The Stovebolt Site Forums The Parking Lot Big Bolts fat intake leak PLEASE HELP!!

hey there, ive got a pretty good leak on my intake manifold where it seals up against the block.should i double up the gaskets just for the intake,im not sure if the manifold is warped.take a look at the pics.its the stock manifold on a 1949 chevy 6400 with a 1956-57 261 engine.i can tell its leaking by having the engine running and spraying some starter fluid right over the part where the block and manifold meet, as soon as i spray it, the engine revs up.all three ports are leaking.Double up the intake gaskets or what? Thanks a lot!
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dantheman49-6400,

If you want to do it the right way...the permanent way, take the intake/exhaust combo off and have it machined at a automotive machine shop. The very least I would try is to loosen up the bolts holding the manifolds together at the heat box, reassemble the manifolds (with alignment rings),then after they were cinched down to the head, tighten the four bolts where they fasten together in the heat box.

Stuart

I had the same problem. I ended up getting it all plained level. But before you go that route, make sure you loosen up all the bolts AND use the alignment rings to close off the intake ports. It was a pain in the butt to get it not to leak. Take your time and good luck!

It sounds like you do not have the alignment rings in the manifold. You really need these rings to seal it up correctly.

And do not forget: If you have the intake/exhaust manifold planned flat to also have the alignment rings planned too! Otherwise the alighnment rings might be too long and prevent a tight seal.

I've been there and done that one too!!!

alright cool! thanks a lot ! ill give it a try

to see if im in the ball park with good manifolds is to take a known good straight edge and place it across each manifold and check for full contact across all three flanges. then bolt the halves together at the heat box but loose enough to wiggle the manifolds and put the straight edge across all six flanges and see if contact is made. my manual says .10 max allowable misalinement of flat surface. ive been able to seal mine with positive results even without alignment rings but its much easier if you have them. ive also had to get them milled flat as a unit in order to get them to mate to the head.

alrighttt well before i go and get them milled, im going to double up the intake gaskets and see what happens.hopefully i get some results.
Thanks again!
Danny

you might solve your intake leak but then create an exhaust leak.

[quote=dantheman49-6400]....i can tell its leaking by having the engine running and spraying some starter fluid right over the part where the block and manifold meet, ....

That could get exciting.

i doubled up the intake and exhaust gaskets today and got results!
my engine idles a lot lower buttttt, it still leaks.So i ordered up some new intake rings from jimcarter trucks.im continuing to do mr "53monster's" favorite thing by spraying starter fluid on all possible leak spots.this proves to be very effective! ill keep a hose nearby :]heres a pic of the truck now
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Thanks Again!
Danny

If you are using the manifold from the original motor, the ports are smaller than the 261. Rings for the 261 will be too large. In the original photo it looked like the intake wasn't meeting the head. If an alignment wring hangs up, it will not seal. To seat it I lossen the bolts between the two manifolds and sfter it is mounted I tighten them again.

By the way I don't think there is such a procedure as "planing" the alignment rings. They are shorter than the combined depth of the two grooves.

Take it from somebody that torched a 1970 Barracuda with starting fluid, It could get exciting, of course there were other issues with the car that contributed but the flash is what started it.

Acetyline or Propane is more convenient, and much safer than starting fluid for spotting vacuum leaks. Just unscrew the head from a Propane torch, leave the metering orfice imn place, and attach a 2-foot length of 1/4" vacuum hose. It's much easier to pinpoint leaks, and there's no dangerous accumulation of flammable liquid like using carb cleaner or ether creates. If your shop equipment happens to include an oxy-acetyline torch, running a low volume of acetyline from the torch tip is another clean, reliable vacuum leak spotter.
Jerry

when i put the second set of gaskets in,i did loosen up the heat box bolts joining the two manifolds,tightened the manifolds to the head,then tightened the heat box back up.im not sure,but im pretty sure that the manifold on there is the one that came with the engine.i have pictures of the engine the day i got it with the manifold on it.i just need to see if theres something on there to tell me that its the same one that i cleaned,painted,and put back on.
http://i612.photobucket.com/albums/tt202/dantheman176/261straightsix003.jpg
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