Freeway speed???

[Macgyver5]

So my housemate just bought a 74 fj40 and I own a 75....yesterday we went to LA to pick it up and drive it home to Santa Cruz....so heres my question...both are stock why would his go faster on the freeway his will go like 80 (unhappily) and mine will do like 60-65 (unhappily) the only differences are his has slightly bigger tires and mine has none of the emissions stuff his has it all...and with the tires shouldn't that throw off the speedo I was pretty baffled by it so any ideas would be good

ps:I don't think his gearing has been changed

 

[IDave]

Must be because 2Fs suck.








Bigger tires will give a boost under those conditions, and if your engine is tired compared to his, well.....

 

[Degnol]

Depending on to what extent your truck was desmogged.....and if you are still running a VSV controlled carb, you might be getting robbed there. If you have no VSV, then there are internals carbwise that are not functioning properly.
You'd be better off running an earlier carb, like a Federal Spec '74.
I don't know much about the 2F carbs, but I think the secondary diaphragm is what may not be working. I think JimC can desmog your carb, or rather make your smog carb work on a non-smogged motor.
This is just one of several things that could be the problem. 65-70 is as fast as I usually want to go, but mine will do 70-75 easily. '74 F motor, 31's, 4.10.

HTH

Ed

 

[65-fj45]

Do you guys have the same Gear ratio? some one could have changed the ones on your friends truck to 3.73.

 

[Lothar]

we have the same ratio....well were pretty sure, i just got mine yesterday. Previous owner dropped a 2F in my '74. the only major differences in our engines are the smog stuff on mine plus my engine probably has a few less miles on it. I have a larger exhaust pipe and larger tires but i think he already covered that one.

 

[Trevor]

I just drove my '77 from Augusta to Atlanta with my father following in his car. My odometer bounced around 60 mph the whole way, he said I was holding 65mph. I briefly got up to 68 to pass, and could have gone faster, but the old 2F was beggin' for a rest. I've never tried, but mine would probably do high 70's if it had to. I'm running 31" tires, 4.11 gears, Jim C. desmogged carb with the air pump still hooked up.

 

[Macgyver5]

OOPS sorry I forgot to mention that I have a GM carb, distributor, and alt so my Carb doesn't have all of the same smog stuff on it just a couple of vac lines not near as many as his toyota carb

 

[Macgyver5]

actually mine is running alittle rich could it be in the tuning of the carb/timing????

 

[Mace]

Must be because 2Fs suck.

Why is that???

At 4K and 4.11's my 40 will do 90 with 33" tires.

What makes the 2F suck??


the larger exhaust allows the motor to breathe easier. that probably has a bit to do with it.

Additionally if hte motor was rebuilt and the PO did not balance the motor you will nto get the RPM's out of it.

 

[Poser]

Pretty sure Dave was kidding Jason....


He only has the early stuff...







Have you looked to see that the throttle opens all the way when the peddal is pressed fully? Could be something as simple as linkage/cable issues...



Good luck!


-Steve

 

[Romer]

I noticed a performance boost (small) when I changed the muffler set-up.

I run 33's and do 70 comfortanly. At 3000 RPM I am doing 74 (62 on the speedo -tire size)

I like to keep mine below 3000 RPM, but I have done 80 before.

 

[Mace]

Ahhhhhhhh

Missed that one.




Never claimed I was that bright

 

[IDave]

Yeah. Kidding. I saw a picture of Degnol's 2F once and couldn't understand why the oil fill was on the wrong side of his dizzy.

 

[FineWynsFJ40]

<hijack>Ok, so a 1974 with GM carb and aftermarket intake and headers with 30" tires should be able to do around 60-65 comfortably? Why does the factory brochure say top end 62, and why does mine sound very angry when I get above 58?</hijack>

 

[Mace]

Thos tires are a bit small for 4.11 gears..

60-65 with 4.11's and 31" BFG's is about 3K

Get some 32's or 33's and you will be happier.

 

[Dave E]

Valve adjustment can rob you of power too.


Dave

 

[IDave]

Fyne Wines, I have 30s on my 71 with a 3 speed and I have no problem going 65. 3rd gear in my rig is the same as your 4th gear ratio. You should be able to do better.

Question: are you sure of your speed? I have been looking at the different speedometer gears available for the transfer cases. You can really be off if you have the wrong combo of tires, speedo gears and the speedo head.

 

[Macgyver5]

Lots of good ideas I do need a valve adjustment and i'll check out to see how far open full throttle really is, as for 33's and a new speedo gear all in due time my friends Thanks to everyone who replied you guys are awesome!...I recomend this site to every person I meet with a cruiser simply because of responses like these
Thanks Again!!!
-Brandon-

 

[snailwagon]

topics like this make me realize my stock F145 in the heavy 55 isn't that bad or as slow as I thought. It will actually do 70-75mph easily with 33"s.

 

[trainrech]

I've never really enjoyed going more than around 65 in mine. Could be the 4" lift, could be the 35" tires, could be I'm getting old...