Hello,
I've just finished up doing an intake and carb swap on a '73ish 360 in my 83 Prospector. This also included new timing set, head gaskets and general tune up items. The TQ came to me completely apart in every possible way, in an ice cream pail. I did my best rebuilding it with a Hygrade kit and new floats as per the kit instructions and online sources. It starts with a few pumps, but stumbles for a moment before smoothing out, then runs nice. My problems are:
- I can't get the curb idle below 900 rpm, even with the idle screw right off he tab.
- I'm unsure of the vacuum hose routing, does anyone have a diagram?
- there seems to be the part that the thermostatic spring in the manifold connects to electrically missing, is the two barrel part the same?
-where should the timing be set? It seemed to like the 83 specs of 12 degrees with the two bbl, and runs well with it there, but not sure if the idle issue is tied to that or not, if I got lower then 10, it backfires through the carb when the throttle is snapped open

The engine has good compression ( all around 130 +\- 5), and idling pulls 20 psi vacuum, though that's at 900 rpm. There is EGR, but it's blocked off. The TQ decodes as from a 75-76 truck 440 standard emissions. It has four vacuum ports, two at the front and two in the rear. I have PCV and distributer off the front, choke off the rear pass. side, rear drivers side blocked, where would the line for the air cleaner hook into? I've taken the carb apart to double check settings, doubled checked timing and vacuum lines for leaks, not sure where to go from here.
Thanks!
Thanks!

 

Unplug the vacuum line from the distributor and plug it. Does the Idle drop? If so you have it hooked to manifold vacuum source and it should be ported vacuum.

Dave

 

No, the idle stays put, there is no vacuum from the port I have it on at idle, which is correct, yes?

 

Yes that is correct.

Dave

 

Figured so. I noticed some play in the throttle shaft, could that draw in enough air to bump idle speed up that much?

 

I don't think so. I have a leak at throttle shaft bushing and mine idles fine.

Dave

 

Played with timing a bit, it's currently at 12*, if I lower it to 10, it does idled down but then stumbles and pops through the carb. I don't think 2* should make the much difference? I'm going to check the dizzy out a bit more closely today. I do have another one I can try, but it's an unknown. I don't even know what year or engine it came from, it's a spare that came with the truck.

 

Have you adjusted your idle air mixture screws?


I've got a 76 440 carb on my 400 bb and it doesn't idle like that. lol

 

Ok, the dizzy seems good. Can't blow through the vacuum line, and it seems to move properly with vacuum applied. I took it for a test dive (couldn't until today, no air cleaner),it cranks a bit longer then I think it should starting cold, and stumbles some if givin throttle before its warmed up, something the two barrel didn't do. it starts fine when hot, idles fine, but bogs when I punch it. It would also sometimes idle at a higher rpm, then the next time back down to the 800-850 mark. I'm going to check the linkage out a bit closer and see if its binding a bit somewhere. I'm still mostly thinking the problem lies in the TQ, I have an old Qjet I can rebuild and try, or perhaps chase down a spreadbore Holley or Edelbrock, but I'd rather work with what I already have. I've never had too much trouble rebuilding carbs (though mostly two barrels), so it is very likely I screwed the pouch there somewhere. Is there a good online guide for TQs?

 

I'm thinking part of your trouble is the SIZE of the carb. That is an 850 cfm carb. I know I have one. There were two Carter TQs made for the big blocks, one was an 800 the other was an 850. The 800 had the better throttle response of the two, but that is also with a larger engine.

You should be looking at closer to a 550 cfm 4bbl.