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Check your intake manifold bolts


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Was doing some routine engine cleaning on my 65 and noticed one of the intake manifold bolts was loose. Checked the rest with a socket/ ratchet set and it turns out they were all loose. They took about 3/4 of a turn each to cinch down. Checked the dual carbs and sure enough they were loose too . They took about 1/4  turn each to cinch down. Fired it up , got it up to temp, then turned the brass idle / air bypass screw in about half a turn and leaned out the  air mixture adjustment screws about half a turn each. Idles much smoother when at a stop where as before  she was a little rough when idling at a stop.Hoping to get a little better milage now too. 

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Posted (edited)
16 hours ago, arnulfo de l.a. said:

she was a little rough when idling at a stop.

My issue for quite some time now and I have only one original AFB that seems alien to my Nailhead.

 

Discovered some sludge around exhaust X-Over ports on the one Cyl. Head last week. Bolts were tight from re-assembly last summer with new composite gaskets. Previous intake gaskets were beaded steel shims.

Exhaust X-Over ports were dry. Not sure why sludge on the one flange? I'm certain I installed them dry.

image.png.8da1f8e64cb06970381cac41649d1870.png

image.png.82920b25e7df951b5c594112d1e226f3.png

 

 

 

 

Edited by XframeFX (see edit history)
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4 hours ago, gungeey said:

from the two middle exhaust valves ports. Cyl 3 and 5

Thanks,

So, oil passing exhaust valve guides on my Cylinders #3 & 5? But the port is dry. Sludge only on the flange?

I see you have a broken valve guide on #4.

 

Only change from last summer when I had this last apart was engaging the Heat Riser Thermo Spring which happens to be on this Cyl. Head. Image below shows no sludge last summer. If I wiped it before taking the picture, I'd remember.

 

Another contributor to that trace of sludge is start-up  mid January and driving it around the block on snow it hasn't seen in 30+ years. The Cold Light went out but, at -30 Deg. C, probably not up to operating temps to burn off oil residue. Maybe? If so, no concern?

 

Last Summer and no sludge:

image.png.89ea3e7f88e7f1398193cd716162c8ba.png

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On 5/15/2024 at 1:21 AM, arnulfo de l.a. said:

Was doing some routine engine cleaning on my 65 and noticed one of the intake manifold bolts was loose. Checked the rest with a socket/ ratchet set and it turns out they were all loose. They took about 3/4 of a turn each to cinch down. Checked the dual carbs and sure enough they were loose too . They took about 1/4  turn each to cinch down. Fired it up , got it up to temp, then turned the brass idle / air bypass screw in about half a turn and leaned out the  air mixture adjustment screws about half a turn each. Idles much smoother when at a stop where as before  she was a little rough when idling at a stop.Hoping to get a little better milage now too. 

... does anyone use thread locker on carb to intake bolts? ...

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Not usually, but if you do, don't use anything other than 'blue' (personally, I wouldn't use any).  Normally, a new gasket will 'take a set' after a few heat/cool cycles and one re-tightening will hold it from that point on.

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7 hours ago, moran75 said:

... does anyone use thread locker on carb to intake bolts? ..

1/4"-20 UNC Bolts? Use good black oxide Studs, NC in the intake and 1/4"-24 NF with Nuts for the Carburetor.

 

I was tempted to use blue threadlocker in my aluminum intake because of dis-similar metal but did not. This is because I may have to move the studs to outer threaded holes in the new intake for a 4MV Q-Jet. 

I don't think those studs will ever seize with my musical carburetor swaps in all my trouble-shooting attempts. Again, still no silver bullet. Waiting for last vacuum leak to be resolved. Taking forever.

 

 

As for Intake bolts, the cast iron intake had no washers. I tried to source collar style washer for new SS Bolts but ended up using Lock-washers.

 

Yesterday with Carburetor Studs:

image.png.aad0fff4b62f8efdb927fa2f4bb9c311.png

 

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On 5/16/2024 at 7:48 PM, 1965rivgs said:

NO

Tom

.... thing is, car had been to a mechanic a while ago to do some work on the intake manilfold and in process,  the carb itself was taken off - been in back of mind as to whether they retained the metal baffle plate, as something looked diff ...anyway finally took carb off to have a look ...that's when i noticed some kind of sealant/thread locker not only on bolts as i originally mentioned, but also on the threads of the brake vacuum line and the trans vacuum line....

 

emphatic NO to the bolts question 😀, how about the threads on the vacuum lines? ...no doubt not solely a locker, but something to ensure vacuum as well? Is it neccessary/good practice?

 

thanks in advance

 

Kev

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2 hours ago, moran75 said:

.... thing is, car had been to a mechanic a while ago to do some work on the intake manilfold and in process,  the carb itself was taken off - been in back of mind as to whether they retained the metal baffle plate, as something looked diff ...anyway finally took carb off to have a look ...that's when i noticed some kind of sealant/thread locker not only on bolts as i originally mentioned, but also on the threads of the brake vacuum line and the trans vacuum line....

 

emphatic NO to the bolts question 😀, how about the threads on the vacuum lines? ...no doubt not solely a locker, but something to ensure vacuum as well? Is it neccessary/good practice?

 

thanks in advance

 

Kev

NO...those are flare lines and seal on the flares, not the threads. Sealant can be used on the fitting which installs into the carb body which is pipe thread-think plumbing

Tom

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