L24 Rebuild -Again!

[Chickenman]

So you got the L-475 grind Steve or a Custom grind? Is that the corrected Cam card? I wonder why the duration figures are off a bit... CTIE???

[Diseazd]

That's a pretty stout cam ( Isky L-490 ) . Might be a bit much for the street, but should be good for track days. The M445 Shadbolt is more of a Stage II... FWIW.

 

Isky L480 specs are very close to Shadbolt M445. Lobe Center Angle isn't shown though which is important. But if I recall correctly, Isky likes to use around 106 -108 on the Stage II and III  grinds and 103 - 105 on the Race grinds ( Z-196 and Z-273 ) for the L series.

I run Stage III Isky regrinds in all but one of my Z's. It's a really nice grind.....no problem on the street.....pulls hard all the way through the rpm range! However, all engines are L28 with P79 shaved heads, except the L24 (72 modified L24) in the 73. Can't speak for the Stage III in L24's, I run a Stage II Isky regrind in it. They are 10 degrees less duration and .480 lift......I would only buy Stage III in the future.

[madkaw]

My Schneider cam -274F grind was a bit smaller and it pulled hard from 1500rpm. I could putt around town all day at 1500rpm in 4th gear. I do have 390 gears. 

 

Guy,

seeing these numbers makes me wonder where you are at with your motors. I'm shaved .030 and I advanced this cam to the third hole. If you did the normal .080 on the P79 then your timing is probably way late. Leaving a lot of torque unused? Better use that dial indicator  

[Diseazd]

Remember, we jacked the towers up .080 inches, so the engine valve train remains bone stock. Z Doctor in Roanoke says that if Isky regrinds a stock Datsun cam, there's really no need to degree the cam......Isky says the same thing ( see Zed Head post 81).

 

Got curious and answered my own question.  You do seem to have an issue.  From the Isky Cams page.

 

http://www.iskycams.com/cam-degreeing.html

 

IS CAM DEGREEING NECESSARY? Because Iskenderian Cams are manufactured with such high precision you can install them on the stock timing marks without any further checking; however, for those who wish to learn how to properly check and verify valve timing, we recommend the following procedure. - See more at: http://www.iskycams.com/cam-degreeing.html#sthash.ETH1vHN9.dpuf

 

I'm extremely happy with the performance of these cams........really makes the cars fun to drive!

[siteunseen]

Anybody know off the top of their head what's the thinnest a head can be before it needs shimming?

[madkaw]

Cliff,

If I took the train I would never get there -

....moving right along like a freight train on the build

[rossiz]

looks shockingly familiar from the outside ;}

 

it will be a great feeling to get it going, well worth the wait.

i'm running a stock cam for now and will switch out to a hotter one in a few months when i feel the need for a little more poke. i'll be watching your thread carefully to see how it all shakes out.

[Zed Head]

Anybody know off the top of their head what's the thinnest a head can be before it needs shimming?

Monroe's How To Rebuild book says .020" is the most you can shave before needing cam tower shims.  Can't remember standard head thickness so can't do the math for minimum.

[siteunseen]

Cliff,

If I took the train I would never get there -

....moving right along like a freight train on the build

Looks good Steve!  Did you use the MN47 head?  Just noticed the block off plate is why I ask.

 

Ready to see and hear some video of 3rd gear chirps. 

[madkaw]

I think a lot of worry on shimming should be confined to folks that shave the top of the head. Shaving off the bottom will loosen the timing chain and effect timing number slightly, and shimming can bring that back. Now if the top side is shaved to make all things parallel, then you directly change the geometry of the cam to the rockers. Whatever you do , you need to compensate . I did not shim though I have taken around .030 off. BUT, I have taken the time to degree my cam so to compensate for the height difference.

[madkaw]

So the guy at Autozone says " how many thermostat gaskets did you say you needed?"

[madkaw]

Should get her fired off today