Intake manifold nightmare
Intake manifold nightmare Alright so i just built a LM7 for my fbody , Stock bottom end , 224r cam , ported polished 5.3l heads with 2.02/1.57 valves milled .030 to 58cc .
Car runs good but i cannot get the intake manifold to seal to save my life.
I have tried both my FAST 78 , and my stock ls1 intake, BOTH leak bad enough to throw off the idle and sometimes even stall , if i spray the base of either intake with starter fluid the idle goes berserk, and when i remove the intake there is oil underneath the gaskets so its not sealing for sure. I feel like i have tried everything, i have counter sunk the valley cover bolts for flush finish , i tried brand new felpro gaskets, i torqued the bolts to spec and in sequence i just cannot get the damn manifold to seal, i really just wanna enjoy my swap so any help is appreciated
Car runs good but i cannot get the intake manifold to seal to save my life.
I have tried both my FAST 78 , and my stock ls1 intake, BOTH leak bad enough to throw off the idle and sometimes even stall , if i spray the base of either intake with starter fluid the idle goes berserk, and when i remove the intake there is oil underneath the gaskets so its not sealing for sure. I feel like i have tried everything, i have counter sunk the valley cover bolts for flush finish , i tried brand new felpro gaskets, i torqued the bolts to spec and in sequence i just cannot get the damn manifold to seal, i really just wanna enjoy my swap so any help is appreciated
Im not sure but your heads have been milled to 58cc? did they mill the side were the intake sits?
I've never had to do it, but when you mill your heads that much Ive heard of people milling the side where the intake sits because that area gets narrow as you take alot of material off the heads...
I've never had to do it, but when you mill your heads that much Ive heard of people milling the side where the intake sits because that area gets narrow as you take alot of material off the heads...
heres some threads on this
https://ls1tech.com/forums/generatio...-side-too.html
https://ls1tech.com/forums/generatio...nger-fits.html
https://ls1tech.com/forums/generatio...-side-too.html
https://ls1tech.com/forums/generatio...nger-fits.html
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I'm going to ask this not to be a d*ck, but to cover the bases. You did install the o-ring seals around each port on the intake, right?
Another thing to consider is if the heads are sitting much lower due to milling (which I would think would be a lot of milling to have this happen), are the intake bolts too long or are you running out of thread on the bolts and they aren't torqueing down the entire way?
Another thing to consider is if the heads are sitting much lower due to milling (which I would think would be a lot of milling to have this happen), are the intake bolts too long or are you running out of thread on the bolts and they aren't torqueing down the entire way?
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From: I've got that Wheeling Feeling, WV
It seems your problem may be one of the following:
1. Your heads are not milled correctly.
A. Intake side is not milled and throwing off the alignment of gaskets on intake chambers on heads.
B. heads are not milled evenly as mentioned above.
2. Gaskets not installed properly. Or gaskets do not protude enough to make a good seal.
3. Intake bolts are not torqued properly.
4. Intake does not clear coolant tubes underneath manifold.
5. Intake is not notched and does not clear heads on corners as mentioned above.
6. Intake is cracked.
Try sorting through the above suggestions, then report back with your findings. Good luck.
1. Your heads are not milled correctly.
A. Intake side is not milled and throwing off the alignment of gaskets on intake chambers on heads.
B. heads are not milled evenly as mentioned above.
2. Gaskets not installed properly. Or gaskets do not protude enough to make a good seal.
3. Intake bolts are not torqued properly.
4. Intake does not clear coolant tubes underneath manifold.
5. Intake is not notched and does not clear heads on corners as mentioned above.
6. Intake is cracked.
Try sorting through the above suggestions, then report back with your findings. Good luck.
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Joined: Sep 2005
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From: Bucks County, Pa.
