[colkerr]

In the midst of assembaling my motor. Block is a 66 289. Crank is a 70 302. Having clearance issues with the rear crank counterwieght hitting #4 cyl wall. It's just nicking it. Just mocking up right now just for this reason, but I thought 289/302 shared the same block? How much clearance is required in this area?

Cheers
Matt

 

[DanH]

you got the thrust bearing installed ?

.060" clearence , can go less the braver you are

 

[colkerr]

All bearings in and tourqued with assy lube. Clearance it also tight at .0020 on the mains.


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[n2omike]

Wow, you should NOT have clearance issues. 289 and earlier 302 blocks are functionally identical. But, if it needs clearanced, it needs clearanced. Double check everything to make sure there isn't something screwy. 0.060" should be good.

Does the crank have 2M stamped on it? As that's a older style 302 crank.

Good Luck!

 

[colkerr]

Well it's my old 289 block and here's a pic of the crank and where it's nicking the cyl bore. Sucks. Now I'll have to wash the block again. Oh well. That's why I check these things. Just seems odd to me.


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[PSIG]

+1 point for checking. That's the right way to do it, and any issues you have are best found now. :tup: You don't have to wash the block again. Just put a blob of grease on the area, file through it by hand with a rat tail or shaping file, and pick the grease and filings off with a paper towel. Easy squeezy.

David

 

[colkerr]

Is .0020 too tight on main bearing clearance? I think spec is .0025-.0030.


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[colkerr]

Measuring is done with plastigauge mind you, so not sure how accurate it is.


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[bmcdaniel]

You're probably ok measuring .002" w/plastigage. Plastigage can be vey accurrate measuring flat surfaces but curved journals don't squish the Plastigage like a flat surface would. From what I've seen, when using it to measure main journals, the clearance is usually .0005"-.001" larger than indicated. Make sure the bearing and jounal have no oil on either side. Some guys will put oil on the bearing before laying the crank in, that reduces clearance. And always use new, fresh Plastigage.