Can I use the old 4 speed behind the 5.3?

[yossarian19]

I looked into keeping the SM420 in my LS swapped '57.
The stumbling block I came to was a vehicle speed sensor (VSS) for the SM420. The engine won't idle worth a damn without one and may stall on the freeway.
I went with a 4L60E.

[71chevystep4x4]

Which is why you get a pulse generator from Dakota Digital, which screws into where your speedo cable goes, and the cable screws into it.

[yossarian19]

Originally Posted by 71chevystep4x4

Which is why you get a pulse generator from Dakota Digital, which screws into where your speedo cable goes, and the cable screws into it.

Wow. I must have missed that when I was looking around for solutions.
Oh, well. The 420 is sold & the 60E runs me down the road.
7:1 first gear, 3.90 rear end & 300 ft-lbs would have been a good smoke generator, though.

[Gooker928]

Originally Posted by e015475

Not sure exactly what manual transmission you want to run behind the 5.3, but you can run a Muncie M20, M21, GM T5, or anything that has that same pilot diameter and input shaft on an LS motor.

You'll need a Sachs flywheel for the manual trans 2500 GM truck (about $70), a clutch from a 70's big-block (about $100) and a '621' GM bell-housing (about $150 used), and of course, the transmission of your choice.

The original GM 621 bell housing will fit the LS motor, except that the very top bolt hole isn't there. You can buy reproduction 621 bell housings with the boss and hole for the LS motor from ebay for about the same as a used GM one without it. Kiesler (now Silver Sport) transmissions sells a very nice one, but it is about $250, but has the correct bolt pattern for the LS motor

There's a few other things you'll need, like a LS2 (?) pilot bearing and the correct throw-out bearing to match the clutch -flywheel geometry. The BB flywheel will also need to be modified by slightly enlarging the bolt holes to allow the use of the metric LS pressure plate bolts.

There's no provision on the LS block for a z-bar, so you'll have to work something out for either and external or internal hydraulic slave cylinder.

I have some pictures somewhere of the 621 bell housing for the LS motor with a Camaro T5 and an S-10 tailhousing (to move the shifter forward for a truck) if there's any interest, I'll post them.

this is exactly what I did in a chevelle. You can drill and tap that raised area on the side of the block to accommodate the pivot bar.

[slotard]

Of course, there are issues with the 4L60E as well - while it has a pulse generator, it isn't all that strong and I'll need to swap my speedometer for an electronic one out of... 88+? or buy an adapter. Or just use GPS speedo...

[FrankenCub]

Which bell housing is the 621 ? Would the 307/3OTT bell housing be the same ?

[FrankenCub]

I found a great writeup on the LS1Tech forum....
Mating a SBC/BBC Trans to LSx

[rwhite692]

It should be mentioned that, while the LS1 flywheel will "function" with an old-school 10.5 or 12" clutch, it is the WRONG solution because of the large amount of material that is missing from the center contact area of the LS1 style flywheel; A typical 10.5" or 12" clutch as we have with an old-school SBC clutch will only have about half of its friction surface actually engaged with the flywheel, because of this.

Like many others, I read may posts here and elsewhere about simply using the LS1 flywheel (Sachs NFW1050) and was all fired up about being able to spend only 65 bucks on that flywheel, and be in business. Not the case.

The McLeod flywheel (460535) is the right flywheel to use, unfortunately it is $400 but there is presently no cheap alternative. Novak also sells a flywheel (which I am 99 percent sure IS the McLeod 460535).


LS1 Flywheel (Sachs NFW1050):




The McLeod 460535:



Excellent depiction of the problem that exists when trying to use the LS1 style flywheel (taken from Novak's site):