Thread: Help building 400 sbc

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I am going to build a 400sbc. I just posted about the cylinder head question. Anyway, I am running a Crane Mechanical Roller .580/600" lift cam and it hits the connecting rods. My question is are there specific cylinders that the rods need to be ground down or is it all of them. Next, how would I go about doing this. Am I just going to grind away some of the rod bolt until it doesn't hit anymore or is there a tried and true method to clearance the rods from hiting the cam on a 400. I know this is a common problem on 400's, but I haven't found specific instructions about how to do this. I may just have a shop assemble the motor and have them do it, I would just really like to know how to do this though.

Thanks.

There will be interference at the cam lobes by the rods if you use 5.7" or 6.0" rods. You can either send your cam back and order a cam ground on a reduced base circle or you can invest in some rods that will clear the cam you have now. Scat makes a nice set of forged 5.7" rods that will clear the cam under part number 25700P. Stock 400 rods will clear the cam lobes, but create significant side-loading of the piston skirts.

The above was posted by techinspector1 on another board and I'd take it as gospel.

Depending on the rod you have, some can be sanded down on a belt sander to clear the cam lobe. You should be able to see where this material should be removed. Both rod material and bolt material will be removed. This must be done before balancing the rotating assembly. You need at least .060" clearance. It might be best to let the shop that will balance your rotating assembly do this. You must check these for the minimum clearance as the short block is assembled.

I'm pretty sure that General Motors engineers did not leave extra material on the rod big ends just in case some crazy hot rodder wanted to grind on them. I strongly advise against grinding on a highly stressed part like a con rod. Use a reduced base circle cam or buy the rods that are engineered to miss the cam lobes.

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