Got the heads installed today, and mocked things up and measured for pushrod length. Ordering those parts tomorrow. We did discover that new guide plates will be needed. The last builder heated up stock plates with a torch and opened them up for 3/8" pushrods with a pair of pliers. They are all over the map for side clearance, and they were heated up to a point where I'm certain they are "soft" (one is actually cracked from the process they used), so we're going to install new ones with the new pushrods.

The length came up right at 8.900", that running the plungers in the middle of their travel. The lifters are Lunati hydraulic rollers. They are pretty short travel, and appear to be very well made. The are showing a total of about .075" available pre-load, so we are going to set them at .040" from the plungers bottom out......Cliff

So Cliff, I am guessing you are going to go with a XE264 for the cam? Just kidding, just kidding. I have been spending too much time on Yellow Bullet, I am turning into a smart ass. All kidding aside I really do appreciate you guys publishing your builds and not claiming it's all trade secret and won't publish numbers. It's a big help to guys like me to learn what works and what doesn't.

We got the rest of the parts last night from KRE. New pushrods, laser cut guide plates and 1" long locknuts.

Finishing up the top end today and scheduling our dyno session at KRE. Should happen around the first of next month.

The only thing left is the carb and distributor, hope to have them done over the weekend........stay tuned, dyno results to follow.......Cliff

PS: if our custom ground HR cam comes up short on power we'll order a Comp 268XE cam for it, or maybe even the XR276HR roller version of it so we can see how much power the big 455 Super Duty can really make!......LOL

Why go to a smaller cam?

To knock about 90 HP out of it! I was being sarcastic. Look at the dyno sheets below, plain old 455 cast crank/Eagle rod/Ross piston build with #96 heads flowing 250cfm.

With the Comp XR276HR it not only didn't make shi# for power it pinged on the dyno hard enough to get a new set of rod bearings.

Changing only the cam the engine idled better, improved throttle response, less "reversion" and quite a bit more power everyplace.........Cliff

I thought you were probably being sarcastic, but was asking to make sure. :)

On a lot of the hydraulic roller stuff I do, I've found that the more aggressive lobes lose horsepower because it's that much harder to control the valves...

With my Ford FE's, the more aggressive camshaft lobes (XE, XFI, etc.) will lose horsepower to the less aggressive lobes, and there's nothing you can do to make it go, short of some really light valvetrain, short travel lifters, etc. However, we're working with 2.250"/1.750" valves, 11/32" that are very long, etc.

With some engines, valve spring pressures and different lifters will help....I think that's what was going on with the dyno sheet you provided, but I'd have to see the cam specs for each cam. Obviously, going to a 114 LSA is gonna make it idle like a Honda....

Why so rich on the A/F ratios? You're about a full point under what we aim for.

"I've found that the more aggressive lobes lose horsepower because it's that much harder to control the valves..."

Could it be as simple as the valvesprings in use were inadequate to keep the valvetrain following the cam lobe profile. And that resulted in premature valve float that prevented the combo from it's full potential. Running stouter springs could solve the problem.


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No sir, some engine families just have their unique traits. I've tried less spring pressure, higher spring pressure, different oils, different lifters, etc. If the other reputable FE builders weren't getting the same results as me, I'd be a little worried....but we all compare notes and get about the same results. You can pretty much count on a hydraulic roller FE petering out at around 6000 rpm. Going to a less aggressive lobe makes more horsepower there.

Pontiacs are a little different animal and although something could have been up with Steve's spring pressure (quite possibly the case), it could have been the particular lobe too.

Again, I'd have to see the specs on each camshaft if he's willing to share. The LSA wasn't what was making the second camshaft work though.....I suspect it was the duration and lobe intensity.

Brent You were probably not on the board then but there was talk of the infamous "lifter crashing" Comp XE hydraulic flat tappet cams. In conversation a few years ago on this board a fellow was having issues with his 463 Pontiac combo that wasn't making power past 4700 rpm. He was using the Comp XE284 HFT cam. And it involved Comp 995 valve springs that had dropped down to under 100 lbs seat pressure and thus the combo was nosing over at rpm. Here the valvesprings in use were inadequate to keep the valvetrain following the cam lobe profile

Here was his comment later within another related thread:

"Do you homework, that cam likes more spring pressure than a typical HFT. Mine was done at 4700 rpm's and later testing proved the springs were too soft."

Later the often hated Car Craft Magazine ran a article that compared various cams. The cam they choose for the base cam was this exact same Comp XE284 hydraulic flat tappet cam that won't rev up in a "Pontiac".

For the article the engine used was a short stroke Small Block Chevy, and noted within the article this engine makes power to 6200 peak rpm with no issues. That said, It is important to note the valvetrain components they used for the XE284 flat tappet cam on this specific combination.

Used were Comp Pro Magnum roller rocker arms, valve springs with 153 lb seat pressure.

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Wouldn't surprise me.

Most guys go by the "recommend valve spring" that's located in the small print under the camshaft description. Big no-no. The cam manufacturer has no clue how big of a valve you're running, how heavy it is, your install height, which retainer you're running, or basically anything else about your engine.

All of these notes in the catalogs are to be taken with a grain of salt....always call an engine builder....not a cam "tech guy".

Personally, I'm not an XE lobe fan as there are other lobes from Comp that are not noisy and make the same amount of horsepower, but in all cases, all of the parts have to work together...

"Why so rich on the A/F ratios? You're about a full point under what we aim for."

For the record I had NOTHING to do with this engine build, or the dyno sessions. My contribution to the project came after the shop owner/dyno operator called me up and told me they "pinged" the first set-up and knocked the rod bearings out of it. Of course everyone involved was blaming the ugly Q-jet carburetor.

I had him give me all the engine specs, told him the cam was shi#, and gave him specs for a replacement cam. He followed my instructions, changed ONLY the cam, and the dyno sheets tell the rest of the story.




"Pontiacs are a little different animal and although something could have been up with Steve's spring pressure (quite possibly the case), it could have been the particular lobe too.

Again, I'd have to see the specs on each camshaft if he's willing to share. The LSA wasn't what was making the second camshaft work though.....I suspect it was the duration and lobe intensity."

Pontiac engines are going to respond poorly or at least not as well to really fast ramp stuff. Couple of reasons for this, one is the flat chamber floors in the heads and EXCELLENT low lift numbers. Why shove the valves right past all that and shorten up the duration, the factory heads flow very well to about .450" lift or so. Second reason is the port layouts, and port flow ratios, combined with very conservative cross section for the CID they are feeding. That statement is sort of an opinion on my part, backed up by quite a bit of engine building, dyno and track testing. To make things even worse for these engines are the long strokes, long rods, heavy internals and undersquare design. From what I've seen here the wider we put the LSA the more we are rewarded with smoother idle, broader power curve (torque), and stronger upper mid-range and top end power. Of course I'm describing street/strip engines, full race stuff and max-effort race car with muffler stuff you can pretty much run the monster cams on tight LSA's and make great power.

I deal mostly with "stock appearing", and we use crappy iron intakes, even the horrible EGR ones, q-jets, factory distributors, etc. Since most are in real street cars, that have to life on pump gas, dead solid reliable in any weather, and still run the numbers at the track on weekends, parts selection, specifically camshafts and compression ratios must be "spot-on" on the entire deal is doomed from the moment you fire it up.

Case in point is the Super Duty 455 we're building here, it was a pretty "high end" build, FULL of "exotic" parts, and very short lived. Even if the pistons didn't lock up in the bores it was showing signs of heavy detonation and a ticking time-bomb anyhow, not to mention the owner was having a horrible time trying to get it to run well for "normal" driving. It simply refused to idle well and behave on the street......Cliff

So are UD lobes considered too aggressive-since their @.050 RAIV version is only 288/296 seat duration?

What's the .050" duration of the UD cam?

Here's how I rate lobe aggression....

On a hydraulic roller camshaft, I don't like to see hydraulic intensity (advertised - .050") under 54° and would prefer for it to be closer to 56-60°. In most cases, when you start getting under 54° HI, you start hearing a lot of extra noise.

The lobes from Comp that sound nice and are not too aggressive include the QXX lobes, Thumpr lobes, *a few* of the Xtreme Energy lobes, the High Energy lobes, and the Magnum lobes.

On a solid roller on the street, I like to see major intensity (advertised - .050") of at least 38°. Those are considered street rollers and are really easy on the valvetrain and lifters. When you start getting to 32°, 30°, 28°, etc., the aggressive really increases and the maintenance intervals will go up.

Vizard’s View: Avoiding Flat Tappet Cam And Lifter Failure

In part....
Flat tappet cams are great at opening valves quickly. Contrary to popular belief they can out-accelerate a roller by a hefty margin if the cam designer so chooses it to. There are safe profiles, and there are power orientated profiles, and just about everything between. The key to knowing which profile you may be selecting is determined by its “hydraulic intensity.”

If nothing else leads to its downfall, a profile ground on a good core can have a hydraulic intensity of 50° – 55° and be a pretty safe bet in terms of reliability.

http://www.enginebuildermag.com/2006...ifter-failure/

And it will vary slightly from Harvey Crane's point of view because cams are rated at different tappet lifts....

"SECRETS OF A CAM DESIGNER"
BY HARVEY CRANE

http://www.4secondsflat.com/Cam_Design.html


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I personally think David Vizard isn't into anything but selling books and seminars, but it looks like we at least agree a little on that.....LOL

He is referring to a flat tappet instead of a roller though…

And Harvey Craine actually has several different terms based on where the lobes are actually measured.

It's not always as simple as subtracting the 0.050" duration from the "advertised" duration.

Again cams can be rated at different tappet lifts. Example Comp's popular XE solid roller lobe 4873 with 236 degrees duration at 0.050" tappet lift is rated at 0.015" tappet lift in the catalog with 274 degrees duration (advertised duration). Subtract 236 from 276 and that suggests a 38 Major Intensity. But note Harvey Crane stated for Major Intensity to subtract the 0.050" duration from the duration at 0.020" cam lift or tappet lift. It's not published in the catalog but Comp's solid roller lobe 4873 actually has 265 degrees duration at 0.020" tappet lift. Now you subtract 236 from 265 and you have a lower 29 intensity number. Is it aggressive or not ?

To further complicate matters note comments from Harold Brookshire (UltraDyne)..

Intensity is a Harvey Crane invention, and is to help everyone understand more about a cam. Major Intensity is Duration at .020" minus Duration at .050". This is used for solid lifters and Solid roller lifters. This has NO relationship to valve lash or ramp height, but measures the difference between .020" and .050".
Both Harvey and I design Unsymmetrical cams, where the opening side and the closing side are different everywhere except at the nose, where we match both sides through the 3rd derivative, at least. We both use different off-sets, the difference between the opening and closing sides, even at .050".
My old 288R that I designed in April, 1980, thought it was a 282 at .020 when it opened, a 252 at .050. Then it knew it was a 258 at .050 when it closed, and 294 at .020, still closing. The 288R was notorious for bottom-end torque, and good power everywhere. It had 176 at .200, one degree more than the Crane R260/4167.
What I use now is the R255416H. This rascal thinks it is a 279 at .020 when it opens, still a 252 at .050, still a 258 when closing, and now a 288 at .020. At .200, 180 degrees. I've lost 5 degrees at .020, kept the same duration at .050, and gained 4 at.200. It has gained power everywhere.
Remember, it is not WHAT the duration is, but WHERE the duration is, that counts in camshafts. Remember, the engine sees WHERE the duration occurs, not WHAT the duration is.l
Now that I've ranted about solid rollers, Hydraulic Intensity is the difference between .004" and .050". Yes, I know that many companies measure at .006", and you can add 6 to 10 degrees to their .006" duration to approximate the .004" duration.

http://www.chevelles.com/forums/13-p...y-formula.html


I think David Vizard and Harvey Crane were trying to make similar points.

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That raises a good point. You can make comparisons as long as it's at the same point on the lobe. Luckily, between my contacts at Bullet and Comp, I can call up and get the numbers I want so I can make an apples-to-apples comparison.

I suppose no matter what you call it (intensity, etc.), it's a valid way of rating how aggressive a lobe is, and the practice of doing so has served me right over the years.

The 4873 lobe is not aggressive at all....there are some errors in Comp's lobe catalog, got into this with a solid flat tappet lobe a few weeks back. Not saying this is the case here, but I would have to call the cam designer and find out.

I try to stay out of the "science" involved with these things, but we do a lot of testing with camshafts. I'm going to be one of the very few who has tested three different cams in the same engine on the dyno with no other changes. Those included a solid flat tappet, flat hydraulic, and hydraulic roller. All of those cams were fairly close in specs if you were looking at .050" numbers and LSA. This is the wrong thread to go into details on that testing, but I did learn a LOT from it.

Going to button up our 455 Super Duty tomorrow. We have just enough clearance for the stock valve covers, had to glue one thin gasket to the covers and put a thick one under it, but good to go there.

Woln't have much else to pass until we put up some dyno numbers. The engine will use the stock SD intake, correct factory 7044273 carburetor (no spacer), and correct factory points distributor. We will be using headers on the dyno in lieu of the Super Duty exhaust manifolds simply for convenience as they are not set up with head pipes for our cast iron manifolds.......Cliff

Looks good!