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HOW BIG OF MOTOR CAN I GO WITH STOCK BOTTOM END?


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Go through the bottom end. If you get good power out of the top end you will be tearing down all over again but this time the bottom end as well because of trying to save time and money which in turn will cost you way more than just doing the bottom end now. Talk to a reputable builder and they will steer you in the right direction

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What everyone is eluding to is that the crank in it's stock condition is weak.  The crank pin needs to be welded to ensure the crank assembly doesn't rotate and become out of phase. 

You can do the basics... pipes, mild porting, jetting etc, but I wouldn't be doing any power launches on asphalt with an unmodded crank.

 

Welcome to the BHQ.

Edited by jayzx750
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The stock crank can accept an array of power mods. The reasoning for going through all of it is more 'wear & tear' related. If you have an engine that has been run for some time, play and fatigue set in. If you are modding for more power it is advisable to build the entire thing so that there are no surprises later.

Years ago I slid a cam into a good running 350 small block. Ran real good when done, within 3 weeks #1 rod had a spun main bearing-lesson learned (I think I was like 17).

 

Replace/rebuild your crank for peace-of-mind, then you'll have a solid foundation for you rotating assembly. Make a Plan for the build, educate yourself, and execute it-you'll get more performane for the dollar this way; rather than randomly throwing parts/mods at it till your either exhuasted, or have spent enough for several builds.

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To answer the question-haha;

Stock bore can be taken to around 66.5mm

With a new sleeve fitted, you can shove a 68mm piston in there and this sleeve maxes out at 69.5mm

 

All sizeable overbores should be complimented with correct/matching porting to restore or enhance the port's job.....

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