USDM crank in JDM - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

azreark1 · 03-08-2015, 06:56 PM

So my JDM SR20 crank was hosed on #3 due to a spun rod bearing, mic'd the crank and it needs to be taken to a machine shop so i picked up a USDM SR20 for dirt cheap so that i could just use the crank out of it and get it back together quick.
My first question is about the balancing of the crank, i know both the JDM and USDM cranks have the same number, but are they balanced differently due to the fact that the USDM rod is smaller than the JDM rod?

Second question is how much does it matter if the connecting rod is out of round? As long as the crank is perfect and the rod is BARELY out of round, will the bearing still ride the crank good? I'm not trying to cut corners here, because my wife would KILL me if i got this back together only to have to tear it back down again in a month due to a failed rod bearing...i'm just curious about the clearances and how bad it would have to be to make it fail again.

GOOD connecting rod measurements are about 2.001 - 2.003 all the way around, bad connecting rod is 2.001 where the halves meet and 2.010 from the bottom of the rod to the top (perpendicular to the connecting faces), Looks like a huge difference to me but i will admit I'm illiterate when it comes to oil clearances.

Sileighty_85 · 03-09-2015, 01:41 AM

Only "V'" series cranks are balanced with rods and pistons.

Inline cranks are balanced to themselves.

I would not run that rod. in sure you can find another used SR rod cheap.

azreark1 · 03-09-2015, 07:41 AM

For rod bearings, getting standard size, saw ACL race bearings for the same price as regular bearings...any idea what the difference is?

Sileighty_85 · 03-09-2015, 09:38 AM

No idea about ACL. Ive only ever used Nismo and Tomei bearings.

m-drift · 03-10-2015, 02:26 PM

Quote:

Originally Posted by Sileighty_85

No idea about ACL. Ive only ever used Nismo and Tomei bearings.

do you think the oem bearings last longer then race bearings?

m-drift · 03-10-2015, 02:27 PM

Quote:

Originally Posted by azreark1

So my JDM SR20 crank was hosed on #3 due to a spun rod bearing, mic'd the crank and it needs to be taken to a machine shop so i picked up a USDM SR20 for dirt cheap so that i could just use the crank out of it and get it back together quick.
My first question is about the balancing of the crank, i know both the JDM and USDM cranks have the same number, but are they balanced differently due to the fact that the USDM rod is smaller than the JDM rod?

Second question is how much does it matter if the connecting rod is out of round? As long as the crank is perfect and the rod is BARELY out of round, will the bearing still ride the crank good? I'm not trying to cut corners here, because my wife would KILL me if i got this back together only to have to tear it back down again in a month due to a failed rod bearing...i'm just curious about the clearances and how bad it would have to be to make it fail again.

GOOD connecting rod measurements are about 2.001 - 2.003 all the way around, bad connecting rod is 2.001 where the halves meet and 2.010 from the bottom of the rod to the top (perpendicular to the connecting faces), Looks like a huge difference to me but i will admit I'm illiterate when it comes to oil clearances.

im doing the same with my sr. did u get the usdm crank for a older nissan sentra?

azreark1 · 03-10-2015, 03:51 PM

You know, I have no idea what year car the engine came out of, bought it off a guy that had it sitting in his garage.

*TheRealSy90* · 03-10-2015, 05:31 PM

sr20de/det cranks should all be the same with the exception of the GTIR sr20 and the sr16ve obviously.

azreark1 · 03-10-2015, 05:35 PM

Correct, that's been clarified a few times around the internet, that's why I picked up the motor...now I have a bunch of other parts I don't need from the donor motor...scrap yard here I come lol

azreark1 · 03-15-2015, 05:36 PM

So i'm getting the motor put back together and here's what I've come across with the middle (#3) main bearing housing...seems there is a small nick where the bearing notch sits and there is a 'groove' between where the bearing sits and the sidewall...not sure if this will make a difference in the longevity or performance of the main bearing...

azreark1 · 03-15-2015, 05:44 PM

...Since i can't post in the For Sale section yet...I also have USDM parts for sale, everything off a SR20 long block except the crank, need it GONE! lol

azreark1 · 03-18-2015, 12:56 PM

So got my block problem figured out...now the freakin thrust washers don't fit!! I mean WTF. I've only seen them in STD size, they measure exactly like BOTH old sets i have, but now they don't fit, i just don't get it.

03-08-2015, 06:56 PM	#1
azreark1 Leaky Injector Join Date: Feb 2015 Location: San Antonio, Tx Age: 36 Posts: 71 Trader Rating: (0) Feedback Score: 0 reviews	USDM crank in JDM So my JDM SR20 crank was hosed on #3 due to a spun rod bearing, mic'd the crank and it needs to be taken to a machine shop so i picked up a USDM SR20 for dirt cheap so that i could just use the crank out of it and get it back together quick. My first question is about the balancing of the crank, i know both the JDM and USDM cranks have the same number, but are they balanced differently due to the fact that the USDM rod is smaller than the JDM rod? Second question is how much does it matter if the connecting rod is out of round? As long as the crank is perfect and the rod is BARELY out of round, will the bearing still ride the crank good? I'm not trying to cut corners here, because my wife would KILL me if i got this back together only to have to tear it back down again in a month due to a failed rod bearing...i'm just curious about the clearances and how bad it would have to be to make it fail again. GOOD connecting rod measurements are about 2.001 - 2.003 all the way around, bad connecting rod is 2.001 where the halves meet and 2.010 from the bottom of the rod to the top (perpendicular to the connecting faces), Looks like a huge difference to me but i will admit I'm illiterate when it comes to oil clearances.

03-09-2015, 01:41 AM	#2
Sileighty_85 Post Whore! Join Date: Dec 2006 Location: Misawa, Japan Posts: 6,815 Trader Rating: (8) Feedback Score: 8 reviews	Only "V'" series cranks are balanced with rods and pistons. Inline cranks are balanced to themselves. I would not run that rod. in sure you can find another used SR rod cheap. __________________ 後輪駆動車１番 1989 Built SR GT2871R -363whp 1998 S14 W/RB25- 250ish (For Now) 1986 SR86 - 200ish 1990 R32 GTR - 320hp Don't Buy Engines from JDM-Online http://zilvia.net/f/businesses/207457-jdm-online.html Don't Buy XS-Power or SSAC Shit

03-09-2015, 09:38 AM	#4
Sileighty_85 Post Whore! Join Date: Dec 2006 Location: Misawa, Japan Posts: 6,815 Trader Rating: (8) Feedback Score: 8 reviews	No idea about ACL. Ive only ever used Nismo and Tomei bearings. __________________ 後輪駆動車１番 1989 Built SR GT2871R -363whp 1998 S14 W/RB25- 250ish (For Now) 1986 SR86 - 200ish 1990 R32 GTR - 320hp Don't Buy Engines from JDM-Online http://zilvia.net/f/businesses/207457-jdm-online.html Don't Buy XS-Power or SSAC Shit

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03-09-2015, 07:41 AM	#3
azreark1 Leaky Injector Join Date: Feb 2015 Location: San Antonio, Tx Age: 36 Posts: 71 Trader Rating: (0) Feedback Score: 0 reviews	For rod bearings, getting standard size, saw ACL race bearings for the same price as regular bearings...any idea what the difference is?

03-10-2015, 03:51 PM	#7
azreark1 Leaky Injector Join Date: Feb 2015 Location: San Antonio, Tx Age: 36 Posts: 71 Trader Rating: (0) Feedback Score: 0 reviews	You know, I have no idea what year car the engine came out of, bought it off a guy that had it sitting in his garage.

03-10-2015, 05:35 PM	#9
azreark1 Leaky Injector Join Date: Feb 2015 Location: San Antonio, Tx Age: 36 Posts: 71 Trader Rating: (0) Feedback Score: 0 reviews	Correct, that's been clarified a few times around the internet, that's why I picked up the motor...now I have a bunch of other parts I don't need from the donor motor...scrap yard here I come lol

03-15-2015, 05:36 PM	#10
azreark1 Leaky Injector Join Date: Feb 2015 Location: San Antonio, Tx Age: 36 Posts: 71 Trader Rating: (0) Feedback Score: 0 reviews	So i'm getting the motor put back together and here's what I've come across with the middle (#3) main bearing housing...seems there is a small nick where the bearing notch sits and there is a 'groove' between where the bearing sits and the sidewall...not sure if this will make a difference in the longevity or performance of the main bearing...

03-15-2015, 05:44 PM	#11
azreark1 Leaky Injector Join Date: Feb 2015 Location: San Antonio, Tx Age: 36 Posts: 71 Trader Rating: (0) Feedback Score: 0 reviews	...Since i can't post in the For Sale section yet...I also have USDM parts for sale, everything off a SR20 long block except the crank, need it GONE! lol

03-18-2015, 12:56 PM	#12
azreark1 Leaky Injector Join Date: Feb 2015 Location: San Antonio, Tx Age: 36 Posts: 71 Trader Rating: (0) Feedback Score: 0 reviews	So got my block problem figured out...now the freakin thrust washers don't fit!! I mean WTF. I've only seen them in STD size, they measure exactly like BOTH old sets i have, but now they don't fit, i just don't get it.