440 exhaust help NEEDED!

[MMiller]

I need tech help on my '75(see signature). Its got a fresh 440 that hasn't any miles on it yet because I can't keep coolant in it. For the 440 people out there the exhaust manifold bolt holes in the head, at the front and rear of the head are drilled into coolant passages. I can't get the rearmost hole in both sides to seal up. I tried the header bolts that came with the headers, then longer 3/8" bolts thinking the header bolts were not long enough for a good seal. I have now also tried long studs from a 3406 cat that completely bottom out in the threaded holes with no avail. I have used silicon, gasket maker from CAT, Pipe sealant, and then some really good sealant from CAT too, to no avail. I don't think the heads are cracked, I have had other 440's and haven't had this problem.



Can any one help? Please? Memorial day weekend in dresser wis. is comming very rapidly and the truck still hasn't gone around the block yet!!!

 

[Doc Tinker]

MMiller - try putting studs in those holes. Wrap the studs with teflon tape and seat them to the shoulder of the stud. If I remember right the front and rear holes had studs in them from the factory.



Doc

 

[Joseph Donnelly]

All the holes came with studs from the factory. You might try Permatex, or red high temp silicone RTV. As hot as they get, I don't think teflon tape will hold up well. I had to replace studs before and had no trouble sealing them. I might have used Loctite on them, don't remember now. Be sure you don't have a leaky head gasket, and that the bolts are the culprits. Good luck.

 

[illflem]

White Loc-Tite is made for bolts/studs that enter the water jacket. Also check that your radiator cap isn't bad and allowing too much pressure to build.

 

[Hammer]

If its a original big block truck they came from the factory as stated above with studs in the front and rear holes only,,I have used teflon tape,high temp rtv and Permatex at various times to seal my race headers depending on what was handy at the time,,One thing you need to make sure of what ever you use run it up the seat as Doc stated,,I have seen the bolt thread develop cracks in(or imperfections)that cause the problems your having also,,You may want to run a tap into the threads just to make sure they are clean and unobstructed making sure they have a better chance to seal,,Also make sure your header studs you use are not too long so the outer bolt has a chance to draw the header tight to head or you'll have a constant gasket problem there,,One thing I have learned over the years of owning the big bock trucks is this also,I'm not sure which header you are using,but,the only proper fitting ones made are the Hookers,,They do cost the most,but the best fit out there,,Let me know how you make out..... Andy

P. S. -If this is a original big block truck i hope you saved the exhaust manifolds,they are hard to find and will command decent coin at a flea market. .

 

[MMiller]

Just an update. I ran a tap down the threads and they aren't great in the beginning but get better the farther they go in. Yesterday afternoon I remmoved the studs in the leaking holes and had a buddy clean the holes and then put on some permetex #2 that is high temp, imppervious to antifreeze, gas, water, diesel, etc, and let it set overnight. Later this evening or tommorow evening I will put coolant back in the truck and try again. Thanks for the ideas.





HAMMER



It is an original 400 4sp truck, that came with headers. I have now owned 3 big block trucks and NONE of them had manifold on them or I would prolly run them, because I have a dislike for headrs. I can't remember the name brand of the headers right now, but I got them from MANCINI RACING with a high torque mini starter. This combo I can remove the starter without removeing the headers, and draining the coolant.





I will post WHEN the problem gets resolved. Thanks again.



Michael