I was wondering if anyone has gone to an aluminum intake and had trouble with vacuum leaks after installation. should I use silicone or some other gasket sealer on the gaskets? I mean around all of the ports, I know it is used on the front and rear seals. Are they torqued down differently than cast iron, (other than the amount of torque). I read somewhere that the 4 middle bolts should only be tightened with a wrench and the others torqued down tighter. Could my manifold be warped? I have put on two sets now and my car till will not idle, it surges and stalls when i try and slow it down.
Are you talking about a sheet metal intake, or cast aluminum like an Edelbrock? They will likely torque down differently, since aluminum is softer and more pliable than cast iron. I know my edelbrock instructions suggest 12 ft/lbs, and the original was spec'd at 25 ft/lbs.
i would just use slicone on the front and rear edns of the manifold... forget the gaskets! as far as slicone on the ports... i usually use the felpros they have a nice bead for that already. but if your using the cheap ones i put a little bit one... it will just be a bitch to take them back off. as far as your questions about what order to tighten. tighten the manifold down in the same order as the stock one requires form the factory. i know this is a dumb questions but are you sure you hooked up all the vac hoses? could also be the carb... what carb is on the car? how long was the carb off the car. could also be a needle and seat stuck too.
I just rebuilt the carb, and plugged all the vacuum lines, except for the distributor. The gaskets i used are mr gasket 223, they have no exhaust crossflow hole. I only used silicone on the end seals at the corners. The gaskets are made of regular gasket material, no metal or sealant rings around the ports, like the felpros. I think i will try another carb to be sure that's not the problem.
Oh ya, the carb is a regular 2150 and the intake is an aluminum 2bbl, from a 1980 lincoln i think. The manifold does add more power than my old one, the car just wont idle, speeds up, slows down constantly.
well i doubt you're losing the vacuum throught the manifold, however,you may, the mr gasket brand sucks. I had a pain in the A$$ time finding my air leak and it turned out to be the head gaskets. (mr gasket premiums). Now i run felpros with copper gasket spray...sealed fine.. Sounds like the carb, although you said you just rebuilt it... and i know you said you used the silicone on the 4 ends, did you use the goop to make the front and back gasket where the intake sits close to the block, or use cork....that could be a problem, sometimes the cork doesnt work well..
I used the cork with silicone on both sides. I have done intakes several times, this is the only one that has been giving me problems.
Just my 2cents. I would not use the cork end gasket's at all, just a good thickness of RTV. Also use a small amount around the water ports too. Have run into this before and found out that the manifold was machined incorrectly. They sent me a new one and it worked great. Also have found the FelPro 1250 gaskets are the best to use and won't leak after time. Aluminum intake's are very different to bolt down, than iron. Must use grade 5 or better bolts with "hardned" washers. Have always tightned them from the middle out and opposite end's as required. Have never gone by torque value's on aluminum either. Just tighten with hand tool's and repeat until they are "all" equally snug. Do not overtighten but make sure all feel the same( around 25ft lbs ). Then check them periodically cause they will loosen up as the gasket's and aluminuim, react to heat and cooling of the engine. May still be a carb problem though. JMO
FIXED!!!!!!!!!!!!! Just to let everyone know, before i went through another intake gasket shinanigan, I traded carbs from my 69 ford truck, which has a carb I just rebuilt also, it runs awesome now. I'm glad I checked it out. I guess I can rebuild 2100 autolites but not 2150 motorcrafts. Thans for all the replies.
See, i had the exact same problem with edelbrock's rpm airgap... they sent me a new one... and this quote above is what i was refering to about the cork gaskets..
It's all in the installation technique, I nearly always use the end seals, with a dab of RTV sealer at the corners where the gaskets meet and a thin film around the coolant ports. Never had any intake leaks. I also torque the aluminum intakes down the same as iron. From the middle outward with a torque wrench to the factory specs. On the small block Fords, I torque all down 3-4 times, then go back and do it again within a week's time. The only time I don't use the end seals is when they're too thick for the end gaps. I check the fit with gaskets before installing any bolts or RTV. If the end gaps are to tight, I just use RTV there. I've used many types of Felpro gaskets and the Printo seals have been the worst of the lot. Especially those for the FE motors.
