brown7373

My 72 350 Q-jet runs great, but doesn't have much power. Today I had my wife floor the accelerator, to see if the carb was opening all the way. It wasn't even getting to the secondaries at all. Jammed through the floor, I am only on the primaries.

I am questioning my pedal linkage. The pedal has the spring installed, so it rotates freely, but the pedal seems way too close to the floor and at rest, there is an inch or 2 of slack before the accelerator cable makes contact with the linkage. I bought a new cable from Fusick, but it is no help.

Is something assembled or attached wrong, or do I have a bent linkage? I can lift up on the pedal and it will travel a good 2 inches before it stops, and the pedal will be a little more than 4 inches from the floor and about even with the brake pedal. Of course this increases the slack on the cable even more.

Where the linkage attaches to the pedal is about 2 inches off the floor, and it is significantly lower than the brake pedal. About how high should the pedal be?

The illustration in the assembly manual (sec 1-1 page 108) shows the cable end contacting the linkage with no slack. Any ideas? Wrong linkage? Bent linkage?

brown7373

Can anyone tell me how high their accelerator pedal is from the floor?

Seff

I had the same issue as you do with slack in it, and I moved the retainer clip to take up the slop. Remember to move the kickdown cable retainer as well if you're running a TH350.

I felt no real change in performance at the time.

Do your secondary air plates open up if you manually manipulate the throttle arm to its full extent? Remember, the car has to be running to do this, as the secondaries are controlled by vacuum, not by the linkage.

joe_padavano

First of all, if you are saying that the air valves on top of the carb are not opening, they won't. You need to hold them open manually and look down into the carb to see if the secondary throttle plates are actually opening. Is that what you did?

Octania

That sounds like a lot of slack. Photos of your cable attachment at the carb? What part is non-factory? [it did not behave like that when made...]



"Do your secondary air plates open up if you manually manipulate the throttle arm to its full extent? Remember, the car has to be running to do this, as the secondaries are controlled by vacuum, not by the linkage."
===================
Mmmmm not quite the best method to investigate this

Remember that 1) the choke must be fully open for the secondary air valve to open. You should be able to simulate this condition by simply holding the choke plate all the way open while you watch the action of the throttle. No need for the engine to be running. However, you will only be able to directly see the upper secondary air valves, until you open those as well, and hold them open. Engine off. Then you can look in and observe the lower secondary throttle plates directly.
2) The secondary throttles are driven thru a spring on the LH end of the 2' [secondary] shaft. It is possible for the spring to request that the secondaries open, but that fails to happen, due to binding or perhaps the choke interlock found on the RH side of the carb base. With some practice, you can see whether the 2' throttle shaft is actually opening by observing the exposed part of the shaft on the LH side.

However, with that much slack in your cable, it sounds like that is the main issue.

You can and should still become familiar with every link, interlock, spring, etc. on your carb, so that you know how they are supposed to work.

I was going to suggest an incorrect cable bracket at the carb may be at fault, but there are not very many different types, so if your bracket is factory correct, that's probably not the issue.

MDchanic

IF the secondaries really aren't opening (as Joe mentioned above), there is little room between the pedal and the floor, there is slack in the accel. cable, and you can pick the pedal up a good distance with your toe, then just unbolt the pedal from the firewall, put it in a vise, and bend the steel lever to a more acute angle.

- Eric

Octania

A good quick fix.

Of course you should still verify that each part of the carb is working like it should- once you learn the mechanism, it's really easy.

brown7373

My wife stepped on the gas, I opened the secondary flaps and looked down inside. The carb linkage doesn't open enough to even start to open the secondaries. But they work just fine when the engine is running and the carb linkage is worked by hand under the hood. Quickly rev it and the flaps open fine.

I also noticed the 350 kick down cable was broken and repaired. I wonder, since it is now shorter, if the previous owner didn't bend the pedal linkage so the trans cable wasn't activated way too early. And that would also explain why all the slack in the accelerator cable.

Does anyone have an extra pedal linkage, or know if anyone sells them? I hate to start bending e is not right now.

I have always had cars with 455s or 400s (350/350 Vette too), so I just though 350s were anemic. It is okay on general driving and the highway cruise, but no kick when you floor ir...no secondaries.

MDchanic

Just bend it - it's an entirely non-critical part that is easy to bend into the wrong shape by mashing the pedal into the floor too hard.

If you don't like it later, you can always bend it back.

- Eric

allyolds68

I bent mine. I get much better throttle now but I don't like the pedal height. I'm going to mess with it again in the spring.

oldcutlass

x2 - but ensure that your not putting the carb linkage in a bind by overbending.

Lady72nRob71

Here's a way to test without bending anything...


Those are solderless crimp connectors that served a different purpose.

Also make sure the throttle cable bushing at the carb is there and is not worn.
The bushing on my car was gone. That and with a stretched cable, my secondaries never opened either.

brown7373

I think a previous owner had the end break off the trans kick down cable. That has been jury rigged and is now shorter. Since it was shorter, it was not long enough to hook-up, so the linkage was bent. So with the that made the throttel cable have way too much slack, and consequently not enough travel to fully open the carb. I ordered a new trans kick down cable today and will correct the rod and hopefully I will discover what it feels like to have ALL of my carb, not just the primaries. Thanks for the input. I will repost and report the results.

brown7373

To update my issues with this problem, I bought another pedal assembly because I believed that mine had bben bent to compensate for a broken and repaired thm 350 downshift cable that was now shorter. The pedal bracket had not been bent, but since the cable was shorter it caused slack in the throttle cable, thus it wouldn't open into the secondaries.

Also, a piece of (new) carpet had gotten under the plastic pedal mount base. That also effected the opening slightly.

After installing a new downshift cable and properly mounting the pedal assembly, I now have the use of my whole carb. Definitely has more power with more than just the primaries.

I also discovered that my accelerator pump was sticking in the bore. It would shot a nice shot of gas, but it wouldn't come back up. I rebuilt the carb in July of 2009 with a kit with rubber impervious to the gas additives, but I guess after 3 1/2 years, even the better parts deteriorate from the crap gas. Fortunately, I had another kit for a different car that I robbed the cup and now it is fine. Apparantly the rubber swelled very slightly. It looked fine, but was too tight in the bore.

Thanks for the suggestions and help in solving my problem.

BILL DEMMER

a '72 olds carb. won't have a spring-actuated secondary throttle lever, it will only have a lever return spring, nor will it have the lockout on the secondary shaft(the lockout will be on the secondary air valves).

bill

Nop

Digging this up, need some clarification...

This is my current setup, 350 with q-Jet (and an ugly Edelbrock cleaner)



Am I right that:

1) The Clip at (1) is missing the two flaps that snap in to the metal retainer? It's wiggling around and doesn't look well fixed there.
2) The two flaps should be orientated at top and bottom, not left/right?
3) The plastic hose (2) that covers the cable was originally attached to the outer cable end point, broke and slipped forward?
4) anything else looking suspicious here?

Just started digging around my gas pedal area and the carb linkage, got more than 1" slack in the cable before anything moves at the carb end and my primaries barely open when I floor the pedal. I guess I just found my missing 50 to 100 ponies there

I only carefully drove the car home when I bought it at a max 60mph and rolled it into my little garage for the winter to work on it, so I can't really say if it goes 100+ and if power is somewhat close to stock.

I read the secondaries don't open without the engine running and already read a lot about the accelerator cable linkage, but I'd like to get some opinions here or even pix how it's supposed to look like.

Downshift looked fine while driving, at least "something happened" during hard acceleration. But I guess I'll first check the gas pedal cable, then adjust the tv/kick down/downshift one.

joe_padavano

Correct on all three. Note that the "clip" at (1) isn't a clip, it's molded integrally to the accelerator cable. You need a new cable. This also fixes problem #3.

Nop

I already guessed that but from pics I've seen it wasn't quite clear if it was molded or just slipped on. Ordered a new one. Thanks!

Anybody have a picture of how it's supposed to look licke when stock? And may I ask for a clear stock image of the gas pedal cabling with clips, also?

KDV

It sounds like you're looking to keep it stock, but just to show you another option...

I went with a new Lokar cable and bracket

Great throttle response!! My next project will be to replace the kickdown and move it to the carb.

IMG_20130808_124939_386_zpsaf5999e8.jpg

IMG_20130808_124920_205_zpscf80ad63.jpg

I did have to make an adapter for the pedal, but I did that by drilling an eye through a 3/8" bolt.

All the Best!

Octania

"a '72 olds carb. won't have a spring-actuated secondary throttle lever, it will only have a lever return spring, nor will it have the lockout on the secondary shaft(the lockout will be on the secondary air valves). bill"
========================
Iiiiiiiim preeeeetty sure all QJets use a clockspring on the secondary shaft, LH side, between the link that asks the shaft to open and the shaft itself. That way, if the shaft can't open, the request to open is absorbed by the spring and not by damage to links or shafts.

I thought that all QJets had a lockout either at the secondary air flap or on the secondary throttle blade shaft, either way on the RH side.


Here's a 1967 carb with the clockspring on the LH end of the secondary throttle shaft

http://www.ebay.com/itm/Rochester-Qu...90688292425%26

Allan R

This should be close to what you want.


EDIT: This picture is a 1972 7042250 Q-Jet

BILL DEMMER

the spring on the linked pix is the secondary closing spring. this spring only serves to assist closing the secondaries. there IS a hard link to the secondary throttle shaft, there is no spring that "requests" secondary throttle opening. this model carb will have a lockout on the air doors.

here is a pic of the later qj's with the setup you are thinking of:

http://www.ebay.com/itm/1984-1985-19...bcaa3e&vxp=mtr

the carb; linked just above, would have a lockout on the right side of the secondary throttle shaft, and a "request" spring to open the secondary throttle shaft(on the left side).

but alas, we were discussing a 1972 704-series olds carb.


bill

Greg Rogers

Allan, I assume the pic you posted is a '72? I just reinstalled A/C on my 71 Cutlass 350. I notice the pic shows a idle solenoid that raises the idle when the a/c is on. Mine doesn't have that. I wonder if it was added in 72?? Also what is that plate just to the left of the carb w/2 bolts? Thanks, Greg.

Allan R

Greg, yes it's 1972 carb. The solenoid you're asking about it the anti dieseling solenoid. I believe it started in 1972. For AC there's another dashpot that you need I think it replaces that one on mine. The block off plate you're asking about is for EGR. The intake on my car is not a 72 intake, as it was converted from 2 bbl to 4bbl and that's what was readily available at the time so it just got blocked off.

brown7373

This is a picture of my 72 350 before the engine was cleaned and painted. The extra cable by the accelerator cable is for an aftermarket cruise. On the left is a accelerator dashpot. Later, it broke in two and the engine runs exactly the same, so I don't know what purpose it served. It is supposed to prevent stalling if you back off the accelerator quickly. Doesn't stall with it or without it.

Octania

Well, right you are, sir
I was confused on that score.

oldsguybry

Quick question .... Given the set up is correct , should there be any slop at all ? Should both cables be right at the linkage on the gas pedal before pushing the pedal down ? Thanks

What I mean is .... Should both crimps on the cables be against the linkage on the pedal bracket given the kick down cable is all the way up ?