poor performance

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Oct 4, 2011 | 12:48 PM

ramrod587

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poor performance

I have rebuilt the engine in my 1971 ford f100, its a straight 6, 240 3.9 lt. The engine starts great the first time, it idles well and runs smooth. The problem I'm having is the performance is poor at high speed, and up hills. It sounds like the valves may be clattering. The engine and head have both been rebuilt.

Oct 4, 2011 | 03:04 PM

elgemcdlf

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From: Alton, MO

Recheck your timing and make sure advance is working properly

Oct 4, 2011 | 03:20 PM

ramrod587

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Thanks, I'll check that.

Does it matter if I use unleaded or would I have to use supper and a lead additive?
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Oct 4, 2011 | 03:50 PM

elgemcdlf

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From: Alton, MO

Fuel shouldn't matter. What you describe sounds like a timing issue. My guess is timing is not set correctly or advance not working. How does the truck start hot?

Oct 4, 2011 | 05:30 PM

jowilker

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From: Creedmoor, North Carolina

I agree, sounds like timing. After you get it tuned up properly, it should run on the cheepest gas on the corner.

John

Oct 5, 2011 | 09:20 PM

ramrod587

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Thanks for the advice guys, it was the timing, It was off by quite a bit. I took it out on the road and got it up to 70 without any problems at all, ran great. I did notice that after turning it off for a few minutes then trying to start it again it takes a pump of gas to get it started but then it runs great.
I had another question, the round red break lightabove the emergency break stays on no matter what. I changed the switch under the truck and also the break switch inside the cab but the light still stays on any idea?

Oct 6, 2011 | 04:40 AM

jowilker

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Joined: Jun 1999

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From: Creedmoor, North Carolina

It is an idiot light doesn't have much value, I'd unplug it.

John

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Oct 6, 2011 | 11:56 AM

stormchaser70

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Joined: Jan 2004

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From: colorado

that is a brake light!

Don't ignore that light. If it is a real problem you'd want to know.

At *least* check your brake fluid level, and make sure your wheel cylinders and master cylinder aren't leaking.

See this recent thread:

https://www.ford-trucks.com/forums/1...-with-pic.html

Oct 6, 2011 | 12:03 PM

#10

ramrod587

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Gas Millage

Today was the first time I drove the truck on the hwy and gave it a really good run. I got right at 12 miles to the gallon, this was hwy miles, drove about 65 all the way. Any tricks to getting better millage?

1971 ford f100 240

straight 6, 3.9 LT engine