[blykins]

Originally Posted by Cliff R

"Cliff, I may send you a bump stick to try...."

What application?

HIS, if you move the cam to a tighter LSA it will INCREASE overlap and decrease cranking pressure. You might offset this some by advancing it, but I've tried all that stuff and the 455 engines absolutely LOVE the ICL in the 108-110 range and LSA out in the 112-114 range.

Doesn't mean they woln't run OK with tighter LSA and advanced intake positions. Even with that said my past experience with these things has shown that until you get into pretty "big" cams, moving the LSA tighter than 112 degrees doesn't work as well.

For our full "race" stuff, we usually have them on 110LSA's, and .050" numbers 260 @ .050" or greater. Since we're over here in the street section, most of our street engines use 112 LSA, and on occasion will move them out to 114. Lots of variables in the equation and decision making matrix for that deal, we just do what works well based on the testing we've done.

I think I posted this dyno sheet earlier on another thread, but here's what happens when you let the customer supply their own custom ground cam highly recommended for their 455 engine build from another vendor.

We built a 455 like many others we've done using the 290cfm KRE heads from Dave at SD. In this instance the owner supplied the cam, 244/252 on a 110LSA. We usually see around 550hp/600tq with the exact same engine using the Old Faithful cam from Dave at SD. Look at the dyno run below and see how much power we left on the table and the engine quit much earlier in the rpm range..........Cliff

Doesn't hurt to experiment a little.....that's how we learn. I've found that the tighter LSA stuff can work well with the right combination.

The 244/252 cam against the Old Faithful cam looks to be just a mismatch of appropriate parts. It wasn't the LSA's fault, but possibly could be running out of valve spring, too aggressive of a lobe, or the duration did not match the cylinder heads/intake.

My drag race stuff is almost always at a 107-108 LSA and I have a '73 250 hp 455 Stock Eliminator camshaft that is certainly not a 112 LSA....

Just thought if you had some time to play, we could float some parts back and forth.

[Cliff R]

"The 244/252 cam against the Old Faithful cam looks to be just a mismatch of appropriate parts. It wasn't the LSA's fault, but possibly could be running out of valve spring, too aggressive of a lobe, or the duration did not match the cylinder heads/intake."

Not so. Actually that cam was supplied by one of the biggest Pontiac engine building shops in this industry to replace the OF cam at much less cost. It did OK, but came up WAY short of the OF cam at every rpm.

The last one of those engines we dyno'd made 552hp/604tq and over 500 ft lbs torque across the entire load/speed range. The ONLY real difference was the camshaft.

The flat solid had PLENTY of spring pressure, same springs we use for the OF and RP roller cams, and it never showed any signs of "lifter crash" like the Comp XE cams do around 5000-5200 rpms.

On paper it's a bigger cam in terms of .050" seat timing. The engine didn't see it that way, and the 110LSA pulled power down in the rpm range.

As far as experimenting with camshafts, I've done a LOT of it, even tested a custom ground HR recently ground on a 111LSA with "better" lobes than Dave uses for the OF cam. It actually did very well, and made the power we were looking for, but showed NOTHING better anyplace than the "lazier" lobes the OF cam uses and wider LSA.

All of my full drag race and circle track stuff in other brands than Pontiac are super tight LSA with few exceptions. I also pull the LSA down in the 3.75" and 4" stroke engines in most cases. With the 4.21, 4.25, and 4.5" stroke Pontiac builds and big CID in street applications we go the other direction. The biggest reason is that it allows for higher compression on pump gas, as it spread out the torque curve instead of narrowing it up. It also pushes peak torque and HP higher in the rpms range, where the events happen quicker and less tendency to ping on lower octane.

Brent, I wished you could have been here the day a customer brought his very well prepared 455 Super Duty engine to our shop for "custom" tuning. He had a TON of money in the build, 9.5 to 1 compression, and XR276HR cam. That engine acted like 12 to 1 compression and POUNDED like sledgehammers with normal timing/fuel curves in it. I've never seen anything like it, had to limit total timing to 26 degrees to get it to quit pounding and really throw some fuel at it. It wouldn't even take 8 degrees from the vacuum unit at cruise or it pinged pretty hard. Without high octane race gas it was a complete TURD everyplace, and we couldn't "crutch" it with any sort of tuning.

About all I could do is install a set of Harland Sharp 1.65 rockers which helped some (acts like a small cam change), but it still wasn't going to effective manage pump gas.

I'd also add that that cam idled like shi#, and noticeable "reversion" around 1800-2000rpms, where the engine kicked and bucked in protest to the early closing intake and tight LSA. I've ran into that a LOT with the longer stroke stuff, and don't know why it happens, but when we run into this it is ALWAYS with 108/110LSA. Our 112/114 cams idle really nice, and smooth off idle and for all "normal" driving.

Anyhow, we're pretty much done here with engine building, at most 1-2 a year these days. They just don't ship in a 12 x 12 x 12 box like a carburetor does!........Cliff

[blykins]

Can you post the specs of each one of those cams please? LSA and ICL are just small pieces of the puzzle.

When someone gets results 180° from me, I'm just interested in seeing why....

I get you on the engine building. If I didn't enjoy it so much, it would be much more worthwhile for me to just sell parts.

[Cliff R]

No need to dissect the cams, the flat solid was chosen as the OF replacement at much less cost. It's spec's out at .015" tappet clearance and the OF is most likely .006" so difficult to compare them anyhow. I did all that back when the flat solid didn't make the grade. It's just a smaller cam, at least that's how the engine saw it.

Going by memory here, as I need to get in the shop and pay the bills, the OF cam is 289/308, 236/245 112LSA, lobes are .381".

The solid was 281/288, 244/252 on a 110LSA, lobes are right at .350".....Cliff

[blykins]

Hydraulics are usually measured at .006" seat duration and the solids are usually somewhere around .015-.020". So, the solid flat tappet should have been larger in both advertised and .050". As I mentioned, something else was amiss here besides the LSA. Could have been that it was more duration than what the heads wanted, more aggressive than what the valve springs wanted, or the cam wanted more fuel, etc. Just doesn't add up though based on what I see here.

Not really a good apples/apples comparison as well. If you would have tried the 236/245 112 cam and then tried the exact same specs with a 110 and lost 50 hp, then it would have been a valid comparison. Too many different variables changed between the HR and the SFT though.

[Cliff R]

There are ALWAYS variable with these things, but nothing was amiss for head flow or spring requirements. We did not see the springs go "stupid" on the pulls which has happened numerous times with the Comp quick-ramp stuff.

Every time I've tested a flat solid against a hydraulic cam I've went at least 10 degrees more duration @ .050" and LOST power. I think they need to be about 15 degrees bigger to make up the lost ground, but that's just an estimate based on the couple tests we've done, and one of them was back to back without any other changes so a bit more valid than this test.

I'd also add here that we spend most of the day on the dyno with the engine in question here, as the very first pulls were WAY off the mark. I tried various different valve lash settings and couple different sets of rocker arms, and timing/fuel curves from one end of the spectrum to the other. The dyno sheets posted were the very best we could come up with, that cam just did NOT make the grade in this application.......IMHO.

You also have to factor in here that we are trying to outrun a cam that Dave at SD has spent a LOT of time working with for his custom CNC ported cylinder heads. It's like some Holley guy sending me his best work and trying to outrun my Q-jet, never happens, because my Q-jet is tuned EXACTLY for my engine, with over 1000 documented drag strip runs, tens of thousands of street miles, and countless dyno sessions to nail down the tune.......Cliff

[77 TRASHCAN]

Cliff, I'd guess you won't be wasting any more time experimenting w/ SFT cams?

[Cliff R]

Correct, as much as I like flat solid camshafts, they woln't run with the flat hydraulic or hydraulic roller cams on a "pound for pound" basis.

I got singed pretty hard twice now hoping one would make the grade. We're sticking with the flat hydraulic cams with Rhoads V-max lifters/high ratio rockers, or going HR instead. I no longer have any fear of "scrubbing" a lobe with flat cams, we simply make sure we use good USA made Hylift or Johnson lifters on them......Cliff

[Half-Inch Stud]

DITTO on Flat HYD cams.

[blykins]

Clarify pound for pound.

[Skip Fix]

Originally Posted by Cliff R

Correct, as much as I like flat solid camshafts, they woln't run with the flat hydraulic or hydraulic roller cams on a "pound for pound" basis..Cliff

The one I stuck in the RAIV motor ran to the decimal the same, pulled a little harder on the top end, it was about 24 degrees bigger at 0.050 but the same seat and a good Harold Brookshire cam.

[Cliff R]

"Pound for pound" simply means that you look at the seat timing of the hydraulic cam being replaced, and try to pick the flat solid with enough duration and similar lobe positions to do the same thing.

The unofficial "rule of thumb" used to be to add about 10 degrees @ .050" for a flat solid when replacing a hydraulic cam. From the testing I've done it's going to take a little more than 10 degrees, probably closer to 15-18 degrees or so.

So the first test we did was to duplicate the performance of the Crower 60919 cam in my first engine. It made 494hp/567tq, with peak HP at 5600rpm's. The 60919 cam sports 304/314 seat timing, and 231/240 @ .050" on a 113LSA. We went into the lobe catalog and chose a Comp lobe with 240/248 @ .050" and put it on a 112LSA. Nearly as I can remember it was rated around 284/294 @ .020" tappet lift, and the lift would be .560" with the rockers we were using instead of .530".

So all in all it looked to be a bigger cam and hoped it would improve power and take the hydraulic action of the lifters out of the equation. When we fired up the engine after cam swap I knew we were in trouble. The 60919 cam even with Rhoads lifters on it made about 11-12" vacuum and noticeable "attitude" at idle, the flat solid was near 14" vacuum and idled much smoother, more of a "deep/heavy" sound with no noticeable lope anyplace....hum?

We started making pulls and were coming up around 480hp/540tq. At the end of the day after trying everything we could we ended up with 484hp/545tq, so a solid 10hp and 22ft lbs off the hyd cam and it quit at 5200rpm's instead of 5600rpm's.

The best pull was actually made with a single plane intake and big Holley carb as the single plane intakes push power up some and improve power above apprx 4400rpms in engines like these.

Anyhow, we threw the towel in and ordered a custom ground HR cam with 284/296 duration, 230/242 on a 112LSA. It had .361 lobes so over .600" lift with the rockers we were using.

We put the stock intake back in place and we rewarded with 497hp and 571ft lbs torque, so the roller made more power than both of the other cams. Since the dyno doesn't tell the whole story with these things, we took the car to the track and were able to run quicker than the flat hydraulic cam.

The best runs the 60919 cam made were 11.64 @ 116mph. The roller cam went 11.52 @ 118mph, so there are advantages with the roller set-up that don't show up on the dyno. Most of it is probably that the engine revs faster and the vehicle gets there a little sooner.

Several years later we built the 455 with the SD Performance 290cfm heads described above, and once again used a larger flat solid cam to replace a hydraulic cam, and came up pretty short in power everyplace.

At this point I'm unlikely to try any more testing in that area, it's costly and we've found some very good combinations that do everything we want.

Anyhow, the SD 455 is finished, dyno to be scheduled for first week in April, results to follow.......Cliff

[slowbird]

We had a solid in our 406 that was 246-254 on the intake replaced that cam with a hyd roller that is 242-248 on the intake and so far we havent ran better than the solid.

[blykins]

Cliff, would you be able to post the dyno sheets between those two camshafts?

[Cliff R]

I don't have the dyno sheets on the three camshafts. There were on my last computer but it crashed and I lost the information. Hard copies are long filed away as this testing was done around 2004, and I don't have time to look for them, sorry.

I will say here that these cams mentioned in the comparisons were not just randomly chosen by myself. In both cases some of the best folks in this industry supplied them after looking at everything we were doing, knowing we wanted to get the power of a well chosen HR cam at much less cost. Two different companies and the same results both times. Makes a guy wonder how much bigger you really have to pick a solid cam to run with a hydraulic cam?

For a flat hydraulic it's easy. Choose it close to the HR, and high ratio rockers and Rhoads lifters and you will have your "poor mans HR camshaft". Just make sure to stay away from the fast ramp/short seat timing stuff and mimic the lobe positions of the cam being replaced closely.

I'm actually very tempted to replace my OF cam when my 455 comes out here in a week or so and replace it with a flat hydraulic cam just to see if I can make the same power. I'd be doing it as a test. I'm thinking about using the 239/247 UD cam or the Crower 60245 (248/252/112). Since I'm upping the compression a bit looking closer at the bigger Crower cam, the Crower cam is pretty "hefty", but I'll run Rhoads V-Max lifters on it to tame it a bit.........Cliff

[blykins]

Originally Posted by Cliff R

Makes a guy wonder how much bigger you really have to pick a solid cam to run with a hydraulic cam?

From what I've seen here, around 10-12 degrees. I can't be spot on because I have never did an A-B test on the same engine. However, I have built two engines with the exact same displacement, same cylinder head flow numbers, same valves, both dual plane intakes, and one had a hydraulic roller and the other a solid flat tappet.

The only caveat is that the SFT motor was 12:1 and the HR motor was 9.5.

The cam specs for the SFT were: 240/246 @ .050", .620"/.614" gross lift, 108 LSA on a 103.5 ICL. Advertised duration was 271/275 @ .020".

That engine made 476 hp @ 5700, 489 lb-ft @ 4400.

The cam specs for the HR were: 227/233 @ .050", .582"/.572" lift, 112 LSA on a 106 ICL. Advertised duration was 283/295 @ .006".

That engine made 422 hp @ 5500, 467 @ 4000.

Both engines had the same connecting rods, both had Diamond pistons and the same ring pack.

The SFT easily pulled higher in the range and obviously made more hp, even with the added compression.

As you mentioned, you would have to compare advertised durations at the same spot, but I would expect them to be extremely similar in that aspect. Overlap is probably, once again, very close to one another.

I use .050" duration to control where the horsepower rpm peaks and I always allow more duration to make up for the duration that's lost with valve lash.

[Larry Navarro]

.....it would be interesting to see an old H-O racing cam like the HC-63 242/252 with a 115 lsa installed in that engine. MY experience was nothing but favorable and with stock SD components and specs.

Ken C. call your office.

[Skip Fix]

Mine was an A-B test. That motor had 4 different cams, 3 different intakes, 2 carbs, 2 sets of headers dynoed or swapped in the car. Cam swaps were all in the car no suspension changes.

[johnta1]

Hyd Roller Cam:
Intake Duration : 283º @ .006"
Exhaust Duration : 294º @ .006"
LSA : 112º
Overlap of 64.50º

Flat Tappet Cam:
Intake Duration : 271º @ .020"
Exhaust Duration : 275º @ .020"
LSA : 108º
Overlap of 57.00º

------------------------

Hyd Roller Cam:
Intake Duration : 227º @ .050"
Exhaust Duration : 233º @ .050"
LSA : 112º
Overlap of 6.00º

Flat Tappet Cam:
Intake Duration : 240º @ .050"
Exhaust Duration : 246º @ .050"
LSA : 108º
Overlap of 27.00º

I wouldn't call these cams 'comparable'?

One reason the 'advertised' numbers don't work well?

The hyd roller cam is pretty mild compared to the flat tappet when using .050" numbers.
(not figuring in the smaller lift which possibly hurts the power?)

[77 TRASHCAN]

Originally Posted by Cliff R

I don't have the dyno sheets on the three camshafts. There were on my last computer but it crashed and I lost the information. Hard copies are long filed away as this testing was done around 2004, and I don't have time to look for them, sorry.

I will say here that these cams mentioned in the comparisons were not just randomly chosen by myself. In both cases some of the best folks in this industry supplied them after looking at everything we were doing, knowing we wanted to get the power of a well chosen HR cam at much less cost. Two different companies and the same results both times. Makes a guy wonder how much bigger you really have to pick a solid cam to run with a hydraulic cam?

For a flat hydraulic it's easy. Choose it close to the HR, and high ratio rockers and Rhoads lifters and you will have your "poor mans HR camshaft". Just make sure to stay away from the fast ramp/short seat timing stuff and mimic the lobe positions of the cam being replaced closely.

I'm actually very tempted to replace my OF cam when my 455 comes out here in a week or so and replace it with a flat hydraulic cam just to see if I can make the same power. I'd be doing it as a test. I'm thinking about using the 239/247 UD cam or the Crower 60245 (248/252/112). Since I'm upping the compression a bit looking closer at the bigger Crower cam, the Crower cam is pretty "hefty", but I'll run Rhoads V-Max lifters on it to tame it a bit.........Cliff

Cliff,
You need to build a 505 for the Ventura , of course after you test the 400 slated for near install! Would the 60245 be a candidate for such an engine?