needs to be torn down,hot tanked,and the tolerances checked in a do-over.And do-overs almost always cost more than the roller conversion would have in the first place.
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Old 02-22-2013, 10:17 AM
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So should I just add zinc additive every time after I do an oil change?
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Old 02-22-2013, 10:24 AM
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Originally Posted by Zerocyde View Post
So should I just add zinc additive every time after I do an oil change?
no,you should buy a roller cam
for all the reasons mentioned
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Old 02-22-2013, 11:35 AM
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For a flat tappet cam and long life I recomend this stuff.
Molyslip Canada Inc. :: Molybdenum Lubricants, Performance Lubricants, Copaslip Anti-Seize, EP2 Grease, Wear Reducing Lubricants, Oil Additive
This is what I use.
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Old 02-22-2013, 11:43 AM
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Originally Posted by vinniekq2 View Post
no,you should buy a roller cam
for all the reasons mentioned
Okay, until I have enough spare cash to justify throwing away the cam and lifters I just installed last night with about a grand worth of upgrades...

Should I add zinc additive after every oil change?
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Old 02-22-2013, 12:07 PM
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Im curious as to what you installed as a replacement cam?
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Old 02-22-2013, 12:51 PM
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Really, like I said way back, you should have torn this engine apart, inspect everything and clean it all out. That metal is all over in there and your bearings and pump will be next, and possibly the cam again.
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Old 02-22-2013, 09:58 PM
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Your not known for lowering risk moves................
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Old 02-22-2013, 10:02 PM
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Quote:
Originally Posted by Zerocyde View Post
So should I just add zinc additive every time after I do an oil change?
In a blunt answer to your question,yes or use Joe Gibbs racing oil all the time.

Yeah know it does kind of tick me off some when manufactures can't be straight with people who are buying their products. Damm it,sure does make it hard for us honest folks who are just trying to help.

Last edited by 1Gary; 02-22-2013 at 10:12 PM.
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Old 02-23-2013, 01:13 AM
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For those that are very familiar with quality roller lifters vs what I imagine are ones a guy should stay away from, what brands would be suggested in ether a retro fit roller rebuild or a roller ready block. As 33Willys77 mentioned before, he had a retrofit roller adjoining bar fail and cause major damage.

Put another way, what brand of cam ( and billet or not ? ) and type of retro fit rollers should Zerocyde have used if he had decided to tear down his engine and start from scratch.
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Old 02-23-2013, 10:39 AM
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Correction, mine were not retro fit, they were aged - rollers were good, but the connector between the lifters fatigued out. I dont know how old they were - could be from the 70's. It was not a bar, more like a peice of sprung (tin like) arched tab. Not like what they are today. I was just saying, I had a mishap and all that metal was all over the engine. I could see it in the pump and in the bearings.
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Old 02-23-2013, 10:58 AM
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Oh ok sorry, that was my mistake for visualizing a newer style retro fit unit with the link bar arrangement. As to it causing metal fragments to bypass the filter and get back into the bearings, never mind the oil pump that WILL suck in everything on the bottom of the pan and damage itself, I can see some horrible visuals of what a cam failure would cause. Thats good to know as I've had friends who did the same thing, had a cam lobe get wiped and just slipped in a new cam and lifters without tearing into the engine further and "hope" for the best. That would be like sitting on a bomb that never went off ... yet !.
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