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Old 01-25-2010, 02:13 PM
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What type of cam has the least chance of failing?

I'm gong to exclude roller cams from this, because we all know they usually don't fail.

In the last 6-7 years I've had a few cams go flat on me in diffeent engnes, all of them being smallblock Chevy's. All of them except my current one being hydraulic. I've had two Comp Cams go flat and two Elgin cams go flat. My current cam is an Elgin mechanical #1091. None of the cams have been too radical, all being around .480-.500 lift.

I've done all of the proper break in procedures to insure good life. None of the cams failed instantly, it always took a few months to a year before I knew.

My current Elgin cam isn't flat yet, it has two lifters that aren't spinning. the cam has around 5 hours run time. I've pulled the cam out and the wear pattern on the two lobes and two lifters is different than the rest.

I'm thinking about going with a cam with slower ramps. I've heard the house brand cams from Summit and Jeg's have these. One cam I'm looking at is #1107. It's the same as the Performer RPM cam. I've heard this cam is old school technology and doesn't make much power. At this point I'm not worried about making big power, I want a cam that will actually last beyond break in.

Is cams with slower ramps better? Are hydraulic cams a better choice too for longer life? I know the XE cams and VooDoo cams make big power, but they are also harder on the valvetrain.

Any help would be appreciated,

Thanks
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Old 01-25-2010, 02:29 PM
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This was discussed a BUNCH in the past here on HR. I can't remember the thread(s).

You didn't mention ZDDP additive in your oil. Oil nowadays is formulated for roller engines, since that's what 99.9 percent are anymore.

Could oils have been your problem?

Spring rates on break-in?
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Old 01-25-2010, 04:02 PM
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Not trying to jump down your throat, but I feel you are doing something wrong - spring rates, ZDDP content, lifter bore fit and finish, quality of lifters, valvetrain geometry, break-in procedure, coil bind, retainer to guide and/or seal clearance, rocker slot length, something is amiss. In over 35 SBC engines I've yet to lose a cam, hydraulics or solids. Can't be that I am just lucky.

Nothing very fast about most of the Elgin lobes.

I use nothing but Valvoline Race Oils and a good moly lube on the lifters and lobes.

Only flattened cams I have ever seen were a couple of late 70's Chevy factory 305 and 350, two incorrectly broke-in BBC Comp Cams Magnum Hydraulic cams(one idled from start for just a minute or two at a time, one with big double springs and didn't remove the inners), and an incorrectly broke in SBC Elgin Solid(interference in the valvetrain).

Does seem to be a lot of people who seem to have problems though .
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Old 01-25-2010, 05:48 PM
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Quote:
Originally Posted by 4speed57
I'm gong to exclude roller cams from this, because we all know they usually don't fail.

In the last 6-7 years I've had a few cams go flat on me in diffeent engnes, all of them being smallblock Chevy's. All of them except my current one being hydraulic. I've had two Comp Cams go flat and two Elgin cams go flat. My current cam is an Elgin mechanical #1091. None of the cams have been too radical, all being around .480-.500 lift.

I've done all of the proper break in procedures to insure good life. None of the cams failed instantly, it always took a few months to a year before I knew.

My current Elgin cam isn't flat yet, it has two lifters that aren't spinning. the cam has around 5 hours run time. I've pulled the cam out and the wear pattern on the two lobes and two lifters is different than the rest.

I'm thinking about going with a cam with slower ramps. I've heard the house brand cams from Summit and Jeg's have these. One cam I'm looking at is #1107. It's the same as the Performer RPM cam. I've heard this cam is old school technology and doesn't make much power. At this point I'm not worried about making big power, I want a cam that will actually last beyond break in.

Is cams with slower ramps better? Are hydraulic cams a better choice too for longer life? I know the XE cams and VooDoo cams make big power, but they are also harder on the valvetrain.

Any help would be appreciated,

Thanks
Stiff springs, heavy valve train, aggressive lift rates and amounts, high RPMs add up to problems whether the flat tappet cam is mechanical or hydraulic. The problem just keeps getting worse with the reduction in ZDDP oil additive chemistry. While you can get this stuff as a booster to add to your oil, it doesn't seem to be as good as when the oil manufacturers mixed it. This probably tells us that there was other supportive chemistry that isn't there any more. Manufacturers have messed around with better materials and processes but these haven't had much effect either. Some race engine builders have turned to making a tray to trap and flood the cam and bottoms of the lifters in oil, others are putting spray bars in the valley aimed at the cam where opening exist above the cam. Others gun drill the cam and put an intersecting hole on the lobe as the ramp starts to pick up the tappet. Still others have tried holes in the lifter foot to trail oil on the cam lobe. Others mill a slot into the side of the lifter to spay pressure oil onto the cam.

For a street engine, the OEMs haven't used flat tappets for 25 years, there's a message in that.

I have always built flat tappet engines that don't have a factory camshaft thrust plate using the thrust button intended for aftermarket roller cams to take the thrust. It's not a fool proof solution, but it does relieve the lobe to lifter interface of the thrust loads and usually improves the lobe/lifter wear situation from enough to be noticeable to forever.

Standard Chevy flat tappet blocks can be converted to use OEM roller cams by using the roller lifters from the 60 degree V6 engines which are short enough to slip into the shorter lifter blocks of older engines. The main oil galley is drilled 1/16th larger in diameter and is then top drilled and tapped to accept the bolts that hold the spider. This is adjusted for height with washers. The bolts need Permatex thread sealer to prevent leaks. On these bolts I like to remove the threads that would locate inside the oil galley to simply provide less interference to oil flow, which is adequate. The pushrods will be normal Chevy flat tappet length instead of the shorter OEM V8 roller pushrods. The cam thrust is requires some work if you're using a GM OEM cam that expects a thrust plate. You'll have to buy the trust plate and the single row roller timing set (space limits the timing set depth) You cut the thrust plate into round object and place it on the cam nose as a spacer and thrust carrier. So it's OD is sized to ride on the blocks thrust surface. Then attach the timing gear, its thrust surface will contact the modified thrust plate. Then use a nylon thrust button, you will have to shorten this, otherwise it's set up just like a conventional thrust button. However, before you do that, test the timing cover for chain and gear clearance. Often the metal timing covers won't clear without an extra gasket the use of which will influence the cut length of the thrust button.

If you use a factory roller cam, you've got to watch for the presence of the fuel pump cam, not all have them since EFI engines use an electric pump and the fuel pump cam isn't needed. A roller cam does not use the steel pump shaft of regular cams in the older engines. This requires a brass or composite tipped shaft. Same for the distributor gear, the factory uses what's called a Melonized gear otherwise it's a brass or composire gear and if an aftermarket distributor for sure its brass or composite to fit the half inch shaft of those units.

Whew, given how many roller small block Chevy's are out there, the best solution is simply a factory roller block.

Bogie
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Old 01-25-2010, 06:15 PM
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Quote:
Originally Posted by oldbogie
The main oil galley is drilled 1/16th larger in diameter and is then top drilled and tapped to accept the bolts that hold the spider. *snip* On these bolts I like to remove the threads that would locate inside the oil galley to simply provide less interference to oil flow, which is adequate.
Why is the galley drilled oversize- seems like that just lessens the spider's bolt thread engagement?

Thanks in advance.
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Old 01-25-2010, 07:13 PM
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Quote:
Originally Posted by cobalt327
Why is the galley drilled oversize- seems like that just lessens the spider's bolt thread engagement?

Thanks in advance.
Your stuck trading thread bite for oil flow, I don't know any really good way of doing this. Which is why these days I recommend just getting a roller block. This method is a left over for the dark ages of roller cams in the 1980s and 90s when the blocks weren't so plentifully.

Bogie
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Old 01-25-2010, 07:58 PM
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When using the shorter V6 or L4 OEM Roller Lifters you need 7.500" Pushrods. Stock OEM V8 Roller Pushrods are 7.200", Flat Tappet Pushrods are 7.800", Retrofit Roller Lifter Pushrods are 7.300".
I don't drill the oil Gallery larger. I use Studs with a Jamnut then epoxy it to the top of the Gallery & washers for spacers. Stud threads don't protrude into oil path this way. So far so good.
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Old 01-25-2010, 08:14 PM
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There are also Crane retro hydraulic rollers that use 7.046" p-rods. Prolly not seen much anymore, but they were fairly common back a few years.
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Old 01-26-2010, 02:47 AM
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I don't believe I'm doing anything wrong. I used Delo 400 motor oil, a bottle of ZDDP, used the grey break in lube, not the red runny stuff, primed the engine, and took out the inner springs on my Dart heads. I don't have any clearance issues because the heads are good for .600 lift and I'm running .500 lift cams. I also ran the engine for over half an hour at 2-3000 rpm.

One thing I'm going to do is run a wheel cylinder hone down my lifter bores and see if that helps.

I did see a kit on Ebay that is suppose to convert your non roller block to a roller. I don't anyone that has ever tried it.

My last cam to fail before the Elgin was a Comp Cams XE284. I've talked to several that have had bad luck with the XE line.

Thanks for your tme and help
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Old 01-26-2010, 07:39 PM
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I recomend you get a genuine Isky cam with Isky lifters.
www.iskycams.com
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Old 01-26-2010, 07:58 PM
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being that the heads are set-up for .600" and you are running 500" cams are the seat and open pressures correct for the cams you have?

also I read somewhere that the guy who designed the Voodoo cams broke a looong standing rule about the lift to duration and ramp speeds to gain an edge on the competition and them he either did some stuff for comp cams or they just followed suite to keep up in the horsepower wars. It's been a while so I'm not sure how accurate that is.

I can only recall one cam going flat on me and that was around 14 years ago but I went to rollers and haven't looked back, but as far as "fail proof" flat tappets that preform well I'm always fond of the old "Duntov 30-30" cams. They have very slow ramps and a good amount of duration, sound great and perform decent. If you look at them don't let the big duration numbers fool you, they are a large lash cam that really gives up a lot of the duration to that lash and slow ramp rates, comparable to a modern 236* @ 050" hyd cam, but easily capable of 7000 rpm in a 350.

If I was forced to pick ONE flat tappet cam for the rest of my life to run in a SBC it would be #1.
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Old 01-26-2010, 09:10 PM
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Isnt Delo 400 a 15-40 synth blend? All flat tappets fail from all manufactures and the problems range from block core shift, lifter geometry,oil types( mostly low zinc contents and the use of synth), cam lobe tapper, lifter crown, and on and on and on. High seat pressures are no where near as hard on a cam as the open loads. I have even seen flaking rod bearings in sbc's take out a cam lobe or two.. sorry not much of an answer in this but I would look at oil during brake in and total spring pressure at max lift.

Last edited by wwilliams181; 01-26-2010 at 09:20 PM.
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Old 01-26-2010, 10:13 PM
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You can say what you want about oils, but Have you noticed almost all failures have been the bread-and-butter production cams with the white box lifters? I always wonder why the manufacturer's custom grinds have basically no problems? Probably premium cam cores not imported from China. Too many failures from builders that went 20+ years without a failure, and they too are experiencing ruined lobes and lifters in the last year or so. Seems like I haven't heard of any Crower cams going flat, but maybe I'm hanging with the wrong crowd. Roller lifters are the cure, but at a big price tag.

Oh yea, most cam manufacturers don't recommend synthetic oil with their flat tappets - the synthetic is a little to slick and the lifters have a tendency to stop rotating. Doesn't take long for even a good cam and lifter set to be destroyed if the lifter sits in the same spot for long.
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Old 01-27-2010, 02:53 AM
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Thanks for all of the replies.

I'm going to double check everything before I do my break in with a new cam. I'm also going to install my new cam, drop in the lifters, and then spin the cam over by hand and see if the lifters turn. That way if I see a problem I can fix it before I go any further.

I'm sure my seat pressure is alot during break in, but thats why I take out my inner springs. I ran it for over 2 hours before I put the inners back in. I would think after that the cam would be broke in good.

Thanks again
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Old 01-27-2010, 05:06 AM
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Seat pressure isn't the problem for the cam, it is over-the-nose pressure that kills the lobe. When the valve is close to the seat(or on the seat) the lifter is on the heel of the lobe, therefor pressure is low. The recommended minimum seat pressure is to prevent valve bounce on returning to the seat(which kills power), while it is over-the-nose pressure too high that kills the camshaft.

Even though you springs are "good to .600" lift" (I detest companies listing them like this, it gets people in trouble)and you are only running .500 lift, the spring rate may well be too high for the cam to survive when you reinstall the inner spring.

Do you know all the spring specs- seat pressure @ 'xxx' height, open pressure @ 'xxx' height, coil bind height, spring rate??

Last edited by ericnova72; 01-27-2010 at 05:23 AM.
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