I am a huge fan of supercharged hot rods. I have 6 cars with blowers. My latest build is the only one with a th350 trans that has a standard valve body in it. Most of my cars are stick, and the few with automatic transmission's are manual valve body conversions. My problem is that my car seems to pull too much vacuum and shifts at unusually low rpms. I have installed the little ball valve blow off with restrictor. I am running a 475 horse small block chevy with a 3000 rpm stall and my cam is 500 lift hydraulic roller blower grind.what am I doing wrong?
On the transmission change the springs in the governor (back left near the tail shaft there is a domed cover) get a spring kit or go over to your local transmission shop and see if they have any springs on hand. It only takes about 10 minutes to change out I will try to dig out what springs I used tomorrow (i think a green and a white).
Thanks. I bought this trans done, and it came with a few different springs. I had no idea what they were for.
Does it still have the kick down linkage ? On my t-bucket I don't have it hooked up but I did pull the cable out some and put a hose clamp on it to lock it in place. I have noticed that where I have it pulled out does effect normal shifting, wither a higher shift point or a lower depending on where I lock it down at.
I went through this years ago, and ended up modifying the BDS Pressure Diverter Valve, so it would work properly. What the transmission modulator wants is manifold vacuum, when there is vacuum, and atmospheric pressure, when there is boost. So you need a device that will block off the signal when it's under boost, and at the same time open the modulator port to atmosphere. Maybe I can send you mine and you can see if you can make it work? I'll see if I can find a picture of it installed in my 55 Chevy. btw, what I do now with boosted cars with automatics, is use a full manual valve body, and don't worry about it.
Like Jim said , this will make your set up work correct 95% of time , None Manual Val body . But the other 5% to fine tune will need to play with governor. Its a simple , it has a SS bb inside , BB moves under Vac & boost . Mine I mounted on trans tail facing forward $80 ish & when missing with governor cover in relation to Governor, The clearance is ""Critical"" if set too tight you will strip driving gear on the governor , transmission will not shift. To loose transmission will not shift correct . When R&R governor cover You should also R&R tail shaft so you can see the Clarence , Just by R&R governor cover can change The Clarence gap .
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