Hey everybody, First off- its a '75 350 with a Edlebrock Performer Intake. I recently replaced a camshaft and after break in and driving it I noticed the passenger side intake gasket was leaking...so much that it puddled up in the low spots where the manifold meets the head and slowy made its way down the back side of the engine, on the bell housing, then to my garage floor. I figured I got a set of bad gaskets...so I redid it...now the driver side is leaking but not near as bad. It looks like it is coming from under the gasket by the exhaust port. I used black permatex around the water and exahust ports on both sides of the gasket, 1/4 inch bead on the front and rear, set the intake down, holes lined up and torqued it down to as close to 30 ft lbs as I could. (center bolts are hard to get to with a torque wrench) What am I doing wrong here? I used Fel-pro gaskets but I'm not sure which ones and already threw the box away...they were the cheap ones I think...maybe $10-$15 and they had a warranty. Is there a better quality gasket out there? Am I doing something wrong? Any help would be appreciated. If I do this job a 3rd time I want it to be the last time!
i'm not really following what you are saying.....exhaust ports on the intake manifold? what is it leaking...oil or coolant? if oil , are you sure it's not the valve cover leaking? and a warranty on gaskets when they were probably not installed correctly? you better post some pictures so we can see what you are doing
Those manifold bolts go into the valley. There is oil there. You need to clean them up real good and put sealer on the threads. Silicon or a good permatex paste.
Have the heads been machined? As in the surface that meets the cylinder block? If so, this will change the angle where the intake fits.
I suspect the angle of your heads is not matching the angle of your intake. Clean every bit of gasket and sealant off of the heads and intake and lay the bare intake down onto the heads (no gasket). See how it lays there and how big the gap is at the front and rear. Then take a feeler gauges and go all around the mating surfaces and see how tight the bare intake fits to the bare heads. You should not be able to get a .002 feeler gauge to slide anywhere between the two, top side or underside. Look for an uneven gap at the front and rear where the two meet. The shop that does our engine machining told me that 4 out of 5 brand new intakes do not fit the head angle perfectly and need machined to get a perfect fit. We had some sealing problems on an engine we did and after they angle machined the intake it never leaked again. They said from repeated heating and cooling cycles used intakes will begin to warp slightly and need machined sometimes. Is your intake new or used and have the heads been machined ? Oh, and toss the rubber end seals that come with the gasket set and use a thick bead of Permatex Right Stuff sealant instead. Also, turn your intake upside down and lay a long steel straightedge the length of the intake and slide it up and down the surface, looking for unevenness. You can also use a feeler gauge to determine if the surface is uneven, placing it between the straightedge and the intake surface. Finally, did you torque the intake down in SEQUENCE ? Get a motor manual and follow the sequence they show. Also, torque them in sequence to 10 pounds the first round, then torque them to 20 pounds the second round, then torque them to 25 pounds the last time. An aluminum intake generally goes to 25 pounds, according to Edelbrock. After the engine is run for a while you will need to go back and retorque to the 25 pounds as they loosen up a little, especially if you are using polished stainless bolts. Don
The exhaust ports are for the exhaust crossover under the intake manifold. . Is the leaking gasket upside down, did the gasket slip down on installation, or did you use the metal restrictor plate? Those are the only reasons I've encountered problems. I usually glue the gasket in place with Gascacinch on the heads and let it dry, and let the rtv tack before i place mine so it doesn't slip.
Yes, the center ports..I was told they were an exhaust port. Its oil and its not coming from the valve covers...I can see it coming from intake gasket. Intalled them the best I know how..."this side up", solicone on water and "exhaust" ports on the head...stuck gasket down, more silicone on the gsket of those ports, 1/4 inch bead on front and rear, layed manifold down slowly to make sure holes lined up, sealer on bolts, torqued them down, let silicone cure over night.
Some good info here...I will try it. The intake is maybe a year old...intalled it with no leaks (used the front and rear rubber gaskets too!) Replaced the camshaft and when putting it back together was told not to use those gaskets and now I can get it to seal....? That sucks for what you pay for a brand new intake that they need to be machined 4 times out of 5! Yes sir..torgued them in sequence...the centers bolts were hard because of the angle however...
Yes i did use the metal restrictor plate...I didn't want to but someone talked me into it. I let the permatex sit for 5-10 before setting the manifold down, then let it cure over night.
No need to put permatex on Intake gaskets Only use it at the front and rear of the intake even if using the rubber gaskets. Is the center of the intake open ? If so I would remove the metal block off plates.
When you say the center of the intake do you mean where the carb bolts to? If so, it isn't...its divided. Edlebrock Performer...nothing crazy I was told, close to stock.
very common problem repaired by putting silicone tape or plummers goop on the threads of the bolts . The oil is migrating out of the valley through the hold down bolt threads .
Buy in the center I mean where Intake and head come together the very center port it is for warming the intake/fuel. You mention that you put the metal plate in there ? If the intake is open I would not block that port off, if the intake is not open there is no need to put the metal plate in.
I've never put silicone on intake gaskets. But I do put ARP Teflon sealer on the bolts. This is important. Silicone on block from head to head both front and back.
That would indicate that there is pressure building in the engine, correct ? Poster mentions that it has not been back together very long since a Cam change ? Maybe PCV valve is bad(if it has one) or new valve covers with no breathers or ?
yes, it is open on both sides...I put the restrictor on the driver side...the side it is leaking on as well.