Top speed of an L-head 134

I would like to know how fast can a bone stock 47 Cj2a go? I had nine up to 41 going down hill is this right?

 

Re: Yop speed of an L-head 134

I guess it would depend on how worn the engine is. Mileage and ring condition plays a big part. Ive had my used f-head (similar) with unknown mileage up to 55 on flat ground and it has a cracked block, leaking coolant into the cylinders. The thing that really worried me was how loud the trans/transfer case wined.

I wouldnt take yours on a highway without an overdrive. Even then dont expect to go much faster than 60.

Curious to hear what others say.

 

Re: Yop speed of an L-head 134

my buddy has a m38a1 with pinto power......top speed 56 mph limiting factor gears....

 

Re: Yop speed of an L-head 134

FWIW, one source I've seen said the redline is 3,200 RPM, but it's not a good idea to sustain more than 2,800 for long.

 

Re: Yop speed of an L-head 134

Various crankshaft velocities for the L-134 Go-Devil
Speeds with 6.00 x 16" tires and 5.38 final drive ratio

Maximum RPM = 4000 = 61 MPH
Maximum Sustained RPM = 3200 = 49 MPH
Medium Sustained RPM = 2600 = 40 MPH
Maximum Torque RPM = 2000 = 31 MPH

The maximum sustained crankshaft velocity is the fastest RPM providing reasonable service life.
The medium sustained crankshaft velocity is the ideal velocity for hiway use.
The maximum torque output RPM is the most efficient crankshaft velocity.
Providing the best MPG economy excluding wind drag.

 

Re: Yop speed of an L-head 134

I believe the dash tag speed data came from the MBs which had 4.88s or some axle ratio like that, IIRC.

 

Re: Yop speed of an L-head 134

I did a little test one day and I couldn't reach the number listed on my dash tag. As far as I know, MB's have the same numbers listed on their tags. JMO

On the CJ2A page, a member (jpet) conducted a similar test, but it was about OD vs. no OD. I think he got up to about the 50 MPH range without shifting into OD and 60ish with OD (F Bill?). Windshield down + OD was a whole other story. He got up to 70 with his 2A.

 

Re: Yop speed of an L-head 134

my 46 will top out at 35mph.
the 34x9.5 swampers do not help but it looks cool

 

Re: Yop speed of an L-head 134

If you are running tires bigger than what came on it new, and you haven't had the speedometer reset, you may be going as much as 10 mph faster than indicated.

Take your GPS along and see how the speeds match or don't match.

 

Re: Yop speed of an L-head 134

my speedo just kinda bounces a little bit. when i recorded my supersonic high speed run of 35mph my dad was behind me in his grandcherokee trying to keep up

 

Re: Yop speed of an L-head 134

bone stock 3A likes 50mph have gone 65 on the down hill. An overdrive doesn't really add any more speed just drops the rpms, the L head doesn't have enough poop to push it any faster then around 60 even with od.

 

Re: Yop speed of an L-head 134

The nice thing about the flat head engines is they can be hopped up to produce around 100 hp. The F-Head on the other hand, is stuck at at the most 75 horses.

 

Re: Yop speed of an L-head 134

Hopped up? with what parts and how? Very interested in a bit more snot out of the old flathead

 

Can you explain how? And why can't the F head be hopped up too? The intake flows better.


Sent from my iPhone using Tapatalk

 

Re: Yop speed of an L-head 134

You can shave the flat-head and raise the compression a bunch, which will increase the horsepower.
Some other things.
Used to be after market heads available with smaller quench areas from some one like Offenhauser for the Willys flat-head 4 in the Coupe that was the same as the flat-head in the Jeep. Some were supercharged.
That kind of thing.