Maximum speed can´t be reached (1 Viewer)

[JimmyConway963]

Hi guys,

I drive a 1978 Fj40 and with this car it´s only possible to reach a top speed of 115 - 120 km/h.
I have already replaced many engine parts and tried a few things (new fuel hoses,installed a electronic ignition ,new ignition cables, new fuel pump, carburetor cleaned in an ultrasonic bath and replacement of the old seals, ignition adjusted and much more) but cannot find the cause of the loss of power.
According to some other Landcruiser drivers, the FJ40 should be around 155 - 160 km/h.
Please don't get me wrong, I don't want to make races with this car, but the lack of performance gives me headaches...

At the weekend I looked with a friend at the carburetor and we found air bubbles forming in the float chamber under full load.
Here is a video that I uploaded to Youtube:


Do you know if this is normal? Could this be the cause of the loss of performance?

BR,
Jimmy

 

[rkymtnflyfisher]

Have you adjusted valves lately? How's the compression numbers?

 

[Advrider639]

95-99 mph in a 40... yeah, no.

Your 75mph is pretty normal. I wouldn’t want to go more than 80 or so. Don’t forget it’s shaped like a brick.

 

[Mark Jennings]

155 Klicks is Terminal Velocity...,, when dropped from 10,000 feet (3048 meters).

155 to 160 Klicks is actually quite good, and is probably your top end for your rig.

 

[Pin_Head]

It sounds like there is no load on the engine and you are just revving it up while it is standing still. I wouldn’t worry about the bubbles.
Is your secondary opening under real load, like going up hill with the throttle wide open at 60 KPH in 4th gear? Do the paper clip test. Search for paper clip here. I don’t think that you really want to drive over 115 KPH in a cruiser. It has the aerodynamics of a brick and the handling of a skate board.

 

[workingdog]

That's an insult to skate boards

 

[Hugh Heifer]

I think 70mph was my top speed with a '79 refreshed 2F, 4speed and stock gears on 35s.

 

[JimmyConway963]

I will adjust the valves again within the next days.
I did also a compression test a few weeks ago. The values seem quiet low.
But not sure if that is the cause. What do you think?

1. cyl: 8,60 bar
2. cyl: 8,45 bar
3. cyl: 8,55 bar
4. cyl: 8,70 bar
5. cyl: 8,65 bar
6. cyl: 8,80 bar

Uphill I sometimes reach only 75-80 km/h even with a cable tie fixed open secondary...

 

[Slapshot]

I think you’re expecting too much out of the FJ40. Definitely not an autobahn car. I always joke that Toyota named it the FJ40 because it’s happiest going 40mph (65 kph)

 

[Pura Vida]

Yea my BJ40 speedo goes to like 160 kph but that’s never gonna happen unless it gets dropped out of an airplane

 

[Solace in Solitude]

Your compression is fine and consistent (122-127 psi) across the cylinders.

Your top speed is realistic, with a 2F (compression in the 120s) and electronic ignition. You should be running vacuum advance.

My electronic ignition (DUI) ran best with spark plugs gapped at .050” and timing at 12 degrees BTDC.

If you lack power climbing hills, at what altitude does the performance degrade? This could easily be a vacuum leak... check all vacuum hoses, intake manifold, carb base, etc.

My ‘78 (gone now) was a rebuilt 2F, 4spd, rebuilt Aisin card, DUI and

Denso (3013) W14EXR-U Traditional Spark Plugs​

Timing and gap as above.

It would easily cruise at 75 (120kph)... had low climbing power above 6k’ (1829m) until I found and fixed a major vacuum leak.

Make sure you are running the correct jets in your carb and that your carb secondary is working. Search for ‘paper clip test for secondary’.

I coaxed 85mph (137kph) out of mine once, while passing an 18-wheeler that decided to race me, and found it a scary endeavor. The safer speed is 60-65 mph.

 

[igotta40]

Hi guys,

I drive a 1978 Fj40 and with this car it´s only possible to reach a top speed of 115 - 120 km/h.
I have already replaced many engine parts and tried a few things (new fuel hoses,installed a electronic ignition ,new ignition cables, new fuel pump, carburetor cleaned in an ultrasonic bath and replacement of the old seals, ignition adjusted and much more) but cannot find the cause of the loss of power.
According to some other Landcruiser drivers, the FJ40 should be around 155 - 160 km/h.
Please don't get me wrong, I don't want to make races with this car, but the lack of performance gives me headaches...

At the weekend I looked with a friend at the carburetor and we found air bubbles forming in the float chamber under full load.
Here is a video that I uploaded to Youtube:


Do you know if this is normal? Could this be the cause of the loss of performance?

BR,
Jimmy

When mine was still fairly new it would go close to 140kph. You could check valve adjustment and timing, what size are your tires?

 

[85roktoy]

Not to hi-jack but I'm having the same issue but lower MPH. Top end of motor was rebuilt and valves adjusted, de-smogged with MDS electronic ignition and 33x10.50 tires. I don't have a tach yet but topping out around 50mph sounds like she's screaming.

 

[GA Architect]

Yeah, 160KMH, really???......not in mine. I may have had it close to 140KMH once, chasing the infamous @POTATO LAUNCHER & Texas Gang across New Mexico. But that was for a short distance.

Now, I have sustained 70/75MPH (120KMH) for 3 to 4 hours on the flat lands, no problem.

 

[Pura Vida]

Not to hi-jack but I'm having the same issue but lower MPH. Top end of motor was rebuilt and valves adjusted, de-smogged with MDS electronic ignition and 33x10.50 tires. I don't have a tach yet but topping out around 50mph sounds like she's screaming.

pretty common suggestion is to check compression

 

[DSRTRDR]

the original poster did not say what size tires he is running

I could do 85 mph on 33's (that's almost 140 km/h) - now on 35s I am sure the truck can go faster, but speed above 85 mph is a criminal offense in Arizona

[don't ask me how I know: I once got busted for doing 87, had to go to court and two full Saturdays of traffic school - I will never risk wasting this much time of my life again ]

 

[Pura Vida]

the original poster did not say what size tires he is running

I could do 85 mph on 33's (that's almost 140 km/h) - now on 35s I am sure the truck can go faster, but speed above 85 mph is a criminal offense in Arizona

[don't ask me how I know, I once got busted for doing 87, had to go to court and two full Saturdays of traffic school - I will never risk wasting this much time of my life again ]

At the start of covid lockdowns, it was great because the roads were clear. 100 mph was easy. I’ll probably never do that again, but I didn’t see an issue with it when I was literally the only car on a 4 lane interstate.

 

[flx]

An European FJ40 was able to do 140km/h all day long when new with the 3.70 gear we got and original 7.50R16 tire size.

 

[AussieHJCruza]

My FJ45 with a DUI dissy, headers and a bit of head work would do 160 km/h without too much trouble. I wouldn't advocate spinning a stock F/2F that hard for long though.

 

[JimmyConway963]

I really need to check the compression loss...
You guys are right, driving above 100 with an FJ is quiet stressful and scary.
...Nevertheless, when your grown up in a country without any speedlimit a little voice in your head says always "go faster, go faster!"
No, just kidding... It is more the poor performance uphill and the fact that something might be wrong with the engine.