58 replies to this topic

[N/A-PWR]

Hi RB,

 

Just to start this up,

 

I had a 30/70 Competition Cam in a 208ci Red Motor, which is a great Medium Cam ( 3100rpm to 7500rpm ),

 

now, that cam had great power ( Cracked a block between 3 and 4 pots ),

 

but did a lobe in later on, I mean it went round in shape,

 

so that valve didn't work anymore, and funny enough, I didn't notice it until later.

 

 

Change to a 41/78 cam x 1/2" lift, and it did the same rev range ( 3100 to 7500rpm ) strange,

 

and the power was much better in Torque, where I could push a 2.78:1 diff easy.

 

 

Next cam is going to be a 51/79 ( hoping for 3100 to 8500rpm ),

 

and I also found that, the same cam in a smaller Cubic Inch motor, the rpm band was 1000rpm less.

MPH Limit was when you take your foot off the pedal

Never did a Drag Race, where we had our own Pits to change and Test, be good to know but.

[N/A-PWR]

Hi Mick,

 

I have no idea on the 30/70, as I threw it,

 

but I still have the 41/79 here,

 

so how do I measure the LSA, I could work it out by doing some research,

 

but the Cam is still in my Lathe Chuck, waiting for me to do the lobe lift chart of it for Oldjohnno, sorry. 

 

G'day mate , what was the LSA on both cams .

[N/A-PWR]

Just done it:-

 

https://www.google.c...406445619692857

 

 

It, is about 107 Degrees, as I still have the Cam in the Chuck, with the Degrees around the Chuck,

 

and is a regrind too:-

 

 IMG_5691.JPG   42.21K   4 downloads

Edited by GASPOWER, 26 July 2014 - 05:36 PM.

[EunUCh]

Not exactly relevant..but when the cam decided to go into 3 pieces in the shit box starfire i got a new solid grind that was close to 

the original hyd.specs, and it is a better cam by far in terms of drivability and top end rpm but when tested on "dyno hill" the top end speed was a bit down.

That could be due to a better profile needing bigger chokes to work with the profile..not sure but things change.

[N/A-PWR]

Spot on RB,

 

Just changing the Cam, and reusing the same engine parts as before, is the best test.

[N/A-PWR]

Hi James,

 

All I did normally, was change the short motor,

 

the other bits all went back in,

 

it was only when the cam wore out was when I change that,

 

the New Engine will have a beast of a cam this time,

 

but still all the parts will be the same,

 

except for the Head, it is going to be shaved more, with new valve/guides etc.

[N/A-PWR]

Sure is RB,

 

and you sure did get real good results to keep persevering. 

 

Thats one change at a time isnt it?

[N/A-PWR]

Great thank's for that Mick,

 

Just worked out, that the Tighes Cam ( 51/79 - 310 Duration - [email protected]) has a LSA of 104 degrees,

 

and an installed Centre line of 104 degrees for both Inlet (ATDC) and Exhaust (BTDC). 

by the sounds, nice and lumpy

[N/A-PWR]

We have lived with worse hey,

 

thank's for the fun and Your Experience Mick.

 

I think it'll be very lumpy , that timing and 104 lsa will make it pretty cranky ,hope u can live with her.

Cannot have a Mild RAT