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Author Topic: leaking intake and exhaust manifold  (Read 9702 times)

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fastback 427

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leaking intake and exhaust manifold
« on: March 18, 2014, 10:30:41 AM »
Looking for some input guys. I picked up a 74 f100 390 2 bbl c6. The intake is leaking so bad it must be fixed. I just hate to pull it off just to reseal it. I have a spare blue thunder intake and 600 Holley not being used. Would the swap hurt performance? Also the manifolds leak so I was going to install a set of Shortie headers I'm not using. I know their not the best header but should easily support my power goal. The truck weighs 4150 on the scale and I'm guessing has 3.00 gears.  I'm not wanting to swap cams yet until I put more miles on it. If the cam swap is a must I'd do it too, looking for more mileage than power.
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Jaime
67 fastback 427 center oiler 428 crank Dove aluminum
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67 fairlane gta cross bolted 12:1 390 Dove aluminum top end c6 3600 stall
65 falcon straight axle project
67 mustang coupe project
76 f350 dually 390 mirror 105 4bbl 4spd
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turbohunter

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Re: leaking intake and exhaust manifold
« Reply #1 on: March 18, 2014, 11:17:38 AM »
One thing to think about on the exhaust side is frozen bolts.
On our old trucks you can be pretty sure you'll run into at least one or two.
They are a bitch. Just factor that into your thinking.
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Marc
'61 F100 292Y
'66 Mustang Injected 428
'66 Q code Country Squire wagon

fastback 427

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Re: leaking intake and exhaust manifold
« Reply #2 on: March 18, 2014, 11:28:57 AM »
Yup, I've replaced a few. The motor was supposed to have been rebuilt about 15000 miles ago, which makes me nervous, but everything looks good so far. I'm going to try soaking the bolts with that wd-40 rust release for a couple hundred miles before the swap. Thanks for the heads up!
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Jaime
67 fastback 427 center oiler 428 crank Dove aluminum
top end toploader
67 fairlane gta cross bolted 12:1 390 Dove aluminum top end c6 3600 stall
65 falcon straight axle project
67 mustang coupe project
76 f350 dually 390 mirror 105 4bbl 4spd
74 f100 xlt 390 c6 factory ac

turbohunter

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Re: leaking intake and exhaust manifold
« Reply #3 on: March 18, 2014, 11:35:22 AM »
Cool.
Have fun (qualified :) ).
Letting it breath is always a good thing.
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Marc
'61 F100 292Y
'66 Mustang Injected 428
'66 Q code Country Squire wagon

fe66comet

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Re: leaking intake and exhaust manifold
« Reply #4 on: March 18, 2014, 11:39:03 AM »
Warm the bolts up and soak with pb blaster and wiggle them back and forth, you might do better to cut the head of the bolts off with a grinder to get the manifold clear. Usually if you have a welder you can get them loose by placing your ground on the head and welding a good bead on the bolt, this burns the rust out of the threads and makes it easy to remove.
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fastback 427

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Re: leaking intake and exhaust manifold
« Reply #5 on: March 18, 2014, 01:04:10 PM »
We do have the welders and the extracting rod but room is tight to weld in the truck. Hoping they come out easy! Maybe if we drink enough beers and look at it long enough the fe gods will smile ;D
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Jaime
67 fastback 427 center oiler 428 crank Dove aluminum
top end toploader
67 fairlane gta cross bolted 12:1 390 Dove aluminum top end c6 3600 stall
65 falcon straight axle project
67 mustang coupe project
76 f350 dually 390 mirror 105 4bbl 4spd
74 f100 xlt 390 c6 factory ac

turbohunter

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Re: leaking intake and exhaust manifold
« Reply #6 on: March 18, 2014, 01:10:29 PM »
Quote from: fastback 427 on March 18, 2014, 01:04:10 PM
Maybe if we drink enough beers and look at it long enough the fe gods will smile ;D
That's the way I do it. ;D
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Marc
'61 F100 292Y
'66 Mustang Injected 428
'66 Q code Country Squire wagon

Lenz

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Re: leaking intake and exhaust manifold
« Reply #7 on: March 18, 2014, 01:45:58 PM »
I firmly believe that beer and staring in the proper order (or in cycles) almost always gets the job done :D. 

As far as the swap, I can't imagine how you'd hurt power as the Holley at 600 isn't too big and you're also going to aid breathing on the exhaust side to help keep things moving.   

I get a bit limited here, but I would think intake charge velocity would be controlled initially by the heads and more or less regulated by the carb.  Therefore things should work well IMO.  I would guess that what the intake charge does between the carb and intake valves would be the key to whether performance would drop.

These are just my thoughts ::), it'll be interesting to catch input from experienced Blue Thunder users.
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Len Zielinski
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fastback 427

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Re: leaking intake and exhaust manifold
« Reply #8 on: March 18, 2014, 02:15:52 PM »
It's got the d2 heads so I know it's a little smaller runner and the blue thunder has the larger cj ports. A street master might be better but I'd like to use up spare parts. Also I have a set of c4 heads with cj valves I could throw on that are a match to the blue thunder. I think the headers won't fit the c4 heads as well as the d2.
Never mind, dug through my stuff and the headers I have are a good match to the c4 heads.
« Last Edit: March 18, 2014, 02:34:20 PM by fastback 427 »
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Jaime
67 fastback 427 center oiler 428 crank Dove aluminum
top end toploader
67 fairlane gta cross bolted 12:1 390 Dove aluminum top end c6 3600 stall
65 falcon straight axle project
67 mustang coupe project
76 f350 dually 390 mirror 105 4bbl 4spd
74 f100 xlt 390 c6 factory ac

My427stang

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Re: leaking intake and exhaust manifold
« Reply #9 on: March 18, 2014, 06:15:08 PM »
Bottom bolts usually aren't an issue on the exhaust, top bolts I don't even try.  I take a torch and get the ears red hot and the bolts back right out.  They cool quick enough that there will be no damage to the head, just heat the ear itself.

 If the bolt sticks while backing out, heat the ear again and it will move again.  Don't take any chances, they love to break and heat is your friend

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Ross
Bullock's Power Service, LLC
- 70 Fastback Mustang, 489 cid FE, Victor, SEFI, Erson SFT cam, TKO-600 5 speed, 4.11 9 inch.
- 71 F100 shortbed 4x4, 461 cid FE, headers, Victor Pro-flo EFI, Comp Custom HFT cam, 3.50 9 inch

machoneman

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Re: leaking intake and exhaust manifold
« Reply #10 on: March 19, 2014, 08:02:23 AM »
2X to heating but will add: while still hot, touch a paraffin candle to the bolts.
« Last Edit: March 19, 2014, 08:04:25 AM by machoneman »
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Bob Maag

fastback 427

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Re: leaking intake and exhaust manifold
« Reply #11 on: March 19, 2014, 01:47:58 PM »
Thanks for the input guys. I sprayed the bolts down with pb blaster and the new wd-40 rust release, then drove it then sprayed it down again. All the bolts were not seized at all and they are grade 8. I guess the beers did appease the fe gods ;D
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Jaime
67 fastback 427 center oiler 428 crank Dove aluminum
top end toploader
67 fairlane gta cross bolted 12:1 390 Dove aluminum top end c6 3600 stall
65 falcon straight axle project
67 mustang coupe project
76 f350 dually 390 mirror 105 4bbl 4spd
74 f100 xlt 390 c6 factory ac

Ratbird

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Re: leaking intake and exhaust manifold
« Reply #12 on: March 19, 2014, 04:51:01 PM »
I shall pay homage to the FE gods with beer as soon as I get out of the office today.

Thought for the day, "beer has food value, food has no beer value". Quote from my favorite Santa Fe brewery.
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bn69stang

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Re: leaking intake and exhaust manifold
« Reply #13 on: March 23, 2014, 12:09:35 PM »
I  agree , sounds like our drinking crew s have a hot rodding problem....http://fepower.net/simplemachinesforum/Smileys/default/grin.gif
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fe66comet

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Re: leaking intake and exhaust manifold
« Reply #14 on: March 23, 2014, 01:21:06 PM »
Thing is when I drink beer while Working on stuff I break things. Not tools or the car but on me LOL, like fingers, an arm or my foot. Got some nasty welding burns too. Then when the beer runs out the pain comes.
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