427 not making the power that it should?

The GT-E was only available for a few brief months in 1968. Total production would not have kept the assembly line busy for more than a half day. If you know anything about a GT-E, it is important, and this is the place to share it. The GT-E registry is maintained by Jim Pinkerton.
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Flasheart
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Posts: 152
Joined: 26 Mar 2014, 15:21
Location: Brisbane, Queensland, Australia

427 not making the power that it should?

#1

Post by Flasheart »

Guys,

I have just taken my GT-E out of storage after nearly four years (1 year in Afghanistan, 3 years in Florida). Fresh oil and filter, old gas removed, new gas filled, new battery. It is just not making the power that it should. It is all stock. Rebuilt in the 1990s, few hundred miles since then. Stock exhaust, stock Holley 4088, stock ignition. Drives very nice, but under load it just doesn’t give that seat of the pants acceleration that my 68 Shelby GT500KR provides. I have replaced the secondary diaphragm, so that is now activating. WOT provides a little more acceleration, more noise, and the occasional backfire. Not the slam-back-into-the-seat that it should.

Where to start?
1968 Shelby GT500KR Fastback
1968 Mercury Cougar GT-E, XR7, 427ci
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Royce
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Joined: 22 Oct 2011, 07:14
Location: Tulsa OK

Re: 427 not making the power that it should?

#2

Post by Royce »

Basic tune up stuff. Make sure the timing is set properly. Mae sure the vacuum advance is working properly. Make sure the centrifugal advance is working properly. Make sure you have enough fuel pressure.
1968 GT-E XR-7 W code 427 Augusta Green / Saddle
1968 XR-7 R code 428CJ Ram Air Red / Black
1910 Model T Ford Touring Red / Black
1914 Model T Touring Maroon / Black
1915 Model T Ford Touring Black / Black
1917 Model T Ford Torpedo Runabout Green / Black
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My427stang
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Posts: 98
Joined: 14 Jul 2020, 11:03

Re: 427 not making the power that it should?

#3

Post by My427stang »

I am with Royce, likely time for a good set of points and condenser if still equipped, and map the advance, see if it's working. Maybe even consider a distributor recurve, stock Ford curve was pretty universal. With the engine off, open the throttle and manually open the secondaries, make sure they didn't stick from sittting, make sure the accel pump is functioning and adjusted correctly, etc
- 70 Mustang fastback, SEFI 489 FE, TKO-600, 4.11, AC, PS
- 71 F100 short bed 4x4, Port injected 462 FE, 3.50, 4 inch lift
- Engine building by-appointment only - 30+ years experience, specializing in hidden concours CJ performance
J_Speegle
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Joined: 10 Dec 2011, 19:15

Re: 427 not making the power that it should?

#4

Post by J_Speegle »

If you've had a back fire through the carb and it does not have the fix done to it since new then you likely also have a blown power valve. That will show up in other driving not WOT
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