poor performance

Reply Subscribe

Thread Tools

Search this Thread

Oct 4, 2011 | 12:48 PM

ramrod587

Thread Starter

New User

Joined: Oct 2011

Posts: 8

Likes: 0

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

Posting Guru

Joined: May 2010

Posts: 1,867

Likes: 3

From: Alton, MO

Recheck your timing and make sure advance is working properly

Oct 4, 2011 | 03:20 PM

ramrod587

Thread Starter

New User

Joined: Oct 2011

Posts: 8

Likes: 0

Thanks, I'll check that.

Does it matter if I use unleaded or would I have to use supper and a lead additive?
<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com

ffice

ffice" /><o

></o

>
<o

></o

Oct 4, 2011 | 03:50 PM

elgemcdlf

Posting Guru

Joined: May 2010

Posts: 1,867

Likes: 3

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

Fleet Owner

Joined: Jun 1999

Posts: 24,552

Likes: 74

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

Thread Starter

New User

Joined: Oct 2011

Posts: 8

Likes: 0

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

Fleet Owner

Joined: Jun 1999

Posts: 24,552

Likes: 74

From: Creedmoor, North Carolina

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

John

Ford's 2001 Explorer Sportsman Concept Looks For a New Home

Verdad Gallardo

10 Best Ford Truck Engines We Miss the Most!

Joe Kucinski

2026 Shelby F-150 Off-Road: Better Than a Raptor R?

Brett Foote

2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!

Michael S. Palmer

10 Most Surprising 2026 Ford Truck Features!

Joe Kucinski

Top 10 Ford Trucks Coming to Mecum Indy 2026

Brett Foote

5 Best / 5 Worst Ford Truck Wheels of All Time

Joe Kucinski

Ford Super Duty: 5 Things Owners LOVE, 5 Things They LOATHE!

Joe Kucinski

Every 2026 Ford Truck Engine RANKED from WORST to FIRST!

Michael S. Palmer

The Best F-150 Deal of Every Trim Level (XL through Raptor)

Joe Kucinski

Oct 6, 2011 | 11:56 AM

stormchaser70

Junior User

Joined: Jan 2004

Posts: 58

Likes: 0

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

Thread Starter

New User

Joined: Oct 2011

Posts: 8

Likes: 0

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