A lot of time on my build was spent getting the stanchion height correct so that all 16 valves were opening and closing evenly and at the desired time so as to get the rocker geometry correct. Now, weather that was due to sloppy machining back then or just age and the natural warping through many heat cycles, I will never know. The point is, most people when they rebuild, won't spend the time and effort to measure, and if they do- like Walt has- will find "inconsistencies". Erik
Here's another copy of the cam spec like above, but this one if from an old issue of the ROA's Riview in which Dennis Manner explains the evolution of the 401/425 cams from '59 through '66. Read what he says about where they started, what they did to improve them over the years, and what they wound up with for use in the dual four barrel engines. It adds some meaning to the numbers. Your part numbers ending in 90 and 91 are both listed. In his write up he refers to the 090 as "smoother and better idling," and the "091" as the original '59 cam but ground 4* retarded. Kind of makes one wonder what the seat of our pants is really telling us.
the 4* retarded you say is the lope speration angle [lsa] which gives you more bottom end not top,makes the car turn on faster,now adays most cams are ground on 110 lsa that seems the best for performance.doc is right again a 109 lsa would come on faster and make more peak power than a lazy 114 lsa. a 114 lsa would pull better in the upper rpms but the nailhead dont rev that high anyways to use the upper rpms
That's Dennis Manner's quote, not mine. Read the article. My opinion is that they retarded it by the position it bolts to the cam sprocket, like you'd retard or advance any cam by using an offset key. Mr. Manner does address LSA in his comments as well.
Not necessarily true. A 109* LSA will produce more PEAK power, but will give up some bottom end. A 114* LSA will produce less PEAK power, but will have more low end grunt. At the same time, it will also depend on the individual engine characteristics, whether the motor will prefer a tight LSA or not. My generally experience is that a 'Nail prefers something wider like a 112* LSA. I agree, they changed the intake centerline. In '59-'61 it was roughly 112*, and in '63-'65 it was roughly 116*. Retarding it that 4* would move the power band UP in the RPM range.
your right sorry misread, the lsa is built in no way to change that.to retard it on the cam sprocket would give it more top end plus 114 LSA more top end too, with a heavy car big carb or 2x4s and not to much gear it would feel real doggie on the bottom but the torque of the nailhead made up for a lot of that.still a 109 LSA with the cam put in straight up would feel a lot quickier.
i still respectily disagree on the part of the 114 LSA will have more low end grunt.its nice to get some back and forth discusstion lol. a 112 LSA will give you a better idle and more vacuum then a 110 LSA.i would split the difference and put mine on 111 LSA next time,mine IS A 110 LSA now custom made from comp cams they put it on 110 LSA with 108 centerline.my only input was i made them give me a lot more duration on the exhaust
Let me stir the pot a little more,,,:laugh: :laugh: My engine was a 1959 single 4 engine out of a LeSabre,,, I was , at the time, building my own GS...I rebuilt it to 1965 super cat specs... with the 091 cam,,,, and also put in a 1966 switch pitch turbo400 and a 65 gto posi with 4.11 gears...stock wheels with g70 polyglass tires....as I recall the car weighed about 3450 or so....and of course the red neck ram air, recurve dissy, and a holley 950 three barrel carb, instead of the 2x4's..... Under the hood it did not look that fast.... but I never had any car in my class beat it... what did beat it was a 57 stripped out chevy, with a unknown engine, and a 1970 Dodge challenger with a 440 six pack.... we raced 4 times straight in a row and he beat me a fender length all four times... I could not catch him....
The cam DID NOT have an offset key. The 4* retard was built into the cam. So when set straight up it was 4* retarded. The main reason behind this was when the 425 came about in late '63 they used the '59-'61/401 cam & instead of doing a re-design only for the 425 decided they could use the older cam specs to account for the extra cubes. It worked!!!! No one can really say it didn't. Yes, you can get a more modern cam grind that will increase bottom or top end, but most times you can't have your cake & eat it too. The best compromise still seems to be a wider LSA. When we went from a 110*LSA to a 112*LSA with pretty darn near the same exact specs we picked up 20HP on the engine dyno. So much so that the dyno operator had wished he picked a 113* or 114* instead. From 110* to 112* gave us a more usable torque/HP curve. Just my observations.
I was only referring to an offset key to try and explain that the cam itself was built with the 4* retard into it. I've read other articles where the owners of the earlier 401's complained to their dealerships that the cars didn't idle smoothly. Changes were made to meet the needs of 99.9% of the Buick buyers, hence the smoother idling cams as they evolved.
I agree. A wider LSA provides a broader powerband, with as you said, more usable HP/torque. A tight LSA has a much "peakier" powerband.
a tight LSA will also lower when peak power occurs, a nailhead does not make power in the upper rpms, why make peak hp in a range you cant use. comp cams came out with there new thumper cam with 107 LSA says its the best cam yet.i woud not run one on the street.dont like a rough idle.
its not always peak hp that makes a car fast its the power curve.were the power stays high for a longer time peroid.
This statement is incorrect. A tight LSA (like 108* vs 112*) will make power peak higher in the RPM range. I agree though that something like the Thumpr wouldn't be the best choice for a 'Nail. It would sound wicked though :grin: .
Guys, I'm not seeing this on the Dyno 2003 simulations....not that those sims reflect real-world Nailhead performance. On Dyno 2003, the tighter lobe center flat out makes more power than a comparable cam with 114 centers. I know Tom has REAL dyno data that supports the 114 centers, but how are you guys determining this?
Walt, generally a tighter LSA (like 108*) will make more power, and make it higher in the RPM range. That's why stock cars and dragsters use tight LSA's, and one reason why they sound so wicked. However, the 'Nail isn't like most engines, as I'm sure we all agree. Because the heads are so asthmatic, and they don't flow as well as other engines of similar displacement, the 'Nail, at least in real world conditions, performs better with a wider LSA. Plus, from what I've found looking at other builds and playing around with Dyno 2000/2003, although the 'Nail might make a few more ponies up top with a tight LSA, it gives up a significant amount of bottom end. That's just what I've noticed. I can tell you one thing, when I finally put in cam in my '62, it's going going to be on a 112* LSA.
Guys, a tight LSA makes more PEAK torque/power & often more AVERAGE also! It will make the PEAK power at a LOWER RPM than a wide LSA. A narrow LSA will also have more overlap and allow running higher static compression ratio's due to the "bleed off" of the extra overlap. Most nailhead cams have very little O-lap. Take a common 218*/228* on a 112* LSA. That cam would have 0* of O-lap at .050" lift! Put the same durations on a 108* LSA and you get 8*. Race motors running very high compression ratio's also run very large cams partly for this purpose. Static compression means very little FYI, it is the effective ratio or dynamic ratio that counts. I came across an article on LSA's and even though it is with a SBC it shows what the same durations but LSA changes do to an engine, granted all have different characteristics. Check this out: Remember Billy Godbold, guru at Comp Cams, said this: "LSA doesn't mean anything except for how it affects the camshaft centerlines." THIS QUOTE REGARDS THE FOLLOWING DATA. "You determine the centerlines, which determines OVERLAP, and THAT has performance effects." Another: The averages were determined by using all the numbers from 2,500 rpm to 7,100 rpm for ALL the cams. Yes, that is quite a range. To see the details of the full range of data, you'd need to get the magazine, but here are some more details about how the cams held on at the highest rpm recorded: For the dual plane test: the 107* cam dropped from 540 ft lbs at 4,800 to 397 ft lbs at 7,100, a 26.5% drop, but it still made 18 ft lbs more than the 110, and 11 ft lbs more than the 113 the 110* cam dropped from 533 ft lbs at 4,900 to 379 ft lbs at 7,100, a 29% drop the 113* cam dropped from 526 ft lbs at 5,000 to 386 ft lbs at 7,100, a 26.6% drop So the narrow LSA clearly held on best here. ------ Still for the dual plane test: the 107* cam dropped from 568 HP at 6,300 to 537 HP at 7,100, a 5.5% drop, but it still made 24 hp more than the 110, and 15 hp more than the 113 the 110* cam dropped from 566 HP at 6,200 to 513 HP at 7,100, a 9.4% drop the 113* cam dropped from 564 HP at 6,200 to 522 HP at 7,100, a 7.4% drop So the narrow LSA clearly held on best here as well. Its interesting that in both cases above, the 110* cam did the poorest job of holding on at the highest rpm. For the single plane test: the 107* cam dropped from 543 ft lbs at 5,200 to 437 ft lbs at 7,100, a 19.5% drop, but it still made 12 ft lbs more than the 110, and 9 ft lbs more than the 113 the 110* cam dropped from 540 ft lbs at 5,100 to 425 ft lbs at 7,100, a 21.3% drop the 113* cam dropped from 531 ft lbs at 5,100 to 428 ft lbs at 7,100, a 19.4% drop So the narrow LSA held on best here too, in pure numbers, though if you care about %, the 113* did a fuzz better. ------ Still for the single plane test: the 107* cam dropped from 607 HP at 6,600 to 591 HP at 7,100, a 2.6% drop, but it still made 17 hp more than the 110, and 12 hp more than the 113 the 110* cam dropped from 609 HP at 6,600 to 574 HP at 7,100, a 5.7% drop the 113* cam dropped from 608 HP at 6,700 to 579 HP at 7,100, a 4.8% drop So the narrow LSA still held on best here also. Its interesting that in these last two cases above, the 110* cam still did the poorest job of holding on at the highest rpm. So much for the commonly repeated theory that narrow LSA cams fall off at high rpm, and that wide LSA cams make the best high rpm power. Looks like another perfectly good theory gets destroyed by a real world test. THE 107* MADE PEAK POWER/TORQUE AT JUST ABOUT THE SAME RPM'S AS THE OTHERS BUT ON A MOTOR WITH A LOWER RPM RANGE(less durations) THE COMP GURU SAID THE DIFFERENCE WOULD BE GREATER, JUST GOOGLE CAMSHAFT LSA EFECTS One reason the nailhead may not rev is the lack of overlap. maybe somebody could try a 108* LSA with the same durations they would ususally run and see the differences? Donations? LOL
