Author Topic: 400+ lbs. flat tappet cam  (Read 1438 times)

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BattlestarGalactic

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Re: 400+ lbs. flat tappet cam
« Reply #15 on: October 20, 2020, 03:17:31 PM »
Your suppose to check lash on solid lifters?  Oh, really.....LOL!!  I've gone under the mantra of: if it sounds okay, don't look!   :o
Larry

blykins

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Re: 400+ lbs. flat tappet cam
« Reply #16 on: October 20, 2020, 04:45:34 PM »
I usually aim for 100-ish lbs seat and under 300 lbs open with standard EDM lifters and a nitrided cam just to be on the safe side.

With non-coated tool steel lifters on a nitrided cam, I have ran 350 across the nose on break-in. 
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plovett

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Re: 400+ lbs. flat tappet cam
« Reply #17 on: October 20, 2020, 05:36:52 PM »
plovett, I have a quick question.

A lot of cam makers, recommend that you brake a cam in, with spring pressures, not over 300#. Did you break it in with lower pressure springs?

I did remove the inner valve springs and I think I also used .0.050" taller locks, for break in.  I don't remember what the resultant pressure was.  I could calculate it.

pl
That's ok. I was just wondering if you took break in precautions.

Well, you got me curious.  :)  It looks like I was roughly at 123 lbs on the seat and 299 lbs. open with my break in setup.

Posi67

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Re: 400+ lbs. flat tappet cam
« Reply #18 on: October 20, 2020, 11:23:53 PM »
I ran a couple of these old 70's Crane Cams and didn't do a thing on break in. Had one in my 390 up until a couple years ago when some other carnage broke the cam. Lame stuff by todays standards but it ran 10.70's with some compression and CJ heads. I still believe a lot of Cam failure is due to bad metallurgy in either the Cam or Lifters. Not hearing as much these day as several years ago but I love a good Solid Cam and noisy rockers to match.   

plovett

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Re: 400+ lbs. flat tappet cam
« Reply #19 on: October 21, 2020, 06:02:34 AM »
Reason for concern on my part is that my cam has fairly aggressive lobes and needed a fair amount of spring pressure to control it at higher rpms.  We put this together a long time ago so I don't remember all the details of what we tried.  Crane was good in helping me get a valvetrain combination that worked to 7000 rpm. I am sure the guy I worked with there is gone.  His name was Urik.

I did have a failed cam break in with the cam previous to this one. I took precautions, but still messed it up.  The lobe that failed had a corresponding rocker arm with the adjuster hitting the tin in the valve cover.   I wonder if that stopped the lifter from spinning well, or the impact and added pressure just killed the nose of the cam.

pl
« Last Edit: October 21, 2020, 06:12:19 AM by plovett »

cammerfe

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Re: 400+ lbs. flat tappet cam
« Reply #20 on: October 21, 2020, 02:08:31 PM »
Back in the mid-60s, I had, first, a '64 Custom/427 and then a 65-1/2 Mustang with the 'K' engine. To keep up on maintenance, I bought a P&G valve-gapping tool. I used it on the 427, and then, after trading the '64 to Brother Lon, I got a new 'barrel' to fit the 'K' 271-289 engine.

Although I made the effort to have the engine at operating temp before checking valve lash, and always went through the same set of conditions, I always found one or more valves that needed a bit of adjustment. Since the car that preceded the '64 was a '54 Customline into which I'd swapped a 312 with both the factory race dual-quads and a Paxton VS 59 blower (also the race set-up), I was used to having to 'run the valves' every once in a while---the Y-block series came only with 'nail-head' solid lifters. And I'm sure that many solid lifter cars from the time went years between adjustments. But I could always hear that one-or-two valves with a louder tick than the rest. I actually had to replace adjuster screws on the 427, and replace rockers when the oversize screws would lose their interference fit. In fact, due to access to the tool-room at T&C Livonia, we ultimately made lock nuts tor the FE adjusting screws, and spot-faced the tops of the rockers to provide a flat for the nut to lock against.

But then, we also made High-volume oil pumps too, before you could get one from Melling. (The essence of hot-rodding is improvisation!)

KS

plovett

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Re: 400+ lbs. flat tappet cam
« Reply #21 on: October 22, 2020, 07:09:23 AM »
Back in the mid-60s, I had, first, a '64 Custom/427 and then a 65-1/2 Mustang with the 'K' engine. To keep up on maintenance, I bought a P&G valve-gapping tool. I used it on the 427, and then, after trading the '64 to Brother Lon, I got a new 'barrel' to fit the 'K' 271-289 engine.

Although I made the effort to have the engine at operating temp before checking valve lash, and always went through the same set of conditions, I always found one or more valves that needed a bit of adjustment. Since the car that preceded the '64 was a '54 Customline into which I'd swapped a 312 with both the factory race dual-quads and a Paxton VS 59 blower (also the race set-up), I was used to having to 'run the valves' every once in a while---the Y-block series came only with 'nail-head' solid lifters. And I'm sure that many solid lifter cars from the time went years between adjustments. But I could always hear that one-or-two valves with a louder tick than the rest. I actually had to replace adjuster screws on the 427, and replace rockers when the oversize screws would lose their interference fit. In fact, due to access to the tool-room at T&C Livonia, we ultimately made lock nuts tor the FE adjusting screws, and spot-faced the tops of the rockers to provide a flat for the nut to lock against.

But then, we also made High-volume oil pumps too, before you could get one from Melling. (The essence of hot-rodding is improvisation!)

KS

It'd be neat to see pic's of some of those cars. 

I also tried to check lash at the same temperature each time.  For me, that is fully cold.  Of course ambient temperature varies.  I wonder how much difference 50F versus 80F makes?   I would think not much compared to running temp's.

paulie

« Last Edit: October 22, 2020, 07:23:51 AM by plovett »

427John

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Re: 400+ lbs. flat tappet cam
« Reply #22 on: October 29, 2020, 12:55:25 AM »
I was going to ask if you still had interference fit adjusters or if you had swapped jam nut adjusters into the rockers,if still interference that may be the source of your needed adjustment.If you match marked your rocker and adjuster at the proper lash that might tell you if that's the case.It would give you a little reassurance about cam wear. 

plovett

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Re: 400+ lbs. flat tappet cam
« Reply #23 on: October 29, 2020, 05:44:03 AM »
I was going to ask if you still had interference fit adjusters or if you had swapped jam nut adjusters into the rockers,if still interference that may be the source of your needed adjustment.If you match marked your rocker and adjuster at the proper lash that might tell you if that's the case.It would give you a little reassurance about cam wear.

I had Harland Sharp rockers with jam nut adjusters.  At some point Harland Sharp changed the adjusters.  Earlier ones take a very small hex wrench while later ones take a bigger one.   The bigger one is better as you can tighten the jam nut on it harder without flexing the hex wrench or potentially rounding off the corners.

pl

Keith Stevens

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Re: 400+ lbs. flat tappet cam
« Reply #24 on: October 29, 2020, 04:08:28 PM »
I think if a solid cam is broken in successfully it doesn’t wear as much as everyone worries about. I think most will agree you don’t adjust them as much as you would think. Not that you shouldn’t check them let’s say if you take the covers off but even when you check they usually aren’t out.

I am in the same camp.  There just isn't any empirical evidence of what causes flat tappet cam failure.  If there was, then we would use that data for best practices and nobody would have flat tappet cam failure.  My theory is that the Internet causes cam failures.  We learned from the Internet that it was poor metallurgy in the cam and/or lifters or insufficient zinc in the oil.  The Internet had solutions for us;  boutique motor oils and extra specialized treatments of the cam and lifters.  While this is a bit tongue-in-cheek, you have to recognize that even if you do everything by the book and then some (light run-in springs, boutique oil, immediate fire up and 20 minute break-in) you can still have a cam failure.  Or valve failure.  Or bearing failure.  Or piston/ring failure.  Or crank failure.  Or rod failure.  Or block failure.  If you build one engine every year, you are in the statistical success, no problems zone.  If you build 100 engines a year, yeah, you have some exposure to failure.

Solid flat tappets are usually pretty stable when it comes to lash.  There were a lot of meek engines that came from the factory with solid lifters.  Chrysler slant sixes come to mind.  And a lot of OHC engines are solid tappets.  You don't hear of anyone "running the valves" every couple thousand miles on those.  You'd think someone was daft for doing so.  I think a lot of checking lash is just looking for something ever so slightly off so that you can feel good about making something better.  Takin' care of your baby.

Just rambling on here so you can protest my opinion.

There is plenty of empirical evidenc why flat tappet cams fail. Oil packages have changes drastically post the last production engine that was equipped with a flat tappet cam 30 years ago.
If you missed a couple of forum post. Many of the cores are coming out of China. Comp Cams was the go-to for years but they have even had many issues in recent history. I am seeing many reports of failure, even with the use of high quality break-in oils like Penn Grade and what I would consider very reasonable seat pressures and over the nose pressures. 100-135 on the seat and 280-325 over the nose. 

The custom cam I had cut was supplied with Johnson hydraulic lifters still had much of the parkerization and coating on the lobes with 1400 miles on the engine. That's impressive with 135 on the seat and 350 on the nose.  I currently have 3600 miles and had to pull the intake because I have a slight leak at the corners where the wall meets the head. It made sense to do it being I am installing my factory AC and the York compressor and AC with R12 isn't something I want to remove after installation. It made sense to do it now.