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| One more intake/exhaust question https://slantsix.org/forum/viewtopic.php?t=49901 |
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| Author: | MLC Duster [ Tue Sep 25, 2012 4:51 pm ] |
| Post subject: | One more intake/exhaust question |
Okay. I am a bit confused. Many of you veterans have indicated that ream out the holes connecting the intake to the exhaust manifold. However, it is not clear which you ream out--the holes in the intake or exhaust? See pics. This is a big deal and I don't want to screw it up. Plan on the install this weekend. Thanks.  
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| Author: | mcnoople [ Tue Sep 25, 2012 6:05 pm ] |
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You have to ream out the hole that stud between runner 3 and 4 goes through when using an older intake with a newer exhaust manifold. Is this what you are thinking of? The older intakes used 3 bolts instead of 2 bolts and a stud. The stud is a larger diameter. |
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| Author: | ESP47 [ Tue Sep 25, 2012 6:26 pm ] |
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This is from Doc in another thread. "You may need to "adjust" (ream-out) the 3 intake to exhaust mounting holes in the intake, to allow the exhaust manifold to shift outward, even with the intake manifold port 'face' surface. Also do a little "off-set" reaming of the centre intake manifold mounting hole, to get the best "horizontal" port alignment possible... and run it. Basically, "fit & fiddle" to get the best port alignment and gasket compression / clamping forces." |
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| Author: | MLC Duster [ Tue Sep 25, 2012 6:41 pm ] |
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Yeah, I saw doc's post. But I just want to be sure of WHICH manifold do I ream the holes--INTAKE or EXHAUST? Doc's indicated the intake, but others implied the exhaust. |
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| Author: | SlantSixDan [ Tue Sep 25, 2012 6:48 pm ] |
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Intake. Ream the intake pass-thru holes if necessary, not the exhaust threaded holes. |
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| Author: | Aggressive Ted [ Wed Sep 26, 2012 8:47 am ] |
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I have done what Doc said many years ago and found it to work well. I reamed all three intake holes and used stainless steel bolts, lock washers and nuts to get the old manifolds to line up. I have done this on several engines now for better fit. No cracked manifolds and no leaks! |
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| Author: | MLC Duster [ Wed Sep 26, 2012 7:17 pm ] |
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Thank you for clearing that up. I'm ready now. |
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| Author: | 65Dodge100 [ Fri Sep 28, 2012 4:15 pm ] |
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Ream the intake holes like has been said already. That will let you line up your intake/exhaust to fit flatagainst the head and still use the threaded holes. Stay away from stainless bolts. They have less tensel strength than grade 8 bolts that you should be using. I guess they work for a while. No one has reported a problem. Stainless sounds good but they just don't have the strength. Use Never seize on everything and brass nuts. Just as good. I even make brass nuts for the two end bolts. Let me know if you want to try them. Mine has worked for 20k miles so far. They are the first ones to break and hardest to find. Danny |
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| Author: | wjajr [ Fri Sep 28, 2012 6:14 pm ] |
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Stainless bolts are great for exhaust applications as they don’t rust and rot, and can easily be disassembled a bazillion heat cycles later, where a steel grade five or 8 will just disintegrate into a ball of rust. In this application holding two manifold castings together doesn’t require a lot of tensile strength where just thermal forces are acting. There are no large moments, or applied external shear forces such as suspension components would see at the joining of these two castings. I use stainless bolts nuts & washers on my collectors… mighty handy when some manifold work needs to be conducted once broken free, two fingers will spin the nuts off, and on in that tight spot. They still look shinny after four years. However don’t be in a rush to use stainless fasteners threaded into aluminum without a bucket of never seize handy. My 2 cents |
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| Author: | wjajr [ Fri Sep 28, 2012 6:43 pm ] |
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Stainless bolts are great for exhaust applications as they don’t rust and rot, and can easily be disassembled a bazillion heat cycles later, where a steel grade five or 8 will just disintegrate into a ball of rust. In this application holding two manifold castings together doesn’t require a lot of tensile strength where just thermal forces are acting. There are no large moments, or applied external dynamic shear forces such as suspension components would see at the joining of these two castings. I use stainless bolts nuts & washers on my collectors… mighty handy when some manifold work needs to be conducted once broken free, two fingers will spin the nuts off, and on in that tight spot. They still look shinny after four years. However don’t be in a rush to use stainless fasteners threaded into aluminum without a bucket of never seize handy. Quote: Use Never seize on everything and brass nuts.
Brass nuts have almost zero strength compared to a grade eight bolt, so the extra strength a G8 brings to the assembly is negated over kill when a brass nut is used in it. All brass nuts do is extend easy disassembly time line over steel on steel. When one is working with 10 ft lbs on intake to head nuts, brass can handle that, and 15 ft lbs connecting intake to exhaust is well within SS fastener’s safe working range. Dito on using never seize with brass nuts & steel studs. My 2 cents |
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| Author: | SlantSixDan [ Fri Sep 28, 2012 7:17 pm ] |
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Danny 65Dodge100 I'd like to see the brass end nuts you make -- can you show us pics? Original end nuts and other hardware availability: see here. |
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| Author: | jcapdvs [ Sat Oct 06, 2012 11:32 am ] |
| Post subject: | intake/exhaust manifold mounting bolts |
I am about to re-mount my manifolds as well. I have a newer exhaust manifold, and the original '69 intake. I bored out the hole in the intake to accept the thicker stud from the exhaust, but I'm having trouble finding 4.25'' lags with the proper thread length to connect the two manifolds. I found 4'' fully threaded bolts, though not tempered steel... I know there's a lot of heat going through that exhaust and I don't want these suckers to break or freeze on me... should I look harder to find the tempered steel 4.25'' or am I worrying over nothing? |
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| Author: | Aggressive Ted [ Sun Oct 07, 2012 9:14 am ] |
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On an old manifold I will drill the exhaust manifold threads out to accept longer stainless steel bolts. All my manifolds the original bolts had seized and broke. This modification makes it much easier to use common sizes with lock washers and nuts. It makes manifold swaps much quicker... I also do this on the exhaust manifold to exhaust header flange. The process goes much quicker especially with the larger 2 1/4 exhaust flange. |
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| Author: | DonPal [ Sun Oct 07, 2012 9:44 am ] |
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Quote: I will drill the exhaust manifold threads out to accept longer stainless steel bolts
Only the two outboard ones? ....not the single inboard one?
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| Author: | Aggressive Ted [ Sun Oct 07, 2012 9:53 am ] |
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Yes, I have always been able to get the center one out because it is large enough in diameter, which helps on removal. A stainless bolt in it's place with some never seize works fine. The two out side bolts are so small in diameter they usually snap on removal after 40 years. |
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