oldsguybry

Ok,I installed the TH350 I bought from Borchardt and the car has tons of power now . However I did notice it shifts a bit weird , I think it may be the vacuum lines from the modulator to the intake perhaps . Here's a picture of the routing I have now , please let me know if anything looks wrong to you . Thanks .....

oldcutlass

What do you mean by weird? The modulator requires full vacuum.

joe_padavano

You have the vac modulator line connected both to straight manifold vacuum and to the thermal vacuum switch in the coolant passage. This is incorrect. Connect the trans to manifold vacuum only. The TVS is only needed if you are using ported vacuum for the distributor. It has nothing to do with the trans.

oldcutlass

I believe the modulator line is connected directly to the vacuum port in the manifold with a tee feeding the TVS. The other line coming off the carb is also feeding the TVS and TVS then feeds the vacuum advance.

joe_padavano

Ah, you may be right. Hard to tell in that photo.

oldsguybry

Thanks guys , I'm not sure if everything is right though , or if I inadvertently hooked it all back up incorrectly with some of this stuff . Obviously I'm clueless when it comes to certain things with cars and how everything jives . All I know is the transmission shifts a little funky going into second and third gear under normal acceleration . It kind of jerks into the next gear , but it downshifts beautifully ,you can't even hear or feel it when it does . I also noticed it shifts from park into drive or reverse kind of hard and sudden , almost like the idle is to high or something . I bought a mild torque convertor when I purchased the transmission . The tranny is rated for 500HP .

.... on a side note , I can smoke the crap out of the tire at just about any speed now because of the one wheel wonder lol .... Also ,sorry I started two threads on this subject , I guess I'm impatient lol

oldsguybry

Ok , here's a diagram I looked up . It seems the only thing different is I had the top and middle vacuum lines switched ( green and purple ) ... The purple goes straight to the ported vacuum on the carb . No EGR/DTVS on this motor . The car seems to shift right now , and I left some big black marks down the street lol .

joe_padavano

Step away from that diagram...

You are only confusing yourself with that late-model plumbing diagram. Your car needs nearly nothing from that.

There are only two sources of vacuum on your motor, straight mainifold vacuum and ported vacuum. Ported vacuum is ONLY used for the distributor vac advance, and frankly that's only for emissions purposes. I'd run the distributor from straight manifold vacuum also. Everything else (modulator, power brakes, HVAC controls, vac trunk, cruise control, etc) all connect to manifold vacuum. Any manifold vacuum port is equivalent in performance. The exact connection point of each hose is irrelevant.

The thermal vacuum switch is only needed if you are using ported vac for the distributor. The problem with ported vac is that by eliminating vacuum advance at idle and low speeds, you can cause the engine to overheat. Olds recognized this and used the TVS to monitor coolant temp and switch over to straight manifold vac if the engine got too hot. My earlier point is that if you are using manifold vac for the advance under worst case hot conditions, why not just use it all the time and avoid any issue?

oldsguybry

Can you put this into perspective for me ? like draw on the diagram or something ? Include any thing I might have to plug off or whatever if you could . I really appreciate it , I was wrong , I'm still having some weird shifting issues after I drove it awhile . Thanks in advance .

oldcutlass

What Joe is trying to say is remove the line from the carb to the TVS and cap the carb port. Remove the line that runs between the T and the TVS highlighted in red. Connect the remaining line left on the TVS that runs to the distributor vacuum advance to the T. Now you will have just manifold vacuum at the vacuum advance. Adjust your idle speed accordingly.

oldsguybry

Thank you Joe and Eric , you guys are the best . I will look into re-routing my lines to try to remedy the issue . I will chime in with results .

oldsguybry

Sorry it rook so long to get back to this .... Here's a better picture with the lines illustrated so we get a better idea on what I have going on ....

RED = Distributor Line
BLUE = Transmission Line
PURPLE = Remaining Lines

oldcutlass

Remove the purple lines, except the one that goes from the T to the manifold port. Cap the port on the carb. Move the red line to the T. Remove the vacuum switch from the manifold and install a pipe plug. Then readjust your curb idle speed.

oldsguybry

So this is the one I'm plugging ? .... ( The one with the black arrow pointing to the circled port )

oldcutlass

Yes the item in the circle will be removed and pipe plug put in its place. Another option is to install an aftermarket mechanical temp gauge using the open port.

oldsguybry

Thanks , I appreciate it .

oldsguybry

Ok , I just put screws tightly in the hoses I removed because I couldn't get that dam thing off the manifold . I routed everything the way you said , and it still has a ever so slight weird shift from 1st to 2nd and 2nd to 3rd . Like I said before , it down shifts so perfectly that you can't even hear or feel it . Not sure what the problem is if there is one

oldcutlass

I don't understand the weird shift description. Does it have a shift kit and the shifts are snappy? Is it shifting early or late? Is it slipping and then shifting?

What you did and the suggestions made for the vacuum lines have nothing to do with the function of the modulator. It made the vacuum advance work off of manifold vacuum at all times.

oldsguybry

Thanks for the input , it don't slip or anything , it just kind of jerks into the next gear a little bit . ( not smooth as glass) does having a leak in the vacuum line to the transmission have anything to do with it possibly ?

oldcutlass

With a vacuum leak it would shift at higher rpms, there was nothing wrong with the way vacuum was plumbed. Does your transmission have a shiftkit, are the levels good, is the fluid a nice red color?

Fun71

A shift kit will firm up / speed up the shifts and you can actually feel the gear change. This is not a bad thing.

oldsguybry

Yeah , levels are good and yes it has a shift kit I assume .

oldsguybry

Cool , I'm not going to worry about it then . I can smoke the heck out of the tire now with no effort at all . I need a posi now before I blow the rear end up .