TR6 69 TR6 carb tuning help

[ichthos]

Hello,
I am having trouble getting the idle to stay constant. I can get it to idle between 10 and 12 thousand, but when I rev the engine and take my foot off, the rpm dives and dies half the time. One odd thing is that I can turn the trim screw all the way in or out and there seems to be no effect. Any idea what I need to do? I do plan on rebuilding a second pair of carbs this summer. Any help would greatly be appreciated.
Kevin

 

[RonMacPherson]

10 or 12 thousand? WOW that's low idle speed for a turbine...

If you run your 6 motor at that speed, expect to ventilate the engine quickly.

Now as for idle quality. Get a can of carb cleaner, or something volatile like carb cleaner. With the engine running at the slowest idle speed you can set the linkage to without it stalling, spray the carb cleaner over all vacuum lines, vacuum connections, base of carburetor, intake manifold gasket, etc. Sounds like you've got an air leak, which most commonly is a vacuum leak. vacuum hose off or rotting.etc.

When you spray a certain component, area and the idle speed increases then you have found your vacuum leak.

 

[ichthos]

Oops, I meant hundred. Thanks, I'll try that tomorrow morning and let you know what happens.

 

[poolboy]

ichthos, fear not about the idle trim screw's effect.
Even the manuals will tell you that the effect of adjusting that screw is not detectable by ear.
It controls only a slight amount of air entering the mixing chamber of the carb and that comes from some of what the temperature compensator allows in.
Bottom line is that it was used to fine tune with an exhaust gas monitor stuck in the tailpipe.
The manual suggest that after the engine is broken in to close it, full clockwise.
As for the vacuum leak, when I deliberately or accidently remove a vacuum line from it's point of attachment, my idle speed usually increases.
An easy thing to check is the condition of the carb diaphrams.
A question. What happens if you run the engine speed up to 2500, in neutral, holding it there for say 10 seconds and quickly let it come to idle? Any poping or backfire? Sputtering? That might help in figuring this out

 

[ichthos]

After the engine was warmed up, the idle speed jumps up and down between 1,000 and 1,200 RPM. I then ran the RPM up to 2,500. When I lift my foot off of the accelerator quickly, it drops to about 8,000 RPM and then rises back to the 1,000 to 1,200 RPM. There is no backfiring or popping. Does that mean anything? As far as the vacuum lines, I only see one going from the back of the dizzy to the top of the front carb and from the front of the dizzy to the bottom of the front carb. I checked the diaphrams, and could not find a hole anywhere. I have the air filter off. Another thing I do not understand. Does it matter if I use carb cleaner or starter fluid? When I spray a small amount of starter fluid into the carb, the RPM decreases, not increase. So, when I spray starter fluid around the areas mentioned, will the RPM drop?

 

[TheSearcherMan]

Are you sure the problem is the carbs and not that advance/retard distributor?

 

[poolboy]

I'm trying to take all of this in. Are you saying that when you spray starting fluid INTO the carbs' opening for fresh air that the speed decreases; or are you saying when you spray ONTO the carbs as in the "outside" of the carbs?
And one more thing, when does the engine "dive and die"? Under what conditions?

 

[ichthos]

Yes, when I spray starter fluid into the carb's opening for fresh air the speed decreases - I know, it doesn't make sense. Maybe I sprayed in too much. I only hold down the button for a second.

As far a when my car dives and/or dies, my car is not consistent. Unless my idle is high, it will sometimes dive when I am waiting at a light. The same thing when I deaccelerate up to a stop for instance. I used to have to pull out the choke, but I just adjusted the idle higher (1,200 RPM)

As far as the distributer, the dizzy does move when I accelerate, but I don't know how to tell if it is working correctly. How would I test this?

 

[poolboy]

"90% of carb problems are ignition problems"..not my Quote.
The distributor is moving? That shouldn't be. See what's causing that and get it fixed. Then check your point gap, at the very least, and set your ignition timing.
You'll probably have to adjust your carbs afterwards, but don't give up.