'69 Ls3

kutmup

Active member
Joined
Jan 22, 2013
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39
Seeing the beauty of the conversion by sssuch was enough to drive me over the edge. This '69 has been sitting around minus it's 383 for a couple of years. The 383 spent some time in my '68 Camaro and now it powers my '72 El Camino. If I had a good sbc sitting around I would have just put the car back on the road in that configuration. Since in order to put an sbc together world have required the purchase of a rotating assembly I decided to add a few more $$$ and go with a crate LS3. I went with the base 430 HP version since the one with a bigger cam costs about 1400 more. I'll probably throw a Lunati stick in it before it hits the road. I put a T56 in the car ten years ago and will stick with it behind this engine. My local Chevy Part Manager has an LS powered '71 Camaro and has been a big help.
 

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You'll be really happy with the LS. I just got my 6.0 LQ9 swap out after it's winter sleep. Still pouts a smile on my face driving it.
 
You'll be really happy with the LS. I just got my 6.0 LQ9 swap out after it's winter sleep. Still pouts a smile on my face driving it.


I can't wait. I have four other LS projects but this will probably be the first on the road.
 
It's resting on wood shims but is very close to where it should end up. The trans is forward about 3/8" from where it was behind the 383. It looks like some LS C3 Vettes move the engine forward more but I don't want to buy a driveshaft. I need to verify that the bell housing bolts can be reached so that the clutch can be changed without pulling the engine. If it looks OK then we stay to the rear.

The engine will probably move up about 1/2". That will help with the water pump outlets and the alternator bracket clearance. I will probably lower the upper control arm mounting points (Guldstrand mod).

I think it will all work OK once I get a straight thermostat housing.


The GM pilot bearing will engage just fine. I did not include the block plate in this go round because the dowel pins will probably be too short if I use it. There was not much engagement.


The Camaro oil pan would probably work but the drag link just kisses the sump at full lock. I don't know which is better Camaro or the batwing, but the batwing looks like it will package better.
 

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Made up the motor mount adapter plates. They move the bellhousing forward about .300". Received the ECU. Dang there's a lot of pages to read.:twitch:
 

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The bracket for the engine side of the clutch cross shaft was easy. The LS3 and LSX blocks have two threaded bosses in a good spot. The bracket is just 1/4" plate with a 1/2 -13 nut welded to it.
 

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Made up the motor mount adapter plates. They move the bellhousing forward about .300". Received the ECU. Dang there's a lot of pages to read.:twitch:

I was kind of shocked that the computer is not a stock LS, why is that??

what did the new computer cost, if you don't mind my prying.....

:eek:
 
Made up the motor mount adapter plates. They move the bellhousing forward about .300". Received the ECU. Dang there's a lot of pages to read.:twitch:

I was kind of shocked that the computer is not a stock LS, why is that??

what did the new computer cost, if you don't mind my prying.....

:eek:

I went with one of the more costly of the Megasquirt options, about $1200. It has more capability than this project needs but the next LS swap I'm doing ('68 Camaro) will use more of the units features. For a tight budget they offer kits the you build like the old Heathkit stuff. All you need is a laptop to access the parameters of the Megasquirt. There is a pretty big community of support from users so an individual can usually get answers to tuning question pretty quickly.


A factory ECU and modified harness can be pretty cheap but then there's the issue of tuning. I'm not interested in having someone else tune and flash an ECU and I did not want to buy software/licenses to open GM ECUs.
 
Long ago I had a 'problem' which turned out to be a BAD CAM, and it gave super rough idle....intermittently......drove me krazy for some years.....and in that time frame there was an older retired GM engineer that stopped by enroute to his Florida place from up north....he did programming for GM FI back when....so he set up his computer and eprom burn stuffs right here on the kitchen counter....he tried, but wasn't until much later that I found the damn cam was at fault....at any rate, point is, that burning chips and modifying computer programs is much better than that later 80's crap I running....

I even tried a MegaSquirt setup but it would run fine, until engine temp reached a certain point, then it would DIE, never did figger out WTF....gave up and sent it back shame really in that I talked several times on the phone with the head man at MS, many years before that.....about yet another FI project I was doing then.....MS was barely established then....been a while....


Dunno about software/license over GM 'puters I would ASSume they are all hacked and open info by now.....


:amazed::huh:
 
The cam I swapped into the LS3 is smaller that the consensus of what fits with adequate piston to valve clearance in an LS3. I didn't want to put in a cam that was so big I'd have to worry about clearance issues. You can see the slight kiss given to the uncut piston by the intake valve. I've read about creating the needed clearance by using adhesive backed sand paper on a spare valve rather and thought I'd give it a try. . The engine is pretty easy to mask and there was not much debris. The head will need a thorough cleaning but the engine stayed clean.

Step one was to determine the position of the piston at the lowest P to V condition for the intake and the exhaust. It occurred at TDC and .020" down. I decided that this is not enough of a difference to be a concern. If there had been a larger difference I would have done the intake and then repositioned the piston to do the exhaust. To help with radial P to V clearance I left the head gasket out and set the piston at TDC for each cylinder and did both valves in one set up. If I did my trig correctly this gives a theoretical extra .012" radial clearance on the intake and .018" on the exhaust. I made the pockets about .080" deep on the intake and .065" deep on the exhaust. Looks like there is now a bit over .08" vertical p to v clearance on the intakes and a little more on the exhausts.

The exhaust valve had a cone shaped indentation on its face. The sand paper came right off when trying to make the pockets. I filled the depression in with brazing rod to give a relatively flat surface for the sandpaper to adhere to. Burned the crap out of a finger doing this. That made the rest of the evening seem to take a long time.
 

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