Conversions & Swaps LSX Engines in Non-LSX Vehicles
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1968 GTO LS1/T56 Conversion

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Old 07-09-2010, 12:57 AM
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Would you mind showing more pics of that relay block with the fuse block as well ???
I'm ready to do an LS swap into my 1970 442 clone, and this is basically the same car.

I really dig the relay block and I'd like to see more details and what all those fuses will be for and how it's wired.
Old 08-02-2010, 05:11 PM
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Old 08-23-2010, 08:41 PM
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Been a long time, sorry!

I installed autometer gages in the factory locations. The look is not as as close to original as I hoped, but I think it works. I also finally got the clutch bled using a vacuum pump on the reservoir. It worked awesome and I didn't even need to touch the bleeder screw that is never to be seen again after these transmissions are installed.

New problem: firewall is flexing. I used a S&P type mounting plate made from 1/4" steel, and I am seeing severe flexing in the brake master cylinder when I press on the clutch pedal. Has anyone had this problem before?

I promise I will finally have pictures this week.
Old 08-24-2010, 07:29 PM
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Here are pictures of the 3" pypes exhaust kit as delivered (it's on the car, but I don't have a picture), my fuel pump and fuel pressure regulator installed, and my super awesome cold air intake.
Attached Thumbnails 1968 GTO LS1/T56 Conversion-img_1427.jpg   1968 GTO LS1/T56 Conversion-img_1388.jpg   1968 GTO LS1/T56 Conversion-img_1565.jpg  
Old 08-24-2010, 08:27 PM
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Originally Posted by pushrod36
New problem: firewall is flexing. I used a S&P type mounting plate made from 1/4" steel, and I am seeing severe flexing in the brake master cylinder when I press on the clutch pedal. Has anyone had this problem before?
Can't believe anything made out of steel that thick could bend.

The firewall on my car moves a good bit, but brakes and clutch work fine. If it ain't broke......
Old 08-25-2010, 07:31 PM
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pop n wood - I always appreciate your wisdom. I believe that what is happening is the pedal force on the clutch master cylinder is creating a moment about the mounting bolts (the four shared with the brake booster). This is where the flex is happening.

I agree with you that everything should work fine....for now. I am concerned about a fatigue failure down the road. I am wondering if the forces are slightly higher than what GM ever intended due to the lack of a spring assist in my set-up.
Old 08-25-2010, 11:14 PM
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Originally Posted by pushrod36
pop n wood - I always appreciate your wisdom. I believe that what is happening is the pedal force on the clutch master cylinder is creating a moment about the mounting bolts (the four shared with the brake booster). This is where the flex is happening.

I agree with you that everything should work fine....for now. I am concerned about a fatigue failure down the road. I am wondering if the forces are slightly higher than what GM ever intended due to the lack of a spring assist in my set-up.
there is little doubt in my mind that you are either a civil or mechanical engineer lol I'm in my 4th year of my ME at USF and I just went through all my fatigue failure and such last fall so I see what you are saying about that, but how much flax are we talking? obviously with your apparent background it must be a pretty substantial movement to be concerned with fatigue falure
Old 08-28-2010, 10:26 AM
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Here is a good reference for how to bleed a T56 clutch. I did mine this way and it changed my life. I'll never use the bleeder screw again. http://www.performanceworks1.com/ls1...h_bleeding.htm

Chevyboy - Yes, I am a mechanical engineer (if I was a civil engineer I would have been confused by the sight of something 'rigid' moving). I have not measured the motion, but it appears that the brake master cylinder is rotating up 3-7 degrees.
Old 09-01-2010, 08:02 AM
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Pushrod36- Thanks for the link on bleeding a LS style T56 clutch. This trick will come in handy down the road. My son and I are doing a frame off on a 66 GTO using an LQ9 Esclade engine and a T56. We used the Pipes 2 1/2 inch system and were very happy with the sound/ease of instillation. I have noticed our 66 GTO master cylinder "flexes" upward when the clutch is depressed just as you are describing. My thought is the leverage caused by using the "Street and Performance" type bracket causes this. I'm thinking that I will incorporate some sort of sheet metal reinforcement to spread some of the load below the bracket when I close up the firewall hole around the clutch bracket. I hope to be addressing this issue in the next two weeks. We are trying to finish prep for paint, so my schedule may slip. Do you (or anyone else) have another idea?

Ricky
Old 09-01-2010, 09:26 PM
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Thank you for confirming this! I thought that I was going crazy being the only person in the LS1tech world that has seen this. My thoughts for curing the problem are the same as yours. A sheetmetal brace between the bottom of the bracket and the firewall should put an opposite moment on it and stop the flex. The other option that I can think of is to have the bracket extend further up the firewall to distribute the load some more.

I am also happy with the sound of the pypes system. I have been terrible about getting more pictures on this, but I am going to redeem myself soon.
Old 09-05-2010, 01:51 PM
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Here are some more pictures. The first one is the autometer gages that I fit into the stock dash. I wanted it to look close to stock, or at least like it could have been stock. I think I did alright.

The second picture is of my modified clutch pedal. The whole threads in bending things was not working out so well, so I cut off the part of the pedal meant to accept the mechanical linkage (stock). I welded on the part off of the camaro clutch pedal that was meant to receive the master cylinder. It worked out very well. You can roughly see where I had to grind away some of the structure that the pedal mounts to because the linkage is closer now.

The third picture of my exhaust system. I had a friend weld the O2 sensor bungs in (other side of the pipe), and add the mounting flange that comes with the edelbrock headers. It turned out nice.

The last picture is my messy engine bay. I wanted to show the remote kit for the oil pressure sending unit. I ordered the Jegs brand that is the same thing as the autometer one, but for about 15% less $$$.
Attached Thumbnails 1968 GTO LS1/T56 Conversion-img_1872.jpg   1968 GTO LS1/T56 Conversion-img_1874.jpg   1968 GTO LS1/T56 Conversion-img_1876.jpg   1968 GTO LS1/T56 Conversion-img_1877.jpg  
Old 09-06-2010, 10:47 AM
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i need more pics of how you mounted those gauges!! what size are those? i been considering making a custom dash from scratch. i have my 68 gto dash sitting here and ive been wanting to do the same thing. just cant decide how to do it.. looks great!!!
Old 09-06-2010, 12:30 PM
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the450r - I transferred the outline of the stock gage bezel onto 16gage steel and cut it out with holes that fit my new gages. Here is picture of the stock plastic part. After I got my new part together (sorry, no pics) I put it in with all of the stock hardware.

I still need to wire in some LEDs or something for turn signal indicators, but I am not worried about it for the moment. I have not checked to see if the signals still work, so hopefully they will.

I do not have a great idea about what to do with the last gage hole, but I might fill it up with LED indicators for check engine light and things like that. The most awesome (and useless) idea I've had is to get a period correct green screen and have binary from the CAN network running on it.
Attached Thumbnails 1968 GTO LS1/T56 Conversion-img_1879.jpg  
Old 09-06-2010, 12:51 PM
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Originally Posted by Aceshigh
Would you mind showing more pics of that relay block with the fuse block as well ???
I'm ready to do an LS swap into my 1970 442 clone, and this is basically the same car.

I really dig the relay block and I'd like to see more details and what all those fuses will be for and how it's wired.
Long delayed response to your inquiry.

I ended up being very unhappy with how my fuse/relay set-up turned out. It works, but it's a total mess. I am working on something more elegant that will go in the same place. I will also use Honda OEM relays which are far more compact than what I have now (pic below).

The picture of the whiteboard shows how I used the 8 fuses. LAF = O2 sensor, IG= ignition switched power, and even/odd are the even and odd banks for fuel injectors and coils.
Attached Thumbnails 1968 GTO LS1/T56 Conversion-img_1579.jpg   1968 GTO LS1/T56 Conversion-img_1424.jpg   1968 GTO LS1/T56 Conversion-img_1422.jpg  
Old 09-07-2010, 09:17 PM
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how close is your intermediate shaft to your headers? when i test fit my headers it fit. and im going back in with the column and the lower firewall bracket and im rubbing the headers big time.
Old 09-08-2010, 06:48 AM
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It was pretty close. I had to remove it to get the driver side header on. I have not measured, but it is between 0.5 and 1 inch.
Old 09-09-2010, 07:09 AM
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i think my engine is farther back than yours. i had to take it out to put in the header also. im trying to modify the lower column mount to put a little more angle in it.
Old 09-21-2010, 05:57 AM
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Had my friend with HP tuners come over (again) last night. The car is running pig rich at idle and won't stabilize. It seems like the problem is low ECU voltage. My friend says that he's experienced misfire and other problems when ECU voltage gets much below 10v, and HP tuners is reading 9.0v. Tonight I am going to check voltage the voltage at many spots along it's path to the ECU. I am concerned that I may have used to small of a wire at some point.
Old 10-05-2010, 08:46 PM
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I resolved the issue with ECU voltage. It is outlined in another thread that I created titled 'Pontiac wiring problem.' However, somehow while I was working on that I caused my starter to not go any more. I am measuring 12v on the wire that provides switched power to the solenoid when the key is in the 'start' position, and the ground is still good. I am stumped. I wish that these problems would go away after the first time I deal with them.

Tomorrow it's back to basics: triple check the grounds and jump the solenoid to make sure that the starter is not fried.
Old 10-08-2010, 07:53 PM
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The problem with the starter ended up being that the solenoid signal wire was clocked such that it was touching the pole that sends battery current to the starter motor, effectively shorting it out.

The car still won't idle without throttle and is super rich. Commanded Injector duty is 20msec, and o2 sensors are reading in excess of 8:1. IAT and coolant temp are reading acceptable values, so this situation does not seem to add up. Currently my best guess is that a crank relearn (https://ls1tech.com/forums/pcm-diagn...l#post13966424) will fix things. Cross your fingers for me!


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