Looking to upgrade the cam and lifters in my 400 Pontiac and would like some help...  I've narrowed it down to a few choices and a couple say hydraulic flat tappet and a couple say mechanical flat tappet...  What's the difference and which is better?


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Exactly.   What he said  ^^^

Not that it matters, but you are talking about a street car or a recreational boat right?

Ok...  Hydraulic roller kits are not an option, way too much $$  So now I'm back to my previous question...  Hyd or mech flat?


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Stay the F away from flat tappet cams if you want your motor to live.
On that note X2 on Chris Straub 1 423- 391-7774
Chris is the man.

When they took the zinc and sulfur out of road oil, those with serious (mostly mechanical) flat tappet cams lost lobes (I think) because of the loads created by excessive spring pressures.  I believe that there was either a change in metallurgy or heat treating processes to make the newer cams live with modern oils, but I am not 100% positive.  If you want to run a serious flat tappet cam, just make sure that you follow the cam grinder’s recommendations for both spring pressures and oil.

Mechanical vs. hydraulic; I have heard that a mechanical is worth about 15 horsepower over a comparable hydraulic cam because you don’t lose so much gross lift because the lifter is a solid piece of steel compared to a hydraulic lifter plunger that will bleed down.  I think part of that is that mechanical cams are typically ground with a little more lobe intensity than a hydraulic.

With that being said, a mechanical cam engine isn’t a put gas and oil in it and go kind of engine.  Expect to run the valves often.  Expect to pay more for oil and you won’t be purchasing it at AutoZone.

A hydraulic cam is a lot more user friendly.  It is a lot more set it and forget it.  You did mention that price was an issue when you looked at hydraulic roller lifters.  When you get serious with a hydraulic, you are going to need the anti-pump-up lifters, so price starts to factor back into the equation.  Aint nothin’ cheap when you start going fast.

Another company that is driving modern cam lobe design with aggressive lift ramps and gentile valve closing ramps and is worth a check is http://www.bulletcams.com

Hope this helps,

Joe

Thanks for the info!  I was looking at a Comp Cams cam and lifter kit so they supply lifters that I would expect to work with the cam


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Forget about comp cams in my experience. I don't even know why they are still in business.

I still and always will prefer rollers, for hotrod applications that is the best route to go, but there are a lot of myths and bogus information floating around concerning flat tappets, be it mechanical or hydraulic. Flat tappets can and do live long and happy lives IF several areas are addressed...

First being using the correct springs and pressures for the cam profile/valvetrain/application. Not using the correct springs, or not checking for coil bind and retainer to guide clearance will for sure, no doubt about it, wipe out a new cam in seconds... be it roller or flat tappet.

Second issue is the quality of the parts used... if you use bogus cheap offshore lifters, or budget "mass production" 75 dollar brown box cams, then your gonna have a much greater chance of a failure... whether it be roller or flat tappet.

Third... and this is pretty damn important... OIL! You have to use a decent quality oil with zinc additives in it to make sure the cam and lifters will live... ESPECIALLY DURING BREAK IN!!! I do not know how many times I heard over the years the absolutely flat STUPID notion of, "Oh, well I'm gonna put cheap oil in to break it in since I'm gonna be changing it right away." That is beyond retarded... a person with a brand new engine using bunk oil to break it in, be it roller or flat tappet... the break in period is the period is perhaps the most critical time to make sure everything beds in, seats, breaks in, whatever you want to call it, properly. it would be akin to saying, "Oh, I'm gonna use this 3 year old gas in my boat because I'm just gonna go for a lap around the lake." I have found that Valvoline VR1 racing oil is about the easiest to obtain oil that you can get damn near anywhere including, but not limited to, Autozone, Napa, and O'Riley's. It is reasonably priced (comparable to regular Valvoline or Pennzoil), a decent oil, and has zinc. I do prefer to supplement the initial break-in with additional zinc additive for insurance policy... I typically use Schneider Formula 2.

Fourth... this is where rollers and flat tappets differ... CAM BREAK IN. There are few things in this world that will be far worse than swallowing a poo sandwich, and is damn near 100% preventable and that is having a cam go flat because it wasn't broken in properly. I have always gone with the method of pre-oil... pre set the timing as close as possible.... base set the carb... fire it up... AND IMMEDIATLY run for 20 mins @ 2000+ rpm. If you doddle around and let it idle while you set your timing... adjust your carb... scratch your ass... etc... and THEN think it's time to break the cam in... forget it... might as well just pull the engine back out and pull it down because the cam and/or lifters are toast or going toast.

Of every single cam failure... nearly all were one or combination of several of the 4 were the culprit... very, very, very seldom do you get a "bad cam" from a reputable cam grinder... I mean it does happen, people have the ability to make mistakes... but in my entire career... I have gotten 2... only 2... one didn't have taper ground it it... and the other wasn't parko'ed properly. Matter of fact, while being in business, I have lost exactly 3 cams... the two mentioned... and 1 that was my own damn fault for not emphasising to the customer the importance of breaking in the camshaft (fella never had a flat tappet before). So this horror concerning flat tappets is way over blown. Granted, there were a mass failure period several years back... but it was a combination of oil changing, offshore junk parts, and many in the industry getting sloppy. Also, keep in mind, application has a lot to do with how something will last... and thinking a hydraulic flat will last in a full on comp jet is a bit of wishful thinking... but for the average Joe with a cruiser or mild hotrod jet... there is absolutely nothing wrong with a flat tappet.

Lastly, consider this... applications dictate the builds, as well as budget, and intended use. Not everybody needs a billet crank, h beam rods, aluminum heads, full roller race motors with fully blueprinted race pumps for their  $2000 1975 Tahiti Whogivesafuck that they plan on going to the sandbar with and occasionally tubing the kids behind.

So, yeah... Personally, depending on what your expecting to get out of this Pancho... and what else you have going into the build, will dictate whether a hydraulic or solid would be the hot ticket. If you need some advice in a direction to go.. I'd be happy to help... or you can give Jerry at Schneider Racing Cams a call... they've been around doing this since 1958 and he's been absolutely fantastic to deal with and the only guy I use for cams.

Well that just hit the nail on the head

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