huricane4 Posted April 17, 2014 Share Posted April 17, 2014 Hi i gonna boore my 4.0 engine this weekend but can't find any tolerance? Gonna use Sealed Power 677AP 0.060 Pistons Couldn't find anything on their website either Link to comment Share on other sites More sharing options...
huricane4 Posted April 17, 2014 Author Share Posted April 17, 2014 I measured the pisons and they are 99.91-99.915 mm 3.9334-3.9336inch at the skirt Link to comment Share on other sites More sharing options...
Incommando Posted April 17, 2014 Share Posted April 17, 2014 Looks like the factory bore was 3.88" of you want to base it off of that... http://en.wikipedia.org/wiki/AMC_straight-6_engine http://www.baeta.org/opie/engine.htm#C Link to comment Share on other sites More sharing options...
jimoshel Posted April 17, 2014 Share Posted April 17, 2014 Take the pistons to the machine shop so they can mike them and insure a proper fit. You want 0.0012-0.0013in clearance. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted April 17, 2014 Share Posted April 17, 2014 Bore. Link to comment Share on other sites More sharing options...
huricane4 Posted April 17, 2014 Author Share Posted April 17, 2014 Take the pistons to the machine shop so they can mike them and insure a proper fit. You want 0.0012-0.0013in clearance. I am planning to Bore it myself... it is a budget build and just want to test if i manage to do it :) Link to comment Share on other sites More sharing options...
Eagle Posted April 17, 2014 Share Posted April 17, 2014 How are you planning to bore it yourself? Do you have a machine shop? You don't bore engine blocks with a Dremel ... Link to comment Share on other sites More sharing options...
jimoshel Posted April 17, 2014 Share Posted April 17, 2014 How are you planning to bore it yourself? Do you have a machine shop? You don't bore engine blocks with a Dremel ... How about a ridge reamer? :rotf: Link to comment Share on other sites More sharing options...
huricane4 Posted April 18, 2014 Author Share Posted April 18, 2014 How are you planning to bore it yourself? Do you have a machine shop? You don't bore engine blocks with a Dremel ... How are you planning to bore it yourself? Do you have a machine shop? You don't bore engine blocks with a Dremel ... I work with milling so i gonna use one of those: http://www.zayer.com/en/product/movingcolumn/30kc-ar30kcu-ar/7 and http://www.bigkaiser.com/finish-dia590.php Link to comment Share on other sites More sharing options...
Comanchemodder Posted April 18, 2014 Share Posted April 18, 2014 From the 1989 Jeep Cherokee service manual for the 4.0L in-line 6: Bore: 98.42-98.48mm Max Taper: .025mm Max out-of-round: .025mm Link to comment Share on other sites More sharing options...
Incommando Posted April 18, 2014 Share Posted April 18, 2014 He looks to be in Russia or somewhere in Eastern Europe. His shop looks fairly well equipped, as well. Good on him for the do-it-yourself attitude. It looks like that was probably the only way he could do a lot for his MJ there. Link to comment Share on other sites More sharing options...
huricane4 Posted April 22, 2014 Author Share Posted April 22, 2014 The block is bored and honed. Didn´t find any upper tolerance so i did it tight (0.025-0.035mm) so it will be a really quiet engine or breakdown :) Thanks for all replies And i am from Sweden ;) Link to comment Share on other sites More sharing options...
Eagle Posted April 22, 2014 Share Posted April 22, 2014 You probably know this, but be sure to check the end gap on the piston rings when you assemble the engine. Especially with a very tight fit, this could be important. Link to comment Share on other sites More sharing options...
huricane4 Posted April 25, 2014 Author Share Posted April 25, 2014 You probably know this, but be sure to check the end gap on the piston rings when you assemble the engine. Especially with a very tight fit, this could be important. Yeah i will control the end gap but thanks for the reminder Link to comment Share on other sites More sharing options...
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