This will probably be a very long post.

Here is the story.
I decided a while ago to do a cam swap.
I called around for shops willing to do with work and for how much. I finally called a shop that has been mentioned (but I will *not* mention until this entire thing has been resolved for good or bad, my over-reaction or not) on team chevelle a number of times, and liked the guy, he was enthusiastic, I checked with a reference who said he does great work.
I've consulted with 2 TC members in private that I have alot of respect for (for their time and accomplishments, and disposition as people) as well as talked with one guy in an "unsolicited email" need I say more.
here is the story. I was originally intending a hydraulic roller to hydraulic roller cam swap. The one shop that was going to do it was too pricey. I called another shop, that I was impressed with, cost a good deal less, and he talked me into a solid roller, which I have been on the edge of for a while anyway.
I said isky red zone lifters, he said, good choice. Agreement. I said cam duration somewhere near the 250's, he said great. Then there was this interlude, where I suggest cams, from the XR286R to some larger UD/Lunati grinds. I had sent a check to him to make it sure that I was serious about this, just for the cost of the lifters, cam and springs.
It turns out, that after I had emailed or called and left messages about what cams I thought would work and why, I got a message with two comp cams lobe numbers and a lobe separation angle. Which were already purchased.
Everyone with me so far?

This is the car:
4020lb, all steel, auto, stereo (with driver), "pro-touring" look 1970 SS 454 (460) (orig LS5 car, one day to be returned to its glory)
2 bolt block .030 over
forged eagle +.250 rods
forged SRP pistons
edelbrock performer RPM intake, rect port
holley 750 upper/850 baseplate "mongrel" DP done by original engine builder ~8 years ago.
Dart 320cc runner, rectangular port heads, with 116.5cc combustion chambers, picked by original engine builder ~8 years ago.
roller rockers with crane stud girdle
MSD pro-billet distrib, 8mm wires, 6AL
2" primary hooker super comps (picked by the orig builder)
compression of 10.15:1
TH400 w 3400rpm stall, GV OD (I'll sell it for the right price, maybe...), 3.90s in a 12 bolt. (original LS5 block, trans and rear..).
3" torque tech exhaust with 20" case dynomax hemi super turbos

I had suggested, a cam motion grind I forget the numbers on, a comp XR286R, and a larger ud/lunati 287/295 256/264 .660 roller on a 110 lobe sep, rec'd by UDharold.
I was told the XR286R and the cam motion were "the wrong grinds" for my motor, and that "he doesn't care for lunati parts."
So finally I get an email with the lobes and a lobe sep.
It turns out they are comp cams CR lift rule series lobes (which had browsed myself) of 287/291 256/260 .643 .643. Seems reasonable.
Until I got to the lobe separation. 113 degrees.
As I understand it-- wide lobe sep kills cylinder filling at low RPM-- which my large heads probably don't help to begin with. It flattens-- but lowers the peak-- the torque curve, which is ok by me. Aside from the lobe sep-- thats alot of duration. But my homework says its not entirely excessive-- the UD 288/296F10 has similar durations at .050, and is powerful and relatively street friendly.
But here is what I am thinking may happen: The lobe sep coupled with the duration and large heads will kill my torque, leaving me with a 2-ton barge that takes off slow and makes great hp at 7200 rpm.
but this isn't a race car. Its a enthusiast very high performance street/limited race car.

the builder said, that in my car, he expects peak torque at 4.5k and peak hp at around 6k or a little over.
That would be fine.
But from who I talk to-- its not adding up.

this whole thing flies in the face of DCR, heavy cars, so on and so forth.

Hobby folks, pros, engine builders, and fans alike--
what do you think?
I am calling him on monday to discuss the cam, mostly surrounding the lobe separation, but because I probably would have went with the UDHarold one or the XR286R on a 110.
I don't want to sound like a jerk on the phone-- its not a huge amount of money for the swap, dyno, and engine removal-install (I'd do it myself if I had known the weather up here was gonna be like this..), but I'd like more of an explanation than gut feeling on the phone.
I understand the cam is already bought-- I can sell the cam later, somewhere else, maybe to an EFI guy or blower guy.

so there it is..

Generally speaking when you say a car will be used on the street, lobe sep angle recommendations get wider . . . the wider LSA won't necessarily kill low end power, but rather widen your power band. It should in theory help your low-end and idle. It may sacrifice some mid and top-end punch in favor of the low-end IMO.

That may not be the best cam pick out there for all out performance, but its not bad IMO.

ps. your big rectal port heads probably won't help low end much anyway -- maybe thats what your builder was thinking when he spec'd 113* LSA. Would be a good cam for N2O . . . ;)

My opinion.

First – clear your mind. Remember all the good reasons you went to this builder in the first place. Remember – NONE OF THIS HAS CHANGED !!

Get them on the phone. You are the client – you have a few questions about the new camshaft, and are feeling a little anxious about it.

What experience does your shop have with this lobe family? Why did you choose this lobe family for my application – and what other lobes did you consider? Why is this camshaft the best for my application? (Carefully ask the last question – because this guy should be able to tell you exactly what your application is). Thank them for there patience in explaining this stuff to you. HANG UP.

Now – in your clearest, unbiased, and calmest state of mind – decide if you are confident that this individual knows what they are doing – knows what you need and are doing. If the answer is yes to both – LET HIM DO HIS JOB.

If you are not confident – get more info (like past dyno info from similar combos through his shop) until you are. At the end of the day – if you’re not confident – pull your stuff out of there – find another partner.

Examine your experience base – honestly answer “Do I know more than this builder has done?”

No insult intended – I have an engine hitting the dyno shortly – being built by someone who I have confidence in – and I have 2 different cams I want to try once I baseline his choice. Tis the nature of a hot-rodder smile.gif .


IMO

MAT

MadMarv,

You've already got some good info here,

I will tell you from my experience,
I've built quite a few performance engine as a side business and cam selection for a customer can be a PITA.

First you have to get a TRUTHFUL answer as to what the vehicle is gonna be used for, expectations, desired ET, desired driveability, and all pertinant info for the vehicle.

As well as future plans.

Then you make a very well educated guess and hope the customer is happy.

I've built quite a few mild SBC's for guys using the same grind but on different LSA's from 106-114 using Comp 268/270 lobes.
I've learned over trial and error that a 110-112 will usually keep them happy.
keep in mind these were 8.5-9-1 motors for a mild street app.

Had a guy tell me he wanted it to lope good..
So I had one done on a 106.
He did not like the results.
It sounded good, loped decent for a mild cam but it made the idle quality just bad enough that he had tochange converters, and it still was a little too "radical" (LOL) for him in gear.

The trade off for his lopey idle was too much in his case...

I've done the same on BBC solid flat tappets.
One on a 106 LSA, 236/248 duration. Idle was pretty lumpy.
Same cam on a 112 was a lot nicer to drive in a manual equipped car. Didn't want to chug at low speeds.

So even for my own apps now I'll give up some ET for a better idle.

A 106 LSA may be better on a strip car with the right setup but in a street car with a sometimes marginal setup most people will be happier with the 110-112 LSA.

So he may be err'ing on the side of caution...
And ET wise I doubt it will lose more than .15in the 1/4...
but that is a guess.

I would ask why a 113 though...
With alum heads and only 10.15 you have no need for the wider LSA to bleed cyl. pressure.
I probably would have selected a 110... and probably about 8 degrees less duration but that is me...

lobe seperation determines where peak torque will occur within the enignes power range. tight lobe seperations (such as 106) cause the peak torque to build early in the basic rpm range of the cam. the torque will be concentrated, build quickly and peak out.and fall of quickly. broader lobe seperations (such as 112) allows the torque to be spread over a broader portion of the basic rpm range and shows better power thru the upper rpm range. wider lobe seperations show a lower peak torque number.....but give you a higher average..........

in your case since your car is heavier you would be better served to have a broader torque curve to carry the cars weight.

i would not be concerned with 113 degree lobe seperation at all........this will alow for a smoother idle then say 108 or 110 lobe seperation cam. tunning the carb in for street use is better served here too using the wider lobe seperation.......since you wont have to deal so much with lose of vacuum idle.........

the guy who is doing the cam is thinking of these things it sounds like since this will be a driven car................now if this car was a drag car i would consider the smaller lober seperation cams for idle and vacuum would not be a concern.......


i have driven huge cams on the street and i have ran 116 lobe seperation just for the ease of being able to tune the car in for driving...........i might have been better served with a tighter lobe seperation but i dont think i missed any e.t. gain from it since the cars was running well into the 11 sec zone.........

also keep in mind alot of the old muscle car grinds were ground on 114 or so back in the day and they performed alot of street duty for gm and there owners.............

Thanks for the replies guys! I may or may not give him a call, I just don't want to be radically overcammed here, since I went in thinking a hydraulic roller in the 240's @ .050, then I was thinking the XR286R, and then I was led to this and its making me scratch my head.

Well-- either way, I'll have dyno sheets for everyone in a few weeks, and I'm doing both engine and chassis, although the engine dyno is done with accessories and my exhaust, so the #'s will look a bit different.
If we are only talking a negligible ET difference-- I really wouldn't care. If it will be a over camm'd turkey of a 2 ton car, then I would.

Matt

I was just thinking about the new, small, Erson Hi Flow AH older style BB hy-cam I have.

It's on 111/111 for just the reasons stated.

And it really gets me that one of the LS1 cams is 119/117.5 or some such weird, WIDE spacing???

I really think the 113 is throwing you a loop b/c I bet if it was either 112 or 114 you probably wouldn't have thought all that much about it, imho, b/c so many other cams are on them. I haven't picked up on many 113 cams myself so it does kinda stick out to me too..

I think you will be fine, again, imho..

pdq67

Comp Cams generally uses 113° LSA as a NO2-cam's LSA, according to their catalog.....

UDHarold