Vacuum Leak Woes

[YotaToren]

Hello folks,
I bought a 1982 5 speed Corolla Wagon with 221k miles on the odometer. It served as a commuter vehicle for a family in rural Idaho and after it stopped running they let it sit for 6 months. I don’t have experience working on cars and bought this vehicle to learn. After a lot of wrenching and $$$ I’m still having trouble getting it to run right. Major vacuum leaks seam to be the issue and I’m writing to make sure I’ve covered everything in my diagnosis.

A list of everything replaced:
– Weber 32/36 DGEV
– Mechanical fuel pump
– Fuel filter (twice to help clean up the old gas)
– Fuel hoses
– Weber redline fuel pressure regulator with mr. gasket gauge, tuned to 3psi
– Fuel tank cap
– Spark plugs/wires/rotor/cap (NGK/DENSO)
– Oil and filter
– Vacuum hoses (immediate to carb/egr/vac advance/pcv/carbon canister filter)
– Vacuum advance module (Original DENSO)
– Battery
– EGR flange gasket
– PCV valve and grommet
– Ethanol free fuel
– Seafoamed the gas tank, intake and crank case.

Almost all smog has been removed and remaining lines have been capped.

The car retains stock exhaust that I suspect may be clogged. There seems to be excessive heat build up at the end of the down pipe. At operating temp, there is a light smoke coming from the seam of the down pipe that connects to the catalytic converter. The rest of the exhaust is rusted through after the cat and does not connect to the muffler.

A compression check shows psi near factory specs within 10psi across all cylinders. The #1 cylinder has the least @ 160. This test was completed using a cheap tool from Harbor Freight.

Timing is spot on at idle according to the factory manual @ 7 degrees retard, though the distributor must be turned very far clockwise in position to achieve the correct timing at idle. Again, cheap timing light from Harbor Freight.

After replacing all those parts it fired right up! But that was only the beginning...

A hissing could be heard in the engine bay. The idle would rise after spraying the intake manifold, intake to carb adapter and carb base. Vacuum leaks! I must have botched the first install of the carb and the intake manifold gasket must be really crusty after 30 years. Note, I did use fuel appropriate gasket sealant with the installation of the carb. But, I’ve read after the install that sealant should not be used with carb installations.

FIRST TRY AT REPAIR
Replaced all gaskets (The intake manifold to carb adapter was cut with Felpro material w/sealant, the intake manifold was a Beck/Arnell w/sealant and carb base was a redline oem piece w/sealant) and torqued the intake manifold bolts to the specific 14-18 lbs/ft. All surfaces were cleaned thoroughly before installation. I fired it up and seemed to have the same trouble. I could get it to idle smoothly within the weber tuning guidelines but when applying throttle the carb would make a loud sucking sound and when applying throttle quickly wanted to die. It also “dieseled” somewhat after turning the ignition off.

SECOND TRY
Replaced the intake manifold and carb base gasket this time both cut from Felpro material (this time sans sealant). Inspecting the carb base I notice a scratch in the area closest to the engine, I ignored this. Started the car and still had leaks. Maybe a little worse this time. But I didn’t really notice it in the intake manifold. I noticed that the carb base was leaking most from the corner closest to the front of the engine.

THIRD TRY
Took everything off, found a nice metal ruler and measured all surfaces for gaps with a feeler gauge like I should have the first time. Everything; intake manifold flange, engine head, carb base and carb base adapter looked flat, very flat. I mixed JB weld and filled in the scratch on the carb base and put it all back together a third time replacing the carb base gasket with an oem piece, adapter gasket, and the manifold gasket all sans sealant. Leaks still persist but the carb doesnt seem to leak where I fixed the scratch.

I’ve been as meticulous as I can in the cleaning and installation of these parts. Should I give it all one more try before taking it to a professional? Have I missed anything?

Thanks to all for helping make this site a great resource!

[Spudenater]

The stalling/dieseling kind of sounds like what my '80 Corolla (w/single 40 DCOE) did when I had it jetted incorrectly. Have you messed with jetting at all?

[YotaToren]

Thought about the jetting but haven't experimented. Thanks for the reply!