Throttle pedal problem

[mgtf328]

As I've only just bought this car I don't know if this is normal for a BJ8 but when I press the accelerator nothing happens for the first 1 -2 inches. It's just a dead spot then the engine picks up smoothly as you'd expect. I've replaced the bush at the end of the pedal shaft and tried different positions for the lever arm on the end of the shaft. A mechanic friend of mine has adjusted the linkage as per the manual but nothing seems to alter the dead spot. Has anyone got any suggestions as to what I should try next. Thanks.

AJ

 

[Bob_Spidell]

I just went through the whole throttle mechanism adjustment rigamarole with my BJ8. In my case, I was forced to do this when I noticed after I pulled the engine for rebuild that the cross-shaft bushings were toast, and one of them had been bent back (probably at a previous engine removal and install). I also spent a considerable amount of time making sure I got full WOT when the pedal hit the metal. The OEM throttle shaft bushings are bronze bushes embedded in rubber; the rubber was dry and crumbling, causing the shaft to 'absorb' some of the movement of the pedal before it moved the shafts that opened the throttles. I suspect this is less of a mileage-related wear issue, and more of one of time (50+ years of engine compartment heat). So, check for play in the throttle cross shaft, at the top of the transmission tunnel behind the engine. Surprisingly, I didn't see any wear in the 'ball-and-socket' joints that connect the whole Rube Goldberg mechanism, but the ears on spring locks tend to corrode and break off easily.

Moss Motors (NFI) sells a set of nylon/teflon--they call the both/either at different points--bushings to replace the bronze/rubber originals*, and I've heard from some who 'rebuilt' the originals by replacing the rubber part with urethane or similar. Unfortunately, these would be a female dog to replace with the engine in place, though the comprehensive instructions that come with the Moss kit explain a method to make re-install easier.

* These were designed by Eric Grunden, a highly-respected Healey mechanic here in the Colonies:

https://www.mossmotors.com/graphics/products/instructions/021-822_980-310_INST.pdf

 

[John Turney]

If you have someone who can press the throttle while you look at the mechanism with the bonnet open (and the car parked), it might give you ideas where the slop is.

 

[Randy Forbes]

When switching to Weber carbs, alterations to the throttle linkage was unavoidable, and after years of dealing with the vagueness and potential failure of the original setup, I concocted a far simpler and direct actuation of the butterflies.

It's not going to fool any concours judges, of course there's so many other infractions, the throttle linkage could go unnoticed...

 

[DerekJ]

The throttle linkage set up is a Heath Robinson affair at best. There is always some play in the system and the cross shaft is virtually impossible to access with the engine in the car. I had the same problem with my first Healey, then my second one had the problem where the throttle does not return to fully closed unless you blip the peddle. I recommend switching to the Denis Welch cable throttle system, massive improvement. Used it with both SUs and Webers without any problem and there is much more feel.

 

[John Turney]

The throttle linkage set up is a Heath Robinson affair at best. ....

Is Heath Robinson Rube Goldberg's English cousin?

 

[Patrick67BJ8]

When switching to Weber carbs, alterations to the throttle linkage was unavoidable, and after years of dealing with the vagueness and potential failure of the original setup, I concocted a far simpler and direct actuation of the butterflies.

It's not going to fool any concours judges, of course there's so many other infractions, the throttle linkage could go unnoticed...

i replaced the original throttle linkage ends with Rod Ends that Toms Imports sells. No slack in the gas pedal linkage anymore.

 

[DerekJ]

Yes Heath Robinson was ~Rube Goldberg's cousin!

Here is his drawing of the Austin Healey throttle system.

 

[fordtrucks4ever]

Yes Heath Robinson was ~Rube Goldberg's cousin!

Here is his drawing of the Austin Healey throttle system.

Isnt that what the Milton Bradley Mousetrap game is based on?