So i've been tossing the idea around of using a switch pitch. Sounds very practical. Good flash on the track with great streetability. So can i use the sp converter from an st 300 in a 400? If so, what parts do I need from the st 300? Thanks. As I am to understand the GM converters are the best ones?
Joe, I don't know the answer to your converter question, but I can tell you that our car really woke up when we went to the switch pitch 400. Big difference at the track, until Tyler broke it. It was old, but is new now and back in.
300 converter will work just fine and will give about a 2800-3000 stall behind a big block. no other parts from a ST300 needed.
So don't bother grabbing an inexpensive GM converter? I can get one cheap. I thought the pump had to be changes as well?
all you can use from the st300 is the converter. you need a pump assy from a th400 switch pitch. JW will want an untouched core to build you a converter
Just put a nice fixed pitch unit in there. I have a 2800 with 20 minutes of run time on it if you need it.
Joe, Are you trying to convert a '68 or later fixed pitch ST400 or TH400 to variable pitch? If so, for the transmission you'll need the pump, input shaft, VP solenoid w/wiring & case connector and a restrictor plug for the case passage behind the front pump. If you're already set up for variable pitch with a TH400 or ST400, switching to a ST300 converter is a bolt-in, as long as your flexplate has the appropriate bolt pattern, which is a bit smaller like the converter. Changing a fixed pitch trans over to variable pitch isn't just a matter of a few parts. The case orifice usually ruins the day if you weren't aware of it to begin with. More info: http://buickperformance.com/switchpitch.htm Devon
The 2800 will flash higher. I got 2800 on the footbrake with my wimpy little 350. Should be over 3k with your big block and flash to around 36-3800.
Now I'm confused. When I look at Poston's cams, they say that for the 364, 401, 425 series, and the 300, 340 series which are the engines that are from the switch pitch era, that you need a stick or a regular converter if you get into much of a cam. Looking at this I thought that my cam and my power options were limited if I wanted to keep my two speed switch pitch setup. As if my options were not limited enough with the 340. Is a stronger built aftermarket switch pitch another option? maybe not mentioned because they don't want you going to another performance site? Educate me!
I wouldn't put a whole lot of faith in what Poston says as far as tech is concerned. There are many guys here on the Board with far more real life experience with performance Buicks that arent trying to sell you parts.
I have a big Isky cam on my blue 66, and the stock GS converter (also used on the small-block cars) is adequate....about 3000 rpm in high stall. A V6 converter will give you an even higher stall rpm.
Exactly. What I read on the parts site is a starting point for me on some things. I also know they have an agenda. That's why I said educate me. I know from what I read that Poston's site isn't the whole story. Not a lot to use as a source of info for the 340, so since they have cams listed they are a starting point. When I get to that point after the body is done and painted, I figured on asking here before I have the trann gone through or decide what I'm going to do with the engine. I learn something or some things every day on this site.
This guy on ClassicOldsmobiles.com has two ST300's with converters for sale out of 65 Olds 442. And they are switch pitch. Use the following link: http://classicoldsmobile.com/forums/transmission/12661-jetaway-worth.html
