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240z LS1 firewall to engine block space!! how far back?


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hello,

 

So I just mounted the ls engine in my 72 240z project car using cxracing engine mounts. The transmission will be a 4 speed auto (4L60e).

 

The engine sits beautifully in the engine bay.

 

QUESTION IS: how far from the firewall should I mount the engine? engine mounts are slotted giving me plenty of room to move the engine forward or backward.

 

I know now the transmission will play a great rule in deciding where the engine will sit. I just want to know what other members did. How far the block edge (right under the flex plat) from the firewall?

 

Currently the block is about 4.25 inch away from the firewall. PICTURES UPLOADED. 

 

Please advise :D

IMG_6112.HEIC.pdf

IMG_6113.HEIC.pdf

IMG_6114.HEIC.pdf

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On the CXR kit it is intended to go in the furthest holes back.  My problem was it couldn't, the lines at the front of the tunnel got into the back of the bell housing, so it went one hole forward.  The exhaust is now tight but it fits.  If there is any way to get it as far back as possible it would help in the long run.  JMHO, Richard 

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2 hours ago, 260DET said:

Ten mm clearance is a great clearance rule of thumb for everything, get that engine back and handle the consequences like you know you can.

I think you mean 10 cm not mm, cause 10 mm is 1 cm which is almost nothing.

10 cm (amost 4 inch) is very comfortable for me. But I’m concern about weight distribution and handling.

the biggest concern is the stress I’ll be putting on the engine mounts by backing up the engine 

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17 hours ago, Richard Oben said:

On the CXR kit it is intended to go in the furthest holes back.  My problem was it couldn't, the lines at the front of the tunnel got into the back of the bell housing, so it went one hole forward.  The exhaust is now tight but it fits.  If there is any way to get it as far back as possible it would help in the long run.  JMHO, Richard 

 

Can I ask how did you figure it out? Did you talk to cxracing or you just looked at their product pictures? 

Excuse me for the question, I’m not trying to troll you, it’s an innocent question 

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I'm about 4 inches +/- from the head to firewall.   I track my car all the time and the balance is great... Keep in mind my car is pretty low (CG) so that always helps.  Again, I'm running the T56 so placement for had a lot to do where the shift pin came through the tunnel.  Ill post a pic in a bit.  Jim

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3 minutes ago, trackzpeed said:

I'm about 4 inches +/- from the head to firewall.   I track my car all the time and the balance is great... Keep in mind my car is pretty low (CG) so that always helps.  Again, I'm running the T56 so placement for had a lot to do where the shift pin came through the tunnel.  Ill post a pic in a bit.  Jim

 

Jim

Great information, very helpful.

i appreciate your input and thank you for the picture 

 

Mohammad

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The general answer to your question is "as far back as you can manage." John's Cars kit puts it at about 4". I moved mine further back, IIRC I'm at about an inch and a half on the pass head. It's not a simple thing. I had to cut the trans tunnel for clearance in front, and the 70 tunnel is narrow so I had to beat it with a BFH to make it fit. If I went further back I would have had to cut the tunnel in the rear too, or just cut the whole thing out and made my own, otherwise the bottom of the trans would have hung below the frame rails. 

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4 hours ago, NC88 said:

LS3/TR6060 in a 240Z with the CX kit here, I went 3rd hole from the back.  I agree with the "as far back as you can manage" strategy.  

 

Update: I tried doing the second hole from the back of the engine, but the transmission would require major tunnel cutting and fabrication to be raised up and leveled.

 

 So I decided to go for the third hole like you. Some little more hammering and my engine and transmission is at 5 degree backwards tilt.

 

that brings up another question, what’s your tilte angle of the engine?

 

Side to side I’m 1 degree of the chassis level, which is almost perfectly leveled with the chassis. Good enough for me.

 

my concern is the engine tilt backward at 5 degree. My research says 3 to 5 degrees of backward tilt is ok. What do you guys have? 

 

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IN the CX pictures it showed mounted all the way back,  unless the parts changed.  Remember I bought the complete CXR kit exhaust and all.  Some others may be more forward and did their own exhaust.  I did have to trim the tunnel just a little to make the CAMARO shifter work.  The GTO shifter was not even close.  Literally we had it all in and tried to put the transmission mount in and the bell housing hit the hard lines for fuel and brakes.  I could have beat the tunnel and probably made it go further back, but did not.  Also I am not sure if it means anything but I have a series one 240Z. Also, I am at 2 degrees down on the engine/trans combo.  HTH, Richard.  

 

Bo, absolutely no problem on asking more questions, I know I asked a lot before I got mine started.  Richard. 

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11 minutes ago, Richard Oben said:

IN the CX pictures it showed mounted all the way back,  unless the parts changed.  Remember I bought the complete CXR kit exhaust and all.  Some others may be more forward and did their own exhaust.  I did have to trim the tunnel just a little to make the CAMARO shifter work.  The GTO shifter was not even close.  Literally we had it all in and tried to put the transmission mount in and the bell housing hit the hard lines for fuel and brakes.  I could have beat the tunnel and probably made it go further back, but did not.  Also I am not sure if it means anything but I have a series one 240Z. Also, I am at 2 degrees down on the engine/trans combo.  HTH, Richard.  

 

Bo, absolutely no problem on asking more questions, I know I asked a lot before I got mine started.  Richard. 

 

I am going to customize the headers or go for a manifold, depend on the cost involved.

I’ll be happy if I reach 2 degrees of angle.

 

thank you for your input Richard, I appreciate your help 

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When I researched my install, I came at cross a thread claiming up to 5 degrees was good to maintain oil around the pick-up in the pan from the monster Miata crowd. I’m siting at about 3+ degrees but it’s just the way it worked out after I  bolted it all up.... I believe CXRACING has it engineered into the kit. The CX headers are long tube and fit nice with the kit for a fair price..... my exhaust is custom from the y pipe back.  Hope that helps. Jim 

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1 hour ago, trackzpeed said:

When I researched my install, I came at cross a thread claiming up to 5 degrees was good to maintain oil around the pick-up in the pan from the monster Miata crowd. I’m siting at about 3+ degrees but it’s just the way it worked out after I  bolted it all up.... I believe CXRACING has it engineered into the kit. The CX headers are long tube and fit nice with the kit for a fair price..... my exhaust is custom from the y pipe back.  Hope that helps. Jim 

 

Jim,

thank you for your input. Problem is that the headers only fits manual transmission, I have gm 4 speed automatic. It will interfere with the trans pan.

 

Are you using the stoke differential setup? 

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