My 1984 F-150 (5.0L) is extremely weak and slow from the take off if I gun it. Now if I'm cruising and gun it then the acceleration is much better but still kind of disappointing. It's a rebuilt 302 with a cam and bored .030 with only 1,000 miles since I bought it. My carburetor isn't so hot but I would like to know where else I can start to see what I can do to make it move when I hit it. I'm not racing anyone but if I gun it I want it to hum-zing and not putt-putt along if you know what I mean. I appreciate any feedback you guys can provide for me. Thanks.

 

What's your cam profile and carb size and type? Maybe whoever rebuilt it went too big (650 cfm is plenty). Do you have mechanical or vacuum secondaries on the carb?

Also, the cam and carb might be okay, but if the exhaust is too restrictive it can spoil the show. What's on the exhaust side?

If your gear ratio is low (like 2.75:1), or you're running really tall tires, the low end grunt will suffer.

These are all ways for your rig to suffer on the low end, yet still seem peppy enough at cruising speed.

 

Ok I do not recall the profile of the cam but I think it's a Competition Cam either 260H or 280H series. I believe it's a 280 but I would have to look at the receipt when I get home so I'll get back to you. Ok my carb is garbage I bought it second hand and its a Holley 600 cfm with vacuum secondaries. I plan on buying the Holley Street Avenger 570cfm. Now I installed Flowtech headers and cut off my catalytic converter and had 2.5" pipe run for dual exhaust with Flowmaster mufflers. The shop was currently out of 3" pipe if you can believe that so I just went with the 2.5" because I was running with straight headers and setting off my neighbor's car alarm. Now I do not know what gear ratio I have but the axle reading on my vehicle sticker inside my door reads "D" which I believe is an 8.8 but I am not sure. Hopefully you know what size axle I have. Now my tires are 235/75 R15. I plan on buying a new set of rims around Christmas time but not sure what size I am going with. I want to run a dual fuel line for the Street Avenger carb when I get it and replace the fuel pump with a better one. What do you think? Well thanks for replying and hopefully this information helps you figure out what the problem can be. It's kind of embarrassing too because I've got this big loud truck but no *** when I punch it. Go figure. Thanks.

 

Well, a 260 or 280 isn't too radical. Where do you have the initial timing set? For a 302, maybe 10 to 12 degrees initial and 35 - 42 degrees all in before 2800 rpm is a good starting point. Do you have a vacuum advance on the distributor? Unplug it and put a golf tee or other stopper in the hose while you do the timing.

The carb sizing is actually pretty good - some folks slap an 850 double-pumper on a small block and wonder where the power went. I'd stick with vacuum secondaries when you do get a new carb (the 570 sounds great). Any issues with thin air / high altitude?

I don't have an axle guide to figure out the gear ratio "D"- the tag on the rear differential should have it stamped on it. I know, it means crawling under the truck and wiping off the grease to read it. Auto or manual tranny??

The 2.5" exhaust is actually a better choice for low end power than the 3". You'd only need the 3" if you were putting out +350 hp.

The tires aren't too huge, so that's not it. I'd do all the easy (cheap) stuff first - new air and fuel filters, distributor cap and rotor, spark plugs, and the aforementioned timing. Remember that a 6000 lb truck isn't going to rip like a 3600 lb Mustang with the 302 out of the hole.

 

My vacuum advance is acting up and I do have to retime my motor. The fuel filter is only about 3-4 weeks old and the air filter is about 2 months old. I do have automatic transmission and I do not expect it to rip like a Mustang but like I said when I hit is I want to move. It is really sluggish. There are not thin air problems in Louisiana. The only problem we have down here is unparalleled hummidity. Now this motor came out of my 1979 F-100 and since my girlfriends wrecked it I put it in my 1984 F-150. I took the plugs and wires from my original 84' motor because they were brand new and I was trying to cut a few corners. The gapping on my '84 motor was required to be in between .042-.046 and I do not recall what the '79 called for. Do you think that it could be different and thus another reason my motor is giving me trouble. I figured them to be the same since all 302 are more or less alike. Now I did not change the distributor cap, which by the way is a good idea, so I am looking to do that this weekend. What size tires do you recommend? I want to buy some new rims for my truck and I would like a wider tire but I am not sure if that is such a good idea. Thanks for you help sorry I could not repsond sooner but I have been extremely busy with work and therefore my truck has been suffering. Thanks.

 

if you want wider but not taller tires then try some 255 70 r 15s. I had them on the back of my truck for a while after i got it. they arent a whole lot wider but about a 1/2 to maybe an inch wider than the 235 75 r 15s i had on the front. But they were the same height.

 

As far as your tire question, 275 60 15's work well on 15x8's you can check my gallery to see how wide they look it really depends on how wide you want to go.

 

Can someone tell me how to adjust the choke on a Carter 1bbl. carb? It is a climatic choke with electric assist. The choke plate is not closing after long cool-off period. Also, how can I set the fuel/air mixture? It is on a 1981 Ford F-100 with a 300c.i. inline six. Thanks!

 

if you look at teh back of teh carb where the choke is, there are a couple of screws that you can loosen and then it will allow you to rotate the choke assembly, and adjust the choke

 

Your truck looks good and I like the way the tires look on your truck. I have a long wheel base and putting on some wider tires will make it look tougher. Thanks for the feedback.

 

is it running sluggishly like its broke, or just because its a dog?

It sounds kind of like a vacuume leak to me, if its broke that is.