Do I need to get a check valve/ball or something for these so they only see vacuum and not boost? Thanks.

Brad...

 

brake boosters already have a one way in them, and so does the cvacuum resvoir

 

I don't have a vacuum resvoir. I have a TH350 tranny and a vac line running from that to a T in the brake line and the PVC is going to the front of the carb. Thanks.

Brad...

 

no a one way wont be required there either, as vac goes away the modulator valve moves inward, if under boost the valve is pushed in further then more power to you the higher the modulator/TV pressure the better in the case of a powerful blown car (this is for a th350 guys)

 

Right on. The PCV valve is a checkball itself so that should be fine. Thanks B4C.

 

I am by no means a Tranny guy. So I have a question for you B4Ctom1 ...I too am running a th350 behind my L98 TPI engine. Do you really need the shift modulator hooked up? I tried mine without it. Ran good, now of course I had to shift manually. But with the shift modulator hooked up to manifold vac. it shifts into 2nd really quick infact it seems to soon in my eyes...Any idea as to why??? Any help would be appreciated.

 

Mine does that to. The 1 - 2 shift is real quick. I think you can adjust the screw in the middle of the modulator to make it shift differently.

Brad...

 

Get rid of your PCV completely....you'll have to much pressure in the crankcase. Just vent it to the atomsphere

Also, it has been my experience with modulators and boost dont like each other. I'd put a one way valve in there, i plan too

 

screwing it in 1/4 to 1/2 a turn at a time will help make the shifts later. make sure you have a nice unobstructed vac line. "stacked 1-2 shift" as it is called can come from a few things, or combination of them. too much vacuum (not usually), too heavy of weights on the govenor or too light of springs on the govenor, modulator with screw removed or older style with no screw (good for grandma's caddy style shifts not for performance). Transgo shift kits come with the pieces to fix this and a new modulator (red or red and black stripe fixes the prob when adjusted properly). Make sure you use the kickdown too if you dont have one installed. it helps crank up modulator pressure to "late-en" the shifts. the standard tranny shop adjustment is 1 shift per each 10 mph when taking off like a normal person (non hot rodder/non launch :-) the performance adjustment should be done so as it shifts fairly close to this. so that the tranny has the shift valves making the shift earlier than redline or earlier than you would if you were shifting manually, so that the trans does up shift imediately to the selected gear when manually shifting at WOT. The last thing you want to do is adjust it to shift too high at WOT, or else when you manually upshift you have to keep reving past your desired shift point potentially overreving the engine or the powerband. most guys have this "misadjustment" requiring them to "lift foot shift". lift foot shifts (lifting the foot to get the modulator to force the shift) are bad. this applys to lift foot shifts on 700R4's too. when lifting the foot you lower TV pressure (whether it is controlled by cable like a 700 or modulator and kickdown on a th350) Line pressure always follows TV, when line is reduced, clutch holding power is reduced. this is probably one of the main resons for failure of the forward sprag on 700's and the intermediate sprag or race on TH350's. I hope this has been helpful.

 

It definately puts some insight on the situation. I know it is a new modulator, infact it is a complete rebuild, but how do you adjust it? There is a actuall screw there in the valve itself, or turn the whole valve itself. A picture right now would be like a thousand words. If anyone has a pic that is. THanks for the input. I appreciate it.

 

Here is a quick pic of mine. Has the red stripe.

 

good pic, good unit, turning the whole thing does nothing, turning the little adjustment screw inside the vacuum fitting is the adjustment. when I build a trans I always set it to an initial tuning setting by unscrewing it until there is no resistance (almost out all the way) and then turn it in until it hits resistance for 1/4-1/3 turn thats the starting point for you. then 1/4 to 1/2 turn in each test drive till it shifts like I previously recommended.

 

All thou I would not eliminate the PCV system, I would add another vent/ baffle/ breather to one or both of the valve cover(s). The additional power/cylinder pressure will cause more ring blow by while under full throttle/high boost.
This "positive pressure" in the crank case is a power robber.
You can also buy and install a crank case vacuum pump to assist in venting the crank case while under power/ boost.
You see these a lot on race cars now.

Try to retain the PCV valve systen as it has too many benefits
and +++'s on a street driven car. Just ensure that it does not leak ( bleed off boost pressure) while under boost.

 

Are you trying to say that a TH350 without the kickdown cable connected will have low line pressure under WOT?

 

yes, there is a direct relationship to the TV pressure at wot with the kickdown as well. you will notice when pulling on a th350 tv cable there is a light resistance then the further you pull it a heavy resistance (2 stage). one is a TV boost helper and one is a overide to command downshift. Of course TV is in constant conflict with govenor pressure (thats why shifting is dynamic) so that if govenor pressure is high due to high road speed then a downshift is "not supposed to" take place. this is so you wont get a downshift when in 3rd gear screaming at 150 (if its set correctly). since line follows TV you will get a additional rise. the way to see this is to locate the line oil pressure test outlet and to connect a (real high pressure like 1000+# gauge for safety) take it for a drive without the kick down and then take it for a drive without, you will probably see what I mean if you dont get in an accident :-)

 

I don't have mine hooked up. How do I hook it up to an Edelbrock carb and how should I set it? Should there be any tention on it? I was almost thinking of just taking it off the other day cause it's always in my way when I work on stuff. But it would be nice to have it working though.

 

I also don't have the TV cable hooked up. It is there, just not hooked up to the TB. Remember this th350 is behind a TPI. THe TV cable for the th350 is to short to reach the TB. Has anyone else run into this problem??? And or does anyone have a clean looking fix? I don't want it to look half azz or nothing. THanks very much for all your help, it is very appreciated. Like I said before. I know nothing about trannys.

Thanks Keiran

 

When I recently had my th350 rebuilt the tech guy did a valve body mod that eliminates the need tor the kick down cable on a th350. This involves valve body mods and a shift kit.
You have to manually down shift the trans as there is no passing gear or kickdown, but proper internal trans pressures are mantained by the vacuum modulator only now.
works real smooth.
This guy is real good and local to you and me. Keiran.

 

Well maybe in the spring I shall go visit this person mentioned. Like I said before I know nothing about trannys. Give me a engine or a rear end or some body and paint ... Yees Haa. Give me a tranny and well I can put the torq converter on and install it. But pease don't ask me to tear it apart. Who might this fella be F-BIRD??????

This tranny I have came out of a 10's Malibu. It was rebuilt by Mark Lawrence in Wellandport. He builds alot of the race trannys around here. It was set up to use a 4000 stall. I have a 2800 at the moment. I have a 3500stall but have yet to put back in. And is suppose to be a manual valve body, yet it will shift to 2nd really quick all by itself. Any ideas as to why???

 

well then there is a HUGE mis-interpretation going on here. everyone i talk to seems to think the Th350 in stock trim doesnt NEED a kickdown, and so no one runs them. I cannot hook mine up, Ive bought a new cable and everything but it will not work correctly. when the linkage pulls it out, it sticks and stays out, causing my tranny to never go into 3rd and wait till 5K to shift to 2nd. really annoying. so i disconnected it, and now its been that way for.. a long time...

and NOW im worried that its goina blow cause its not connected! so is my neighbor who though the same thing! and my other friend who heard it was OK to not have it conected...

your absolutelly SURE th350's from 1975 increse line pressure when the kickdown is pulled? its not just a downshift thing, its an actual holding pressure thing?

 

I did a search on the TH350 kickdown question. Here are the results. https://www.thirdgen.org/techbb2/sea...by=&sortorder=

Brad...

 

I must say it does make sense. I have pulled on mine when is was running..it feels just like B4Ctom1 It is like ther are two steps in the cable. After all the TV cable does move with the throttle linkage, and doesn't kick down to first till you mat it to the floor. I am goin to try to get mine hooked up...just need to figure out how without it looking ugly. After all they don't make a cable for a th350 that is hooked up to a TPI.

 

His name is Stan. He used to own West Coast transmissions.
I don't know what his company is called now, but he still does transmissions. My friend took my trans to him and picked it up.
I'll find his phone # for ya. Or just bring the trans to my friends shop in Fonthill.
Unless you have a full shift kit like the B&M transpack installed
the kickdown should be hooked up. The shift kit kicks up the line pressure enough that you won't harm the trans without it.
I'n my trans the valve that the kickdown cable acatuates is blocked partially depressed. My trans does not shift hard, but does shift firm and real clean. Part throttle shifts are clean and normal,not harsh. What ever he did to it, it works very good.
A hard harsh shifting trans is not desired for durability. I actually wears the trans and breaks hard parts.

On a stock th350 (without a shift kit) if the kickdown cable is unhookedor broken the trans goes into a "Limp mode". (safety feature) line pressure is then held high enough so it will not be damaged, but WOT shifting can slip. Not recommended to run without the kickdown cable unless the trans is properly modifyed.

 

Well I won't be pullin the trans any time soon. I need to be able to move the SS for the time being. I will have to get a hold of the guy who built it and see exactly what he has done to it. I do know that it was built to shift hard and to shift manualy. I would still like to have it checked out in the spring though. Thanks F-BIRD

Keiran

 

dont mistake a kickdown for a TV, I was talking about 700r4 when I mentioned the TV cable the th350 it is purely a kickdown with a tiny TVhelper. the TV on a th350 IS THE modulator. there are some shiftkits that do away with this cable and of couse all of the manual VB and trans brake VB kits do away with it. I have met many people that never run them it is merely my opinion to run one.

 

right so my question is does the kickdown cable boost line pressure in a TH350 when pulled out?

thats what I want to know.

 

yes when operating

 

ouch. thanks tom. i wonder how long till it blows up then? will it REALLY matter with my "shift improver kit" since the shifts are so fast is there REALLY a chance for slippage in the time between?

It doesnt really FEEL like its slipping. maybe after the clutches get old? heh im replacing it with a STOCK 700R4 from 92BLUE's camaro. he just put a 6 speed in his (my next mod!) and sold me his old 700R4. cant wait to have overdrive in my pile of cra.. i mean my nice red car.

 

you are probably ok. your shift improver usually comes with some springs to boost line, and a few other items which help, maybe even more than the kickdown itself on a stock tranny :-)

 

For any of you guys with TH350s that need a kickdown cable, Lokar (the street rod guys) make universal style, cut to fit cables (and matching throttle cables) with either OEM style black casings or braided stainless. They have brackets to attach to most popular carbs, TPI, etc. Check them out at http://www.lokar.com

 

Thanks kindly for the link LT1guy...I just emailed a supplier and em on my way to fixing my problem. Thank you to all who helped, I appreciate it very much.

Thanks again,

Keiran

 

Glad to help. I used the Lokar kickdown cable and throttle cable/bracket on my '63 Nova SS,and was very pleased with it.

 

Well now I can hope for alot better times at the track this year. Not only will my tranny wait alittle longer to shift but I will not be spinning the first 100 feet. Yee Ha:hail: