How to choose a cam for your engine?

[Jesse/DVK]

Well the title says it all. How to choose a cam for your engine? What do you need to look for? Wat does duration do? What does valve lift do? How to compare camshafts? I would like to get to know some basic theory so I can choose a nice cam for my first engine.

Jesse

[Zach Gomulka]

First question to answer is what do you want the engine to do for you.

[Rennsurfer]

Second question; will this engine be your daily driver and in your only car?

[Harry/FDK]

There is plenty of reading-food out there.

[Jim Ratto]

Hi Jesse....  do you want to know how a cam works or did you want to talk about which cam works for your engine/plans?

Duration and lift are related, and they are not a "more is better" type of deal. And while related to engine cc, there are many other variables that should help you decide. Carburetion is a BIG one. Too many guys think they can use small-ish carbs and a big cam, especially on a big cc engine, and they end up with a doggy.
conversely, a lot of guys sell the engine short on duration, and fall victim to the fear of "I won't have any bottom end..." if they dare to venture beyond the monkey see, monkey do thing.
Rayburn's car is proof that wild cams don't have to be undriveable. My newest 2165 too...
Lift is a good thing, but go too wild and you'll be wearing valvetrain parts out.

So what is your future engine going to be?

[Jesse/DVK]

Well I wanted to make a topic a bit of both, what cam I will choose but also some general information for everyone to look up in the future.

Use of my car, ok it's my only car but I go to school with public transport and I use my mom's car most of the time to go the gym for instance. I use my bug to go to meetings and to drive around town just to take it out for a spin. In the summer I use it a lot more to go to the beach etc. So it will see mostly street use, maybe a couple of drags a year, like Das Drag Day, EBI etc.

Engine is going to be a 1776 because I just bought a set of 041 heads with 39x35.5 valves, single springs and alu retainers with some porting done on them. They are 43cc and I want the CR to be around 9.5:1 - 10:1. For the carbs I want to go for dual 40 DRLA's. The gearbox will be stock 1200 at first but thinking of saving for a Rancho.

[Bewitched666]

W120 is good for what you want Jesse,good all around cam for street and will kick some ass on the strip

[Jim Ratto]

W120 is good for what you want Jesse,good all around cam for street and will kick some ass on the strip

Ditto! Or Web #110

[Jesse/DVK]

Okay thanks guys, I was already considering these cams, or a web #163. The single springs will hold it out? I would like to know why these cams work good? What happens when you have more or less lift/duration?

Just like to know why thinks work

[Jon]

I think that you will need to upgrade to dual springs to use such torque cam's. Due to the steep ramps on such a cam.

[streetvw]

Jesse I used to run a 1776 with an engle W120 in it with stock heads and 40DRLA's it made loads of torque low down and was a great daily driver (my girl friend use to run it as a daily no problems) it went 15.71 in the quarter. Oh I had dual springs as well and would recomend them on anything iver a engle W110.

[Diederick/DVK]

wrt the springs; the heads were used on a 1776 with a w125 cam.
i'd go with a w120 if i were you jesse.

[Jim Ratto]

Okay thanks guys, I was already considering these cams, or a web #163. The single springs will hold it out? I would like to know why these cams work good? What happens when you have more or less lift/duration?

Just like to know why thinks work

I'd use dual VW diameter springs. Bugpack 4046 are what i have been using since 1994 or so.

At buggy house, back in mid 90's we built this chick (cute, too) with a white Karmann Ghia coupe, a 1776 with Engle 120, 44IDFs, merged 1-5/8 and 044 out of the box heads and it ran very sweet. It was her only car, and "somebody"   talked her into this motor, as she told this "somebody" she needed some power on the freeway. Turns out this was one of the smoothest engines we built for a customer.

duration is influenced by these things:
engine displacement (bigger cc can use more duration)
compression ratio (high CR with more duration, low CR use less)
intake design (venturi/port per cylinder can use more duration than siamesed ports or shared venturies)
exhaust design (engine has to be able to breathe...)
car weight (lighter is less sensitive to increased duration)
application (pretty obvious here)
final drive ratio (tall gears like less duration, and vice versa)

an Engle K8 can have two different "personalities" depending on the above variables:

big enigne: torquey, all around street or off road cam/ little engine: high rpm, not good torque low rpm
high CR: snappy powerband, all rpm/low CR still good power, just softer, but bigger engine will "conceal" this
2 2bbl carbs: smooth off idle to redline/1 2bbl or stock carb, less driveable, may protest or buck or have flat spot at low rpm/mid rpm
nice merged header: good power all around /small header or non 4-into-one: bad low end, no top end flat spots
light car: engine comes into powerband faster/heavy car: car will lag, bog, buck, run soft
kid's hot rod: will use the powerband/old lady's grocery getter: not a good cam for this
low final drive ratio: engine will rev faster, multiply torque thru gears is better, stay on "boil"/tall gears: accelerate slower, harder to tune, wider gaps in gear changes.

[67worshipper]

ive got an fk8 in my 2276.running 48idas 42,37.5 mm valves.seems like a good match.no lag at all.pootle it or plant it it feels nice.also running 3.88 r+p with 3.78,2.21,1,58,1,21 gears and 8.5 to 1 ratio cr. may chang 3rd and 4th for something with more than 60mph at 3200rpm. its certainly a flyer

[Bewitched666]

Go for double springs like a few say here