OCHOHILL

Now that I have your attention:

I have been researching for several months now and can't find a good sticky on camshaft selection. Camshaft selection isn't exactly voodoo but it does require some extensive engine knowledge and understanding. Things like dynamic compression ratio, duration and lift and how it effects other engine compenents and performance.

Many guys, like myself, are trying to build a motor around compenents they already posses. Others are trying to build in stages. I think it would be great if a knowledgeable guy could share his/her knowledge.

Things that I have learned that may surprise you. If I am wrong please correct me.

Static compression ratio means boo. Dynamic compression ratio is where it's at. Aluminum heads can run higher compression only with the proper quench. (Quench is the piston pushing air against the flat part of the head which blasts it into the chamber creating a combustion chamber with minimal hot spots- quench kinda acts like a fan)

8.5/1 dynamic on pump gas can only be achieved if the engine is properly quenched and timed. Otherwise, detonation will kill it.

Cams affect the dynamic ratio depending on when the valves open and close in relationship to the piston location (piston location is determined by valve events and crank shaft location with the math for the rod length and angle)

Think about this for a moment. Longer duration cams stay open longer. They may open sooner or later. If the valve is open when the piston is anywhere but at BDC then you are not compressing the same amount of air as a static compression test.

I don't fully understand all this stuff yet. I may never.

Here is what I do know. I have a set of Holley 2.02 heads. They have been ported. I believe these flow very well. I am on the fence as to what to do with them. I have a goal of 400hp at the crank. I would prefer to spend as little as possible. If it takes money to reach my goal, I'm OK with it-but why waste good dough right. So, since researching is free, I started running different camshafts into a dynamic compression calculator. My isky 265/275 makes a dynamic of about 8.00 while a ford X cam with 286/286 and more lift makes a lower dynamic of 7.65. I realize that the X cam would require a little more static compression to get a better dynamic but my question is which one will work better. How much compression can you give up for more lift and duration to make better power? Is there a cam that will do both for me? What should I look for? Is this where custom cams come in?

The bummer part is if I switch to a 347 down the road the cam may not work with the new displacement and rod length.

The best advice I can offer/find is bite the bullet and buy your goal motor as an assembly at once from someone you trust-OR- do a ton of research before buying parts for your build.

There is a sweet spot there somewhere. That's why some guys/magazines can make impressive numbers without all the high dollar stuff. They found just that right combo of dynamic ratio, lift duration, intake/head flow that makes a motor that seems better than its' parts.

I digress, is there a guru or swami that can create a camshaft sticky that can get a majority of us pointed in the right direction?


David

lxman1

Your best bet is to gather all of the info on your build and get with the experts at www.compcams.com and they will guide you where you need to go. May even be a custom grind.

mjr46

those flippin idiots at comp will sell you an OTS cam and call it custom, most of them are 7 dollar an hour wanna be's..........for someone who knows what's up talk to ED at www.flowtechinduction.com, I'm running 2 of his custom cams and they litterally blow the socks off any letter cam or ots cam, they have been taylored to my combo and wishes, the last one I had done for a 306 litterally rocks!! lots of lift, low duration and it can turn some rpm!!

DeltaElite121

How much did he charge you for a custom cam and does he charge you for the cam core + labor, or what?

OCHOHILL

Lets not confuse fact with opinion. I am sure that most if not all companies have their share of stellar and dull employees. I know mine does. I was hoping to get some good cam info in all in one place so that people with simple understanding can get their home built project going in the right direction. I wouldn't say that any of the off the shelf cams are bad. They might work best in certain combos and fall on their face in others.

No cam gurus yet?

XPBaller

The REAL cam "gurus" arent going to give you any REAL advice until you show them some money. And by REAL cam "gurus", i mean jay allen, ed curtis, buddy rawls etc...


All you're gonna get on this board is some guys who have been there done that a couple times, and can speculate an OTS cam that 'might' make good power with your combo. If you want a cam that'll be tailor made to your car from a "cam gurus" perspective , you're gonna have to bite the bullet and go custom...


On a side note though, the comp XE and Anderson Ford Motorsport lines have some pretty nice OTS cams to choose from.

OCHOHILL

I was hoping for some good general information. I realize that a cam builder can't come on here and tell a forum member they need a specific cam. I was hoping for someone to tell us the effects that duration, lift, lobe seperation angle, etc. etc. has on a build. Maybe a little section on certain camshaft no-nos. It would seem that a sticky like this can eliminate a lot of camshaft related posts on here. The obvious end all be all of camshaft advice is to consult your engine builder. That means that we should bite the bullet and have our motors built by professionals. Even if I did go that route, I would still want some solid general knowledge before hiring a builder. That is important for good communication. I am sure that engine builders think that a full half of their customers don't have clue. I think it would also help people understand what we want and can afford may not be the same thing.

I also think that a good post on camshaft selection, especially if made a sticky, would do nothing but sell more product for that builder. It's like free advertising.

OCHOHILL

read this once-then read it again.

http://www.popularhotrodding.com/tec...ics/index.html

RICEBORDEAUX

I have seen the Anderson cams work we'll with the superchargered car here locally at the tracks in Illinois I can vouch for that for my own experience but custom to me is the way to go and that's where I'm going...

mjr46

325.00 for the cam delivered....most comp ots hyd rollers are 270-300 range, for the expertise ED gave and contuinued advice through the build was well worth the extra 25 beans, so NO NEED for a cam thread that most here will never grasp when ED or Jay the cam guru's take all the guess work out of it, some things in life you just pay for so you know it's done right........even with all my expertise and knowledge ED and Jay have the programs and Hoppers to run your data build through so the end result is on the money and not just the "so called" best OTS cam based on ones understanding from reading a magazine article you can get

and if any one wants the cam gurus they can be found at www.flowtechinduction.com or www.camshaftinnovations.com:)