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I might not have a full understanding of the stock eliminator "cheater" cams but
I thought they had to have stock lift and duration.

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This is a bad ascii drawing of a stock cam lobe vs. my impression of a cheater cam lobe.
The cheater cams are said to be brutal on the valve train...
Both of these lobes have the same lift and duration. The square one (I know it's an exaggeration) is going to result in more airflow.

If I'm way off base, let me know.
 

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"...I thought they had to have stock lift and duration..."

No, there was a time when there were some limits on the duration AND valve spring pressures. BUT, they changed Stock Eliminator DRASTICALLY, when they changed the cam rule to allow ANY duration, and any spring pressure.

They also now allow solid lifters. Until very recently, if the engine came with HFT lifters, you were supposed to run HFT lifters. But, most of the quick racers were running high dollar "trick" lifters that were basically solid, but had just enuff plunger movement to be legal. The lifters they run are also made of extremely hard metal and/or coatings, so that they'll live with the high spring pressures & high rpm. There have been several types of trick lifters & cams.

Nowadays, NHRA says how much lift the cam can provide, at the valve. And, the engine must use the factory rocker arm ratio. All the NHRA valve lift figures I've seen are more than what came in the engine from the factory. I don't know how they arrived at those higher figures. Anyhow, the cam cannot exceed those NHRA valve lift figures. BUT, there is NO limit at all on the amount of duration the cam can have.

Because of all the non-stock spec parts allowed, the Stockers of today are quicker than the Super Stock cars were, back when we were racing Stock. From the times I've seen, Stockers are about 2 seconds quicker now, than the same car/engine combo was back in the mid '70's.

Just as an example: Truman Fields won the '73 US Nats, with his RA2 '68 Bird. He set a new nat record of 12.06. Those RA2 Birds can now run low 10's. In the pic below, notice also that the car Truman beat ran E/SA. That car also set a new nat record of 12.77. In '75, our E/SA Bird ran 12.80's, which was quick enuff to win several races at area tracks. If I remember correctly, TJ shifted at around 5500 & crossed at about 6000, with 4.56 gears.

Nowadays, E/SA Birds run 10.70's, at well over 7000 rpm, maybe closer to 8000. Just yesterday, Julie Biermann ran a 10.777, which was good enuff for #13 on the Q-list. She runs an E/SA '68 Bird 330hp, just like we ran, but a little more than 2 sec quicker.

https://www.dragracecentral.com/DRCStory.asp?ID=356758&NewHash=NHRA-SUMMIT#indextop

Randi Lyn Shipp shifts her '67 400 Bird at 6800 & crosses between 7800 & 8000. Has run a best of 10.31, at C/SA weight.

https://www.msn.com/en-us/autos/enthusiasts/randi-lyn-shipp-is-fearless-in-her-wheel-standing-1967-firebird/ar-AAvQZ5h?li=BBnbfcL&;ocid=UP97DHP
 

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"...I just wanna be in that lineup someday!..."

Yeah, I'm hoping to get my Super Low Budget Bandit Bracket Bird to a T&T at our local track this year. Don't lack too much. So, IF I don't have any setbacks, I should make it.

It'll be real slow, cause I haven't had enuff coins to use the parts I really wanted. But hey, at my age, I just wanna make a few full throttle passes down the track. Don't plan to race every week, tho I'd like to. But I would like to get the car sorted out enuff, so that it could be competitive, if I still can. I did it enuff in the old days to know that if everything ain't right, you can't cut good lights & run the consistent times it takes to win. But hey, at this point, it'll be fun trying ! :)
 

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OK, reading other posts and trying to make sense of all the data and recommendations, including the cam you designed Jim, would an 068 cam work well in a 400 with #16 heads (running 91 octane + Torco accelerator)? How about with the #14 heads (lower compression)? My thought being, just install a HFT cam and lifters with the #14 heads; if still unhappy install the #16 heads (as is); if still unhappy build the bottom end and buy KRE aluminum heads and call it a day...
 

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You should be good running any of those heads as long as you use the booster in the fuel. I ended up swapping some 87cc #15 heads (off of a 1970 455) onto the 068-cammed 400 in my '67 GTO simply because I got tired of detonation and running boosters in the fuel. I ended up with about 9.3 CR, and it runs fine on 91 octane 95% of the time....it will still ping on a 105 degree day pulling a grade, though. It was impossible to get it to run on pump gas with the stock 670 heads. I tried every trick, none was workable.
 

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My personal opinion on this is that if you are building a street/strip engine you can enjoy and make dependable, then I feel any thing under .550" lift can use a flat tappet cam and I would go with a solid cam at that. As most know, I am also a firm supporter of iron heads.

I also wanted to clarify a bit on this statement. If using factory iron heads and the stock type valve length, and not the longer RA IV valves, you want to check the retainer to valve guide boss clearances. Pushing your lift near .500" may be close. You don't want that spring retainer slamming into the top of the valve guide.

Longer valves can provide more clearance for higher lift cams as well as machining down the valve guide (which lowers it) for Viton valve seals. On my 455 build, I went with the longer Ferrea RA IV stainless steel valves as well as bronze valve guides and machined the guides for Viton valve seals. My machinist said I was good for at least .600" lift - but I am not going anywhere near that. :thumbsup:
I know Jim is aware of this but for those who do not, you cannot compare duration @.050 from hydraulic cams to solid cams; a HFT duration at .050 will put out more power than a solid with the same duration at .050. To get them "equal", you need to add about 10-15 degrees duration @.50 to the solid cam. This is to account for lifter ramps and other engineering things. Just sayin':smile3:
 

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Discussion Starter #27
I know Jim is aware of this but for those who do not, you cannot compare duration @.050 from hydraulic cams to solid cams; a HFT duration at .050 will put out more power than a solid with the same duration at .050. To get them "equal", you need to add about 10-15 degrees duration @.50 to the solid cam. This is to account for lifter ramps and other engineering things. Just sayin':smile3:

You just had to go there. LOL. I read the same post/write-up and when I read the statement about the duration differences, I said "Whaaaaat?"

Apples and oranges, yes, sort of.

The hydraulic cams are generally measured at .004" or .006" - SAE standards are .004", and also is the seat-to-seat number which is the bigger advertised duration number we all kinda look at.

The solid cams are generally measured at .020". So it becomes apples and oranges because of the juggling done at where the measurements are taken, and even this number may be different between manufacturers.

This is taken off the Chevelle forum and written by Harold Brookshire aka UDHarold (now deceased) who designed cams and was known for his UltraDyne line of cams:

" a solid cam acts kinda like a hydraulic with 8 degrees more at .050". However, that is kinda, not exactly. Hydraulic lifter cams come off the seat at a much lower velocity than solid lifter cams do, and this makes the hydraulics have much larger seat durations, more overlap, more reversion, and less snap and bottom-end torque.

Engines see valve lift, not cam lift.

Advertising 280 degrees duration at the seat, is that .004" or .006" for hydraulics? SAE says .004". For the solid, it depends on what the valve lash is.......

If we had a 230 degree duration cam at .050" on both cams, and a theoretical 1.5:1 rocker ratio:

The hydraulic has .050" X 1.5, for .075", less any deflection.
The solid has .050" X 1.5, for .075", less any lash.
The difference, at the valve, is about .069" for the hydraulic, and .050" or so for the solid. A difference of at least .019"-.020".
What does this mean in the running of the engine? NOT MUCH!

Hydraulic cams have opening ramp rates varying from .0005" degrees to .00125" degrees, or faster. Solid cams have opening ramp rates varying from .00125" degrees (I've never designed one this slow.....) to about .003" degrees, depending on valve lash. Looser lash cams can opening the valve faster than tighter lash cams. When and how fast a valve is opening has a much bigger effect on an engine than a 8 degrees difference in relative .050"s. That 8 degree difference is what it takes, the way I design cams, for a solid to equal a hydraulic at the .050 equivalent at the valve. A hydraulic with 230 degrees at .050" and a solid with 238 degrees at .050" have about the same duration at .050" off the seat at the valve.
But this is like comparing 2 cars as to their fastness when you are looking at what shade of RED they are......

The gentlest solid I have made is that 272, that is 238 degree duration at .050". It has such gentle ramps that everyone says it goes over 12 months without needing a valve lash adjustment. It only has .485" gross valve lift. If you ever dyno'd it in the same engine as one of those popular 280 degree duration hydraulic cams - 230 degree duration at .050", .480" valve lift, and 110 LSA cams - you would be amazed at the difference in torque, power, and throttle response, yet their .050" equivalents are identical, and the hydraulic would have more valve lift.

There's lots more to this than just a bunch of numbers. If there wasn't everyone's cams would run the same......."

So, the statement of "To get them "equal", you need to add about 10-15 degrees duration @.50 to the solid cam" and in my mind just doesn't add up. UDHarold stated that number was actually 8 degrees more would be needed, BUT, that the solid cams come off the seat at a much higher velocity than hydraulic lifter cams do, and this makes the solid have much shorter seat durations, less overlap, less reversion, and more snap and bottom-end torque.

So yes, apples and oranges, sort of when measuring one against the other using the typical advertised numbers we all look at. However, there are measurements built into the design that we don't know about or see - cam designer "secrets" that can make the solid cam superior over the hydraulic cam even when comparing the "as advertised" specs side by side.

I just like the sound of a good solid cam in the morning. :thumbsup:
 

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Thanks for posting this info.

I was about to run nitrile positive valve seals on 6x heads that have cast iron valve guides. From your info I think I’ll just stick to the o-rings. You probably just saved me from an expensive mistake.

On another subject. I heard that I didn’t need to pull the inner valve spring on cam break in because the open pressure was less than 250 lbs. that was from comp cams tech

I’m using comp cams 988 springs on a Como cams 275DEH cam

I don’t mind pulling the springs to be safe but don’t want to float a valve or something on break in. Should I worry about it?


Sent from my iPhone using Tapatalk
 

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Discussion Starter #29
That I cannot say. I had my 7K3 heads rebuilt with heavier springs and asked the same question of my machinist who does complete engine rebuilds and breaks them in on a test stand. He too said I did not need to pull the spring for cam break-in. He just said to make sure I use a good cam break-in lube and oil with the ZZDP in it.

But, look what the Comp Cams website says, "Flat Tappet Break-In All flat tappet cams will require special attention during the break-in process. Due to recent changes in motor oil formulas, a switch to a diesel or non-synthetic racing motor oil in combination with COMP Cams® #159 Camshaft Break In Lube is mandatory in order to avoid camshaft failure during break in. Cams requiring dual valve springs during normal operation will also require that the inner valve spring be removed during break in so that critical lifter rotation can be established. The appropriate COMP Cams® lifters, and correct valve springs, rocker arms, and pushrods are also absolutely essential to ensure long camshaft life. Please refer to the instructions in your cam box for complete procedures or page for our tech bulletin on the topic If ever in doubt, please call the COMP Cams® CAM HELP® line at 1-800-999-0853."

Hmmmmm. A contradiction from what the tech guy told you.

Many cam companies offer a version of a cam break-in lube. Some are a little thinner and runny, so you would want to put this type of stuff on prior to firing up. If it will be a while, I have read the thinner lubes can run off over time.

Always check for coil bind and make sure you have enough clearance between the underside of the spring retainer and valve guide.

The 275DEH looks like a good grind. However, I am not a fan of the 110LSA with a high compression engine - they work better on a 9:1 compression or less. The 110LSA cams have a tendency to build additional cylinder pressure and can increase the tendency for detonation - unless you are planning on running a high octane gas OR are at a higher altitude where more cylinder pressure is needed.

You want to prime the engine with oil first. Valve covers off so you can see oil coming out of the pushrods. Rotate the engine 45 degrees and prime again. Repeat until you have gone 360 degrees - back to where you are ready to fire the engine. This will ensure oil gets to all parts.

The most important is to have the engine ready to fire once you spin it over. Get the timing as close as possible. Then one fired, it is the splash oil that lubricates the cam and this is why it is recommended to keep your RPM's up near 2,000. My Machinist says he only goes about 1,500. When I am ready to break in my engine, I'll go for the 2,000 RPM range and then vary it up and down a few hundred RPM's for about 20 minutes and then shut down and let it cool off to room temp.

It is then good to drain the oil and change the filter. Personally, I plan on running it another 20 minutes at the above RPM's one more time. However, I won't change the oil and filter until I hit the road and get about 100 road miles on it.

I would also suggest you put a little break-in lube on each end of the pushrods, a little under the rocker arm ball that seats in the rocker arm cup, and a dab on the valve stem where the rocker arm will sit on top of.

You did not mention if this is an engine rebuild or just a cam swap. Did you check rocker arm geometry to make sure your pushords are the correct length IF you had the engine rebuilt? If you did, then you can skip the following suggestion.

So just rambling here.............

If you want to go a step further, put a dab of white paint/marker on each pushrod in a place where you can see it. I would get the oil deflectors from Summit if you are using stock rocker arms (won't work on other rockers like rollers). You will need 2 sets - one per side. Valve covers will be left off for this, so have a few rags handy. ALWAYS HAVE A FIRE EXTINGUISHER HANDY JUST IN CASE. Have your valve covers fitted with their gaskets and ready for installation. When you fire the engine, watch the pushrods. Should not take a few seconds to run a visual over all the pushrods. The deflectors will keep oil splash to a minimum You should see each one spinning, letting you know that the lifter is rotating on the cam as it should. If you do not see a pushrod spinning, it could mean trouble and that the lifter is not spinning on the cam - and can cause wear. What I have found is that this means the rocker arm is too tight (and suspect some cam failures are due to this and improper pushrod lengths after an engine has been rebuilt). Back the rocker arm nut off to loosen the rocker arm just enough until you see the pushrod spinning.

If you have factory studs and are torquing down the rocker arm nut and you back it off to get the pushrod spinning, then you may have a pushrod length problem. You cannot back off on the factory nuts and run the car like that as they will back off and you will damage the engine - they need to be torqued down, period. The correct fix will be to get the pushrod length needed for your engine. But, most likely you should be OK.

If you see all the pushrods spinning, pull off the oil deflectors and pop on the valve covers. Wipe any excess oil off that you can.

I can say that I never ever did a pushrod check on any engines I rebuilt. But, in rebuilding the few that I did, I did not have any major milling to the heads or block as some do, and these were original to the car and not something that could have been rebuilt a time or two in the past. If anything, I would have them simply milled enough to get the surfaces clean & straight which was hardly anything, so all stock replacement parts worked just fine.
 

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Is there a difference between brands of solid flat lifters like there is with hydraulic flat lifters (ie: Hylift Johnson vs Morel vs Eaton vs Delphi vs Summit) as some aren't machined right/poor steel and can cause cam failure. Hylift Johnsons, Rhodes, Delphi are supposed to be good HFT's and others are suspect, possibly Chinese. Do solids have this problem? Are some brands better than others for being made of good steel, machined right and not Chinese?

Thanks, all.
 

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Discussion Starter #31
Is there a difference between brands of solid flat lifters like there is with hydraulic flat lifters (ie: Hylift Johnson vs Morel vs Eaton vs Delphi vs Summit) as some aren't machined right/poor steel and can cause cam failure. Hylift Johnsons, Rhodes, Delphi are supposed to be good HFT's and others are suspect, possibly Chinese. Do solids have this problem? Are some brands better than others for being made of good steel, machined right and not Chinese?

Thanks, all.
Have not heard of any flat tappet solid problems. Everything is a crap shoot. I don't worry about brand or select one over the other as some do. There are too many variables as to why a lifter/cam will go bad. We hear the stories, but no one ever diagnosis the true nature of the failure. Of course the Chinese get blamed, but maybe its an American company trying to smear a more inexpensive product because it is cutting into their market and dollars. When was the last time you read that the "lifter/cam" was soft and this was proven through an independent lab that measured the rockwell hardness of the base of the lifter or cam lobe as well as a metallurgy analysis of the composition of the steel itself?

My take is that most of the so claimed "soft" lifters/cams is owner error, assembly errors, mismatched parts, or not the correct part for the application. Who is going to admit it was their screw-up? How easy it is to blame the Chinese because we can all relate to that- ya, they make junk.

Keep in mind most who tinker with our cars rely on what we read on the internet or "our buddies." For those who try to squeeze out every last bit of HP, sometimes it can be overdone. Point in case is all the talk about and suggestion about windage trays, crank scrapers, baffled oil pans, and plugging lifter galley holes to meter oil flow. How does a flat tappet cam get its lubrication? From oil splash. So in adding all these so called improvements, you are also removing the needed and required oil that would normally be lubricating the cam lobes. Are you seeing what I am getting at?

I read in one of the "old" magazines that the windage tray should be left off when first breaking in your engine to ensure that splash oil gets thrown up on the cam lobes to help keep it oiled and not prematurely put wear on the lifter/cam lobe. Once the cam/lifters are broken in, then re-install your windage tray. Hmmmmm. Old school thinking - man, how stupid and out dated. Sure, oil pushes out of the crankshaft's bearing clearances, but if the bearing clearances have been tightened up or kept stock when they should have been widened for performance requirements, splash oil could be minimized as well.

But in any case, this has got to be one of the best reads yet on camshaft failures. I am going to post this as a separate topic in the engine section. Some thoughts on cam and lifter wear | Camcraft Cams
 
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