Piston and Cam help....

[Jon Miller]

Hi Guys,
As you can see from the picture, I'm shopping for new pistons and a cam kit.



The bent piston is a TRW forged that had 30,000 miles on it, and may have been bent since it's break in 15 years ago. The lifter was brand new and looked like this after about 40 minutes of run time. The cam lobe looks almost as bad....

I've see Hypereutectic pistons for about half the price of the forged variety. Is there any reason to pay extra for forged seeing as how they bend anyway?

I'm thinking that it might be a good idea to go with the Edelbrock Performer RPM cam kit just for simplicities sake. It looks like it will give the "Proper" lumpy idle, and still be drivable. I've got Edelbrock heads, timing set, 2x4 intake, 500cfm carbs, water pump, air cleaners, and most important of all, an Edelbrock Tee shirt. I would thinnk that all of their stuff would work well together.....or maybe not. What do you guys think? I'm running 3.31 rear gears, and about 10.5:1 compression depending on what pistons you tell me to buy

Thanks!
Jon

[Barry_R]

If that would have been a hypereutectic piston you would be shopping for a block right now. That kind of damage is normally caused by severe detonation or possibly a cylinder full of water (hard to tell by one photo but I'd wager on the former). It was not the piston's fault - that I can promise.

Get another set of forged pistons. The Edelbrock cam kit is nothing special - - I sell the same basic grind for less dough. But that's not important part - you need to be certain to get decent quality AMERICAN MADE lifters. Many of the big name guys are bringing in cheap stuff from Mexico or China. That junk'll kill ya. Ask and check. Then use GM EOS with Rotella or Delo oil for break in.

[Excaliber]

I'm running a 427 side oiler with a flat tappet Comp Cams 292S. Good lumpy idle, pulls nicely from 2000 rpm, loves my 3:31 rear gear ratio. 2X4 intake with 600 cfm carbs. Perfect match for me! 10.5 to 1 should be fine with alloy heads, I'm running 9.8 to 1 with iron heads. The 292S tops out around 6200 rpm, enough rpm for me! I went with a 'kit' which is highly recommended no matter WHAT cam you get. Get matching lifters, springs, etc. In my case I also went with new valve retainer kit as well. And SHIMS to set correct valve installed height.

BREAK IN is very important with a new flat tappet cam and the new EPA mandated engine oils which are MISSING key ingredients we USE to have. These new engine oils DO NOT provide sufficient oil protection and during break in you MUST use certain additives. As well you should remove the INNER valve spring for break in and re-install afterward.

Yup, no doubt those forged pistons saved your motor! I went with custom forged pistons myself, thats one area I just didn't want to cut corners on. Use new spiral locks for the wrist pins. You might consider 'custom pistons' if you want to add 'quench' or get that 'perfect' compression ratio based on your combustion chamber size. For both of those reasons (nailing the perfect compression ratio AND adding quench) is why I went with custom slugs. Stock 428's basically have no 'quench', you need to know for sure the CC of the heads to calculate compression ratio.

See my engine blog for more detail on cam breakin and oil additives, a MUST for flat tappet cams.

[olddog]

Originally Posted by Excaliber

BREAK IN is very important with a new flat tappet cam and the new EPA mandated engine oils which are MISSING key ingredients we USE to have. These new engine oils DO NOT provide sufficient oil protection and during break in you MUST use certain additives. As well you should remove the INNER valve spring for break in and re-install afterward.

On another web site I visit, an Engineer that knows a lot about oils, said the same thing about EPA mandated removal of additives that is causing flat tappet cams to wipe. He even mentioned that older well broken in engines are having cam failures as a result. I'm no expert on this, but I have heard a bunch about wiping cams all over this site and others. Maybe there is something to it.

All the rituals about breaking in a cam does not make sense to me. I hear it all the time. I could be wrong, but I think it is a bunch of voodoo practiced out of superstition, not science. The cam manufactures push this, as it gets them off the hook. Breaking in would mean that the cam lobe and lifter bottom are going to wear and polish off metal until there is a better fit and then this polishing off of the metal is going to miraculously quit. Why would it quit? The metal is not going to get any harder as it wears down. If it is going to get smoother, why wouldn't the manufacturer just polish the metals to the correct smoothness and then harden it? Since the lifters rotate in the bores there is nothing that needs to be fitted better. A film of oil should always be between the two parts, and they should never touch, so there should be no wear. If I have it all wrong, please educate me.

My guess is that the lifter fit too tight in its bore. Too many people do not pay enough attention to the lifter bores or how tight the lifters fit. I would recommend getting this figured out or the next cam may wipe too.

[Jon Miller]

The heads are are just like Vic Edelbrock intended them to be....bone stock. I don't have the budget to go messing with them now. That's one reason I was leaning toward the matching Edelbrock cam kit. In theory I will not have to change anything.

The problem with the wiped lobe is very likely self induced. I have been building the motor over the last 10 years, and the cam has been sitting in the block for most of that time. I saw in another thread that one should not let the moly lube sit for very long before break in....I also did not remove the inner springs. I did have good luck with 15/16ths of the lifters, in school that would have been good enough for an "A" The cam was a PAW house grind and the lifters were Comp Cams.

Custom pistons are also not in the budget. I'll most likely get the TRW's again.

Thanks,
Jon

[olddog]

I wouldn't mix lifters and cams or springs for that matter. Buy them all in one kit. At least then you have a chance of getting some help if there is a failure.

[Excaliber]

Good point about the buying the heads AND matching cam\lifters 'kit' so you don't have to 'mess with anything'! I concur, custom pistons are a HUGE expense, with care the hypers should work fine. 292S cam may flow more air than those heads will allow for, a milder grind may be warranted.

The lifter turning in the bore is the KEY, man did I worry about that. Don't care what kind of oil you got, if it don't turn, your screwed. It seems reasonable to me that with less spring pressure pushing the lifter onto the cam lobe you increase the likelyhood the lifter WILL turn. I DO think the individual cam lobe and lifter bottom 'wear in' to match each other, that takes about 20 minutes, and it either happens or it don't.

It's ALWAYS been standard operating procedure to match used lifters on the same cam lobe they came from if your remove lifters or cam for some reason. So, nothing new there.

And wiped cam lobes\lifters have always happened to some engines, at some point, nothing new there either. Whats different is the much larger number of cam\lifter failures we have seen in recent years. Cam manufacuters attribute this to the new oil formulations, I tend to agree. In addition I suspect 'we' are also seeing higher spring pressures than were common 'back in the day'. Thus, a double whammy effect, more pressure, bad oil, deadly combo.

Whats REALLY disturbing is another question you touched on. AFTER breakin, are we STILL subject to loosing a cam prematurely due to the missing additives in the oil? Maybe! Especially considering that many of us don't drive our replicas 'daily', indeed they may sit for weeks or even months at a time. While the oil slowly drops away and returns to the pan. On startup, your recreating the fundamental problem you have with a new motor, limited or no oil on critical components. You are now COUNTING on that breakin period for the cam lobe and lifter to work together with minimum lubrication.

Which is exactly WHY I'm dumping synthetic oil and going back to Shell Rotella for Diesels. Which DOES have more of the missing ingredients than other oils curenntly on the market! Paranoia or science? I don't know, my gut tells me, go with Rotella.

BIG QUESTION:
So the motor has been sitting for weeks or months (like all winter). The lobes and lifters are mainly oiled by 'splash', thats why you hold the rpm up around 2000 and vary it when breaking in a new cam for the first time. The question is: When starting a motor thats been sitting a long while, do you bring it right up to 2000 or better to 'splash' the cam\lifters again? Or do you let it idle at a low rpm until the oil starts to flow and gets around the internals before your 'rev it up'? The question itself makes a case for ultra light weight oil to begin with, 5-40 or something of that nature.

[Jon Miller]

Option 1: Spend $400 on forged pistons.

Option 2: Spend $200 on Hyper pistons and $200 on an Accusump.

Option 3: Win lottery and get custom forged pistons, roller cam, and Accusump.

[Excaliber]

Accusump may be THE best answer to the "BIG QUESTION" I asked above!

My solution is:
I never let my motor sit more than a week without running it up to temperature. But then again, I live in Hawaii, which makes that a little easier than in many other places.

[olddog]

An N-law uses a thing (cannot remember the name) on his dirt track car. It's basically a piston in a cylinder with a spring on one side and oil pressure on the other. It pipes up to the oil filter mount (a spacer screws on to block then filter to the spacer). A solenoid valve is in the line. Valve opens when engine runs. Valve closes when engine is off. This keeps pressurized oil trapped when engine is off. Valve opens before starting engine and oil system is pressurized and flowing before you turn the engine over.

It also supplies oil to engine in the event that the oil is shoved to the side of the pan in a spin out, causing the pick up tube to starve for oil.

I kind of think the put the lifter back in the same spot, may have as much to do with keeping it matched to the lifter bore as the cam lobe. It is a flat tappet cam. The lifter rotates, so it cannot wear to the lobe curve or it will quit rotating.

[Carnut427]

Originally Posted by Barry_R

...use...Rotella or Delo oil for break in.

This oil has the "ZDDP" that's missing in standard oils. Olddog, what you describe is an accusump, an excellent piece of equipment, but it won't help with the cam and lifter wear. Proper break-in is a must. It's just like breaking in rings, only there's so much pressure pushing the lifter against the cam that it wears in quickly...and yes, you're "fitting" the lifter to that lobe, so if you ever pull the lifters, put them back in the same spot. EOS is GM assembly lube, excellent for cam lubrication, etc.

Dan

[Jac Mac]

If there is one 'trick tip' that has come from racing over the last few years it would have to be the practice of cutting a vertical groove from the bottom to approx half way up on the left side [ looking from front to rear ] of each lifter bore so that a fine jet of pressure oil from the lifter gallery is directed onto each cam lobe /lifter . In fact I think this method works better than the lifters with the small hole on the face. Comp Cams has a special tool & diagram of the process in the catalog.

Jac Mac

[Jon Miller]

The machine shop finished measuring things today......

I've got to go to .040 over on the bore, and .020 under on the mains and rods. The machine shop bill is about $1100, and the parts came in at just over $900 from Summit. I went with the TRW forged pistons, and the Performer RPM cam kit. The Accusump will have to be on the Christmas list, that would be Christmas 2008......

Thanks for the help!!
Jon

[Excaliber]

Sounds like a solid plan! Good luck.

Are you going to have it balanced as well? That ran about $300 for me, including pressure plate and flywheel.

[Carnut427]

Originally Posted by Jac Mac

If there is one 'trick tip' that has come from racing over the last few years it would have to be the practice of cutting a vertical groove from the bottom to approx half way up on the left side [ looking from front to rear ] of each lifter bore so that a fine jet of pressure oil from the lifter gallery is directed onto each cam lobe /lifter...Comp Cams has a special tool & diagram of the process in the catalog.

Jac Mac

This is indeed an excellent tip; however, if your block isn't drilled for hydraulics or the hydraulic galleries are blocked off, there's no oil to be had in this area, only that which drips from the rockers. This is also true of the lifters with the hole in the face. In these cases, most oil getting to the cam and lifters is thrown up from the crank and rods, and that's a lot.

Dan