Sticky-ish throttle when car is hot/coming off the highway

[v76124]

Hi folks,

I daily drive my 76 and it seems to have picked up a throttle issue over the past week. It starts fine with fast idle around 1750 rpm and idles fine (around/under 1k) once the temp goes past the 50 mark. Its a bit 'jerky' when I start off (not up to temp, still just past the 50 mark), especially when setting off from stops- the power comes in surges (a short tug to get going, nothing, then full power) till 2k then is smooth once in 3rd. Not sure if this is normal, but once the engine is warm the issue disappears.

My main issue
I drive about 10 miles on the highway at 65 and once I get off the highway, the RPM returns to idle very slowly. For eg, I rev to 2.5k in 1st and clutch in, the RPM does not drop, it stays at 2.5k (or near) when I am shifting (it drops once in gear). When I come to stop in neutral the RPM starts dropping, but very slowly.

It runs fine when I lug the engine, letting off the throttle in 3rd/2nd it slows down normally and the RPMs go down but if I clutch in at 1.5k for eg, it stays there (or rises slightly) for 5-10 seconds before starting to drop slowly.

I thought it might be that spring under the water choke, but its seated properly. I'd kicked it off accidentally in the past when I was tinkering with the choke and it was idling at 2k rpm.

Anyone have any ideas on what to look for/check?

Another note, my throttle pedal has a distinct tightening and 'snaps' loose about 3/4ths of the way down. It's never bothered me when driving, but when I pump the throttle to prime the carb it definitely 'snaps' before going all the way down. Is this normal?

[RRoller123]

Sounds like it is time to replace the throttle cable itself, may have a fray along it that is causing it to bind. Safety issue, it could stick wide open some time, should be replaced asap.

I have the same problem with my Jaguar, there is a little stick point along the way somewhere. New cable is 80 bucks..... Will go on order today....

[v76124]

Thanks for the reply. I've ordered one from Autoricambi but the problem seems to have 'fixed' itself for the moment. I fiddled with the idle a bit and its running really well the last 2 days.

I'll keep an eye on it and probably replace it next weekend, if it gets delivered by then.

Thanks again - and ouch about that Jag...I don't even want to look at other part prices. I was contemplating a XJS V12 before I got the Fiat. Lovely engine, when it ran but after all the nightmare stories, I moved on lol.

[txspider]

If you have the original spring loaded return on the carb instead of the cam mounted linkage on the later models then what happened to me was that corrosion set up in the spring and unless I sprayed a good lube on it about every 6 months it would drag and not return as you described. Change to cam mount and you'll have no more issues!