saleenpride1986

Although woodsy and I had a minor tiff a while back, I'm with him on this one..

gearbanger

well the engine ( if it helps) is a 347 with forged crank rods and pistons.. compression is 9.5:1. afr 185 heads(58cc) and rpm2 intake... as for cam specs that all the info i got.

jtmustang

man if u are spending 300 on a ots cam there is no reason not to contact someone like jay alen at www.camshaftinnovations.com and talk to him to set u up with a custom cam..

it would benefit u a lot better as he would tailor it to your motor and type of driving..and so on...

Portmaster

To quote you" These Numbers are Useless to a degree, how agressive it is at .200, .300, .400 thats what you need to know"

I'll explain

Lift

Lobe lift this tells you how far the valve opens (obviously) but I thought I'd throw it in so other people will know that are curious. Just assuming this cam has a lobe lift of .350 at the lobe (the only accurate way to measure lift)then mutiply that by the rocker arm ratio. With a 1.5 rocker the lift at the valve would be .525 assuming you have good rockers, most are close and rarely dead on. if you put a 1.6 rocker on lift at the valve would be .560 and 1.7 Rockers would make it .595. Changing the rocker arm ratio changes lift throughout the duration of the lift cycle. So knowing the lift on your cam tells you how far your valve will open.

Duration

Duration is measured on crankshaft rotation and not camshaft rotation. Advertized duration varies from one cam grinder to another. The duration measures from where the lifter starts to rise to the time it hits the base circle of the cam. Each type of cam has it's own ramp angle so if you know what type of cam you have Hyd flat tappet, solid flat tappet, hyd roller, solid roller. You can tell how agressive the cam will be. If you have a Hyd Flat tappet cam and advertised duration is 292(most cam grinders measure advertised duration at .006-.008) Then some years ago in oder to give it's customers a better idea of how agressive the cam would be they agreed to measure cam duration at .50 lift. So if this cam has a duration of 244 degrees@.50 lift it tells you that the cam is going to be fairly agressive when you figure ramp angle from 292@.06 to 244@.50 But were not done yet.

Lobe seperation lets you know a little more about how agressive your cam will be. Lobe seperation can run a wide range but I'll give you two examples one cam at 110LSA and the other at 114LSA. Assuming both cams have the same duration, the same lift here is how they will react.

The cam with 110 LSA will have more cyl pressure, Less Vac signal (so forget those power brakes) More Peak Torque, Real rough idle quality and will fall off at high RPM.

The cam that has a 114LSA will have a better Idle, better vacuum signal and while the peak torque won't be as much as the 110LSA the torque curve will be a lot wider and flat. Then it won't drop off RPMs near as soon. One reason Pro Stock Cars run super wide LSA.

So if you wanted to build a drag car to run 1/4 mile that has no power brakes and no concern with idle quality and is RPM limited and a steep gear the 110LSA will do a better job.

If you have a car that has power brakes, Needs better idle qualilty, needs to run really high rpm, is light and has to make power right into the stratosphere the 114 works better.

I hpe this gives you a better understanding of what I was talking about. Please teach me what you know, I'm always looking for a better way.

Portmaster

With just that information assuming you have somewhere between a 3:23 and 3:73 gear in the rear and your car weighing 3500 pounds with driver and full tank of fuel I'd pull an off the shelf grind. A Comp Cams XE274HR would make a nice street cam. It's going to have a little bit of chop, still be compatible with your fuel injection and going to make gobs of power from 2200-6000 rpm. While I could come up with a grind that would make better low end or high end power I put you somewhere in the middle and left you with a little chop in the idle. I think sound quality in a street car is a good thing even though sometimes it isn't optimum for Time slips at the drag strip. A lot depends on your gearing, weight, where and how you use it and a bunch of other varibles. In your case I don't think a custom ground cam is really where you want to go. 7 out of 10 engines I've built got a custom grind. Thats only because the use of the engine was specific to the car and a specific use and nothing else. There are a lot of off the shelf cams that will do you great for your street car without the cost of a custom grind, When it comes to custom grinds I have only three places that I would let grind a cam for me. Comp, Crane or Isky. Thats a personal preferance for what it's worth.

w8less

im subscribing to this one....
i think i am going to try and invite a guest to this one

woodsy

Cam "events" are the things that will make or break a camshaft. Taking max lift and duration at .050 is useless. Tell me how you are going to take those numbers and apply them effectively. The cam events, the rate at which the lobe accelerates, the lift, the dwell at lift. Those are what make the intake and exhaust centers, the centers make the LSA. If you focus on the LSA, your backwards.

You have no idea what lobes were used in that cam, comp cams alone has 10,000+ lobes to choose from. For all you know it might have a cranking compression of 155 and rev up like a diesel truck or might crank 215. I hope you have answers for your customer when he calls you back wondering why his junk either wont start or wont move out of it's own way.

Im done with this thread.....

WhiteWindsor

What does he know?? It's not like he builds engines for a living

gearbanger

i didnt mean for anyone to get mad lol.... yes i got 373's thw car wight was 3400 with me in it. with the aluminum heads ill be around 3350 and mabe less if i take off the a/c... the guy that recommended me this cam told me it would be a good cam because of the gearing i have... im still looking around its either this one or a comp cam. i need to get my shizznet straight soon.

Portmaster

I may not be able to explain myself well enough for your understanding but all I keep hearing out of you is "Your Wrong" "Your Backwards". I realize there are so many differant cam profiles and every cam is a little differant. As far as "Cam Events" what the hell do you think I've been saying.Comp Cams (who I've dealt with on almost a daily basis for the last 20 years until last year) isn't stupid enough to put the wrong ramp profile on a special order cam. I would think someone of your intelligence and stature would have thought of that. While I may not be as smart as you are I can hold my own but I'm always willing to learn something new and it certainly won't me the first time I was wrong in how I decribed something.

There is a big differance between types of cams as well when it come to Hyd,Solid, Hyd Roller and Solid Roller. The ramp profiles are differant for each.
While many people think a Flat Tappet rides on the flat it actually skateson the edge rotating the lifter in it's bore and this is why a flat tappet has to establish a wear pattern. The ramp angle will be differant than a roller cam. Also a solid flat tappet cam with the same specs will perform differantly. The biggest drawback to a flat tappet cam in either solid or roller is you can't use real strong valve springs where the Solid roller takes over. You can't use the same type of profile on a roller cam as you can on a flat tappet cam. Trying to do that would make the roller lifter jump the ramp thus roller cams have to smooth out the "Event". The slight taper on flat tappet cams as they spin the lifter in their bores pulls or pushes the cam into the block thus no need for a cam Button. Roller cams need something to hold the cam in place becuse they can "walk" it's the differance in the profile of the cam, taper and lifter type that determine the ramp angle.

While some people think a hyd roller is the end all type of cam a good solid flat tappet of good grind will make more power and more RPM without near the ramp profile. Hyd roller cams are good because it gives you good lift without the constant valave adjustment of a flat tappet solid lifter cam. A Hyd Flat tappet will spin higher rpm than a Hyd roller but because of limited lift loses power from lack of flow. The Solid roller is the most power productive cam because you can use super strong valve springs and huge lift but all that comes at a price. The lifters get beat to death and when one of them comes apart it's bad, in most cases, real bad. i've had a solid roller come apart and ruin a 9000 dollar short block. I changed the lifters in my Merlin Big Block Chevy every 2500 miles. It's expensive to keep up.
The Hyd roller cam offers good performance, low maintenence but comes at a price as well. It's very RPM limited and Valve spring pressure can't be very high and that causes drop off of High RPM. In most cases by the time a Hyd roller cam with the right springs is done below 6700rpm. The first set of Valve springs I had in mime dropped off at 6200 rpm. I swapped out the springs to a set of behive Comp springs made for Big chevys, swapped out the rockers for something lighter on the valve and picked up another 500 rpm. While it will spin past 7000 it falls off so bad at 6700 that it's useless to go farther. I could throw in a solid lifter flat tappet cam and it wouldn't stop spinning until the rods go on vacation.

Suffice to say every type of cam has a differant type of ramp profile. I knew that and tried to explain to you how it works. I would invite you to challange my train of thought because even at my old age I'm a dog that can learn a new trick. I can tell your a smart guy by telling me how wrong I was with no need to explain your point. I would hope that you would think enough of me and all you buddies here exactly your theory. I'm sitting on the edge of my seat waiting for your reply.

While I've made some real blunders in cam selection in the past and have a stack of old cams to prove it I've always exceeded my customers expectations on what they paid me for. Most of the blunders I made was back befor Hyd rollers and we would have sit down sessions and talk about it and then when it was ground it just wasn't what we thought it would be. It was never a case of the car wouldn't start but just a case of the engine didn't make power right where we wanted it to. But then again once in a while we hit upon something special and unexpected.

I'm retired now and sidelined due to some health problems and I just piddle around but I havn't lost my mind yet as you seem to think. i'm not rich and I don't have a yard full of 9 second street cars but I've built some pretty nice examples over the years. I fully expect my little Coupe to bust into the 9's (way up high) and it has one of those "My Grind" cams in it. It made 581 Hp at 6300 rpm and 499 lbs ft or torque at 4800 rpm. No Blower, No Nitrous just all motor with nothing exotic just some careful selection, good port work and one of those cams I had ground. Must have go lucky for a guy who doesn't know what I'm talking about. Please fill me in because I could use anothe 50 hp or so. That shouldn't be a problem for a guy of your caliber.