missing under load help

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Jun 30, 2004 | 10:43 PM

bspeedy

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From: lincoln, ne

missing under load help

i was hoping someone else could help me i have a 85 ford f150 with a 351w auto trans. my problem is my engine starts great and idles and revs perfect while in park but when im driving and i step on it it misses terribly. i put new plugs gapped at 44 new wires, new cap and rotor, new electronic ignition, and i even tried jetting the carb a few steps higher. nothing has helped i tried advancing and retarding the timing a little and nothing changes it any help would be great.

Jun 30, 2004 | 11:30 PM

daerhldgs2

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sounds as though you aren't getting enough fuel , have you checked your accelerator pump or power valve in your carb?What about the fuel filter?

Jul 1, 2004 | 05:56 AM

bspeedy

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From: lincoln, ne

well i just replaced the power valve in it and the accelerator pump squirts, and the fuel filter is a brand new glass one could i maybe be too lean on the jetting its a holley 700 double pumper with the secondaries unhooked im running a #72 jet now was running a 68 but no difference between the two.

Jul 1, 2004 | 07:15 AM

RTM

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From: Sunny Florida

I had some what the same thing and it turned out I my dizzy was loose or getting looser from when I replaced the timing chain. The motor would start missing arouond 3K and started to act up around 2800rpm until I discovered it was loose.

Jul 1, 2004 | 01:39 PM

Kemicalburns

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From: Bend,OR

why such a big carb on there. i would also get rid of the holly unless its 2wd. Whats your timing set at and are you sure about the firing order.

Jul 1, 2004 | 04:22 PM

bspeedy

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From: lincoln, ne

dizzy is tight, big carb just because thats what i had lying around in the shop when the other carb went bad timing is set at 10 btc at about 600 rpms i just upped the main jets to a 78 and seems to be a little better i may try to go even larger better to richen it up than to lean it out.

Jul 1, 2004 | 04:24 PM

bspeedy

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From: lincoln, ne

oh yeah also the firing order was a complicated ordeal i used the firing order on the intake and it would bacfire through the carb horrible so i switched it to ho firing order and it stopped but now it just popps when i step on the throttle