COMP CAMS FOR L SERIES?

[Rasp933]

Whats up ratsuners

Got a question about which comp camshaft would b perfect choice over my stock cam for l20b wit 38/38 weber downdraft?

[KlassicMotion]

What kind of driving do you intend to do?

 

Is the rest of the engine stock?

What head?

What intake do you have?

What exhaust manifold/header do you have?

What size exhaust pipe do you have?

What do you plan to do with it?

What are you looking for out of it?

    Where do you want your power?

    Top end, or low end power?

How heavy is your flywheel?

What transmission and rear gear ratio?

 

**From http://www.davidcmurphy.com/olddat/html/tech/head_ID_2.htm :  "There were a  few variations of the SSS cam. The most common version had .410" lift and 248 degrees duration. This is the same as the L-20B cam that came to the U.S."

 

 

http://www.compcams.com/catalog/194_195.html

 

[KlassicMotion]

More opinions:

 

http://community.ratsun.net/topic/582-schneider-cam-kit/

[Rasp933]

Stock intake manifold

Stock valves

U67 head

4.1 long tube header

Electric dizzy

5 speed outta 280zx

Stock diff

2.25 in pipe

[EricJB]

Comp sure isn't aggressive with their grinds. The first 3 or 4 really don't offer much over the stock L20 (u67) cam. A bit more duration perhaps.

 

I have done business with Iskendarian cams, and they treated me pretty well. Many Schnieder users here as well. 

 

What carb are you running?

[Rasp933]

38/38 dgas weber down draft

[KlassicMotion]

So, what do you plan to do with the car?  And what are you expecting out of it?  Where do you want your power?  High in the RPMs or low down off the line?

[Ranman72]

ASK REBELLO IN ANTIOCH 

[Rasp933]

I Think the engine needs power on higher revs .that s when I feel the need for it

[Rasp933]

At higher revs I feel theres need for more power

[KlassicMotion]

Here are some other companies:

 

I know, Schneider Cams requires your old cam for a re-grind:

http://schneidercams.com/naturallyaspirated-7.aspx

 

260F Nissan 4 Cyl Camshaft
RPM Range: 1500-5500

 

260-70F Nissan 4 Cyl Camshaft
RPM Range: 1850-6000

 

274F Nissan 4 Cyl Camshaft
RPM Range: 2200-6400

 

270-80F Nissan 4 Cyl Camshaft
RPM Range: 2500-6600

 

284-94F Datsun 4 Cyl Camshaft
RPM Range: 3250-7250

 

290F Datsun 4 Cyl Camshaft
RPM Range: 3500-7500

 

300F Datsun 4 Cyl Camshaft
RPM Range: 4000-8250

 

311F Datsun 4 Cyl Camshaft
RPM Range: 4500-8500

 

314F Datsun 4 Cyl Camshaft
RPM Range: 5000-9000

 

 

Isky cams:

http://www.iskycams.com/onlinecatalog.html

 

 

 

Rebello Racing:

http://www.rebelloracing.com/nissan1.htm

Cams

Duration/Lift Lobe Center Spring Set
220-     .440 106B 111 Mild 4 or 6 Cyl A
279-     .487 63DE 109 Hot A
279-     .540 63DI 109 Hot B
300-     .600 325C 104 To 108(Road Race) C or D
We have our 50 other Profiles for custom applications.

 

Racer Brown cams:

Racer brown wrote a small booklet on Camshaft theory.  It's a great read...  I can't find it at the moment, but search around for it.

Racer Brown used to be the guy to go to, but I've heard bad things about the guy that took over his business.

[banzai510(hainz)]

cams cost money for the new rockers and lash pads and maybe valve springs and retainers.

 

If a 38/38 is ok on your L20 just live with it as this will add about near or over 500$ and by then youll want to get sidedrafts to get max output from that cam

[KlassicMotion]

You could try this spacer on there first:

 

http://www.amazon.com/Trans-Dapt-2107-Datsun-Holley-Adapter/dp/B000CQ47RE

 

I just bought one, haven't put it on yet, but for $36.21, it's worth a try.  I don't expect it to "Wow" me, but I'm curious what it will do.

 

Have you tuned the Weber yet?  I had to increase the size of my primary and secondary idle jets, plus a fuel pressure regulator to get my 38 to perform like it should.

 

**Note: This adapter may cause issues with the stock linkage.  Check my 38 install (below)

 

 

[EricJB]

What manifold are you using? If stock, You might want to make a plenum beneath it, like this.

 

[KlassicMotion]

That reminds me...  On your intake, do you still have the two seperate bores of the stock intake?  To get better performance from that 38, bore out that intake so the intake is port matched to the adapter, and the adapter port matched to the carb.  If you don't, it will kill your performance.

 

I know none of this helps your question, we just want to make sure your getting the most out of what you already have first.

 

http://community.ratsun.net/topic/56764-i-love-my-weber-38-dges-heres-my-38-dges-install/

 

Here is my intake port matched:

 

 

 

Stock manifold (someone else's pic)

 

[Rasp933]

I already have the spacer just like in the top pic

[Rasp933]

No its not two separate bore .its just like one big bore

[datson4life]

kelowg has some nice new cams he was selling, hes in modesto u should contact him

[Z-train]

A Mike Klotz adapter stitched to the manifold.

 

 

[banzai510(hainz)]

OH I like that!!!!!!!!

I would assume a weld bead all the way around

[Z-train]

Inside was channeled ,then filled and blended.Outside,"you getz what you seez".

 

Here's a better shot(a little).

 

[KlassicMotion]

Here is some good info I just ran across.  Never mind that the question is about V8's, the theory should be the same:

 

 

Quote:

Originally Posted by Johnny-LT1-runner

I've stumbled across a cam maker that happens to make alot of cams with a high duration/low lift(HD/LL) combo.

What would be the advantages/disadvantages of this vs a low duration/high lift(LD/HL) cam like most go with?

Lift is simple. It raises torque by a somewhat small amount at all RPM (unless very excessive, in which case low end torque is slightly compromised).

But to understand what lift is best, you must understand a few things.

First, not all lobes are equal. Even if they have the exact same lift and duration, their lobe acceleration rate (ramp up rate), ie how quickly they reach maximum lift, will vary. As is plainly obvious, the sooner a cam reaches a given amount lift, the more power it will make. A big part of how aftermarket cams increase power is through increasing lobe ramp rate.

As I said before, lift ideally increases torque at all RPM. But, that is only to a certain point. Unless the heads and intake both are set up to take advantage of increased lift, then using a higher lift cam won't help anything. Both LS1 and LS6 heads flow only a few more cfm from 500 to 600 lift. Furthermore, an LS6 intake isn't good for much above 250cfm coming from the heads. A fast 92mm intake is good for about 285cfm from the heads.

Both ramp up rate and valve lift wear the valvetrain more quickly. A major problem with high lift, high ramp, cams is that even good double springs wear out in 30,000 miles. Good beehive springs aren't worth much trust beyond 10,000 miles. This is exacerbated by the fact that big cams are often meant to be used at high RPM.

The more significant component of spring wear is lift. By increasing lift, the spring is more fully compressed, and even the best springs will eventually stay bent.


So, the cam manufacturer could be doing a number of things, since they design cams for every marketable purpose. Perhaps the lift was decreased so that ramp up rate could be increased without too unreasonably increasing valvetrain wear. Or, perhaps the manufacturer understands that a stock LS head and intake don't flow extra above .500 and sees no point in it high lift.


...as far as duration goes, duration is, in simple terms, how to control where the engine makes its torque. Take two otherwise identical cams (lift, ramp rate, LSA) but with different durations. Induction systems not limiting, it will make a given amount of torque at any RPM, and where that torque happens will depend upon the duration. If the low duration Cam A makes 400ft-lb at 3000 RPM, but begins falling off afterward, and the high duration cam B makes 400ft-lb at 6000 RPM, but had low torque at 3000RPM, which one is better? It's all about what you're trying to do with the vehicle. For racing, all you care about is having POWER in the in the narrow RPM band where you run wide open throttle between gears. For this, Cam B would be best. But, when driving normally, you don't want to have rev your engine high or downshift just to be able to accelerate like you're used to. For this, Cam A would be best.

 

Quote:

Originally Posted by Johnny-LT1-runner

And what about a high vs low LSA on them?

A lower LSA will give you a narrower, but taller power band. Peakier power. Usually, going lower than 110 will actually reduce performance at all RPM. Comp Cams Thumpr cams can have LSAs as low as 106. This is because those cams run like **** on purpose. Many people directly correlate a poor idle with power and masculinity. Having to run a vacuum pump for less power is a unique calling. Also, you normally don't want to exceed an LSA or 116 or you will again start to lose power at all RPM. So, low LSA gives you more power for less time, and a high LSA gives you less power for longer.
 

Quote:

Originally Posted by Johnny-LT1-runner

And would it have any advantages/disadvantages if used with a stock head vs a ported head?

Ya'll see where I'm going with this, so take it and run.

A ported head will usually make a cam behave as if it had more duration. By running larger runners in the head, the effect is the same as running higher duration. More air is allowed to flow, but that air is flowing in more slowly. To reach peak torque again, the engine must be revved higher. This means more power, which will win you races but also make your car more of a hassle to drive.

On the other hand, optimizing the flow geometry of your heads, or getting different heads that have better flow geometry (less harsh of an angle, low turbulence, etc) will increase torque at all RPM.

The best way to make an engine is by designing all of the components to match for the intended uses.

Heads and intake manifolds with very good flow geometry are often prohibitively expensive and can be too large to fit under a hood. Heads with monstrous runner volume and cross sectional area can flow air for high RPM torque (and thus high power), but make big compromises on low RPM torque.

You can push a bad induction system (poor intake, heads, and/or exhaust) to squeeze out the the last few drops of top end power by using a monstrous cam, but the engine will never reach its true power potential and will be horrible to drive on the street.