Locating vaccum leak

timboamx

How can one find a vac leak? Or an exhaust leak. Last week I swapped out my 1bbl (intake & carb) for a 2bbl only to find out later that the 2bb carbl had a crack. I put the 1 bbl back on and even doubled up the gaskets only to have it run worse than it ever has. Back firing thru the carb thru almost the entire RPM range except for idle. I have the timing advanced so far now, that the vac line from the distro is up against the block. I put new plugs in it with the new TFI upgrade I did last month (ran way better than ever), But now I cant remember ifin the gap is right. I'll check again. But can that cause the issue? Tim

pyagid

Vaccum leaks I usually spray every place down with carb clean slowly. Any place a vaccum leak is possible. When the RPMS jump you found your leak. Exhaust if i cant find it visually and by ear. I will pull a small vaccum line, and dip it in to a oil bottle cap with oil in it. It will burn smoke, and come out any holes in the exhaust you have -Paul

timboamx

Well I didnt have any of that to spray, but I had some launtry detergent/water mix in a a spray bottle. I first sprayed around the carb base (my first thought) - Nothing, then I sprayed around the carb - nothing. I then sprayed around the intake vac port, pvc port and where the intake & head mate up - nothing. I walked in the house to get my smokes (left the car running) came back outside (a min or so later), and she was running pretty good and smooth. (before at Idle it was like it had a big block w/ a cam in it) just shook the heck out of the car). I was scratching my head trying to figure it out, when I realized nearly everything that I sprayed had ice on it (22 degrees outside with out the wind). So I put on my uniform (so I could go to work - left the car running) and went to work. Well it runs alot better, but still pops thru the carb (no where near as bad though) - but mainly when I punch it, or at slow coasting (like onbase). So I guess it means I do have a vac leak, just need to locate the exact spot (I'm still guessing the carb area). Also I have another problem (and I know this aint the spot for it) but I am haveing a heck of a time adjusting the kickdown linkage, it just do seem to be right to me. I shifts too darn fast, before I even hit 30mph, its in 3rd gear - any thoughts? Thanks, TIM

youdidwhat

timboamx wrote
even doubled up the gaskets only to have it run worse than it ever has.

Tim

Tim,

two gaskets where only one is needed will create a vacume leak in and of it self.

pull the extras gasket.

and start at square one.

retard the timming back to normal and start checking the basics again.

to do the carb cleaner trick requires carb cleaner or starting fluid, and even the starting fluid is not always gonna work.

While you had the one barrel off did you rebuild it?

are there any extra open vacume lines off of the carb.

follow all your rubber vacume lines and check to see if there are any cracks splits or breaks.

you did plugs but did you check on your wires, cap, roter, and fireing order?

is your coil in good shape and sending a hot enough spark too your cap and roter.

is the dist. in good shape.?

I do not know what you are working on so these are some basics I would goto with just about any engine.

as far as the quick shifting.

does your passing gear linkage have a slotted or elongated mount or is it just one hole. some of those are adjustable.

Hope this helps.

Matt A.