Intake Vacuum Leak

While I've been trying to get my jeep going, I've been searching around here and asking questions (some may say stupid questions) and looking up sources of vacuum leaks since my jeep goes dead not too long after cranking. When I installed my aluminum intake, I used a felpro valley pan gasket. I used black rtv around the coolant ports and copper rtv on the ends, as well as around the intake ports. Was the rtv a wrong idea around the intake ports? I've read it isn't compatible with gasoline. If so, then the mating surfaces are going to be separated a minuscule amount around each port, causing vacuum leaks around each port, correct?

I can't see where I may have a vacuum leak anywhere else. I have the distributor advance hooked up to the carb, and I've plugged everything else. My pcv grommet and connection seems tight.

 

use some wd 40 or similar to spray the intake in the suspect spot while its running when you get to the leaky spot it'll smooth out the wd will temporally fill the leak and you will know if its leaking.

 

You say it goes dead "not too long after cranking" so how long is "not too long"?

 

5-10 seconds. Choke is operating. I tap the accelerator to close the choke, and that works. It cranks with very little grinding on the starter. It revs at high idle for at least 5 seconds, then it acts like it's starving and dies. We've messed with the curb idle screw to finally get it to run, but it has to idle high (1000 rpm) to keep from dying and engine shakes. We've messed with the mixture screws with little change between 2 and 4 turns out. I can feather the accelerator and it stays running, but it's not running right.

 

Well the mixture screws are only in the idle circuit. They are below the throttle plate so anything above fast idle and the screws are null and void. The main thing is to have enough air flow passing the venturies to suck the proper amount of fuel-air to the intake. Have you connected a vacuum gauge to it and see if you have about 15-18" or more. You will loose manifold vacuum anywhere above half throttle or more but should have good vacuum around 1/4 throttle.

 

I havent. I have taken a time out waiting on my new intake gasket to get here. I dont want to do anything else until i get the proper sealant on the joint. I also ordered a new thermostat housing. Mine must be ever so slightly warped because im getting some seapage. Those 2 things will be done when the parts get here by the weekend.

 

Try carefully spraying the carb with carb cleaner will it continue to run? it would have to be a major intake leak for it not to run. proper fuel pressure/ supply? as far as intake leak plain water from a squirt water work great to find a leak no fire danger.. You can also close the butterfly by hand will it continue to run? if so lean condition.

 

Well, maybe I've found the issue. When taking my intake off today, i didnt take the carb off seperately. After i sat them down on the table and crouched down removing the rtv, i noticed a gap between my carb adapter and the intake. Although the bolt patterns are correct to adapter the 2100 to the edelbrock intake, the gaskets dont seal everything. The adapter is a Trans-Dapt brand, and i need to search for another one. The box said 4 barrel carb to 2 barrel manifold. I have the opposite but understood you could turn the adapter over.

 

I tried that too. The adapter isn't designed to work that way. It will bolt on, but you can't seal it without vacuum leaks.