hereinmissoula

looking to make big mid range.. basically looking for highest cyl press. between them approx 6200-6500 redline

help?? lol


rebuilt 327
flat tops
vortecs (rebuilt, pinned press studs, 981 springs)
almost 10:1 depending on gasket i use
edb perf rpm vortec and 1 inch spacer
1 5/8 3 in coll. reduced 2 1/2 with flows
4.10 geared stick car
no power brakes
650 dp

http://www.lunatipower.com/Product.aspx?id=1874&gid=268

http://iskycams.com/timingchart.php?..._number=201278

Irockz

iTrader: (1)

I personally don't think you'd like either of those in a street car.For very little more than the cost of a shelf grind,most cam munufacturers will grind a cam that fits YOUR exact needs,rather that trying to buy a "one size fits all" shaft.

AlkyIROC

Those are both oval track cams and not designed for street use. The LSA is very small and won't be a good choice for any kind of street driving.

To increase the cylinder compression, the intake valve needs to close sooner so based on those cam choices, the Lunati should create more cranking pressure.

Exactly what do you intend to do with the car?

hereinmissoula

the lunati looks like it has advance ground in the isky not so.. is this right.. earlier intake opening and closing should produce little narrower power band but higher torque peak???

hereinmissoula

actually in a truck.. 4.10s were typo.. 4.56 and 4 speed.. 35 inch tires 4 in lift.. looking to stomp mud holes.... not a third gen but have gotten great engine advise hear

drivability not a concern... its a toy

skinny z

You don't have nearly enough static compression ratio to use either of those cams. Something more along the lines of 11:1 would suit the longer valve seat timing.
If you want to build torque, as in compression pressure, choose a shorter cam. Something with around 270 degrees advertised duration. Try to get as much lift into it as your valve train will allow. The Vortecs flow well up to .550" lift so take advantage of that. Be sure your exhaust has no restrictions. If you're mufflers are just off of the collector then you're in the ballpark. If the exhaust is up to par, then a single pattern cam would help with building torque too.
With the 4 speed you have more control over the rpm and COULD be build an engine with a peaky torque curve but with more peak torque. That would suit a tighter LSA and the 327 would probably prefer 110 (as opposed to a 350 which works better with 108 LSA). If you would rather have a broader torque curve, widen the LSA but I would think that 110 is about right for the parts you have.
The problem is your intended RPM of 6200-6500, the duration needed to make peak power there and the limits imposed by the low compression ratio.
Have you considered having the heads milled to help bring up the SCR? Then you could select a cam intended to make high rpm hp. At this point, the limiting factor to high RPM horsepower will be your valve train. The 981 springs probably aren't up to the task of controlling the valves at high rpm and the pinned studs are marginal at best.
If you would think about making power about 1000 rpm lower, you'd have better results and still have an enjoyable ride (again that's considering the parts you have already).

hereinmissoula

thank you for input skinny z... alky, thank you as well

my reasons for these cam choices were the tight lsa's and relatively early intake opening and closing, as well as having enough duration to make good power.. the tighter lsa should peak sooner than duration would expect and the lunati is quite advanced also bringing curve down into reasonable low 6k and building good cyl pressure in midrange...

i think taking .030 or so off the heads is great idea and thought of it my self, would love to be able to keep decent timing in it without pinging on 93 but.........

hereinmissoula

i ported and polished the exhaust and left intakes alone on the heads also.. why i am on single pattern.. and this should help torque as we correct ???

skinny z

Are you familiar with this article?

http://cochise.uia.net/pkelley2/DynamicCR.html

hereinmissoula

8.00 dcr
.018 shim gasket
60cc chambers. about .030- .035 off i figure
9.63 scr
figures w lunati cam

hereinmissoula

or 7.65 dcr using 65 as intake closing.. though pretty sure lunati is 59.. seems low though

305sbc

iTrader: (3)

Neither cam.

For high cylinder pressure in the midrange you want your intake duration to be between 212* and 219* @0.050" <-no that's not a typo.

You're shooting yourself in the foot by not porting the intake side.
Improving the flow of the intake port will increase power across the board, and will be especially pronounced in your midrange operation.

skinny z

My calculator says 71 degrees intake closing angle based on Lunatis 290/290 advertised spec and 106LSA/106ICL.

60cc Vortecs?

hereinmissoula

64's milled down to 60.. 906 heads

and lunati is on 100ICL

skinny z

I see that now. That said then yes, your intake closing angle should be 65 degrees.
With your calculated SCR of 9.63, the DCR falls off the map. If you can get your SCR up to about 10.25, then the 290 cam will start to work. DCR approaches 8.2 depending on other variables like piston height, valve relief volume and final choice of head gasket.
For what it's worth, my understanding is that tighter LSA's tend to work in larger cid engines whereas a smaller engine, like a 327 prefer broader angles. 108 for a 350, possibly 110 for a 327 although if you keep the overlap under control, 108 works too.

88IROC350TPI

There are zero cam experts on this site that I know of... I'd recommend you call Cam Motion if you want expert advice

skinny z

Really?

88IROC350TPI

Can you name one cam expert on this site that posts somewhat regularly? I don't know of any and I've been here over a decade.

I say this because I've learned a lot of hard lessons when it comes to camshafts and I've learned that the average hot rodder on the Internet can generally give you decent advice but rarely great advice when it comes to recommendations... It takes 10 minutes to call a company like Cam Motion and speak to someone that devotes their life to camshafts.

Im not knocking the folks here giving advice, they'll probably get ya a cam that will work well but a real expert will get you one that works better than most would ever imagine. According to most Internet gurus my cam is way too big and is a very bad choice yet my car ran better than similar combos, got decent gas mileage, and was 110% streetable.

skinny z

It would be difficult to tell who's an expert or not considering the format of the forum.
For what it's worth, cam science isn't that difficult to understand. Even less so if you're into a specific engine and even less again with specific heads. That's the stage set in this thread.
With computer modelling and the millions of gigabytes of information and testing that's available to anyone who cares to look for it, selecting an appropriate cam is not like it was when I started out 35 years ago.
Something else I've found is that most of the cam tech people I've spoken with are generally working off of some spread sheet and their advice often comes off no better than what you might find here. Of course there are exceptions and maybe your Cam Motion is one.
The issue is credibility. I don't blindly follow any advice that's given here without substantial support from other sources. That only makes sense.
It's all about research and sometimes it starts right here.

AlkyIROC

If you want a custom cam then don't go looking for off the shelf grinds like the ones you listed. The advice you're going to get about them is the same as you pointing a finger at a grind and saying it will do fine.

The expert advice you want is to call a cam manufacturer directly. Give Bullet Cams a call and have a camshaft ground specifically for what you want to use it for. Ask for Mark. Your second option would be to call Cam Motion. The list can go on and on from there but in the end, you'll probably be happier with a custom grind than a catalog grind.

hereinmissoula

i really appreciate all the input.. this has helped me out...

this is a budget build, i have put this together amazingly cheap ( i got the heads for 120$. 70k on truck they came off of, 327 for free very low mile rebuild) i work for an auto parts store so i got springs, seals, gaskets, pushrods, etc.. good price was trying to educate myself and try ( with some good opinions ^^hint hint^^) make a decision myself. don't really have 300 for cam.. i bought a motor that had cam made by Buddy Rawls and was fantastic (when i had a 5.0, dont hate me plz

skinny please elaborate on the cid relating to lsa?? i have no knowledge on that


thanks again for the help

hereinmissoula

i thought tighter lsa's like 108 and under tend to narrow power band, making it kinda peaky, but with big middle numbers and wider lsa's 110+ will tend to make a broad power band and better top end.. hence the 106's common in circle track to get off corners why i was choosing the 106, especially with the lunati that is advanced, should work well... as well as having enough duration to get things goin and make some power.. i wanted good torque number, never said low rpm even so i don't anticipate it be to high..

have not run this on any sim's as i have not played with those

skinny z

At the risk of being accused of trying to pass myself off as an expert I'll say now that I'm not. I will say I'm an avid student and in particular have paid a great deal of attention to heads in question and how they relate to MY particular build.
As I mentioned before, cam theory isn't all that difficult to understand. What does make it complicated is trhe scope of the field. Cam company tech personel have to be educated in applications across the board. SBC, modular Ford, Honda.....the list goes on.
I"ve narrowed my field of study to basic cam science and how this works with respect to the Gen 1 SBC and in particular, streetable high performance for lack of a better category. I don't jump into threads that are asking advice on TPI or turbos. These are outside my area of knowledge and I wouldn't think to offer an opinion that would lead anyone in the wrong direction.
As far as choosing a correctly spec'd cam for the OP, I'd like to think that at the very least there will be an exchange of ideas and he'll be equipped with a little more information than he had before he posted the first thread.
I have all the respect in the world for the guys who make a living at it, at least most of them. Some I have spoken with, and it became clear after some time in conversation, that they were a) preaching the company line, b) have to be conservative otherwise some guy will come back to them later saying the poor advice blew up his engine.
As was pointed out earlier, anyone who tours these forums and takes advice blindly by whoever dishes it out is asking for trouble.
Research.

skinny z

As far as LSA, SCIENCE says the the more an engine becomes undervalved, the tighter the LSA needs to be. What works in a hot 302 won't be even close to what's needed in a 383.
That said, yes, tighter LSA's tend to have torque curves that are not as flat a wider ones.
As an example, if you were building a 327 with a close ratio 4 speed for the drag strip, the choice of a tighter LSA (say 106 vs 110) will build a peaky torque curve. However with the close ratio trans, the ability to stay between peak torque and peak power allows you to put more average power to the ground.
You're correct in your thinking regarding the 106LSA/100 ICL. The advanced intake closing helps preserve some of the cylinder pressure lost because of the larger duration numbers. Another thing to consider is the amount of overlap that cam has. At 78 degrees, you better have your exhaust dialed in like the circle track cars do. Without a tuned exhaust as part of an overall package, the effects of the large overlap period will be wiped out and you'll have a poor performing/poor driving result.
As for the Lunati grind you've listed (I haven't checked out the other), I would think there are better choices.
Running the Lunati through a simulation shows why when compared to a shorter duration hydraulic roller.
The shorter cam makes more torque everywhere in the rev range. It's not until 5500 rpm, long past the point of peak torque, does the Lunati match the other cam.
At 2000 rpm, short cam: 365, Lunati: 338
Peak torque at 4000 rpm, short cam: 416, Lunati: 408.
The peak power numbers for the Lunati are about 500 rpm further up the rev range compared to the short, this by virtue of the larger duration numbers.
Keep in mind, this simulation was done on identical 350's with Vortec heads.

skinny z

For the record, I wholeheartedly agree.
Research.

AlkyIROC

The cam I use in my BBC has 114 LSA. The wide LSA helps it idle smoother with big lift and long duration.

skinny z

I know nothing about big cubic inch alcohol burning racing engines.

hereinmissoula

well skinny to be honest im thrilled the lunati is down so so little.. i know 4000 below not gonna look as good.. expected that and is okay w me.. the fact that the hyd. flat lunati ran numbers close to hyd roller is great.. there lobes far superior, though much more expensive!!! cam, lifters, better springs...

could u post results from your sim for me ... interested

hereinmissoula

and how does it hang to 6500, when does it surpass the short cam (if it does)

can u find a better hyd. flat???

InfernalVortex

iTrader: (4)

Im always going to be skeptical of what some so-called "expert" at some manufacturer is going to tell me. All they're trying to do is sell you their idea of the best cam. Unless you write them a novel about what you want to use your car for and every single mod on it I find it hard to believe they can get the cam that much more perfect than I can.

Do you really think they have that rigorous of a program to qualify for the "cam tech" position? Do you really think they are any less opinionated on these things than any other performance industry professional. I dont believe half the garbage Smokey Yunick says, I dont believe for a minute that some random guy answering phones at Comp is more experienced and/or qualified than Smokey Yunick. There's always opinions and personal convictions thrown into these sorts of things, and you go to a cam company and talk to 3 different techs and I wouldnt be surprised if there werent 3 different answers. Cam theory is NOT an exact science.

I go off what I see here, results I see here, and results I see in first hand, plus dyno tests in the mags. Take everything with a grain of salt, toss out the anomalies, go with what makes sense, and you're 90 percent there.

If off the shelf cams were so terrible the cam companies wouldn't bother selling them. You can get 90 percent there if you know which parameters to pay attention to, and beyond that how much more specific do you really need to be? Within that kind of margin does it really matter if you should trade off another 5ft lbs for another 5 hp at 3800 RPM?

If you want to trust what some paid employee of a cam company tells you then by all means, but at the end of the day they have a job because they're trying to sell you their cams and I listen to their advice but I dont weight it any more heavily than anything else I see, especially not more heavily than real world results I see in other people's combos.

I think this is my inherent distrust in "authority" coming out.

skinny z

Can you recap? What do you have for components?
I'll run some numbers but if I have specifics like induction cfm and manifold type, exhaust design (headers, dual mufflers, tailpipe), piston heights and dish volume, it makes for a better result.
I can work with the Lunati specs and stock Vortec cfm.

88IROC350TPI

I honestly don't think there is any point in buying an "off the shelf" grind... My current Cam Motion solid flat tappet cost me $157... That's cheaper than some off the shelf grinds and only a few bucks more than most... Paying the $20-50 extra knowing you have the right cam for your combo is worth it.

I love building my own stuff and learning everything possible but when it comes to cams I'll trust the pros over myself or the Internet any day although I DO NOT trust "major" cam manufacturers because they definitely have idiots working the phones using spreadsheets. I called Comp Cams three times over the course of a month with the same exact combo and got 3 different recommendations that varied wildly...

skinny z

I've been deep into this camshaft spec'ing since the flat tappet went away in my own 350 a few years back. While I picked a shelf grind, partly for convenience but mostly because, at the time, the tools and information I had available didn't allow me to get the data needed to make an informed choice. With the need for new heads this year (pulled the trigger on RHS 170cc Vortecs) I got back into the cam thing again and after speaking with some of the "majors" and doing HOURS of research, I came to the conclusion that the current spec was doing about all I could ask. However I do know that there's more on the table and once I sort out the new heads and get a baseline for this season, I'll make the rounds of the cam companies again to see if there's any kind of consensus on fine tuning a new profile.
I WILL make a point of contacting Cam Motion and Bullet cams to get their opinions.

hereinmissoula

skinny....

4 eyebrow flat tops -4cc or so??
650 dp holley, not hp, standard dp'er 4777 think is #
standard rpm vortec.. edelbrock, not knock off.. (heard runners are IDENTICAL to air gap)
havent measured yet (smog heads still on it) but sure pistons are .025 in the hole (maybe someone decked this and i get lucky)
1 5/8 full length 3 in coll. reduced to 2 1/2.. gonna try to get mufflers as close to collector as i can, might trade my flows for some bullets buddy has..

mildly ported exhaust and polished... was told to leave intakes alone unless i know what im doin with vortec runner, which i don't pretend to...

alsoi dont even have to modify my heads for more lift, or get crazy with springs with cam i chose.. if you can offer opinion on somethin better plz do

infernalvortex.... i wish there was a "like" button.. could not agree more, why i am trying to learn for myself and gather educated opinions

88iroc.. i had no idea u could get a custom cam ground so cheap, may look into this

skinny z

You may want to investigate the intensity of the "lift rule" cam you're working with. While it's not big on lift, the speed of the ramps combined with the rpm you intend to turn , demands a top quality valve train, particularly springs. I can show you independent testing where a relatively small cam (.500") combined with one of the more popular Comp 987 springs loses control at engines speeds approaching 5500 rpm and is completely unstable with big power loss by the time you're turning 6000. Something to think about.

skinny z

This is very similar to last seasons 350 I was running. I'll see how the data stacks up as a 327 and try to post a graph or two.

skinny z

I ran three quick simulations.
This is based (and this is important) on achieving a 10:1 SCR with whatever combination of parts you assemble. It also uses stock Vortec flow numbers and assumes a valve train capable of handling the RPM targets.
Check out the peak torque numbers and the rpm they occur.

(I hope you have Microsoft Word and can open the files. )

skinny z

I've been thinking about this since my initial post and while I don't have any experience with engines of your type (as I stated earlier) what does come to mind is why cam companies generally provide cam profiles with a wider than optimum LSA in the first place. It's largely to provide some level of idle quality and (not in your case) drivability.
The wide LSA reduces some of the overlap which has become excessive because of the large amounts of duration spec'd.
By paying more attention to the overlap period and combining it with an exhaust system designed to tune to a specific rpm range, then the need for the wider LSA isn't needed as overall duration can be reduced without a loss in power.
That's just the theory.

hereinmissoula

thank you so much!!!!!... would you mind running a non roller xe274???

smaller cam much better (as a roller atleast)

hereinmissoula

isky looks better than lunati.... wonder why.. maybe lunati too far advanced... isky alomst matched roller

awesome results

skinny z

Less duration, more cylinder pressure, more torque.

skinny z

XE276H and XE268H.