Can someone shed some light on a few things here for me ? I had to pull that old 300 out because the guy who was selling it took it upon himself to “ do me a favor “ and get the car running after sitting outside for 12 years. And you know how that went . He did get it running but bent a few pushrods and scored up the cylinders pretty bad doing it so I’m doing the deed and swapping in a gen 3 LS 5.3 . I’m so confused with this stock ( or is it ) transmission. The hand written paperwork from 64 says it’s a 3 speed..And so did the seller. Research tells me it’s a ST 300 . 2 speed. It’s a two door coupe. I have a list of questions... It looks like it’s is set up for switch pitch. My first time with one of these..There’s a plunger and a bunch of wires up there attached to the throttle linkage.. some ( I think 2) go down to the trans. Can I just disconnect this and shift manual after the engine swap? OR.. try to hook it up to the new motor.. I’m going to run an old edlbrock 600 I had. No EFI. How can I tell what trans it is ? Can I just put a spacer in there behind the flex plate and be good to go ? I understand the crank is .400 short on the LS.. Am I wasting my time with this tranny or what do you guys think ? At this point I really don’t have the money to put in different tranny in and have to shell out for a new driveshaft. Your help is appreciated!! All suggestions welcome thanks Matt
Bolt pattern for the BOP bell housing will not direct fit the LS. You will need an adapter. You may still have to change drive shaft length no matter what you do. It might be less money to sell the ST300 outright, or at least the Switch Pitch converter (being a 12 inch, guys with ST400 Switch Pitch look for the smaller SP converters). Take that money (and what you would spend for adapters, etc. to get the ST300 to work) put it toward transmission that will fit the LS, and you will likely be ahead of money and frustration to make the ST300 work. As for the Switch Pitch function. If you do not wire it, it will simply be in low stall (think, normal stall), and will work fine as is. If you do want the switch pitch function, there are several options. (if you already have functioning switch/wiring, ignore the following text. If not, read on.) The easiest is to wire the "12v power/hot" from the brake light switch the to the Switch Pitch stator control (top/horizontal blade on the driver's side of the transmission) so you have "high stall" when brake is depressed for shifting from park to Reverse/Drive to reduce the "harshness" when clutch applies. And a "micro" switch can be used at the throttle bell-crank to also supply "12v power/hot" when you get 3/4 or more throttle to actuate the converter to "high stall". So, if you can get an adapter and bolt the ST300 to the LS, you can run it just fine with the wiring disconnected. No need to manual shift, it will simply be a 2 speed automatic and the Switch Pitch just will not function. Hope that helps. If it is confusing, post back.
So the castings won’t bolt up ? The ST 300 has a different bolt pattern than the old powerglides and TH 350/400 ? Thanks for the insight on the switch Pitch
The ST300 will only bolt to a Buick Pontiac or Oldsmobile engine (BOP) in the 60’s and 70’s you had BOP bolt pattern transmissions and Chevy bolt pattern transmissions. Doesn’t matter if it’s a 300, 350 or 400. The LS probably uses the Chevy bolt pattern. Not sure never touched one
The LS engines use a modified Chevy pattern... One of the bolt holes on the passenger side is not there by design; the rear cylinder casting is too close to support a bolt. That said, I don't think ANYTHING on an LS will bolt directly to anything on the Buick: motor mounts, transmission, etc. I believe you even have to cut the engine cross member to get the LS to fit with A/C.. Not worth RUINING a Buick...
