would someone be willing to explain cams to me.



I know a little but not much.


like how you can tell about smooth the idle might be and what is the best for which application?


thanks
-Brandon-

 

What a can of worms you've opened!

Basically, idle quality is a function of the advertised duration of the cam and the displacement of the motor. Say you had a 284 degree cam. The idle would be really noticeable in a 352. Now if you put it in a big motor like Scouder's 521 (where is he, anyway?), it'd probably sound like a stock motor.

Cam selection:

Easy method:
Look at the range of recommended compression ratios for the cams you're looking at. Pick one where your engine's compression ratio falls within the manufacturers recommended compression ratio range for that cam.

Hard (more precise) method:
You need to figure up the dynamic compression ratio the motor would have with the cam you're looking at. Since the equations are rather complicated, here's a calculator:
http://www.kb-silvolite.com/calc.php?action=comp

For a simple open chamber motor (like the M block, for example) you want to keep the dynamic compression ratio under 8.25:1. For a motor like the FE, assuming you take full advantage of quench, you can probably raise that to 8.75:1. This means keeping piston to head clearance in the .025" to .040" range. Here's an article:
http://www.popularhotroddingweb.com/...power_squeeze/

Of course, then you've got the Octane factor. You can obviously run more dynamic compression with higher octane gasoline.

People who say "Just keep it under 9:1," are really taking the easy way out IMO. It shows that they really dont know what they're talking about.

So, building a motor is a lot more than simply throwing a bunch of parts together. Really, if you want to build one of these FE motors correctly, there is very little room for error in the parts department! Every engine is a precise combination, and even one error in parts selection can throw the whole thing off. If you find yourself saying "Oh it'll work," it's time to put the tools down, send the things back, and go back to the drawing board.

 

i am planning on building a 351W for my brothers truck

and then later a stroker motor (maybe a 460) (big plans with a low amount of money) (so i will have to draw it out over time)


I am trying to think up some ideas for each motor and maybe a horse power range.


351W about 400hp
460 about 600-700hp


so i know a good a major part is the cam so this will be a starting point for me for now.

 

Get an OLD Summit catalog out...pick the cam that says " you want the BADDEST sounding hot rod".......and buy it!!! LMAO!!! Remember those ads? Man, they were the coolest. Course there were alot of bad sounding, SLOW cars back then!

Rusty has it pretty much covered. A big cubic inch motor will make a BIG small block cam sound mild. Like mentioned, they all have to work together to make peak power, usable power.

The 351 motor should not be too hard to make 400 hp, and not be a too radical. The 460 will be a bit more off the wall to get those numbers. It would be easier to put a 514 together and make the power with torque and be more streetable.

Short story,,,,, buddy has '64 galaxie with 460. It was 12:1 motor, CJ heads, real stout to make 550 hp(dyno tested). He build a pump gas 514 that made SAME numbers. Now he fills up at corner station and can drive it. Still can run mid 11's on slicks. Purrrrfect!