Size of cam?? - Chevelle Tech
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post #1 of 9 (permalink) Old Jan 28th, 20, 1:12 PM Thread Starter
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David Estes
 
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Size of cam??

Is there any way that I can determine what size cam is in my big block? I bought the car and there is no build sheet available. Claimed it was a 502, but I have my doubts. The block casting number comes up with a '78 truck 454. It does have 781 heads, but don't know valve size. It has full roller rockers, but I'm pretty sure it is not a hydraulic roller. I know I can use a dial indicator and get the lift number, but what's all this about 0.50 ATDC and 0.50 BTDC?
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post #2 of 9 (permalink) Old Jan 28th, 20, 1:22 PM
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Marcus
 
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Re: Size of cam??

You can degree it to check the nr’s but little tricky if in the car.
If you remove the valvecovers and use a flaslight you should see if it has roller lifters, look for a linkbar.


https://www.lunatipower.com/how-to-degree-a-cam

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

Chevelle Malibu ss 64
489 BB with parts from Lewis racing
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Th 400 Edge 9.5" converter
57 3/4” wide 12 bolt: Eaton posi, Us gear 3.31, Toms KA 33 splines axles
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post #3 of 9 (permalink) Old Jan 28th, 20, 2:07 PM Thread Starter
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David Estes
 
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Re: Size of cam??

Thanks, I've watched those, but I have no clue what mine is supposed to be as I don't have the cam card or even know what brand the cam is! So could I use this to find out the duration? It does not have links, but is hydraulic. Should I check valve lift at the valve and divide by 1.7 rocker arm ratio to get the cam lift number? And to make it hard it is on the car. I can rotate the engine clockwise at the crank with a ratchet, but when I try to go back the bolt loosens up!
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post #4 of 9 (permalink) Old Jan 28th, 20, 3:08 PM
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Gene
 
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Re: Size of cam??

Never go back David, only crank one way! I dont think you'll find ANY easy way to ID your mystery cam unless you pull it and it has some numbers on either end. Of course, when its out, its way easier to measure it as well.

Gene
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post #5 of 9 (permalink) Old Jan 28th, 20, 4:10 PM Thread Starter
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David Estes
 
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Re: Size of cam??

In the video you have to rotate backwards to find true TDC
"Rotate the engine clockwise until the piston contacts the stop. At this point you should mark the degree wheel."
"Next, rotate the engine counterclockwise until the piston contacts the stop again."
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post #6 of 9 (permalink) Old Jan 29th, 20, 3:14 AM
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Marcus
 
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Re: Size of cam??

Remove the sparkplugs and you should be able to turn it by hand using the damper.

Chevelle Malibu ss 64
489 BB with parts from Lewis racing
Alumitech radiator with dual spals
Th 400 Edge 9.5" converter
57 3/4” wide 12 bolt: Eaton posi, Us gear 3.31, Toms KA 33 splines axles
Malibu ss 64 is online now  
post #7 of 9 (permalink) Old Jan 29th, 20, 7:45 AM Thread Starter
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David Estes
 
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Re: Size of cam??

They are out, but I didn’t try that! DOH 😖 what was I thinking
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post #8 of 9 (permalink) Old Jan 29th, 20, 8:17 AM
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Jeff
 
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Re: Size of cam??

I have that motor in my 69 el Camino. Its a brute torque wise, I love it and wouldn't change a thing, except I would like to run a short duration, wide lobe separation mechanical cam in it.

I find mine runs best with no vacuum advance and the initial set at 22 with the mechanical set for 14 all in by 2300 rpm.. Mine runs like a bear like this and on 87 octane.

This motor has caused me to change my whole way of thinking as far as needing 10:1 compression and 308/320ish cams.. I wasted a lot of time on high compression, expensive premium gasolines and those miserable, long duration, lumpy cams that idled like a Model T.. This is the first motor in 20 years I didn't have to chain down because of vibration braking the motor mounts.
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post #9 of 9 (permalink) Old Jan 29th, 20, 2:18 PM Thread Starter
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David Estes
 
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Re: Size of cam??

Quote:
Originally Posted by hydro462 View Post
I have that motor in my 69 el Camino. Its a brute torque wise, I love it and wouldn't change a thing, except I would like to run a short duration, wide lobe separation mechanical cam in it.

I find mine runs best with no vacuum advance and the initial set at 22 with the mechanical set for 14 all in by 2300 rpm.. Mine runs like a bear like this and on 87 octane.

This motor has caused me to change my whole way of thinking as far as needing 10:1 compression and 308/320ish cams.. I wasted a lot of time on high compression, expensive premium gasolines and those miserable, long duration, lumpy cams that idled like a Model T.. This is the first motor in 20 years I didn't have to chain down because of vibration braking the motor mounts.

Yes, very torquey. I have a turbo 400 and 12 bolt 4:11 posi and wanting to change to a 3:73 or 3:55. Mine has small piston domes and open chambered heads. So your total timing is 36° right? That's why I want to set my pointer at true TDC and thought while I was at it do some other things before setting the timing. What plugs you running? I just bought some AC-R44T
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