70 LT1 Throttle Return Spring

[Jephrey S.]

I was having a problem with my throttle sticking around the 10% throttle point. The new spring I ordered from Dr. Rebuild arrived and was visibly shorter than the one I was replacing which was a good sign. With the engine completely cold, the new spring consistently returned the throttle to closed upon release.

As soon as I get even a minute of heat into the engine, however, the sticking throttle returns. Tested by hand on a warm engine, the spring only returns to about the 10% position. Without the spring I cannot feel any bind or roughness in the linkage movement but the spring just will not pull hard enough when barely stretched to finish the job. Likewise, I do not feel a bind on the throttle cable itself. I treated it to a nice helping of graphite last year while trying to troubleshoot and everything still feels smooth.

I suspect that Dr. Rebuild has the original GM specs for his springs, and they are of the same high quality of all of his parts. My throttle cable mount appears original, as does the linkage on my Holley 4555 carb.

So, my questions are:
1) Was this a common problem with this set-up or do I have something out of whack?

3) Was the throttle return spring identical for all 1970 engine configurations? That seems strange to me, but the only reference I could find in my AIM was GM P/N 3972624. Does anyone know how that compares to the -214?
4) If 1-3 do not get me anywhere, is there a place I can order something that will work? Since I am living in Germany I cannot just walk into a random speed shop and find a selection of throttle return springs on the shelf. Likewise, a runaway throttle past 5,000 rpm before 7 am in a sleepy little village is not good for international relations.

A picture of the 3459-214 is attached.

Thanks as always.

[Joe L.]

Re: 70 LT1 Throttle Return Spring

I was having a problem with my throttle sticking around the 10% throttle point. The new spring I ordered from Dr. Rebuild arrived and was visibly shorter than the one I was replacing which was a good sign. With the engine completely cold, the new spring consistently returned the throttle to closed upon release.

As soon as I get even a minute of heat into the engine, however, the sticking throttle returns. Tested by hand on a warm engine, the spring only returns to about the 10% position. Without the spring I cannot feel any bind or roughness in the linkage movement but the spring just will not pull hard enough when barely stretched to finish the job. Likewise, I do not feel a bind on the throttle cable itself. I treated it to a nice helping of graphite last year while trying to troubleshoot and everything still feels smooth.

I suspect that Dr. Rebuild has the original GM specs for his springs, and they are of the same high quality of all of his parts. My throttle cable mount appears original, as does the linkage on my Holley 4555 carb.

So, my questions are:
1) Was this a common problem with this set-up or do I have something out of whack?

3) Was the throttle return spring identical for all 1970 engine configurations? That seems strange to me, but the only reference I could find in my AIM was GM P/N 3972624. Does anyone know how that compares to the -214?
4) If 1-3 do not get me anywhere, is there a place I can order something that will work? Since I am living in Germany I cannot just walk into a random speed shop and find a selection of throttle return springs on the shelf. Likewise, a runaway throttle past 5,000 rpm before 7 am in a sleepy little village is not good for international relations.

A picture of the 3459-214 is attached.

Thanks as always.

Jephrey------


That looks like exactly the correct spring, to me. As far as what might be causing the problem, I don't know.

[Paul O.]

Re: 70 LT1 Throttle Return Spring

Jephrey

It does not sound like you have a problem with the return spring could be, but my guess is not. Sounds like your problem maybe in your throttle plate shafts when heated they maybe binding in the throttle plate or some other area where binding can occur due to heating.

Paul 18046

[Edward J.]

Re: 70 LT1 Throttle Return Spring

Jeff, I see this alot on quadrajet and holley carb.s once there rebuilt and they install shaft bushings. the throttle shaft as Paul says do tend to stick, the problem is when the engine is running its pulling a vaccum and it pulls the plates shut, and causing them to stick uder light throttle, sometimes what you can do is head down to the auto parts store and sometimes you can buy a assortment of return springs or just find one that a little heavier.

[Patrick H.]

Re: 70 LT1 Throttle Return Spring

On one of my Q-jets I lubricated the throttle shaft at the bushings and the problem went away.

[Joseph K.]

Re: 70 LT1 Throttle Return Spring

Jeff, I see this alot on quadrajet and holley carb.s once there rebuilt and they install shaft bushings. the throttle shaft as Paul says do tend to stick, the problem is when the engine is running its pulling a vaccum and it pulls the plates shut, and causing them to stick uder light throttle, sometimes what you can do is head down to the auto parts store and sometimes you can buy a assortment of return springs or just find one that a little heavier.

I had the same thing happen on a Q jet after a rebuild and I solved it just like Edward recomended. You can always take the heavier spring off before it is judged