HIGH COMPTESSION FLATHEADS ?

From: aussierob (aussierob@odyssey.net)
Date: Sat Aug 04 2001 - 03:53:39 PDT


Hello listers ...I'm looking for information on just what difference the
Higher compression head makes to my jeep flathead. ???
I have one of these heads that I might put onto my nicely running, new
motor.

Having driven this brand new engine now for several hundred miles, I have
inherited "some problems" that a previous owner or two have created !!! To
add insult... I went ahead and put in an Warn overdrive.

I know these sidevalve engines are not designed to operate at 2001 highway
speeds ...however, the slightly larger tires definitely give me "more"
speed (unfortunately, only up to a point)

 But, the Lil' flathead is really at the end of its rope to actually sustain
that performance up and down the backroad hills, forget the dual highways.

(By the way I got 15+ miles per gallon on a recent 120 mile run with the new
engine)

Now the previous owner (or two) has changed the rear ends from what I
"think" they said was a 5.6:1 ratio ...to a 4.1:1 ratio
This would give me even more, more, top speed except that the Lil'
flatheads are out of steam by the time you get to 50mph !!!

Oh, I know some will write and tell me they easily get 60mph out of theirs
...true, and so do I ...BUT on the slightest grade your out of power.
Why ?
Because you're already at the top of this engines power abilities.
Anyway, who wants to run their engine at totally full power while running
down the highway everyday ?

That said, I do have my standard MB (nice running) ...so I DO have a
complete comparison here.

I would like to get a few more horses and a few more foot pounds of Torque
Therefore, the Higher Compression head question.

Basically the two changes to this jeep - larger diameter tires and the
faster differential - both combined, actually by together, have created an
awkward situation where I have to slip the clutch too much to get the jeep
rolling in first gear, then there's not enough power left at high speed to
make too much use of it This is probably at the point where the Overhead
valve engine shines - big time with it extra 12+ horse power ...eh ?

I have, what I am told is this.
One of my engines has the ribbed high compression flathead. So, just how BIG
a difference would this make?

1]
So, Is there anyone out there that has run their jeep with the standard
head and then switched over to the high compression head ...there must be
someone who has felt the difference???

2]
Anyone know the compression ratio of the standard head compared to the high
compression head.
Sorry for the length of this post.
Regards
Rob Pearson upstate, NY
42MB and a handful of Cj2As and a DJ bitza !



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