Performance issue
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New User
Joined: Nov 2006
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Performance issue
I have an 84 f-150 I rebuilt the motor. It is bored 30over, Edelbrock performer rpm heads, Edelbrock performer rpm intake, comp cam with 512 lift, 355 gears, TCI trans, 2000 breakaway torque converter,msd ignition, and a holley truck avenger 670 truck avenger carb. My problem is that the truck does not get off the line as fast as I thought it would. It's kind of slow, my ford expy gets off the line faster. Sometimes I smell fuel when it is ideling so im not sure if the carb is to big. So if you can help me that would be great.
Post Fiend
Joined: Oct 2003
Posts: 9,176
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From: Western Central NV
First thing I always ask is if your not an engineer, did you spec this engine with someone who had experience with the combo of aftermarket parts. You can stick a bunch of great aftermarket parts into an engine & trans and if they aren't ALL matched for the application you have and want then. Then performance is affected.
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Joined: Nov 2006
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I ordered all of the parts through JEGs and their tech guys are the ones that sayed these parts would be good. besides the cam I ordered that through comp cams and that was the cam they recomended for my aplication.
Moderator
Joined: Jan 2001
Posts: 56,997
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From: Virginia
What size tires do you have? Does the engine start pulling well once you get going?
You also need to experiment with the timing. You can't go by the book anymore. You need to keep advancing it as far as you can go, without it pinging. Do this with the vacuum advance disconnected. After you get it as high as you can, and the engine still turns over easily when it's hot, then add the vacuum advance in. If you have the stock dist and advance, the vacuum advance will be too much, and you need an adjustable one.
You also need to experiment with the timing. You can't go by the book anymore. You need to keep advancing it as far as you can go, without it pinging. Do this with the vacuum advance disconnected. After you get it as high as you can, and the engine still turns over easily when it's hot, then add the vacuum advance in. If you have the stock dist and advance, the vacuum advance will be too much, and you need an adjustable one.
Cargo Master
Joined: Dec 2004
Posts: 3,362
Likes: 22
From: Florence, SC
Sounds to me like the carburetor is too big. The most common mistake most people make when building up their engines is to use too big of a carburetor. You say it is slow off the line and you smell gas. Classic symptoms of running too large of a carburetor. A smaller carburetor, that is, a carburetor that is better matched to YOUR engine, will give better throttle response and should smoke the tires with all of the upgrades you listed. Not to mention give you better gas mileage and eliminate that fuel smell. "Bigger is better" may apply yo cubic inches, but it should never apply to carburetion.
What size is the engine? If it is a 302, I would go with a carburetor in the 500cfm range (Holley 470 Truck Avenger). If it is a 351, I would go with a 600cfm (Holley 570 Street Avenger). Unless, of course, you are drag racing the truck and plan to stay in the higher rpm range, say over 6000rpm.
What size is the engine? If it is a 302, I would go with a carburetor in the 500cfm range (Holley 470 Truck Avenger). If it is a 351, I would go with a 600cfm (Holley 570 Street Avenger). Unless, of course, you are drag racing the truck and plan to stay in the higher rpm range, say over 6000rpm.
