Vacuum/ in gear idle issue.

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GDL

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Ok, so the 340 is giving me fits. Timing is about 13 degrees initial and full 36 with the vac canister hooked up. However I think the carb has a vac leak since I was hearing a high pitched whistle (thermoquad) which just developed. So my question is if there isn't a vac leak and would an adjustable canister help for vac advance since the distributor is the original 318 2 bbl distributor?

And my issue is it's seemingly hard to start (buying a new starter) and idle is at 850 rpms but in gear it's dropping about 400 rpms... Ideas?
 
Ok, so the 340 is giving me fits. Timing is about 13 degrees initial and full 36 with the vac canister hooked up. However I think the carb has a vac leak since I was hearing a high pitched whistle (thermoquad) which just developed. So my question is if there isn't a vac leak and would an adjustable canister help for vac advance since the distributor is the original 318 2 bbl distributor?

And my issue is it's seemingly hard to start (buying a new starter) and idle is at 850 rpms but in gear it's dropping about 400 rpms... Ideas?

What sort of ignition are you running?
It would work out to your benefit to find out what it wants to start better (more fuel/less fuel) then you have a direction.

I'm kind of wondering if maybe you have a low powered spark and some miss tuning.
The mini starter would help a little if this is what it is because they take less amps to turn the engine over and this may leave more power for the coil.

The whistle may very well be a vac leak, or an internal gasket leak.
Can you use a small hose and narrow it down by using it as a sort of stethescope for the source of the sound?
 
I'm gonna pick up a few parts and just trouble shoot tonight....

Thing was it started just fine then this cropped up.
 
Timing is about 13 degrees initial and full 36 with the vac canister hooked up. [/QUOTE

You can check for a vacuum leak by spraying a little carb cleaner around where you suspect it to be and listen for the rpms to change. Check hoses and such for cracks. TQ phenolic bodies have also been known to warp.

Your timing sounds like it might be off. To check your timing properly you need to do it with the vacuum canister capped off since it has nothing to do with timing at idle. Vacuum advance is generally only for part throttle operation to help with fuel economy, it should not in any way figure into your advance curve. Figure out what your total timing is without the vacuum and make sure it's where it's supposed to be. 36 degrees might be a little too much for your combo which sounds like it might be sort of mild.

Do you have an adjustable vacuum canister? If not, you might want to get one to fine tune the amount of advance you are putting in.

Best way to figure out how much initial you need is with a vacuum gauge. You set it to 13 but you may not need so much. That may be your hard starting. Warm it up, put the vacuum gauge on (under throttle blades) and with a timing light, advance the initial until the highest vacuum reading is reached. Once you see where vacuum peaks, back off timing a few degrees to where the vacuum drops 1". Once you get that nailed down, get the motor running up to about 2,500 -3,000 and with your timing light see how fast and where the timing stops advancing. You can increase it a few hundred rpm at at a time and plot the curve. In any event, that number will be your total, wherever it is. Vacuum advance is added to that. Depending on what distributor you have, you may need to limit mechanical advance if you wind up at a number higher than 34-36.

It might also benefit you to drive around with a vacuum gauge. See what it says at part throttle and play with the advance canister to get it just right and not ping. Vacuum advance can add 10-20 degrees to the total. Start conservative.
 
13* initial should whip over on the starter no problem. I'd check the pos/neg cables because the ends will often go bad. My Deisel PU did this. Acted like the battery was dead. The wires where they entered the ends were toast. Replaced all the ends and the truck wings over with ease.

Camshaft plays a big part in initial timing. My stock 340's get ~16 initial. Bigger camshafts into the 20's or locked out.

The vacuum gauge method mentioned is a good way to find your initial point as long as your electrical system is up too snuff. Each time you bump the initial, you need to reset the idle speed as it will likely pick up and observe the reading. As long as the starter will crank it over with additional initial timing, you're good. Then you get to fix the mechanical part of your distributor.
 
Vac booster line plugged into the back of the manifold was loose. Go figure.
 
Vac booster line plugged into the back of the manifold was loose. Go figure.

Thats a bonus, nice easy fix! All the advice given on here is something every one should do IMO to fine tune...wish I hadda learned this years ago...
 
Now onto putting a new starter in...

You still might want to verify where your timing is at since you may find that it runs better at one point or another. It's also useful to know how much vacuum your engine is making at various points.

Making a leap to a further point, an air fuel gauge is an invaluable tool for this type of stuff if you want to really tune your car. Takes some of the guess work out of it.
 
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