I am getting ready to pull the trigger on my engine order for my 1972 Chevelle. I am looking at the LS3 376/480 because it looks quite streetable, has lots of power, and is ripe for a power adder down the road a bit.
I also have a LS1/T56 pull out I scrounged from a 1998 WS6 that was gettting parted out and used it for the LSX mock-up on the chassis. Before I dive into the LS3, I was wondering what SNAFU's I will have mating the LS1 T56 to an LS3? I already have found that the flywheels are different - check, order a new LS3 flywheel and LS7 clutch/pressure plate with engine. Will the stock slave work okay, or will the added pressure from the LS7 pressure plate necessitate a replacement? Anything else?

Tom Ringlein
Clovis, CA
1972 Chevelle - Ready for an LS3/T56!

 

Be sure to run an LS1 style pilot bearing. The LS3 probably uses the later design ball bearing type with required a shorter input shaft to work (it seats into the area where the converter would center itself in an auto car).

The stock style LS1 slave will be fine, but I'd istall a new one. Some people have difficulty getting a full release after an LS7 install in their f-bodies but apparently the pressure plate adjusts itself somehow (I'm still not sure how this is supposed to work though). Some go with a shim to move the slave closer, but since you're doing a conversion you'll probably be going with an adjustable master setup like the wilwood most guys are using. That should solve any dissengagement issues you may have.

 

Well, the Wilwood master may work, but I already had my firewall and pedal modified for a stock replacement master - so I want to keep it that way. How big of a shim may I need for the slave? I really have no idea.
Good info on the pilot bearing - I will install a new one when I do the swap.

TJR

 

the wilwood is a direct replacement for the stock unit, you will not have to change anything switching from one to another. just swap the line and resivior over to the new unit and install.

 

Yea - looking at the part again you are right. You seem to know alot about this, and I seem to be slightly clueless - so what size bore do I need for my setup?
TJR

 

What kind of stock replacement master, an f-body? If so, theres no wilwood cylinder that directly replaces it. The f-body master mounts at a very strange angle. Mcleod did make a custom one, but they are backordered right now.

We're actually working on our own adjustable cylinders : https://ls1tech.com/forums/manual-transmission/969314-teaser-thread-tick-performance-s-revolutionary-new-adjustable-master-cylinder.html It will bolt up to an f-body by using an adapter. The bore size of the factory cylinder is 3/4", so if you go with something custom fabbed like a wilwood you would want to step the bore size up just slightly to give it some adjustability.

As for the shim, you'd really need to take a couple of measurements to determine if its needed. With the clutch, flywheel, pressureplate, and bellhousing all bolted up, you should measure A. from the surface of the belhousing down to the pp fingers by using a straight edge. The take an alternate measurement B. from the throw out bearing surface that contacts the pp(with it fully seated or bottomed, remove the spring to make it easier) to the surface of the tranny that mates to the bellhousing.

With you measurements, you want measurement B to be about 1/8" less than measurement A. If the difference is greater than 1/8", you can add a shim under the slave to move it closer to the pp. If measurement B was actually greater than A, the throw out bearing would actually always have some preload against the pp which would cause premature clutch wear or slippage.

 

ok, your right willwood makes a rebuild kit for the Mcleod adjustable unit that had problems holding an engagement point. i got them mixed up.

 

Okay - I am running an F-body master, and yes, it sits at a wierd angle. I have an S&P type bracket I scored from ATS that mates it to the Chevelle. It is designed to give the M/C full compression with the Camaro/Chevelle pedal setup. And the bolt holes are at an angle also, so the Wilwood master would not work too well (the resevoir would be at a 45 degree angle to the side).
So, back to square one on the master. However, when I fabbed up the clutch pedal, I have the master extension mounted so that it has full compression when the pedal is pressed. I hope this does it.
I will measure A and B and make sure they are within spec, and hope for the best. If not, I will set up an adjustable clutch.
Thanks-
TJR

 

Alright - got the engine in last night and it looks #$%%@#$ sweet. The literature that accompained the engine specified the 12571611 flywheel (good, got that one on order), and the 12557583 pilot bearing. A quick search of that part # confirms my suspicions, that it is the roller bearing type I was warned to avoid with the 1998 T56. Now bear with me, I am still pretty dumb, but getting smarter. The pilot bearing mates directly with the input shaft of the T56, so the LS1 type pilot (p/n 14061685) will mate perfectly with my tranny, and my LS3 will be none the wiser. Anyone smarter then me want to confirm I am on the right track here before I start taking things apart?

Rinky
Clovis, California
Not in Germany anymore
1972 LS3 Chevelle

 

Okay - obviously still trying to find time to button this part of the project up. I finally got the F-body oil pan/windage tray/oil pickup on the LS3, all my clutch parts came in, and got the old engine out of the way. When I went to test fit the bellhousing to the LS3 I saw that the LS3 motor has 2 bellhousing guide dowels on the block, and the bellhousing has one on the passenger side. Seems as if the old block has a guide dowel on the drivers side of the block, and the passenger side of the bellhousing. Now I cannot get the bellhousing on with two "male" ends of the guide dowels on the passenger side. So do I remove the one from the block, or remove the one from the bellhousing? Whichever it is, how do I do it without jacking something up?

Rinkys

 

im not 100 % sure but those are just dowels. you just happen to have one stuck in your bell housing. i little penetrating oil maybe a little heat and alot of wiggling?

 

That would make sense. Since I am new to the LS1 engine after working on classic small blocks for years, I was not sure if the dowels were supposed to be one in the block, one in the bellhousing. I have some WD40 on it and I will hit the bellhousing with the torch in the morning and try to loosen it up.