Help me pick some cams please

I understand cam specs, and generally how they affect performance. But I have no real-world experience with matching cams to performance goals.

This will be a street-driven autocross car, so torque to pull out of corners will probably outweigh outright horsepower. Other engine mods will be motorcycle ITBs with megasquirt, header, and basic port-matching on the manifolds and head. I would upgrade valve springs if needed, but I don't want to get into serious head-work, bump compression, etc.

I've listed specs on the 3-contenders below, the left number is intake, with exhaust below.

Set-1 Adv. Duration 276 252

@.050 228 222

Lift .393 .393

Set-2 Adv. Duration 236 232

@.050 214 210

Lift .381 .374

Set-3 Adv. Duration 281 281

@.050 228 228

Lift .381 .381

(Yes, this is for the Zetec going in the Europa, and I've done research on the Ford forums, but I trust you guys for unbiased and educated advice.)

When a customer asks me for a camshaft recommendation, I need to know the weight of the vehicle, the final drive ratio, other mods (which you've included) max RPM, and possibly the stock duration specs. A lighter car with more gear will be much more forgiving, and a car with ITB's will also allow more duration and still give a strong low to mid pull.

Final drive is 3.56 - in fact, the entire drivetrain specs are in this spreadsheet I posted here.

The car will weigh right at 1650lbs wet.

Stock cam specs are:

Adv. Duration 276 273

@.050 206 205

Lift .346 .341

I think what you need is what Ford Racing used to sell as their Stage 2 cam. They are what I have in my Focus. I looked but FR no longer lists them.

I don't have the specs for the cams handy right now but will look to see if I kept the sheet tomorrow.

I can say that I would not go more than .381 lift. The .393 lift cams are dangerously close to changing the engine from non-interference to interference.

Of the 3 you have listed I would go with Set 3.

Thanks Hal, it's interesting that you picked the 3rd set, as one(seemingly intelligent) discussion I read stated they had too much duration for an N/A build?

But that's exactly why I posted here - to separate fact from fiction.

In reply to mguar: Thanks! How much would you charge to do it??? :D

petegossett wrote: Thanks Hal, it's interesting that you picked the 3rd set, as one(seemingly intelligent) discussion I read stated they had too much duration for an N/A build? But that's exactly why I posted here - to separate fact from fiction.

I'm with him on 3.....the thing I like in the numbers appear to show a better exhaust side with that one...

petegossett wrote: Thanks Hal, it's interesting that you picked the 3rd set, as one(seemingly intelligent) discussion I read stated they had too much duration for an N/A build?

I am certainly not an expert but I always heard that you wanted a longer duration for NA and a shorter one for Forced Induction.

I just found an interesting old-school article about cam selection from Hot Rod here.

Based on their info - which I realize doesn't translate 100% to a DOHC 16-valve engine - I'm thinking set #2 from my first post may be the best choice?

3/4 cam

... from related thread

It's a tough call. I don't like any of those grinds, but grind 2 is definitely the safe bet.

16V 4 cylinder motors require less duration to do the same thing as an 8V does, and drivabilitty and bottom end power go away faster as you add duration. Your final drive is not ideal, but with the smaller tire size, light weight and ITB's, you can probably pull the bigger cam (although I'd like to see a little more compression). I would prefer to see 220 D @ .050". I normally put about 10 degrees more on the exhaust side. It gives better over rev (power doesn't drop off as quickly at redline). I don't like to see shorter exh. duration, but I'm also not familiar with that head. I'd prefer 220 on both, assuming it doesn't need more on the exh.

In reply to Zomby Woof:

Hmm... Well there's these:

RPM Operating Range: 1800-7000

Duration: Advertised: In: 281 Ex: 281

Duration:@.050": In: 228 Ex: 228

Valve Lift: In: .381" Ex: .381"

Centerline: In: 112deg Ex: 112 deg

Still looking at others too...

EDIT: These are right at 220 -

RPM Operating Range: 1400-6000

Duration: Advertised: In: 273 Ex: 273

Duration:@.050": In: 220 Ex: 220

Valve Lift: In: .381" Ex: .381"

Centerline: In: 112 deg Ex: 112 deg

And all the sets either have matching duration for intake/exhaust, or more duration on the intake.

Hydraulic or mechanical lifters in this Zetec?

Mechanical.

I had assumed hydraulic. That would explain the 200+ stock duration. I feel more comfortable with the 228 now, but the 220 is the safe bet, and should still give you strong low end, and 7000 RPM with your mods.

Cool, thank you sooo... much for your help!

observations... set 1 and 3 seems to have a somewhat soft ramp rates (48+ degrees between seated and .050 lift) set 2 has a quicker ramp rate 22 degrees to cover the same .050"

Do you happen to know the valve timing events for these camshafts???

intake valve closing event in particular........

oldeskewltoy wrote: observations... set 1 and 3 seems to have a somewhat soft ramp rates (48+ degrees between seated and .050 lift) set 2 has a quicker ramp rate 22 degrees to cover the same .050" Do you happen to know the valve timing events for these camshafts??? intake valve closing event in particular........

Don't waste your time comparing the cams using advertised duration. There's no standard for measuring it, and you have no idea how it was done. It's essentially a meaningless number.

Unless there's something really goofy with this motor, count on intake centerline being 108-112 and lobe centers 110-114. Being a bucket lifter design, the lobes are symmetrical, so it's easy to calculate the events within a few degrees.