cam won,t spin without cam lobes hitting connecting rods?

Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
Hey guys, Ive had a few friends that referred me here. Im a ford guy (i know, boo) and new to the chevy scene. Im slowly making my way over to the dark side though as i sold my f250 in favor of a duramax.. well now i bought a boat with a 350 chevy, but cracked the cooling jacket. While the engine was out, i decided to go with something a bit more stout.. this is where all the trouble began.

I ended up ordering the BluePrint engines entry level 383 short block.. it comes with sealed pro 12cc pistons, new crank, rods etc in a fresh 880 vortec roller block. But im having issues finding a cam. I really want the Comp Cams 08-417-8 which is a .495/.503 cam with 218/224 duration. I plan to run this shortblock with a set of AFR 180cc heads, comp lifters, comp roller rockers, holley 750 etc.

My question is, is this cam profile too big for the 383 stroker assembly? (cam lobes coming into contact with rotating assembly). I got a bit scared when i put the cam in with out the timing chain in, spun the crank, a little, then spun the cam only to find out that a couple of the lobes hit.. now is this normal with no timing chain connecting the two? or should there be zero interference? or am i just worrying too much and wait for the timing chain to come in then measure clearance?

Thanks again for all the help.

a standard chevy sbc cam will not rotate randomly and freely and clear the connecting rods,
in a 383 engine, if its not properly timed with a timing chain in place to force the cam being indexed correctly, so cam lobes, are indexed to avoid hitting the connecting rod bolt shoulder area,
,you need to correctly degree the cam in...BUT EVEN THEN,
.in some cases a small base circle cam must be used to clear some connecting rods in a 383.with its 3.75" stroke, remember the original 265/283 SBC has a 3" stroke
.
block-clearance.jpg


plastigty5.jpg

clearancedrod.jpg


rodcaptocamclearance.JPG

rodcaptoblockclearance.JPG



BaseCircleDiacv.jpg

read ALL the linked info carefully and then ask questions

http://garage.grumpysperformance.com/index.php?threads/cam-degreeing.9010/#post-35474
http://garage.grumpysperformance.co...ing-a-383-sbc-combo-planing.12168/#post-71932
http://garage.grumpysperformance.com/index.php?threads/small-base-circle-cams.3810/#post-72512
http://garage.grumpysperformance.co...e-springs-and-setting-up-the-valve-train.181/
http://garage.grumpysperformance.com/index.php?threads/383-information-overload.11137/
http://garage.grumpysperformance.com/index.php?threads/bits-of-383-info.38/#post-7680
http://garage.grumpysperformance.co...gine-to-match-the-cam-specs.11764/#post-55571
 
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