Rod clearance issues
01-05-2013, 08:01 PM
#1
Rod clearance issues Need some help here yet again with bearings folks. Im using plastigage (I know im searching out the mic and bore gauge now). But heres a quick parts rundown:
Iron block .030 over, eagle 4" stroker crank, eagle H beam rods with arp bolts.
Using std size clevite bearings I was comming up with .001-.0012 clearance
So logically my next step was go to a sealed power .001 undersize sicne I learned with the mains that clevites generally run tight anyhow. No luck, clearance got better .0015-.0018ish but still not what I was shooting for.
So back to autozone, I got a sealed power .002 undersize bearing. My clearance didnt improve any, its pretty much stayed the same, I thought this would get me where I needed to be.
Not only are my clearances not where I want them for the rods, but my side clearance is super tight as well. im not sure what people are running for side clearance but mine is super damn tight.
Im not sure if maybe theres a problem with the crank and it needs to be machined or what, but Id hope a new crank wouldnt need additional work.
Now I know the logical and right answer is get the right tools and or have a machine shop look at it. Im currently looking for someone that has the tools to do the real measurements for me, and if that doesnt work out it will go to the machine shop.
thoughts? ideas? tips/advice?
Iron block .030 over, eagle 4" stroker crank, eagle H beam rods with arp bolts.
Using std size clevite bearings I was comming up with .001-.0012 clearance
So logically my next step was go to a sealed power .001 undersize sicne I learned with the mains that clevites generally run tight anyhow. No luck, clearance got better .0015-.0018ish but still not what I was shooting for.
So back to autozone, I got a sealed power .002 undersize bearing. My clearance didnt improve any, its pretty much stayed the same, I thought this would get me where I needed to be.
Not only are my clearances not where I want them for the rods, but my side clearance is super tight as well. im not sure what people are running for side clearance but mine is super damn tight.
Im not sure if maybe theres a problem with the crank and it needs to be machined or what, but Id hope a new crank wouldnt need additional work.
Now I know the logical and right answer is get the right tools and or have a machine shop look at it. Im currently looking for someone that has the tools to do the real measurements for me, and if that doesnt work out it will go to the machine shop.
thoughts? ideas? tips/advice?
01-05-2013, 08:43 PM
#2
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Man your havin a heck of a time. I have seen Eagle cranks for old school chevys that were on the tight (big) side. I would say about .012 to .015 on the side clearance.
01-05-2013, 08:53 PM
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.0015 is too tight. I would check it again, even with the bearings that you have. If it is that tight, you will need to address that issue before anything else.
01-05-2013, 09:16 PM
#6
What's the part number of the bearings you've tried? Are you sure you're getting the bearings for more clearance and not less? For example, Clevite CB663H-1 will give you .001" less clearance than standard bearings and CB663HX will give you .001" more clearance.
Side clearance should be at least .010" or so. Use a feeler gauge to measure. If you're not getting enough side clearance, make sure the rods are hung correctly. They could be backwards causing the chamfer on the bearings to face the wrong way and hang the bearing up on the radius on the crank...which actually might explain the bearing clearance problem.
Side clearance should be at least .010" or so. Use a feeler gauge to measure. If you're not getting enough side clearance, make sure the rods are hung correctly. They could be backwards causing the chamfer on the bearings to face the wrong way and hang the bearing up on the radius on the crank...which actually might explain the bearing clearance problem.
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01-05-2013, 09:37 PM
#9
Wrong bearings, those are for a crank turned .001" and .002" smaller so they will get you less clearance. Try the CB663HX from Clevite.
01-06-2013, 09:01 PM
#15
KCS is giving you great advice. I'll add by saying sometimes you may find that your X bearings might leave you a little looser than you target, and the std. is too tight. In this case, run the std. Upper and the X lower for a .0005 extra clearance over std.
