4.75 stroke crank Callie's ultra xd(xtra clearance) I beam's 55mm cam. Just not going to spin without some extra work.

I'm waiting in the belt drive. Using old timing chain setup for mock up purposes. I new going in this was going to be an issue. It's not my first go round with long stroke stuff. I just want to cover all my bases cause I'd rather not have a situation where the motor clearances itself. The cam is degreed where it needs to be I will clearance the rods so it will spin. Then I will back it up 6-7 degrees spin it if all is good I will advance it 6-7 degrees and check clearance. It was recommended by the rod manufacturer to use a long zip tie to measure cam/Rod clearance... Feeler gauge is a no go.

I will be doing a detailed build thread at some point so I can share with my fellow OSO'ers the joys of building a big cubic inch motor. It's a whole lot of putting together and taking apart.

Ok, is the backlash in a timing chain that is not brand new any less, or more than a belt?

The chain set I have (which is very tight) moves the cam as soon as the crank turns. This is using a degree wheel and dial indicator.

Where it gets very interesting with a standard cam core and roller springs is how much the front of the cam turns before the back. When you put any kind of spring pressure on a standard cam it twists it up like a pretzel.

Have you checked it yet? The XD rod will sometimes clear a 55mm with a 4.75". If it hits, the clearancing will be very minor. Here is the interference on an Oliver rod, which has a bigger shoulder then the Callies. [ATTACH=CONFIG]539260[/ATTACH][ATTACH=CONFIG]539261[/ATTACH][ATTACH=CONFIG]539262[/ATTACH]

Wow. Looks like the Oliver Rod is close to clearing. Mine isn't even close with the XD rods.