72455

Hey all, I actually have a couple questions. As many of you know (or may not know), I have a 72 Cutlass Supreme with a slightly built 455. When I'm crusing at highway speed and stab the throttle, I'm not sure if 1) the secondaries are opening and, 2) if the kickd toown solenoid is engaging. I'm thinking it should throw me back in the seat, but I'm not getting that burst of acceleration like I think I should. The carb is a 670 Holley Street Avenger with vacuum secondaries, and from what the previous owner told me, it was recently installed new. As far as the solenoid, .the car upshifts and downshifts fine, so I'm not sure if maybe there's another issue with the solenoid, or does it seem like I'm overthinking this?

So if anyone could point the direction I need to go, I would appreciate it.

Dave

olds 307 and 403

Get a 300 cfm larger carb and tune it to your motor.

BangScreech4-4-2

I was gonna say, 570 CFM seems a little small for a 455, especially if it's "slightly built". The Street Avenger is a great carb, and I know they come in 770 and 870 CFM. They come with spring kits to adjust the secondary rate of opening, so if you're determined to keep your 570 you should be able to get one of these kits from Holley.

Your tach (or ears) should tell you whether or not the kickdown is working. Have you tried downshifting manually?

72455

I plan on stepping up, but for now I just want to make sure things are working as they should.

72455

Are you talking about a diaphragm spring kit? And no, I haven't tried downshifting manually. I will do this the next time I drive it. What will a manual downshift tell me? And would I do it when? Normal throttle or full throttle?

VC455

The suggestion was intended as a first step in trouble-shooting. If you downshift manually during full acceleration and you feel a burst of power, then your automatic downshift is not working.

In that case, let us know which transmission you have so we can help you identify the problem.

72455

Check on that. Just for a few seconds, right?

Fun71

Wait a minute - how fast are you going at these "highway speeds" and what rear gears do you have? Depending upon these parameters, the engine may be above the safe downshift RPM point.

Try this instead:

1) Cruise along at a steady 35 MPH and punch it. That will be low enough speed for the trans to safely downshift (to either 1st or 2nd, depending upon the rear gear ratio).
2) From a stop, manually shift into 1st gear and drive at a steady speed, then go WOT. If the secondaries are opening properly, you will feel it.

72455

Hwy speed 65-70 and 3.08 gears

RetroRanger

72455

Turbo 400

Koda

That is not too fast for a kick down. My typical run up in a car with 2.73 rear, stock 350, and quadrajet, is to be sitting at about 2000 at 60, punch it, downshift to second (up to ~3000) then hang on until redline shift at 4500 at 90, then it shifts to third on its own and I'm at 3200 rpm at 90 or so in high, and there's plenty more power to take me to 100, where I chicken out.

Do you have a tach? Can you temporarily install one if not? At 70 in 3rd you should be, with that rear @2800 rpm. In 2nd, you'd go to 3800. Definitely punching it at 60 would make it downshift, unless something is wrong.

72455

Yep I have a tach and your numbers are correct. I'm turning about 2800 at 70 mph. As I said above, when I punch it doesn't feel like it's downshifting.
I say that because I don't feel the kick.

Fun71

Does it downshift from 30 MPH or so?

72455

Dunno yet...gonna try it tomorrow. And it's a 670 Street Avenger...not a 570...I thought 570 sounded kinda small when I typed it...lol

BangScreech4-4-2

I had a 670 on a Chevy L-79 327/350 hp. It was perfect for that engine.

Koda

Don't need to feel the kick, watch the gauge, and put the windows down. If it just sounds like it's accelerating, then your kickdown is not working.

A kickdown going from 2800 to 3600 or so on a 455 will be noticeable. You will see the RPM jump 1000 or so in a second, and the engine will go:
burrrrrrrrr-BLAAAAAAAAAAAAAAH. I had a car which did not downshift. Removing the carb and working on some other issues cured it.

I would start troubleshooting the kickdown circuit. Could be something as easy as a disconnected wire.

72455

Will do. If I'm not mistaken, the solenoid is on the left side of the tranny, towards the rear, correct? When I trace the wires going back, where do they go?

oldcutlass

The kickdown switch is mounted to your gas pedal.

72455

Underneath?

VC455

Look above the pedal and find a slide switch with an electrical connector. It is adjustable for position so that the kickdown occurs sooner or later.

72455

Ok, so I gave this a try. I couldnt tell if it was downshifting, but I held it to around 55-60 and II fel it upshift. I dunno if it's because I wasn't out of second at 35 mph or if it downshifted. I do know that when I punch it at 55-60, the tach doesn't jump, it just steadily climbs.

72455

I did this, and it felt like someone hit me from behind, so I think my secondaries are ok. Agreed?

72455

Is this the switch? If so, how do I adjust it?

cutlassefi

72455

Bueller? Anybody?

oldcutlass

If its attached to the gas pedal assy then yes.

VC455

Yes, that is the switch.

First, check the switch. A test light would be ideal, but sometimes the following gives enough information. Slowly push the cream-colored slider by hand--you should hear a faint click when the switch actuates. If you don't hear the click, you will need to use a test light and repeat the check.

Next, try the same thing by slowly pushing the gas pedal. You should hear the same faint click. You can figure out from these two tests if the accelerator pedal is actuating the switch.

You can physically adjust the position of the switch to make the downshift occur sooner or later. (I don't recall exactly how to do the adjustment, but I know it is apparent if you inspect closely.)

Greaser007

Hey Koda,
How is that ride if you get up around 120 ? . . . . post #12

I ask because when you mentioned "chicken-out" at 100, I chuckled because I have been driving a Subaru WRX for 11-years, and it scoots to 100 real easy, and then _ _ _
the little car begins to feel LIGHT if you know what I mean, and that is where I normally "chicken-out" especially if there is a slight curve ahead ! hahaha
I am actually 'chicken' of finding out if it is truly governed at 142. _ _ _ a slight drift to the gravel shoulder followed by a rollover would be Catastrophic even at 100.

I wonder if 72455 got his kick-down switch working ?
Len

72455

I hear the "click" when I move the switch by hand and when I press the gas pedal, but still no sudden jump off the tach when I stab the throttle .I also slid a piece of hose over the slider to see if the switch would engage sooner. What else should I troubleshoot?

cjsdad

Make sure you have 12 volts to one wire of the switch when the throttle is at the idle position and then make sure it has 12 volts on both sides of the switch when the throttle is fully depressed. If yes to both, then follow the wire that goes down to the transmission and make sure the 12 volts is getting to the trans when fully depressed.

72455

Thanks for the advice. What I'm going to do is turn the ignition on (but not start the car...don't wanna upset the neighbors...lol) then press the pedal and listen for the solenoid to click. If it does, then I'm guessing it would be a vacuum issue, correct? If the solenoid doesn't click then I will back track and check for voltage. Hopefully I won't have to replace the solenoid.

VC455

I never thought about listening to the transmission solenoid. With the engine off, listen underneath as someone actuates the pedal switch. If you hear the transmission solenoid click, you can forgo the electrical checks. Something may be wrong inside the solenoid. Try replacing the solenoid to see if that corrects the problem.

If you don't hear the solenoid click, you need to check for voltage, working backward or forward in the circuit. There is no vacuum involved with this kickdown problem.

As cjsdad said, check for 12 V at both terminals of the accelerator pedal switch when the switch clicks.

If that part is OK, disconnect the electrical connector on the side of the transmission and check for 12 V supply when the switch clicks.

If you don't get 12 V at the transmission, figure out where the voltage is stopping and fix or replace that wire or terminal.

If you get 12 V at the transmission, check to see if both sides of the connection are corrosion-free and the female terminal inside the electrical plug fits snugly to the electrical tang on the transmission . If all that checks out, replace the solenoid inside the transmission. Removing the pan is the messiest part. Once you have done that it's easy to replace the solenoid.

BangScreech4-4-2

Please forgive the late reply -- I didn't notice you called me out until now. The reason I brought that up is that there had been some conjecture about whether a 670 CFM Street Avenger would be a big enough carburetor for a 455. I thought my experience using one on a much smaller engine might be helpful in proving that it's probably too small. Sorry if I didn't make that clear in my post.

Greaser007

Dave,
Once you get the kickdown working properly, you'll have a Big smile on your face
and earned a run down to the burger stand for a cheeseburger and fries. _ _ no romping on-it. hahaha

cutlassefi

Koda

Sorry for late reply. My 442 doesn't drive well right now. I have a Monte Carlo that I will do the above in. The hood used to come loose on bumps, up to the safety latch. I took the latch off and greased everything and put it back. No problems in ten years, but still worries me. Nowadays I do stop at 90 since the car gets back into high gear at a WOT run there.

It was getting a little light at 100 in the steering and starting to sway. I imagine 110 would be fun, 120 might be scary.