79' Scout 2 345 revs up without choke

M

MightyMonte88

New member
Hey guys I need some help. I started doing a tune up on a friends 1979 Scout 2, 345, manual. This thing was pretty neglected so it needed a full tune up and go over. So far I've replaced plugs, wires, cap/ rotor, pcv valve and all vacuum hoses, except the hose that travels from the air cleaner to the driver side valve cover ( pickup for crankcase vent right? ). Had to grab a new air cleaner assembly, just went with what was recommended for the edelbrock. Aside from that everything else was standard, fluids and seals.

The original thermoquad was done for, the resin body was cracked. So after doing some homework I found that an edelbrock 1406 seems to work pretty well with a stock IH 345 in a Scout so that's what I went with, out of the box set it up to edlebrocks calibration 19, allot people claimed they had really good results with that calibration.

The problem is, as soon as we fire the engine it wants to rev up high unless I keep the choke closed by hand. This is where we stopped, ran out of daylight to diagnose any further, so I figured I'd post up all the variables on here and see if yall can spot something I missed. Any help would be appreciated.


Had my vacuum gauge on while we ran her, it gave a very steady reading, but it was low. I suspect a vacuum leak? One thing that slipped my mind was the hose I mentioned above, the one that travels from driverside valve cover to air cleaner, I didn't have it hooked up to anything. Will this cause a vacuum leak?


Also, I tried hooking up the distributors advance to both ported / manifold sources of vacuum on the carb. The reason I tried both is because the emissions system was deleted by a previous owner, I'm not sure if the distributor is curved / setup for emissions still.

Sorry for the novel, this thing is a special case haha


btw, engine did not do this before tune up. It just ran like hell due to lack of maintenance / carb was leaking pretty bad. And even after warming up, if you open the choke she revs up.
 
Well, I prefer the t-quad myself but lots of folks here run the edelbrock (carter t-quad/avs/afb cross-breed clone).

Can you post some photos of the situation under the hood?

Your location?

Hook up the breather hose (left valve cover), pcv valve & hose (valley pan), etc properly first. Sounds like a vacuum leak.....

Can you adjust the idle down with the idle set screw?
Do you have the double throttle return spring attached with proper tension?
Did you check for vacuum leaks?? Yes/no?? What method did you use??
 
Sounds like a bad air leak. Are all unused vacuum sources plugged, specially the pcv/brake vacuum ones? Could also be the fast idle cam is stuck on, not releasing properly. With the low vacuum reading I'd say a large vac port isnt plugged somewhere or there is a leak someplace else.
 
First off, welcome to the forms. We can guide you down the correct path.

You say revs up, but how far up? I am suspecting a hanging up throttle connection. Do this.

Remove the throttle connection to the carb from the truck so the carb it no longer hooked to the truck in any way other then the fuel and choke cable or wire if needed. Manually open the choke and back the high idle screw off so it is not effecting the throttle opening. Back the idle speed screw is it also is not touching the stop.

Start the engine and see if you still have the high idle.
 
Hey thanks for the quick replys.

I'll nab some pics as soon as I can, won't be heading back over to continue working on this Scout till tomorrow. The only reason I suspected a vacuum leak was because of what it was doing, I ran out of daylight and didnt get a chance to do a vacuum test ( I use starting fluid to see if I can locate a leak).

My location is hilton head island sc, sea level.
Yes I have a double spring for throttle return
no I can't adjust the idle down, I also did try unhooking the linkage to the truck and it made no difference. The throttle blades are closed and opening like they should be.

All un-used vacuum ports are plugged, double checked that before we fired off. Checked again afterwards hoping to find a quick fix, but everything was tight.

Robert, my test tac broke right as we fired the engine yesterday, so I was without any type of rpm reading. I'm not sure how high it revs up but it sounds like it's hitting around 3000 rpm.

I was not aware there was a high idle screw for this carb, I'll have to check that. The idle stop screw on the linkage was backed all the way off, blades where closed. Linkage was off. Hoping this is a vacuum leak, because I'm kinda stumped otherwise..
 
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