I've acquired a excellent condition truck, low miles, with little or no knowledge on my end. Basicly I needed something with more ability than my previous truck (96 dodge dakota) but looks and frills didnt matter to me. Once the dakota was gone ($2000 in) I found the 84 ford ($700 out). The previous owner had bought several years ago from the first owner (making me the third), it sat in his yard - his main ride was lost in a divorce, he was forced to make the 84 roadworthy and when he got back on his feet and upgraded to newer / better things I was there to take the 84 off of his hands.

I am beginning to think that the full size straight six ford has not been an improvement from the v6 dakota. My goals for this truck is for my weekend side business (beer and vacation money) lugging around a 3000lb pressure washing trailer.

Improvements thus far, (some by me and some be the p.o. For those by me, it was under/with the supervision and advice of a qualified individual.)
-new springs and shocks, helper spring in rear and stopper block
-new exhaust
-new water pump, thermostat and housing, hoses, sending unit
-alternator, battery and solenoid
-reese style hitch (to get the trailer off of the bumper)
-brake job

Issues (gripes) thus far
- over 55mph is darn near impossible. When I lift the truck falls back to 45mph quickly. I believe we have a 3spd - would that make this a rear end gear issue? Would a gear change kill my ability to tow my pressure washer trailer?
- auto choke carb? Sometimes it seems like we hang up in the cold mornings and I am stuck at high idle for a while.
- Eagerness when put into D. Truck seems to lunge when in gear. If the brakes are not firmly applied we are moving forward rather quickly - but when the throttle IS applied the acceleration does not increase all too much.

The folks on this forum seem to really know there stuff. I could never claim to be an expert, but I am not crazy about making ill advised decisions or hoping a garage makes all the correct decisions for me. I can handle some basics on my own, with my few skills but I am not too proud to ask for help from the above mentioned "qualified person" that has helped and oversaw the improvements thus far.

Any advice or well wishing is much appreciated in advance.

 

I don't see where you: changed the air filter, fuel filter, plug wires, spark plugs, cap & rotor, cleaned the throttle body, and a few more things that I can't think of at the moment. I'm sure that there may be something wrong with your engine but you need to make sure it's not something simple.

 

Yes sir Jim, all of the above that it listed has been addressed (replaced). All done by the po and I checked again after acquiring. I've had the truck for six months, everything you mentioned was day 1.

 

I wonder if you have the c6 or c4 three speed. I know in later years..the 300 was backed by a c6 or had the option. If you ask "why does it matter"..its cuz although both are stout trannys..the c6 was Beefier. That's why we saw them behind the fe's and such. But..the c6 also robbed a lot more power as it was heavy. Just throwing that thought out there.
What is your current rear end ratio? What about rpms running at 55 mph? Is it struggling at 55 with or w/o the load?

 

68Cabby,

Where do I find the tranny type and gear size info on my model? I tried decoding the vin, but that only told me the details on engine size, fuel type, manufacturing place.

As far as RPM, I am not sure. I'll get with my "qualified friend" to check on how much trouble one would be to install.

Its struggling just slightly more with the load - trying to get maintain 55 mph.

Forgot to mention earlier - I knew that fuel economy would not be what I was getting in my 96 dodge - but this truck is getting about 11mpg with or without the load. I'll start to be more precise with my mileage logs so that these numbers will be more accurate.

 

68Cabby,

Where do I find the tranny type and gear size info on my model? I tried decoding the vin, but that only told me the details on engine size, fuel type, manufacturing place.

As far as RPM, I am not sure. I'll get with my "qualified friend" to check on how much trouble one would be to install.

Its struggling just slightly more with the load - trying to get maintain 55 mph.

Forgot to mention earlier - I knew that fuel economy would not be what I was getting in my 96 dodge - but this truck is getting about 11mpg with or without the load. I'll start to be more precise with my mileage logs so that these numbers will be more accurate.

 

The '84 Broncos came with a C6. I've never heard of a C4 being used in anything that new.

The sticker on the inside of the door will have your axle code, but you can also lift the rear end, rotate the driveshaft, and count how many times the tire turns. This can be a better way to tell since it's almost impossible to know if the rear end is original unless you bought it from the original owner and he filled you in. No knowing what people have done over the last 30 years.

It's true that the C6 does rob a bit of power, and the 300 with a C6 is a very stout, but sluggish combination, but you shouldn't have issues going 55, and 11mpg is abysmal. I get 11mpg in the middle of winter with cold starts driving back and forth to work.

The '84 300 uses a feedback carb setup that has a lot of extra sensors under the hood and a computer inside the cab to set the fuel mixture and timing for the engine. It's a great system when it's working. But, more often than not, at this age, it's not. When it's not working, it richens the mixture and prevents the distributor from advancing the timing. This would equate to bad gas mileage, and sluggish performance.

The system is generally so old that a lot of the repair parts are either really expensive, or difficult to find. Especially since Ford only used it for 3 years. Most people don't fix it because the truck doesn't really give any signs that anything's wrong. One day, you just notice it's getting terrible mileage and doesn't quite have the oomph it used to (unless it's your first time driving it).

The most common way of addressing this issue is to convert the ignition system to a DuraSpark II setup, which is what Ford used from around 75 to 83. It's much simpler, very effective, easy to install, and works great. There are a lot of writeups on these forums for how to convert to the setup, but generally what you do is pull everything out of the engine bay that has to do with the ignition. Lots of plugs running into the cab, across the engine, to the carburetor, the solenoids on the valve cover, etc. etc. About the only thing you don't touch is the wiring for the alternator and starter over on the passenger side.

Then, you replace the distributor, coil, and carburetor with the DuraSpark II setup. After that, you'll need the wiring harness to plug it all in. Fortunately, it's completely plug and play and goes into your existing wiring. Generally, the wiring harnesses are found in junk yards. Or, if you're good with wiring, you can make your own.

 

Thanks abandoned bronco - I am making a to do list for this weekend. Adding counting the tire rotations and researching duraspark system.

Would the transmission type be stamped on the case anywhere?

 

Heck Justin..u beat me to the punch! I forgot to even think about the carb and ignition. Also..if those all check out..would egr do something like that?

 

If you have an '84 with a 3spd auto, I can almost guarantee you have a C6 unless someone swapped it for a C4, but I can't see why anyone would do that.

One quick way is to look at the shape of the drain pan:





Hrmm..... I think if the EGR's going out, it'll only really affect your idle and make it difficult to keep running when stopped. But wouldn't affect your cruising or mileage. At least, as far as I know.

 

And heres the official stats of the old girl

3.08 non limited slip gear
c4 or a c5 transmission - the bolt patterns look really similar, but I am leaning towards a c5.

On a side note, this is exactly what the door sticker decodes - 3.08 and c5.

The door sticker reads 4800 GVWR. Even with the upgrades to the suspension, I am kinda scared that I am extremely testing the limits of the tow cap.

Based on the above -where do I need to steer.

Also need to set my story straight from way earlier in the thread. Truck was purchased for $1300 ($700 was the difference left to invest in upgrades after the $2000 sale of the dodge). The pressure washing trailer is 2k to 3k. Guess I need to visit the scale so we can complete the accuracy of the stats.

 

Hmm..is the truck a half or 3/4 ton? I don't have much experience deciphering from the gvwr. 3.08 rear? Seems kinda small for a load of 2500-3k. May wanna find something up in the 3.50 range. That way you pull better but don't sacrifice the mpgs.
I'm still curious..are you having trouble maintaining 55 with the 3k load or empty? Cuz it might be the weight

 

Post a picture of your Certification Label, we can see how it came out of the factory.

 

Honestly though..I'd look into what AB said. Those feedback carbs were only good when they ran right. There's many write UPS on how to convert over

 

DSII DS2 CONVERSIONS (SWAPS)
https://www.ford-trucks.com/forums/1...on-how-to.html
https://www.ford-trucks.com/forums/9...-86-i-6-a.html
https://www.ford-trucks.com/forums/1...g-harness.html