I can never remember - are 350 Chevys usually free spinning? If so, is it typical to grind the rods on a 383 enough to make it so the rods never touch the cam regardless of the crank to cam phase, or are they usually only ground enough to clear the cam when the timing chain is correctly connected to the cam? I set my 383 buildup aside for the summer, but now that the cold weather is just around the corner, I expect to get back to it soon.

Degree the cam as you will run it and then clearance. Never hurts to advance and retard the cam a few degrees and check clearance again. Only take a few crank degrees to close the clearance in a big OUCH way.

Small Blocks are generally not free spinning motors. The cam can come into contact with the rods if phased wrong.
I tell everyone running more than 3.5" of stroke to run a small base circle cam... its not worth screwing with

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A 383 usually requires rod clearancing to clear a few cam lobes even with the timing chain properly installed. If you snap a chain and the cam stops in the right position you WILL have contact, regardless of whether the rods have been ground down or you have a small base circle cam- it'll probably hit anyway.

With a 350 I dunno. Never checked.



[This message has been edited by Damon (edited September 20, 2005).]

I checked with a couple of cam companies, Crane and Competition Cams, and both tried to steer me away from a reduced base circle cam. So, I thought I'd clearance the rods - it didn't look like it would take too long - but after I put the cam in and starting noting the interference points with the crank, I started wondering if the rods could be clearanced so that the crank would spin free, or if they could only be clearanced enough to clear the cam when the cam is properly installed. Checking the clearance advanced and retarded sounds like a good idea, since timing chains do wear.

Crane said a hydraulic cam lifter will through the bore with a small base circle cam; do people usually only run reduced base circle cams with mechanical or roller lifters?

Clearance the rods and forget about them, I ran my 408 with stock 350 rods and stock bolts to 7200, no worries on any strength lost by grinding part of the bolt head away. A piece of bent 1/16" welding rod makes for a great go/no go gauge.

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The main things that cause people to clearance the rods and/or use a smaller base circle cam are: the cam itself (higher lift and roller cams have less clearance becuase the lobes are "fatter" and taller) and the type of rods used (I can make stock rods clear most flat tappet cams pretty easy with relatively little metal removed- big fat aftermarket H-beam rods can require a LOT of material taken off by comparison).