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Old 10-21-2012, 05:47 AM
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Avoiding Flat Cam Syndrome-Engine Builder

I saw this article in Engine Builder Mag and thought maybe you guys know this already and may be not. Want to give credit to Engine Builder Shop solutions and to Norm Johns.


Along with the use of assembly lubes, break-in oils with ZDDP (Zinc Dialkyl Dithiosphate), and a lifter bore grooving tool our shop does this; on all flat tappet cam engines our shop has added one step before final assembly.

With the block in a bare and clean state we’ll put in the two end cam bearings and install the cam with only light oil. Next we install the lifters with only light oil. Install a bolt in the front of the cam and spin it quickly clockwise with a speed handle and observe each lifter’s spinning action when the engine is running. You can use a felt pen to mark the lifters so it’s easier to see them spinning. If you find any of the lifters not spinning, this could be a potential problem if it leaves your shop like that. Lifter bore or even cam bore alignment could be the problem.

Many times the cam bearing bores get closer (fall) towards the crank centerline going front to back, (especially on BB Chevys) which in turn causes the taper on the cam lobe to be lessened towards the back of the motor. Zero or too little taper can keep the lifter from spinning, and this can cause the cam to fail shortly after fire-up.

To remedy this problem without reboring lifter or cam bores check local listings or the internet under custom cam grinding to have the cam reground with more taper grind into the lobes. After regrinding we do the test again. We’ve had great luck and no flat cams when all of the lifters spin before we fully assemble the engine, even with today’s lousy oils! Yes this will cost more, but what will really cost more – an extra cam grind, or a flat cam, or a comeback and angry customer? Thanks and good luck.

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Old 10-21-2012, 08:44 AM
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flat cam

My room mate in college rebuilt his Ford Fe and the cam went flat in 100 miles, he pulled it apart at their farm shop and got another new cam from the dealer and it went flat again in about 100 miles. I went to his house for weekend to help and found that the cam was catching two lifters with the same lobe. Factory replacement cam and original block, it only got new rings and bearings the first rebuild. I ended up getting a transmission thrust washer from a box of spare pieces the dealer had in their parts room, and every since then I drop in one lifter at a time and rotate tthe cam to check.
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Old 10-21-2012, 12:33 PM
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Quote:
Originally Posted by 1Gary View Post
I saw this article in Engine Builder Mag and thought maybe you guys know this already and may be not. Want to give credit to Engine Builder Shop solutions and to Norm Johns.


Along with the use of assembly lubes, break-in oils with ZDDP (Zinc Dialkyl Dithiosphate), and a lifter bore grooving tool our shop does this; on all flat tappet cam engines our shop has added one step before final assembly.

With the block in a bare and clean state we’ll put in the two end cam bearings and install the cam with only light oil. Next we install the lifters with only light oil. Install a bolt in the front of the cam and spin it quickly clockwise with a speed handle and observe each lifter’s spinning action when the engine is running. You can use a felt pen to mark the lifters so it’s easier to see them spinning. If you find any of the lifters not spinning, this could be a potential problem if it leaves your shop like that. Lifter bore or even cam bore alignment could be the problem.

Many times the cam bearing bores get closer (fall) towards the crank centerline going front to back, (especially on BB Chevys) which in turn causes the taper on the cam lobe to be lessened towards the back of the motor. Zero or too little taper can keep the lifter from spinning, and this can cause the cam to fail shortly after fire-up.

To remedy this problem without reboring lifter or cam bores check local listings or the internet under custom cam grinding to have the cam reground with more taper grind into the lobes. After regrinding we do the test again. We’ve had great luck and no flat cams when all of the lifters spin before we fully assemble the engine, even with today’s lousy oils! Yes this will cost more, but what will really cost more – an extra cam grind, or a flat cam, or a comeback and angry customer? Thanks and good luck.
It's looking like the days of running a flat tappet cam, on the street at least, are about closed. Around the Seattle area it's getting increasingly difficult to find heavier weight oils including 15-40 and 20-50 as the EPA wants all the ZDDP carrying oil off the market plus these new engines use very light weight oils with no ZDDP. We just put in a supply of 15-40 DELVIC cause our local distributor says when that's gone boys there ain't gonna be any more.

I'm thinking the race sanctioning bodies are going to very shortly have to rethink their ban on roller lifter cams as well. I guess the 60's truly are over.

I have for decades used a cam button on Chevy flat tappet cams, I feel the lobe and lifter, as well as the distributor gear have plenty enough to do without also holding the cam in the block. The two things that come out of this is that we hardly ever experience wiped lobes and lifters even with today's low ZDDP oils while the so called spark scatter problem even with the 7 tooth SBC oil pump is mostly gone. We, also, do not use oil restrictors even with solids and we use standoff vents rather than closing the drain back holes in the valley along the cam. This does shut off the mid block drain back from raining on the crank while allowing some breathing space so all the blow by isn't trying to get into the valley on the ends where I'm also trying to get the drain back oil to drop into the pan.

Bogie
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Old 10-21-2012, 07:03 PM
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Camshaft install tips and tricks
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Old 10-22-2012, 12:12 AM
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Originally Posted by hcompton View Post
Most cams factory oem and aftermarket are made by Camshaft Machine Corperation in michigan. They are top quality manufacturer of cams. Most bad grinds come from old templates and in house ground cams. Not sure about the lifters but they usally fail and wipe out the cam. For most cases of failure its either inproper installation or bad lifters. Possibly before and after the heat treatment.

Since they are mostly cnc ground. Its kind of hard to convince your cnc not to do what its told. They are also scanned with lasers to make sure grind was correct. This is the same process and companies that ford and chevy use.

that being said there is alot of junk out there. With a big lathe and some skill you can make your own cams. Regrinds are even easier. And alot more common than you may think. This where you get into trouble.

Isky is a great cam but i bet they make just as many bad ones as anyone else. But they do alot of quaility control to make sure they never reach the public. And that makes a world off diference. I did not see anything on isky site saying they make them in house. But that is fine.

there is so much misinformation in this post, I'm not even sure where to start.
isky, comp, bullet, elgin, erson, crane. that's a large amount of the aftermarket and they are NOT ground at that place. and I'm not even mentioning any of the smaller custom grinders that do their own in house. not saying anything bad about it, but they certainly don't grind cams for these places.
next, you cannot, no way, not physically possible, make a camshaft on a lathe.
i have been a machinist for many years, run everything from small lathes to
mills bigger than a house, and a lathe simply can't make a cam. maybe you could rough one out, but without getting into the technical aspects of it, it just can't be done.
and just to clarify, isky does manufacture in house, and is among the top cams out there.
they all have issues, any manufactured part will to some extent, but their stuff is top quality and i see very few issues with them.
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Old 10-22-2012, 12:43 AM
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My engines have never had a cam go flat. Never use assembly lube just 30wt oil. Prime good while rotated and have a break in procedure. The thick pastes might impede the lifter rotation and cause the failures I read about. There is alot happening and the hobbies regulating itself, slowing to a standard. Hydraulic flat tappets are long term and not going anywhere.

Nothing i build sees more than 5500rpm, and not per say, raced.

Flat hydraulic cams from edelbrock, comp and lunati have beem my choice. Almost always staying under .500" cam lift and racing high seat spring pressures. That could have something to do with the margin for error.
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Old 10-22-2012, 10:41 AM
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Originally Posted by spinn View Post
My engines have never had a cam go flat. Never use assembly lube just 30wt oil. Prime good while rotated and have a break in procedure. The thick pastes might impede the lifter rotation and cause the failures I read about. There is alot happening and the hobbies regulating itself, slowing to a standard. Hydraulic flat tappets are long term and not going anywhere.

Nothing i build sees more than 5500rpm, and not per say, raced.

Flat hydraulic cams from edelbrock, comp and lunati have beem my choice. Almost always staying under .500" cam lift and racing high seat spring pressures. That could have something to do with the margin for error.
You must be living in an alternate universe, the SBC has had so much trouble with wiped lobes/lifters it became the foundation of a class action law suit which the consumers lost to GM but never-the-less it was a huge problem up till GM started using roller cams in car engines in 86 and they neutered the truck cams to very low lifts less than .4 inch and durations of less than 170 degrees till the roller Vortec came on line in 96 with baby buggy valve springs to reduce the load between the lobe and lifter.

Bogie
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Old 10-22-2012, 02:49 PM
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There are shops that turn down jobs that are not rollers. With the potential of customers bad mouthing the shop and the losses due to comebacks,it just isn't profitable to do flat tappets.
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Old 10-23-2012, 06:49 AM
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CMC DOES grind most of the flat-tappet hydraulic cams ground in the USA today. Comp AND Lunati have told me this. CMC was the main "vendor" to the car companies prior to the advent of rollers. It made perfect "sense" to use their equipment. Comp, Crower, Lunati, etc. (the "big" cam companies) own their own "masters" and CMC uses them for propietary grinds (like XE and VooDoo). Most of the generi-grinds (Elgin, Wolverine, Edelbrock...) are "re-hashes" from older grinds.

There are MANY applications for flat-tappet hydraulics. We still sell a bunch. The cost of rollers runs many people away. Pop had a "saying" that fits here. "When all else fails, follow instructions!" If one were to follow specifically, the instructions for "break-in" provided by Comp, Crower, Lunati, etc., most "flat lobes" wouldn't have happened. Excessive spring pressure is another cause. Many believe you "need" more spring than you really do...

FWIW

Jim
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Old 10-23-2012, 07:02 AM
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Originally Posted by oldbogie View Post
You must be living in an alternate universe, the SBC has had so much trouble with wiped lobes/lifters it became the foundation of a class action law suit which the consumers lost to GM but never-the-less it was a huge problem up till GM started using roller cams in car engines in 86 and they neutered the truck cams to very low lifts less than .4 inch and durations of less than 170 degrees till the roller Vortec came on line in 96 with baby buggy valve springs to reduce the load between the lobe and lifter.

Bogie
I vividly remember my father and uncles replacing several broomstick cams in 307s; that and the plastic geared "silent running" timing sets used to drive people nuts around here
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Old 10-23-2012, 11:52 AM
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fe cam isues

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My room mate in college rebuilt his Ford Fe and the cam went flat in 100 miles, he pulled it apart at their farm shop and got another new cam from the dealer and it went flat again in about 100 miles. I went to his house for weekend to help and found that the cam was catching two lifters with the same lobe. Factory replacement cam and original block, it only got new rings and bearings the first rebuild. I ended up getting a transmission thrust washer from a box of spare pieces the dealer had in their parts room, and every since then I drop in one lifter at a time and rotate tthe cam to check.
if the engine is 1963 and older it should have a spring and buton on the end,had a simler isue and builder had left them out.1964 and up have a thrusr plate and a diferent gear that holds the cam in place.pre 64 fes can be easly converted as hard to find the spring and button as well as clip'i have 1 left cliff
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Old 10-24-2012, 09:53 AM
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Originally Posted by timothale View Post
My room mate in college rebuilt his Ford Fe and the cam went flat in 100 miles, he pulled it apart at their farm shop and got another new cam from the dealer and it went flat again in about 100 miles. I went to his house for weekend to help and found that the cam was catching two lifters with the same lobe. Factory replacement cam and original block, it only got new rings and bearings the first rebuild. I ended up getting a transmission thrust washer from a box of spare pieces the dealer had in their parts room, and every since then I drop in one lifter at a time and rotate tthe cam to check.
That would be true of the early FE's, they came from the factory with a thrust button that had to go back in or the cam would jump around to where lobes could catch multiple lifters, another common error is to get the cam tunnel plug behind the flywheel/flexplate too deep which will hold the cam forward enough to where lobes are lifting multiple lifters. Ford finally learned its lesson and put thrust plates into the engine about the 1963-1/2 model when they used to do a lot of mid model year updates.

Bogie
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Old 10-24-2012, 01:56 PM
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fe cams

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That would be true of the early FE's, they came from the factory with a thrust button that had to go back in or the cam would jump around to where lobes could catch multiple lifters, another common error is to get the cam tunnel plug behind the flywheel/flexplate too deep which will hold the cam forward enough to where lobes are lifting multiple lifters. Ford finally learned its lesson and put thrust plates into the engine about the 1963-1/2 model when they used to do a lot of mid model year updates.

Bogie
the rear cam corplug actually is a specel plug and it goes in backwerds to the normal core plug. some service manuals mention installing this plug corectley
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Old 10-26-2012, 01:02 AM
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I have always wondered if wiping cam lobes is a modern phenomenon, due specifically to modern oils or if it was always a problem, even back in the heyday of the muscle car era.

I'd imagine the risk was always present, but was less to worry about back then. Is the problem mainly that we are using cam's with very aggressive ramp rates, high lift, and heavy springs in the presence of "bad oil"?
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Old 10-26-2012, 07:04 AM
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We wouldn't build flat tappet engines for customers anymore. But back when we where,we told customers to use the oil additive for the entire life of the engine,not just for break-in.
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