Project 1977 F100 - New radiator + electric fan!

[bobo333]

Hi guys,

i replaced the earths on the battery which fixed all of my voltage drop issues:


i also added this distribution block on the firewall to the end of the extra 8ga cable run i put into the cab for any accesories i want to put in later on:


and installed my fire extinguisher next to the driver seat:


i also did my first fill up last night which was quite dismal, 6.98mpg... although most of the tank was either sitting still with the engine idling or at high load/high RPM while servicing and tuning the engine, so im not too worried about gaining lots next tank

its still not quite running right when cold and takes ages to get started but once its warm it runs great now

still on the to do list are change the oil (will be using 10w-40 synthetic as i have it laying around already), change the spark plug leads (already done the rest of the ignition system), and possibly a higher output coil, then a new radiator and electric fans to replace the crank driven one

i also need a new diff ratio, this is what mine currently is, which apparently means it has 4.11 gears which explains why its revving so high, now i just gotta figure out what ratio i want


thanks for lookin

[bhazard]

Possible 5 speed swap?

[Christ]

3.08 is a decent road gear, 2.73 is a little low, but manageable.

If you're interested in a 5 speed swap, the M5R2 Mazda transmission that comes in newer F150's has a decent OD and 1st is low enough to get you moving if you want to haul weight.

With my 4.9 1996 F150 and the same trans, I hauled a mobile home (16x84 custom) about 16 miles up and down hills, but I had to get started in 4LO and "pop" it into 2wd while moving, hard on the transfer case.

That particular trans doesn't do well with really heavy loads over time.

Another option is the ZF6, which effectively has 2 OD gears and a super low 1st (compared to other trans).

If you get a ZF5 or 6, make sure it's the one you need, which has a shorter input shaft and the small block bell housing.

[Sporty Modder]

IME(in my experince) 3.55 gears are a good compromise between hauling and highway running. My Suburban has 3.08 gears and can not maintain speed below 60 mph without down shifting.

[Christ]

Originally Posted by Sporty Modder

IME(in my experince) 3.55 gears are a good compromise between hauling and highway running. My Suburban has 3.08 gears and can not maintain speed below 60 mph without down shifting.

No comparison, really. Different transmission gear ratios, different transmission settings (kickdown, etc), different weight/aerodynamics, etc.

I've personally run 3.08's in a F150 (OEM LS differential) and it went just fine. It would downshift if loaded up short hills and such, so I'd just take it out of OD if I was in hilly terrain to keep it from shifting all the time.

[bobo333]

thanks guys,

according to my calculations i need around 2.9:1 to get the rpm down to around 2000 in 4th at 60mph, so either 2.73 or 3.08 are pretty close depending on availability (there is an F truck wrecker near me)

A 5 speed is also a possibility as a friend of mine has a similar year F100 ex ambulance with a 5 speed, not sure what gearbox it is but apparently is ex canadian if that means anything.

the price of the diff VS the new gearbox will determine which i do first, i need to go have a look at my friends car to see what gearbox it is too and hopefully find out the ratios

other than that i havnt done much in the last couple of days, the gas system is playing up a bit causing the car to not start until ive turned it over for a minute or more which is annoying, it only does it after sitting for a while though, after the first start it starts straight away every time which makes it difficult to diagnose. Im going to see a mechanic sometime soon so hopefully he will know whats goin on

thanks for lookin

[Neen]

Sounds like you need to rebuild that old carb...vapor lock perhaps? Either way a rebuild will net you benefits all around.

[bobo333]

Yeah the carby definitely needs a rebuild, i cant run it on petrol at the moment because it leaks like a sieve, which kinda hurts my mileage a bit...

would the carby needing a rebuild affect the LPG system though? i thought the only part being used when its running gas is the throttle plate?

[Neen]

Oh you are running LPG right now? Nevermind....this is out of my knowledge base. Carb may still affect it if there is an air leak I guess.

[bobo333]

yep its duel fuel so i can switch between LPG or normal petrol, but with the carby leaking like it does and the price of petrol being more than double LPG in my area id rather get it goin as good as i can on LPG