Cam Recommendations?

[FatBoy]

Originally Posted by blykins

Your cam needs more split between the duration and the LSA needs to be shortened up by at least 4 degrees.

I've never had to spec a cam before, so are you able to elaborate a little please?

"more split between the duration" does that mean more or less duration, or something else?

With regard to the lobe separation, do I need to be looking in the 110-112 region? What does changing the lobe separation do and is it the inlet that is opening later, or the exhaust that is opening sooner or a bit of both if I reduce the LSA?

Whilst I'm more than happy to accept your experience, I do like to understand why I'm doing something.

ATB,
Paul

[cycleguy55]

Originally Posted by FatBoy

I've never had to spec a cam before, so are you able to elaborate a little please?

"more split between the duration" does that mean more or less duration, or something else?

With regard to the lobe separation, do I need to be looking in the 110-112 region? What does changing the lobe separation do and is it the inlet that is opening later, or the exhaust that is opening sooner or a bit of both if I reduce the LSA?

Whilst I'm more than happy to accept your experience, I do like to understand why I'm doing something.

ATB,
Paul

"more split between the duration" means you'll have more duration on the exhaust side than on the intake, often in the range of 6°. For example, you could go 242° duration @ 0.050" on the intake, and 248° on the exhaust.

LSA:
TECH QUICKIE: Camshaft Lobe Separation Angle And Power Relationship

Camshaft Shootout: Lobe-Separation Angle Tested and Explained - Hot Rod Network

[eschaider]

Originally Posted by FatBoy

I've never had to spec a cam before, so are you able to elaborate a little please?

"more split between the duration" does that mean more or less duration, or something else?

With regard to the lobe separation, do I need to be looking in the 110-112 region? What does changing the lobe separation do and is it the inlet that is opening later, or the exhaust that is opening sooner or a bit of both if I reduce the LSA?

Whilst I'm more than happy to accept your experience, I do like to understand why I'm doing something.

ATB,
Paul

Paul,

I have attached a zip file with a browser application (runs like a page in your browser) that will help you visualize the effect on opening and closing events that duration, centerline and LSA (Lobe Separation Angle) has.

The app was written by a good friend of mine, Mark Olson, and is free for all to use.

Installation procedure:

Unzip all 4 of the files in the CamChart.zip file into the same directory.

The files are:

CamChartCandDr1.htm
CamChartOandCr1.htm
wz_jsgraphics.js
CamChartReadMe.txt

How to run the program:

Make sure Javascript is enabled in your browser's options.

Double-click on either of the .htm files.

If the browser asks if you want to "allow blocked content", run a script or allow an active control, click "yes".


The app essentially lets you create a cam card for any cam you wish to that will illustrate the effect on valve opening and closing points that duration, centerline and LSA have.


Ed


Ahhhh, the forum will not allow zip files greater than 39KB. This zip file is 745KB. PM me an email address and I will send it to you by email.

BTW this is what the output looks like. For some reason the CC image comes up fuzzy but the actual screen image is sharp.