Ok, you guys convinced me to stick with the 4 barrel carb on my 86 351w HO in my 1978 f100 ....now I need to know where my throttle return spring is supposed to hook up to, if the carb is supposed to have one? the thottle will return almost to idle when I let off the gas(just revving it in the garage...I haven't drove it like this), but I have to close the linkage by hand to get it to normal idle again. There is no stud or anything I can see on the manifold to hook a spring to, and I would say it needs one, unless the springs on the carb itself are worn. any ideas? thanks again, Ben

 

Trying to remember, but I think the (dual) spring(s) go(es) to the coil bracket. Yes, the carb might have a spring but you still should have an external. Can you say redundancy? Always run more than one spring in case one breaks.
Just my 2¢
Greg
Or was the spring built into the end of the throttle cable?

 

On my '84 the throttle return spring is part of the throttle cable.

What kind of carb do you have? Most carbs should also have a spring on the throttle shaft that will keep the butterflies closed.

I would disconnect the throttle cable from the carb and work the throttle by hand (engine off, of course) to see if it opens and closes smoothly. The butterflies could be hanging up or rubbing against the gasket or EGR plate.

 

One more thing...

Make sure the fast idle cam for the choke is not sticking. This is the part that increases the idle speed when the choke is closed. Sometimes the choke butterfy will open fully but the cam doesn't drop back all the way.

 

Ben, when I put a Holley Street Avenger on my 351W I had to fabricate a bracket for the throttle linkage to mount to. Basically it's just an L shaped piece of angle iron that mounts to the intake behind and in line with where the throttle cable connects to the carb. I drilled an extra hole in this bracket and connected my return spring to that. There is also a spacer made (but I forget the name of the company that makes it) that mounts under your carb that has a tab coming off the back corner with a place to connect a return spring. Anything like that will work.

 

ok, I'll answer one at a time

Macguyver--- I am not using the stock 86 351w coil mounting place...it was mounted to the big mess of power steering/AC bracket or whatever that bracket was...i am using the same set up that was on my 78 302 that was original in the truck

John Barleycorn....i will check the fast idle cam, and I do not have the throttle cable setup, I am using the throttle rod that goes from the pedal linkage to the carb. the carb is stock for the 86 351w HO holley 4 barrel 4160 I beleive

hotwhlz85..i will probably have to figure something out like that, there just doesn't seem to be any bolt holes on the intake that line up close enough to where the linkage is.

thanks for every one's replies...maybe sometime this year I will get the beast back on the road again ...Ben

 

Try to set up carb. return spring like your original motor had. My 86 has spring on throttle cable and carb. Carb spring is probably wore out. Mine is!
After reading your other posts on vacuum. A diagram would probably not help much. Unless you have all original stuff to go with. There are so many valves, one ways, filters, and such it would be hard to get it all right. I have my schematic on my truck if that will help. At this time I have no way of transfering to you.
As for the little plunger thing at the accelerator, some ten years or more there was a recall on emissions. The dealer capped it. Never used since and no back-fire noise, either.

As for the choke cam. About every 6 months I clean around it with carb. cleaner. It will stick, but you usually notice after it warms up and you try to "kick it down".

Hope this helps.