Full throttle?
 

Hi guys so I got my 68 Ohc6 4bbl engine running great. But I always thought it was not performing like it should and I parked the car for approximately 8-10 years.. I just realized I’m not getting wide open throttle. The quadrajet carburetor seems to be functioning well. I don’t see any adjustments for the cable and wondering if the cable may be stretched ? I looked around and have not found a new replacement cable. Are new cables available ?. Has this happened to anyone and you fixed the problem ?. Here are a few pictures of the secondaries position peddle to the floor pic #1 and by manually open fully by hand Pic#2. Have good throttle peddle response and drivability. Please help after all these years I want to see the performance of this engine.
In the third picture the cable does have some movement where the cable clamp holder is? Is the cable housing suppose to be locked in place ?. Huuum now wondering if that could be the problem ?.

Secondary linkage
 

I would check to see if the primary throttle blades are at 90 degrees when the gas pedal is on the floor. If it is, then the cable is fine.

It looks like the clip for the throttle cable may not be on right. I think the top hooks over the fixed part and it then squeezes the cable end when you tighten the bolt. You might try that to see if it takes away the slack.

This picture shows the linkage from the primary to the secondary throttle blades.
I do not think the factory setting for the OHC has the secondary butterfly at a full 90 degrees at wide open throttle so yours may be about right. Are they about 3/4 open?

The Cable bracket is not hooked on correctly.

See my '66 as a reference, even though it's at the bottom.

Full throttle
 

Hey guys you were right I fixed the cable bracket tab and it is now clamped in place correctly. But still while giving full peddle the secondaries are only opening at 30 degrees with no additional slack in the cable. I can move the throttle back by hand an additional 1/2” with the secondaries opening approximately to 45 degrees. I don’t see any adjustment for the linkage ?
Any ideas ?
Here’s another picture of the linkage.

Absolutely, there is always room for improvement on 50+ YO parts.
I would do just that. I had a similar issue at the pedal. there was about a 1/2" of movement before it would pull the cable.

It is possible that you have a one barrel OHC or maybe a V-8 bracket that’s been modified to work.
From you picture it looks like it has been trimmed or cut down, and I think the clamp usually has the nut and bolt on top.

I noticed the same issue on mine back in the day... I think I fixed it by modifying the cable/clamp, but my mind is full of cobwebs. Do what you need to do to get it right.

George

I had the same issue with my wagon. The cable gets stretched with use over time. I would adjust all you can at the engine. (Cable clamp) if that is not enough, get underneath the dash and try to take some of the slack out of it at the pedal linkage where the cable attaches. (Move the cable stop) That should take care of it.

Full throttle
 

Hey guys I finally figured out my problem. Ok I admit it I’m older and slower and should have caught this before SMH. I now have full throttle. Secondaries opening approximately at 45 degrees pedal to the floor (Before only 30 degrees) All this time approximately 10 years this engine has never performed like this and I always knew something was wrong because the engine was just a pig. (Bought the car like this and due to lack of performance I parked the car 8-10 years). Ok ok thanks to you I kept fiddling around with it and the cable clamp was still not fastened correctly (I’m sure someone else has got to be running around with it wrong too) Here are pictures of the cable housing and clamp incorrect pic #1, and the housing clamped correctly in the groove of the clamp pic #2 (full throttle). Picture #3 back of clamp with cable housing in the groove. Now my engine performs like a 250 with a 4 barrel carburetor and pulls through the gears. Thanks to PY and technology being able to post and with pics so members can see what I have going on and set me in the right direction. Thank you all.
Hmm ok maybe I am the only fool that had it wrong.

Glad to hear you got it running better.

BTW that is a great looking Firebird!