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Degreeing an A series oem camshaft help!


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#1 afracer

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Posted 19 November 2017 - 08:39 AM

I could use some help trying to degree a factory camshaft in my Datsun. All I have is this image (link below) which should suffice but where are these readings of intake/exhaust opening and closing taken? .020" lift or .050" lift??? If its .020" I'm showing 5 degrees Atdc instead of the specified 14 btdc if its .050" its like another 15 degrees off. I just want to make sure before I make adjustments and button it up! This is a A15 engine http://datsun1200.co...hotos/20179.jpg



#2 Stoffregen Motorsports

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Posted 19 November 2017 - 09:06 AM

I think you should search online for those instructions. I doubt you will find any Datsun specific info, but it sounds like you need basic theory first.

 

On an A motor, it's easier to degree the cam with the head off, but if the head is on, you just set the dial indicator at the tip of the pushrod.

 

And you say factory camshaft...? Why do you need to degree a stock cam? And where did you find stock cam degree specs?



#3 datzenmike

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Posted 19 November 2017 - 09:40 AM

20179.jpg

 

None of my FSMs (factory service manual) show any valve clearance specified so it must be a direct reading on the cam lobe where it starts and ends. Most cam makers specify readings at a 0.050" lift. Naturally a reading at 0.050" will be far after the beginning and before the end of the actual lobe ramp.

 

 Usually the crank and cam sprockets are marked and the number of links between them specified in the FSM. Just follow this.


Posted Image

#4 afracer

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Posted 19 November 2017 - 10:29 AM

The readings I took is with the sprockets and timing lined up stock IAW the FSM. I have an adjustable cam gear to make changes but need to confirm where Nissan takes those readings at.

#5 afracer

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Posted 19 November 2017 - 10:33 AM

Btw the head is off, I have all the appropriate tools set up properly and understand how to degree a cam but without knowing how they got those measurements its hard to check. Most aftermarket cams are all done at .050" but there is a blurb on 1200.com that says Nissan "may" have used .020".

#6 afracer

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Posted 19 November 2017 - 10:39 AM

I shouldn't have to explain why anyone is degreeing a stock cam. Manufacturing throws a lot of variances into clearances. If you've ever built or blueprinted an engine you'd see this. Adjusting the cam, even a bone stock one to account for these variances can yield more power and driveability.

#7 G-Duax

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Posted 19 November 2017 - 11:39 AM

All my HKS, JUN, TRD, and Toda cams call out .25mm lift (.010").

No one in Japan uses .050", that's just for American pig-iron V8s.

.020 isn't out of the question for an OEM to use.



#8 Stoffregen Motorsports

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Posted 19 November 2017 - 11:45 AM

I shouldn't have to explain why anyone is degreeing a stock cam. Manufacturing throws a lot of variances into clearances. If you've ever built or blueprinted an engine you'd see this. Adjusting the cam, even a bone stock one to account for these variances can yield more power and driveability.

Apologies. The wordage in your first post implied that this was your first time around the block. Adding that you were using an adjustable cam sprocket may have been enough.

 

There are plenty of cam timing threads going on here right now, and I am a strong believer in proper cam timing, so I hope you get the info you're after. I was thinking you were installing a stock cam using stock components, which would have been easy enough.

 

 

 

Good luck.



#9 afracer

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Posted 19 November 2017 - 09:06 PM

I guess I'll try .010 and see what it comes out to. .020 seemed close, definitely closer than .050". Without knowing for sure it's a total crap shoot/pointless.

Just trying to maximize what I've got, no hard feelings. This is a rare A14E cam I got from Malaysia, which is a newer "GX" cam... Hottest factory A series!

#10 distributorguy

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Posted 20 November 2017 - 12:45 PM

I'd just look for a 106/107 Intake centerline.  Maybe as low as 104 if you want more top end and less bottom end.  



#11 afracer

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Posted 20 November 2017 - 04:09 PM

Yeah its at 107 intake centerline on stock settings

#12 Tom1200

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Posted 20 November 2017 - 07:37 PM

Go to the link below, page 13-14 it has a spec for twin carb engine under 64 degree cam.

http://www.datsunche...Rennteile75.pdf

If that one doesn't have what you need there is also in for it will be Rennteile81 there are a couple of years check datsuncherry.ch