What Cams Will Live In Our Engines?

[Blown&Injected]

This should answer the replies - thanks for all the experiences - it is helpful.

When I did the first rebuild, I had the machine shop do it all including the heads and cam install. It was, I think an ESP Stage 3 - something like a Schneider 205/214 (the numbers should be close - probably not exact). I remember hearing that LT-1 springs are the way to go. The machine shop said we just use LT-1 springs for a setup like my engine but I later thought 70's LT-1 or the newer style??? They are checking it out - the heads and springs.
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Originally posted by gnx7
Maybe your cam break in procedure has something to do with it?

I break in flat tappet cams with tired stock GN springs as the cam physically hardens in the first 20 minutes of break in time. Thereafter I swap out the springs for my HD LT1 springs or comparable. I was recommended to do this by a friend and other reputable racers have done this also... never had a flat cam.

But yeah, the first cam was broken in on brand new LT-1 Springs. I was thinking about putting my old stock springs on for the first 30 minutes, but I thought if I was good about the first 30 minutes of RPM control I should be good. I rationalized the second cam break in based on the springs now have about 12,000 miles on'em.

Should they be the 70's era or modern era LT-1 springs?

Originally posted by 86brick
Nope! Just spend the money now and get a hyd. roller cam kit (ductile or Billet) from a vendor like Nick Micale.... The ductile kit is cheaper than the Billet (mainly because you don't have to machine/modify the front cover).... Spend now or spend more later! In the long run you will be happy you got the roller!

I hear ya! I'm spending right now because of that mistake the first time, but back then I did not have the benefit of Internet to learn of all the problems

Originally posted by EightSecV6
Comp ductile rollers are vey durable, no machining to the nose of the cam is required either, around $400 more than a flat tappet.

Not bad, I was thinking it was a lot more than that - the Comp Cams site kept locking up when I tried to look. Is that for everything - lifters and pushrods? Also, is it nuts to use the stock 300,000 miles 18 year old rocker shafts and arms?

Originally posted by Nick Micale
Guess I missed where it was proven?

I have read so much about it that it seemed to be accepted . I recall somebody saying something about GM knowing about the problem and something about notations on the prints??? Seems like something is up with that #3 exhaust.

But then science does not try to prove a theory but rather to prove the null hypothesis. Since there are some reports of lots of miles and no failures, it would seem that at least some do not have #3 issues.

Originally posted by disco stu
Hey blown& injected, I have a used ATR RP309 G Billet roller I could sell, no springs, but custom, lightweight one piece Smith Bros pushrods. Might make a package deal with 1.5 T&D's.
This cam WILL live in your car, and makes big mid range power. 214 int 210 ex.

Let me know what you want for it and also for the T&D's. I am going to talk to the machine shop sometime this week and will need to make some decisions.

 

[87GN_70GS]

Guess I missed where it was proven?

Prove it for yourself. If you've ever had an engine apart, you would've noticed that there is one lifter that is not lined up over a lobe like the other ones on that side are. Simple as that.

 

[Nick Micale]

Originally posted by 87GN_70GS
Prove it for yourself. If you've ever had an engine apart, you would've noticed that there is one lifter that is not lined up over a lobe like the other ones on that side are. Simple as that.

Yes, I have had a "couple" Buick motors apart.

If you would review the Buick drawings and dimensions for the machining of the stock block, it is shown that the no.3 lobe is positioned different than the others.

To verify this, measure a couple bare blocks like I did last week. We were verifying the dimensions of the TA alum block with various stock blocks and ALL lifter bores were positioned the same way, no. 3 was different.

As was said elsewhere in a referenced thread, V-6 Buick motors have run many thousands of miles on a stock cam and then wipe an aftermarket in a few thousand. Is this caused by lifter bore mis-alignment?

 

[Drac0nic]

Originally posted by WarpSpeed
Bummer.
I have an eldelbrock 204-214 cam that's been in for several years, and still going. It said not for computer controlled cars, but, it works for me, and passes emissions. @100 bucks with lifters( as i recall.)

ps: 224 224 is a lot of cam

Where'd you dig that bad boy up, for $100 I want one!

 

[Blown&Injected]

Originally posted by Nick Micale
As was said elsewhere in a referenced thread, V-6 Buick motors have run many thousands of miles on a stock cam and then wipe an aftermarket in a few thousand. Is this caused by lifter bore mis-alignment?

So that #3 lifter bore is different and lots of people experience wiped cams on #3. What does this mean and what is the solution? Soft springs?

I can certainly understand why some have accused the #3 to be not properly placed. Does the 4.1 have these problems?

 

[Ash]

Pull your valve covers off and push down on your springs with your thumb. If you can push them down like i did on my car then your very strong or your spring was soft. The spring dosnt have enough pressure on the valve to retun all the way back into place. So insted of your lifter riding on the cam it floats and when the cam lobe comes around again it smacks the lifter causeing little chips to come off of the lifter and the cam lobe. If your cam is wiped then you have to change out the lifters and the springs. Snag a spring compressure scale from a automotive shop and check the pressure on your old springs and compair them to new ones. If your springs are good then it could be the alignment problem. Its easyer to check the springs first.

 

[87GN_70GS]

If you would review the Buick drawings and dimensions for the machining of the stock block, it is shown that the no.3 lobe is positioned different than the others.

The V6 was based on the design and therefore the drawings of an earlier V8 block, 300 or 340, can't recall exactly which model. There was an error made in transferring lifter bore dimensions over to the V6 drawings, as was found out later. The cam remained basically the same except was "chopped off", i.e. used to same old lobe spacing. Thus, misalignment.

Trivia - there were 2 OEM cam blank suppliers at that time: Wayne and CMC (camshaft machining corp.)

V-6 Buick motors have run many thousands of miles on a stock cam and then wipe an aftermarket

The GM engineers found this error out too late in the production cycle to correct it. The solution? Put a reverse taper on that particular lobe. Verify it for yourself - check the taper on a stock GM cam and see if it's not a reverse taper, on that lobe.

Then as a systems-level check, assemble a stock cam with stock lifters (use oil, no grease). Turn the cam by hand, which way does that lifter spin? Opposite of the ones on that bank. Or, idle the engine with the valve covers off. Which way does that lifter spin? Opposite.

Why else would aftermarket cam guys put a reverse taper on that lobe? Cuz it spins opposite. In the early days, they didn't, thus failures. I'm not sure they are all doing it now. The ones I've checked do have the correct reverse taper; Comp, Reed, and Lunati.

A better solution would be to contact Wayne or CMC, and revise the blank drawings for better lobe placement.

 

[Nick Micale]

Originally posted by 87GN_70GS
......Why else would aftermarket cam guys put a reverse taper on that lobe? Cuz it spins opposite. In the early days, they didn't, thus failures. I'm not sure they are all doing it now. The ones I've checked do have the correct reverse taper; Comp, Reed, and Lunati......../B]

Thank you for the great information.

Did not know all the pertinant history you provided, but it sure explains the problem, and more importantly, the solution.

 

[Blown&Injected]

We Have a Winner!

Ah Thanks!

So we have at least three manufacturers that do the reverse taper thing. So if I understand correctly, the correct reverse taper type cams from Comp, Reed, and Lunati will not wipe like other cams that I have had that keep wiping #3e.

 

[87GN_70GS]

reverse taper type cams from Comp, Reed, and Lunati will not wipe like other cams

There's no guarantees, but the proper taper helps. The Comp I have will spin, slower than the others but still spins, and it lasted. I had 2 Lunati's fail fairly quickly, but they had the proper taper. I had a Reed that went ~20,000 miles, and when I pulled it, it was showing signs of wear, had a few thousands less lift. The Lunati's actually had more taper than what is spec'd (1.5-2 thou vs .5-1 thou) , to try to help out. I think the lifters have more crown (convex) also. Every block is different. The margin is so small for spinning or not. The lifter is almost dead center on top of the lobe, just a few thou off center to the wrong side. I think someone measured it and posted the number, like 20 thou or something off to one side. I'm guessing that fast ramp cams (like most aftermarket ones) only make the problem worse. With the gentle action of the stocker, it probably helps last longer, my opinion.

If I had to do it again, I would've kept the stocker.

If I had to put an aftermarket one in, I would do the spin check by hand first while assembling, then upon initial fire-up, leave that valve cover off and check the pushrod for spin. I didn't do that until my fourth cam - I'm a slow learner.

 

[Blown&Injected]

DAMN IT!

It is not satisfying when a problem has no clear answer, especially when we seem to have a good grasp of the problem.

But Seriously. Thanks for all the detailed information.

 

[750H.P.V6]

More cam info

I hope this helps.

http://www.cranecams.com/?show=faq&id=1

Neal

 

[87GN_70GS]

That's some very good info.

Sometimes you may need to help spin the pushrod to start the rotation process during this break-in procedure.

And that's kinda scary....success or failure is dependent on you spinning it by hand?

 

[gnx7]

I'm a firm believer in using tired springs for break in and then swap them out after the 20-30 minute break in.

Here is what that link said:

"NOTE: Increased spring pressure from a spring change and/or increased valve lift can hinder lifter rotation during cam break-in. We have found that decreasing spring pressure during the break-in period will be a great help. This can be accomplished by using a shorter ratio rocker arm to lower the valve lift; and/ or removing the inner spring, during the cam break-in time, if dual springs are being used. "

-Mark

 

[Intercooler]

I guess we all differ. Run the intended springs IMO. We don't have dual springs so it doesn't apply to our rather small pressures. I would do it if I was running something with mad spring pressures but not a single spring with a dampner. It is going to live or it isn't. We aren't exceeding stock spring specs by leaps and bounds.

 

[SinistrV6]

I've been following this thread with great interest. I'll be buying the rest of the internals for my new motor soon. My question is: Why are the aftermarket cams so inferior in quality to the stock ones? It's not unusual to see a stock cam run for 100-200k miles and yet I read time and again where an aftermarket cam that gets 30k miles before it's worn out is a GOOD ONE!

What gives?

Anyone got an aftermarket cam in their car that's been 50, 75 or 100k w/o going flat?

 

[Quick6]

Alot of different theorys on cam break-in.....but I don't think the factory used any special springs or had to turn pushrods and the stock cams seem to last pretty long? Fact is i bet the factory break-in was when it drove off the dealer lot.

 

[Intercooler]

Originally posted by SinistrV6
I've been following this thread with great interest. I'll be buying the rest of the internals for my new motor soon. My question is: Why are the aftermarket cams so inferior in quality to the stock ones? It's not unusual to see a stock cam run for 100-200k miles and yet I read time and again where an aftermarket cam that gets 30k miles before it's worn out is a GOOD ONE!

What gives?

Anyone got an aftermarket cam in their car that's been 50, 75 or 100k w/o going flat?

Well..... Their used to be two suppliers of cam blanks for the Buick where their is only one now. More than likely most all of the blanks come from the same lots. You will have fall-out in quality or batch to batch differences that can cause some of the failures. MOST of the time it is install or break-in IMO. As for going 30k miles on a RACE engine? I am sure someone has but if you are driving it very little or mainly racing it then 30k may never come. Ideally you should freshen it up every couple of seasons which for the price of a flat tappet cam I am sure some just go back in with new. Probably some are changed out due to contamination of head gasket failures or something unrelated. Most of the cams are of a RACE version in RACE cars so in RACING you roll the dice. Nothing lasts forever! My .002.

 

[SinistrV6]

Is that the excuse the cam makers use? Race parts? I don't expect a radical cam to last 100k miles. But, for the most part, there's nothing radical about the cams we run in our motors.

Anyone make a stock replacement cam? If the quality was good, why wouldn't it last like the stock cam? (Assuming the proper break-in procedure is followed)

Calling all aftermarket cams "race parts" seems like a cop out by the cam makers to me.

 

[87GN_70GS]

I don't think it's an issue of inferior quality. Things are different between aftermarket and OEM. Aftermarket cams are usually higher lift, which requires a smaller base circle. That chages geometry somewhat, which may reduce the force available to spin a lifter and also alters lifter preload (but I'm sure everyone corrects preload). Also lobe profile velocity (or rate) determines where the lifter/lobe contact point is: the higher the rate, the closer to the edge of the lifter the contact point is (some of Ultradyne's fast solid profiles put the contact point only 0.014" from the lifter edge, not much margin for error). That could be a factor.

Next time I'm going to bleed a chicken over it, smoke some Peyote and mutter some incoherent Gregorian chants.