Exactly
Hot Rodders - The death of the flat tappet cam.
- Thread starter DuckRyder
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There is no such thing as too much cam. You need more motor. And trans. And Rear. It goes on...
Among the several reasons i switched from a big block to an LS is because the Crane flat tappet cam found it`s way to the Fram filter. Said cam had been installed per Crane instructions and included lube. Used about 9,000 miles over 20 years.
the roller contact angle changes as the cam rolls over it, that tames it down.
My point is more that this is precisely the kind of cam that is going to be affected by this cam core issue. The mundane and common stuff used in countless engine builds.
I tried to get a Howards American Muscle Cam for an FE a while back, now I guess I know why it's unavailable.
Then, we are in violent agreement.
This is the kind of cam used for a restoration, or an older car, or a mild build without modification.
I was rebuilding an engine to keep a car on the road, and parts were readily available for that engine, but now?
The hobby is going to be greatly impacted by this.
I'd also say that the manufacturer has been dropping the ball over the years. Many reports of people wiping the lobes even with proper break in procedure, quality oil and spring pressures. They just don't seem to be as robust as they used to be.
Though the cost is much higher for a roller cam due to the higher cost of the roller lifters...it is the way to go these days. The cam is broken in the second it is running.
Wipe a lobe on a flat tappet cam, sending trash through the engine and its going to cost a whole lot more than the difference between a roller set up.
For the racing guys that have to run a flat tappet cam for their class....I'm sure they have some big bucks in their engines anyways. They are probably running billet cores to begin with.
Though the cost is much higher for a roller cam due to the higher cost of the roller lifters...it is the way to go these days. The cam is broken in the second it is running.
Wipe a lobe on a flat tappet cam, sending trash through the engine and its going to cost a whole lot more than the difference between a roller set up.
For the racing guys that have to run a flat tappet cam for their class....I'm sure they have some big bucks in their engines anyways. They are probably running billet cores to begin with.
If I ever pull apart one of my classics again I will stab a hydraulic roller and be done with it.
I don't know anyone that runs flat tappets any more. My friends and I have been running rollers for years.
In what application though?
I mean, Jeff Keryk has a classic 1960s Oldsmobile, and he’s just looking to keep it on the road. He wasn’t looking for more performance. That engine was built from the factory with a flat tappet hydraulic set of lifters and cam, and when he had the engine rebuilt, that’s what he put in there. And it’s been running that way for decades.
So, sure, the performance crowd has been willing to make the modifications, but the restoration, and casual cruising crowd, just needed the same thing that was there from the factory.
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I have a 496" big Mopar. One of my friends just built a stroked 360 Mopar, 410" with a roller. First for him. I have a friend with a 427 in a 67 Chevelle, my brother has a 327 chevy in a 65 Pontiac Tempest that has had a roller in it since the late 80's. I keep bustin' on him to update the valvetrain. He would totally benefit from modern springs and better valvetrain geometry.
Once flat tappets were starting to have problems with the current oil, I viewed them as unreliable.
None of us are running monster drag race cams. I plan on doing Power Tour one day so mine needs to run somewhat like a normal car.
Once flat tappets were starting to have problems with the current oil, I viewed them as unreliable.
None of us are running monster drag race cams. I plan on doing Power Tour one day so mine needs to run somewhat like a normal car.
No, but these are all modified cars with modified engines, and I would call them “muscle cars” or “hot rods”.
There are a lot of what I’m gonna call “antique cars“ that are simply driven and enjoyed where the engines never received those types of modifications, because the owner wasn’t looking for more performance.
Pre-1986, everything was flat tappet, so every car built from the early days of V8, in the 1950s, through the 1980s is affected by this. I don’t know about the sixes that predate the 1950s.
But, several decades of cars are suddenly going to be without cams, unless the owner is willing to update to a roller.
I don’t think updating is necessarily bad thing, but it is more expensive and it is a modification.
For the record, my 1932 Packard came with a roller cam. I do think the roller is the better design, the flat tappet was a way to lower production cost.
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That's a prime example of where too much cam is a bad thing. Just 5° earlier EVO and it's lifting the blower off in a fireball. The cam is way smaller than they'd like it to be.
My friend has been wanting to cam swap his 351w in his f150 but quality issues with lifters kept him from pulling the trigger. I told him if he can still find one maybe buy the camshaft now and figure out lifters in the future (hopefully we can find a quality supplier).
It's going to be too late for my 76 350 olds. Only reason it's still a stock camshaft is originally I didn't have any $, but eventually after 18 years and 130k miles it seems like it will last forever and I don't want to mess with that. This winter it finally got new valve cover gaskets, plugs, belts etc.
There is a school of thought that says to use a solid flat with high ratio rockers instead of a retrofit hyd roller to get a long-lasting valvetrain with similar area-under-the-curve with none of the drawbacks of the retrofit setups. I'm not so sure, I have a retrofit hyd roller in a Pontiac V8 and so far, so good.
I would still like to see flat tappets available for cost saving reasons, however, I've got a BBC and a Jeep 4.0 that are not hot rod engines and I would prefer to stick with flat tappets for those applications in the event I need to replace a cam. As far as flat tappet failures go, it seems there are a lot of factors, but using a lazy factory-style lobe like the comp high energy series instead of the newer, faster lobes like the XE series will likely reduce your chances of a failure.
I would still like to see flat tappets available for cost saving reasons, however, I've got a BBC and a Jeep 4.0 that are not hot rod engines and I would prefer to stick with flat tappets for those applications in the event I need to replace a cam. As far as flat tappet failures go, it seems there are a lot of factors, but using a lazy factory-style lobe like the comp high energy series instead of the newer, faster lobes like the XE series will likely reduce your chances of a failure.
What about going to a larger cam core diameter and bigger wheel on the roller lifter?
Perhaps going for more rocker ratio is a better route.
Question; What is the rocker ratio in the 6.6L LT gasoline engine in a 2500 Chevrolet?
I heard this from several cam companies back 4 months ago when I wanted a stock grind for my 68 Pontiac. I lucked into finding a new cam produced prior to 2007 (Elgin) and replaced the annoying choppy idle cam for a smooth idle. I am holding on to that cam to be reground if needed. FWIW…the majority of the current American manufacturers’ cams (roller) are coming from Mexico. Not sure where the blanks are from though. The issues with todays roller lifters in GM and Stellantis is because of the lack of quality control from these plants south of the border…..Flame suit on!
Have to machine the block and find new cam bearings--the lobes have to be smaller than the cam journals. Maybe instead reduce the lobe base circle, but I'm sure that brings its own issues (faster ramps, more side loading leading to worse lifter bore wear?).
On the lifters, at some point again, they have to drop through the lifter bores. Those can probably be opened up more easily, no bearings to contend with. But I'm not sure if anyone has tried oval shaped lifter bores, so as to get larger rollers... probably still have issues.
High rocker ratio means more force pushing back down on the cam lobe, just like running a more stiff valve spring. Not sure how that works out, if the cam lobes and/or lifters were already problematic with wear issues, then adding more pressure to the mix surely can't help.
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