Guest butlersZ Posted May 28, 2004 Share Posted May 28, 2004 Hey Guys, I'm building my fourth SBC and this time I have a problem with putting the pistons in the block. Ok, I have brand new forged pistons and moly rings, I put the ring compressor on the piston and tap it in and it goes in just fine. Then I put the rod cap on and then start another piston. After getting to the fourth piston or so I go to spin the crank with the pulley bolt and a ratchet and it barely spins and even locks up. WHY??? The lips on the rod caps are facing toward the crank like they should and the large side of the chamfer on the rod cap as well as the rod are toward the crank. Should this be reverse or what? Can anyone help me or tell me whats going on? I have had the parts to put it together for 3 days and this is the only thing holding me back. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted May 28, 2004 Share Posted May 28, 2004 Did you plastigauge your bearings? Quote Link to comment Share on other sites More sharing options...
Guest butlersZ Posted May 28, 2004 Share Posted May 28, 2004 nope, everything is standard though. I mic'd everything and everything seems to spec. I can put in one bank and then when I start the other side it starts to bind. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted May 28, 2004 Share Posted May 28, 2004 loosen the rods one at a time until you find the bad one...or maybe your pistons are just too tight? Quote Link to comment Share on other sites More sharing options...
Guest butlersZ Posted May 28, 2004 Share Posted May 28, 2004 well i just pulled the rings off one fo the pistons and it goes in the cylinder with ease. It's not the piston. And it's not the rings. My guess is the bearings or the rods. They are 305 rods which the engine I'm building is a 350, though they share the same crank casting and bearing size, right? I'm Going to tighten one of the caps to the rod out of the block and measure the I.D. with the bearings in then measure my crank journal again. Quote Link to comment Share on other sites More sharing options...
Guest butlersZ Posted May 28, 2004 Share Posted May 28, 2004 well 2.099 on the rod journal and the bearings are 2.106, what am i doing wrong? Quote Link to comment Share on other sites More sharing options...
jt1 Posted May 28, 2004 Share Posted May 28, 2004 Are the rod journals radiused? Maybe the chamfer on the rod bearings turned the wrong way? How about the side clearance between the rods? Should have around 0.020. John Quote Link to comment Share on other sites More sharing options...
BillZ260 Posted May 28, 2004 Share Posted May 28, 2004 It looks like you are on the right track. Make sure you don't get in a hurry, I usually get frustrated and what to jam it all together when stuff like this happens. Set aside everything and measure every OD and ID cyl by cyl. That is what I would do. If there are not tight clearences check the crank with no rods attached and check for clearance issues, and to get a feel. Check for burs on the rod ends and everything else. If you have done this 3 times before you know more than me. So just take your time and you'll find the problem. Let us know Quote Link to comment Share on other sites More sharing options...
Tim240z Posted May 28, 2004 Share Posted May 28, 2004 Did you put assembly lube on all the bearing surfaces? Quote Link to comment Share on other sites More sharing options...
Guest butlersZ Posted May 28, 2004 Share Posted May 28, 2004 Well I pulled the bearings back out of the rods and cleaned them inside and out, reassembled them and measured all the OD and ID of everything. My motor is in my kitchen on an engine stand, anyway, As I was going to put it all back together again I put the chamfers toward the crank, and everything went well, all eight pistons in this time. Turning the crank got a little stiffer after each piston went in which is normal I think. I got it all together and the crank takes some effort to turn it over, around 90-100 ft lbs. Everything is real tight. My problem was the chamfers, the wrong piston in the wrong cylinder. Thanks for the help guys. Quote Link to comment Share on other sites More sharing options...
BillZ260 Posted May 28, 2004 Share Posted May 28, 2004 TOLD YA, YOU WOULD FIGURE IT OUT! NOW, only 5400 posts to go.... Quote Link to comment Share on other sites More sharing options...
DaleMX Posted May 30, 2004 Share Posted May 30, 2004 Grumpy had something intresting he posted today along these lines. http://hybridz.org/nuke/index.php?name=PNphpBB2&file=viewtopic&t=34369 Dale Quote Link to comment Share on other sites More sharing options...
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