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Flat tappets are designed to spin while in operation. If they slide and don't spin, there goes your cam.

With poor quality products being prolific these days, flat tappets are no different. They have to have a small crown machined into them on the bottom to promote spinning during operation. Flat tappets are not truely "flat" unless they are poor quality. If they really are "flat", your cam lobes will be "flat" in no time also.

A good way to check for the crown on a flat tappet is to place it onto a piece of glass or known hard flat surface. It should slightly rock back and forth.
 
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There’s no free lunch with the roller cam conversions. Just google link bar failures, etc and you can see plenty of destruction if you have the stomach for it.

just saying there are pros and cons to every engine building decision. At some point you just have to throw the dice and hope they don’t come up snake eyes.

Z
 

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Do solid rollers sound the same as solid flat tappets? at idle and upper rpm?
To me the "sewing machine" noise at idle is a big part of the nostalgia of a proper high performance motor from the muscle car era.

Z-Ray, interested in your input on this.
 

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Yes, this is a duplicate post:
I have a question for all who have historical knowledge ... what did Ford (and GM and Mopar) do at the factory? Did they actually run these engines on a stand (or in the cars) to break-in the cams.? If not, what has changed (other than CCP crap)?
 

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Do solid rollers sound the same as solid flat tappets? at idle and upper rpm?
Not really. My solid roller cam is fairly quiet with respect to valvetrain noise. But I do love the sound of an engine with a solid lifter flat tappet cam at idle
 

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Yes, this is a duplicate post:
I have a question for all who have historical knowledge ... what did Ford (and GM and Mopar) do at the factory? Did they actually run these engines on a stand (or in the cars) to break-in the cams.? If not, what has changed (other than CCP crap)?
While I have no first-hand knowledge of the Big Three break-in procedures, I can share what my brother told me. He worked at a Mercury Marine engine factory in the 1980s. He built what were essentially Chevrolet V8s designed for boats. He said when the engines got to the end of the assembly line, they were connected to a battery, given a small fuel supply then started.

They would rev the engine pretty high then bring it down and rev it high again. My brother said they did this for a pretty short time. If it started, ran and had oil pressure, it would be shipped. If there were any problems, it would get sent to diagnostics.

Occasionally, they'd have a problem such as the engines would all fail to develop adequate oil pressure. When something like that happened, they would shut down the whole line and bring in engineers to diagnose the issue. At least one time the issue was the bearings were mislabeled. Thus, an entire shipment of bearings were too small which created excessive clearance.

I suspect engine plants of the 1960s did something similar? It is interesting that I almost never heard of a cam getting wiped back in the 80s. My buddies and I would put the included grease on the lobes, stab it into the block, apply the same grease to the lifter faces and drop them in. Then we would start the engine with regular Valvoline and go. Break-in? What's that? I don't even remember the cams coming with break-in instructions. No wiped lobes and I knew guys running some pretty aggressive cams back then.
 

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It is interesting that I almost never heard of a cam getting wiped back in the 80s. My buddies and I would put the included grease on the lobes, stab it into the block, apply the same grease to the lifter faces and drop them in. Then we would start the engine with regular Valvoline and go. Break-in? What's that? I don't even remember the cams coming with break-in instructions. No wiped lobes and I knew guys running some pretty aggressive cams back then.
Ditto for all my friends rebuilding Triumph and MG engines in the 60s and 70s - never wiped a cam or heard of it happening. That's why I find this entire discussion disheartening.
 

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I wiped one several years ago. the debris took out the block and scuffed the pistons.
cost at least 1500. next iteration was a hydraulic roller and I haven’t looked back.
Now my build was performance oriented. I suspect some of the wiped cam issues are aggressive lobe profiles and inferior cam cores, along with the oil issues.
 

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When I upgraded my engine to GT40P heads, carb, intake, etc. I ask myself the same question. My initial thought was also to go with a more "modern" roller cam. But if you dig into this topic and start talking to very experienced engine builders they will tell you the same information as stated above. You will not have a huge benefit for a non performance oriented engine. You will add costs but not take advantage of the possibility you can get from a roller. Getting oil with high zinc is not a big deal. So it comes down to the break in procedure. And yes, it is a bit scary if you do it for the first time. Be well prepared, have another set of eyes with you and the 20min will pass very quickly. If everything is set correctly the engine will fire right up, bring it to 2000+ rpm and you are good. In case you have leak or the engine overheats shot it off, fix the issue and continue until you have the 20 min total time in.
 

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I don’t see any mention of the EDM lifters. I know CompCams sells them, maybe other do also. They have a small hole in the lifter face. The ones I’ve used have a hole diameter of 0.012”. Others may vary.

with the EDM hole you have pressurized oil squirting out directly into the cam / lifter interface. Fantastic lubrication.

I put a set of these lifters into my latest K code when I installed a Weber friendly cam. I was initially concerned that with 16 lifter holes of 0.012” diameter there might be a drop in oil pressure. I ran the K code pretty hard. Over 25,000 miles on these lifters without any issues. Many of those miles were all day driving at 4,000 to 5,000 rpm hour after hour.

My oil pressure concerns were without merit. The before and after oil pressure, as measured with an permanently installed AutoMeter mechanical gauge, was unchanged. Not even 1 psi lower.

I have a K code so I used the ESM solid lifters, I don’t know if they come in a hydraulic lifter variety

Here is one article about the lifters, A google search will reveal others I’m sure.


 

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Klutch, you clearly know more about this than i do, but I would suggest that the film of oil is just a coating, and not the same as pressurized oil, such as a rod or main bearing. In fact, it is the friction that causes the surface hardening of the lobe during break-in. I enjoy this discussion, which I would enjoy more over a beer!
On the bearings it's also just a coating. The pressure is just needed to supply the oil to the bearings and does not play a part in separating the parts from each other. The oil film does that and is build up by the difference in velocity between the two (that is, the crankshaft spinning and the bearing standing still). That is also what causes the friction: the shear forces in the oil film. One side of the film sticks to the bearing shell and the other to the crankshaft. You can compare it to laying a sheet of plastic on a wet table and then try to slide it around. The faster you try to slide it, the more resistance.
 

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While I respect Lunati cams, they are trying to sell us the more expensive roller cam. And, while it might be technically true, I think the difference is so slight so as not to really matter. Wondering how many of us has actually worn out a flat tappet cam.

Another anecdote; when I ordered my cam for Bullet Racing Cams, I asked them about running a roller cam. The on the phone was the guy who machined my cam and he said, "A roller cam won't do anything for you. It will just cost more."
Klutch,,,,,,it seems to me like the engine builder said a roller cam wont do anythin"FOR YOU". Granted I dont know much about the science and I am relatively new to the hobby. But it seems to me that the roller cam is more for reliability, from what I have heard they haveless frictional parts. Street rodders might not see much of an advantage but the guys pouring thousands into their engines to race. I am sure that they are trying to squeeze every horse they can for their enginesand even a gain of 5 to 10 HP might give a slight advantage.
Like I said im new to the hobby just my 2 cents.....but my response was longer than 3 sentences.... do I get a beer too?
 

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There’s no free lunch with the roller cam conversions. Just google link bar failures, etc and you can see plenty of destruction if you have the stomach for it.

just saying there are pros and cons to every engine building decision. At some point you just have to throw the dice and hope they don’t come up snake eyes.

Z
Most of those failures are going to be solid roller cams, running very high springs pressures over the nose, rather than the hydraulic cams being talked about here.

although, I think a broken roller is what took out my engine, but I was spinning those lifters about 1500-1800 RPMS more than Morel said they were good for.
 

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To be clear, I'm not at all an "angry warrior" about the flat tappet vs. roller tappet issue. I tend to be skeptical about most things. LSG explained my position pretty well above. Basically, although roller cams do offer advantages, I'm simply skeptical that the typical street rodder is going to benefit from those advantages. High RPM racing? Sure, a roller cam can help. Otherwise, not so much.

When we break out of "Pandemicland", I would like to discuss it over beers with anyone willing and available. Even if we disagree, that's cool with me. Talking smack over beers is a big part of American Hot Rodding!
🍺🍺🍺🍺
 

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Most of those failures are going to be solid roller cams, running very high springs pressures over the nose, rather than the hydraulic cams being talked about here.

although, I think a broken roller is what took out my engine, but I was spinning those lifters about 1500-1800 RPMS more than Morel said they were good for.
Exactly how high were you turning your engine? I have the same lifter and I'm a bit concerned about this. From what I understand, the Morel lifter uses needle bearings on the roller trunnion and the Isky and other premium lifers use a bushing. The cost difference is lifters with bushing- $1200. needle bearing- around $300 or less.
 

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Exactly how high were you turning your engine? I have the same lifter and I'm a bit concerned about this. From what I understand, the Morel lifter uses needle bearings on the roller trunnion and the Isky and other premium lifers use a bushing. The cost difference is lifters with bushing- $1200. needle bearing- around $300 or less.
6500-6800, regularly. The few times I’d run the 1/4, rather than the 1/8, 7200-7300.

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Those needle bearings are a well documented weak point . Their failures are why the bushing rollers were developed.

Z
 

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Yes, but pretty rare in a hydraulic lifter. Most of the failures are on solid cams with high spring pressures. Hard to blame the lifter in my situation, when I was knowingly take it beyond its limits. It would have been the same if I broke the Scat 9000 cast crank, instead of the lifter. Taking a cast crank to over 7000 RPMS, with enough power to go mid 9s, is asking more from the parts than they were designed for. It looks like the crank took it better than the lifter. Lol
 

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Back in the day, we were circle track racers. A very well respected engine builder in the area ( built for several different racers) told the guys to take it for a warm up lap. If pressures and temps looked good--- go racing. His engines held several track records.
 

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Discussion Starter · #40 ·
Thanks to all for the input. I think that the cost of repair of a wiped cam outweighs the extra expense of a roller. I too would love to get together for some bench racing after vacine.🍺

Don H
 
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