sr20 nnew motor question. - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

dragooner00 · 09-12-2012, 10:27 AM

so, i have just rebuilt my motor (had most of the work done at a shop its a full build) and my buddy just did a basically oem rebuild on his sr20det. now we have assembled everything seperatly and both are having the exact same problem. the block and head assembly (with no trans attached) will not be phsyically turned over by hand. we have both put a breaker bar/torque wrench on the crank to try to turn it over and we get a soft spot of about 3 degrees from top dead center in either direction. the motors are timed correctly. we both assembled by the fsm. neither vehicle has been started sicne the rebuild and does not have oil in them. did we somehow manage to fuck our motors up or should you not be able to turn it over by hand.

JANK240 · 09-12-2012, 11:00 AM

Sounds like you may have the wrong size main bearings causing it to be really tight. Was assembly lube used or was it assembled dry?
Have you tried turning it a complete revolution? There is gonna be compression so there will be resistance.

Edwin562 · 09-12-2012, 11:36 AM

is the crank in good condition?

GroundPerformance · 09-12-2012, 11:38 AM

I would recommend you read the FSM all over again. GL!

dragooner00 · 09-12-2012, 01:23 PM

It was assembled using assembly lube it was done at a machine shop, I'm just afraid to put a ton of torque on it to force it crank over. Everything was polished and balanced and everything is perfect, it's all be replaced with new parts I hit a hard spot at about 5 degrees past tdc, it's been over bored and re honed and it moved freely before I put my head on, I think it's just a lack of oil and how hard it is to rotate it with the compression.

Hashiriya415 · 09-12-2012, 01:38 PM

What kind of ring gab do you have?

dragooner00 · 09-12-2012, 01:51 PM

Not sure offs the top of my head if have to look, but what I find strange is that I know for a fact the block itself turned over prior to installing the head on both of our cars but once the head got installed and stuff got bolted on and the timing chain got hooked up, now neither one of us can turn it over by hand, I'm gonna probably leave it up to the fact that we are wusses.

dragooner00 · 09-12-2012, 01:53 PM

Turn either of our motors over* since we are both having the exact same prPblem of them rotating before everything got hooked up

bkt808 · 09-12-2012, 02:47 PM

Take the spark plugs out so there is no compression and try to turn it over

Hoffman5982 · 09-12-2012, 06:29 PM

Have any of you guys ever even tried turning a motor that's fully assembled over by hand? Maybe with no head or anything you can turn it by hand, but with cams and all, when it's actually building compression, there's no way. I've never been able to do it.

OP- I'm assuming that soft spot is when the compression is releasing. I know exactly what you're talking about, that's just the conclusion I came to. You should be fine.

dragooner00 · 09-12-2012, 07:34 PM

ok hoff, thats what i was thinking. its got a fully upgraded valvetrain, retainers, valves, valve spings, cams, all of which are made for 12k rpm applications. i'm 90% sure that because the motor turned over with no head on it, had no clearance issues with valves, all of a sudden would stop working. im really thinking its because im a pussy who doesnt have the strength to get through that little oomph part. i'm fairly certain that once the motor is in and oiled properly it shouldnt have any where near a hard time turning itself over.

dragooner00 · 09-12-2012, 07:35 PM

btw hoff, thanks for answering my other question on /r/240sx lol your a lifesaver, if you ever come to IL hit me up when im 21 im buying you a couple of beers.

Pinggg · 09-12-2012, 07:56 PM

Make sure your chain are align ion the guides properly. Mine was doing the same thing till i fix that.. it might or might not fix your problem but it'll only take a few mins to look.

Hoffman5982 · 09-12-2012, 08:20 PM

Lol I didn't even notice the screen names. Free beer is always a good thing.

Gunmetal-Coupe · 09-29-2012, 12:47 PM

Hey guys i was kind of having the same problem with my build, i was wondering if this was normal or not. When i torqued my main caps down my crank turned by hand no problem, but after torquing down my arp rod bolts i can no longer turn the crank by hand. Is it normal for this to happen since i have all new pistons and rings?

09-12-2012, 10:27 AM	#1
dragooner00 Join Date: Apr 2011 Location: Illinois Age: 33 Posts: 34 Trader Rating: (1) Feedback Score: 1 reviews	sr20 nnew motor question. so, i have just rebuilt my motor (had most of the work done at a shop its a full build) and my buddy just did a basically oem rebuild on his sr20det. now we have assembled everything seperatly and both are having the exact same problem. the block and head assembly (with no trans attached) will not be phsyically turned over by hand. we have both put a breaker bar/torque wrench on the crank to try to turn it over and we get a soft spot of about 3 degrees from top dead center in either direction. the motors are timed correctly. we both assembled by the fsm. neither vehicle has been started sicne the rebuild and does not have oil in them. did we somehow manage to fuck our motors up or should you not be able to turn it over by hand.

09-12-2012, 11:38 AM	#4
GroundPerformance Zilvia FREAK! Join Date: Oct 2008 Location: Socal Posts: 1,479 Trader Rating: (44) Feedback Score: 44 reviews	I would recommend you read the FSM all over again. GL! __________________ SoCal KA24DET/KA24ET Owners << Join the FB Group >>

09-12-2012, 06:29 PM	#10
Hoffman5982 Post Whore! Join Date: Jan 2009 Location: Definitely NOT FL.... Age: 33 Posts: 2,504 Trader Rating: (25) Feedback Score: 25 reviews	Have any of you guys ever even tried turning a motor that's fully assembled over by hand? Maybe with no head or anything you can turn it by hand, but with cams and all, when it's actually building compression, there's no way. I've never been able to do it. OP- I'm assuming that soft spot is when the compression is releasing. I know exactly what you're talking about, that's just the conclusion I came to. You should be fine. __________________

09-12-2012, 08:20 PM	#14
Hoffman5982 Post Whore! Join Date: Jan 2009 Location: Definitely NOT FL.... Age: 33 Posts: 2,504 Trader Rating: (25) Feedback Score: 25 reviews	Lol I didn't even notice the screen names. Free beer is always a good thing. __________________

09-12-2012, 11:00 AM	#2
JANK240 Leaky Injector Join Date: Nov 2011 Location: 903 Age: 35 Posts: 78 Trader Rating: (7) Feedback Score: 7 reviews	Sounds like you may have the wrong size main bearings causing it to be really tight. Was assembly lube used or was it assembled dry? Have you tried turning it a complete revolution? There is gonna be compression so there will be resistance.

09-12-2012, 11:36 AM	#3
Edwin562 Post Whore! Join Date: Nov 2009 Location: Whittier (562) Age: 35 Posts: 4,721 Trader Rating: (35) Feedback Score: 35 reviews	is the crank in good condition?

09-12-2012, 01:23 PM	#5
dragooner00 Join Date: Apr 2011 Location: Illinois Age: 33 Posts: 34 Trader Rating: (1) Feedback Score: 1 reviews	It was assembled using assembly lube it was done at a machine shop, I'm just afraid to put a ton of torque on it to force it crank over. Everything was polished and balanced and everything is perfect, it's all be replaced with new parts I hit a hard spot at about 5 degrees past tdc, it's been over bored and re honed and it moved freely before I put my head on, I think it's just a lack of oil and how hard it is to rotate it with the compression.

09-12-2012, 01:38 PM	#6
Hashiriya415 Zilvia FREAK! Join Date: Jun 2007 Location: San Francisco Age: 37 Posts: 1,007 Trader Rating: (22) Feedback Score: 22 reviews	What kind of ring gab do you have?

09-12-2012, 01:51 PM	#7
dragooner00 Join Date: Apr 2011 Location: Illinois Age: 33 Posts: 34 Trader Rating: (1) Feedback Score: 1 reviews	Not sure offs the top of my head if have to look, but what I find strange is that I know for a fact the block itself turned over prior to installing the head on both of our cars but once the head got installed and stuff got bolted on and the timing chain got hooked up, now neither one of us can turn it over by hand, I'm gonna probably leave it up to the fact that we are wusses.

09-12-2012, 01:53 PM	#8
dragooner00 Join Date: Apr 2011 Location: Illinois Age: 33 Posts: 34 Trader Rating: (1) Feedback Score: 1 reviews	Turn either of our motors over* since we are both having the exact same prPblem of them rotating before everything got hooked up

09-12-2012, 02:47 PM	#9
bkt808 Zilvia Member Join Date: Feb 2010 Location: Wailuku, Maui, Hawaii Age: 37 Posts: 245 Trader Rating: (1) Feedback Score: 1 reviews	Take the spark plugs out so there is no compression and try to turn it over

09-12-2012, 07:34 PM	#11
dragooner00 Join Date: Apr 2011 Location: Illinois Age: 33 Posts: 34 Trader Rating: (1) Feedback Score: 1 reviews	ok hoff, thats what i was thinking. its got a fully upgraded valvetrain, retainers, valves, valve spings, cams, all of which are made for 12k rpm applications. i'm 90% sure that because the motor turned over with no head on it, had no clearance issues with valves, all of a sudden would stop working. im really thinking its because im a pussy who doesnt have the strength to get through that little oomph part. i'm fairly certain that once the motor is in and oiled properly it shouldnt have any where near a hard time turning itself over.

09-12-2012, 07:35 PM	#12
dragooner00 Join Date: Apr 2011 Location: Illinois Age: 33 Posts: 34 Trader Rating: (1) Feedback Score: 1 reviews	btw hoff, thanks for answering my other question on /r/240sx lol your a lifesaver, if you ever come to IL hit me up when im 21 im buying you a couple of beers.

09-12-2012, 07:56 PM	#13
Pinggg Zilvia FREAK! Join Date: Dec 2010 Location: Coconut Creek, Florida Age: 31 Posts: 1,255 Trader Rating: (22) Feedback Score: 22 reviews	Make sure your chain are align ion the guides properly. Mine was doing the same thing till i fix that.. it might or might not fix your problem but it'll only take a few mins to look.

09-29-2012, 12:47 PM	#15
Gunmetal-Coupe Join Date: Aug 2010 Location: Long Island, New York Age: 35 Posts: 6 Trader Rating: (0) Feedback Score: 0 reviews	Hey guys i was kind of having the same problem with my build, i was wondering if this was normal or not. When i torqued my main caps down my crank turned by hand no problem, but after torquing down my arp rod bolts i can no longer turn the crank by hand. Is it normal for this to happen since i have all new pistons and rings?