Oh damn I literally can’t make that day. Bentley Car Club is having our show Saturday and then the Beast of the East rugby tournament is Sunday
You have the 12 inch SP300 converter in it now right? What is the supposed stall speed again when it's in the SP400? I like the whole idea of getting this heavy beast fast. It's what makes it more interesting. Not that weight savings is what the JW 9.5 converter is all about, but I would hate to see you try to go a weight savings strip down.. John, "knock on wood" but do you think you lost another 1/2 second?
Here's some food for thought John, pick yourself up a th400 and tear it down and rebuild it over time while funds permit all the while still enjoying your SP. Once your build is done with all the performance parts/mods you want pull the SP and store in in the back corner of the garage for later just incase you (or the next owner if you sell it)wants to put it back to original. You get the best of both words on your time and dime
The ST300 12 inch Switch Pitch converter in an ST400 should stall around 2000 at low stall, to 3000 at hi stall behind a big block. Maybe a bit higher with more hp/lb-ft. I had Jim rebuild my ST400 and the converter from my St300, and once I get it back together, I can post the numbers on the stall. (Going behind 430, with ST2 SE). Since it is mostly going to be street, I really don't want to be up in the 3500 RPM, while creeping around town in stop and go driving so the low stall will be nice. I have had several cars with a Switch Pitch, and I just like the way they drive.
I purchased one of JWs SP converters and front pump. I put it in a Turbo 375. With a 3:73 rear end. It worked great, Very cool to be able to switch the stall. But wilh my Rear end, it was not fun on the interstate. Slow lane hit 70 MPH , @ 3200 RPM. So I drove slower those few times. Over the years on this forum, I saw Larry ran a gear vendors overdrive, and others 200 4R, and some 700 R4. I chose the 700R with a 2500 stall. Best move I ever made. Great off the line, and 2200 RPM @ 70 MPH. The Turbo 400 is the strongest choice, and the Gear vendor overdrive could always be added later. Of course depending what rear gears your running if its needed.
Ive been told lower and higher. I've never looked it up. I think my car launches better after a burn out with the 700. The 700 requires the adaptor plate. So John's car came with the 300 Transmission?
No, John has the ST400, the ST300 is a 2 speed transmission. The ST400 has the same gear ratios as a THM400.
Thank you. I will save this. I see the numbers on the 4L80 and Th400. I think 4L60 and 4L80 requires some electronics?
They both require a computer. However for a short time gm referred to a normal 700r4 as a 4l60, with out the "e". So that adds to the confusion some.
Yes, I've been told, that's an added cost. My friend said around $500+ on top of what he paid for the transmission. There may be less expensive options. My 700R4 used a cable.
Talk of higher stall converters is academic unless John gets real serious and invests in some good Drag Radials first. I have as yet to hear anybody say their car is faster with a JW converter and regular street tires. The only thing I hear is that they put on better a smoke show on the street tires. (Before anybody gets the wrong idea I already have a JW converter behind my '69 400 and I can't complain.) The nice thing about the SP converter is that you can keep the tire spin down by keeping it in low stall off the line with regular tires. As mentioned even with a stock 12" SP converter and, especially with his heavy car, should stall 2000/3000 with no problem and TRACTION. John, time to get rid of "Tuning for 13.999" in your signature. That is so 2019. If it doesn't run better than that on its' worst day then go back to the drawing board, something's not right. With all the good upgrades you've done to it since the last time you went to the drags I would have to say "Tuning for 13.199" would be about right. Maybe a smidge better in great air. The only reason I'm not saying 12.999 is because of the 25 cubic inch handicap of a 430 instead of a 455. Hopefully we'll get some nice Spring weather sooner than later this year. Good luck.
I have a big heavy 69 Riv with some engine and trans mods. I put one JW'S 9.5" converts and it indeed did make my car faster on street tires. It woke that big boat up. I noticed a huge difference in off the line acceleration and top end power. The car certainly runs quicker/faster than when I first got it. There isn't a track close to me to run some test runs to see my time but my test runs on an old farm back road worked just fine to let me know there was a BIG difference. I'm running 255 45 ZR18 street tires on all 4 coners for what it's worth info wise.
So, you have a TH400 in your 69? Do you know your rear gear ratio and tire height? I'm just curious. If not, no big deal. Oh, and. How's your RPMs on the Highway at say 60 or 70 ?
P255/45R-18 is 27" tall. I believe his rear gears are 3.08, so 60MPH should be about 2400 RPM, 70 , about 2800.
Hey, that's not too bad. Larry, you have alot of knowledge in that head of yours. I did not expect that car to have a 3:08. Thanks again. John has had a busy weekend from his previous post. I'll be curious to see what he does next.
336/tire height X gear ratio X MPH =RPM 336/27 X 3.08 X 60 = 2300 RPM 336/27 X 3.08 X 70 = 2683 RPM Add 100 RPM for converter slip.