Stage 2, M151A2 MOD
High Performance M151 Engine
Modifications
Modifications
Installation of Ron Rietfors Ported and
polished Head and Custom Header
polished Head and Custom Header
Click on Photos to see fullsize
After the Great increases in performance
experienced with the K&N air filter mod and the
bosch platinum four spark plugs I was anxious to
see what Ron Rietfors customized cylinder head
and free flow header would do for my M151A2
MOD. Ron had sent me the whole set up earlier
in the summer and I at last had a couple of tdays
free to do the install.
experienced with the K&N air filter mod and the
bosch platinum four spark plugs I was anxious to
see what Ron Rietfors customized cylinder head
and free flow header would do for my M151A2
MOD. Ron had sent me the whole set up earlier
in the summer and I at last had a couple of tdays
free to do the install.
I backed the Mutt into my basement Garage and
parked the M718 in front of it and using the
body extension as a tool bench got ready for a
simple cylinder head replacement job. I removed
the the old head following the 34 manual (its a
great thing to have the 34 rebuild book) and the
pistons and cylinder walls on the Mutt engine
were found to be in great condition. I installed
the exhaust header on the head per Rons
instructions using a spray copper gasket sealent
on the gaskets and used anti sieze on the the
studs and bolts because they come in contact
with water passages in the head. Ron did a great
job of port matching between the manifolds and
the head. Next I used the same spray copper on
the head gasket.
I put the high performance head in place ,
torqued to specs, replaced the O ring on the oil
feed line , bolted and torqued the the rocker
assembly being carefull to get the oil lines
correctly in place and remembering to put the
caps on the exhaust valve stems.
The intake Manifold was modified to contact the
middle two tubes of the header for good cold
weather warm up of the engine,I installed it and
the rebuilt early M151 Holley carb Ron
provided, in his experience he has found that the
Holley has better air flow and better
performance than the later Zenith carb.
Now I ran into MR Murphys law! I realized the
high performanc head had a plug in the hole for
the Heater return water line. It must have been
there since new not having ever been in a Mutt
with a heater. I tried the get it out, rounded it,
(soft steel) , drilled it for an easy out and broke
off a #4 easy out in it!!!
I drilled again and used a #5 easy out, well over
100 pounds of torque and I broke the easy out
again, I ground it out for a 3/8 square drive and
used a breaker bar which just made the hole
round (soft steel) .I was getting scared of
messing up the head at this point. Now was the
time for Zen in the art of Mutt mechanics,The
Tao of Mutt, deep breaths and prayers. I used a
small carbide cutter on my dremil tool and very
slowly and with great care ground it out until
there was only threads left, then I got lucky with
a tread tap , caught the start of the threads in the
head and what was left of the plug peeled right
out with the tap leaving the threads in the the
cast iron head intact and in good condition.
Whew, that was a close call, this one little fitting
took longer than the whole rest of the project!
What a feeling of satisfaction when I got it out
with no damage to the threads in the head!!!!
parked the M718 in front of it and using the
body extension as a tool bench got ready for a
simple cylinder head replacement job. I removed
the the old head following the 34 manual (its a
great thing to have the 34 rebuild book) and the
pistons and cylinder walls on the Mutt engine
were found to be in great condition. I installed
the exhaust header on the head per Rons
instructions using a spray copper gasket sealent
on the gaskets and used anti sieze on the the
studs and bolts because they come in contact
with water passages in the head. Ron did a great
job of port matching between the manifolds and
the head. Next I used the same spray copper on
the head gasket.
I put the high performance head in place ,
torqued to specs, replaced the O ring on the oil
feed line , bolted and torqued the the rocker
assembly being carefull to get the oil lines
correctly in place and remembering to put the
caps on the exhaust valve stems.
The intake Manifold was modified to contact the
middle two tubes of the header for good cold
weather warm up of the engine,I installed it and
the rebuilt early M151 Holley carb Ron
provided, in his experience he has found that the
Holley has better air flow and better
performance than the later Zenith carb.
Now I ran into MR Murphys law! I realized the
high performanc head had a plug in the hole for
the Heater return water line. It must have been
there since new not having ever been in a Mutt
with a heater. I tried the get it out, rounded it,
(soft steel) , drilled it for an easy out and broke
off a #4 easy out in it!!!
I drilled again and used a #5 easy out, well over
100 pounds of torque and I broke the easy out
again, I ground it out for a 3/8 square drive and
used a breaker bar which just made the hole
round (soft steel) .I was getting scared of
messing up the head at this point. Now was the
time for Zen in the art of Mutt mechanics,The
Tao of Mutt, deep breaths and prayers. I used a
small carbide cutter on my dremil tool and very
slowly and with great care ground it out until
there was only threads left, then I got lucky with
a tread tap , caught the start of the threads in the
head and what was left of the plug peeled right
out with the tap leaving the threads in the the
cast iron head intact and in good condition.
Whew, that was a close call, this one little fitting
took longer than the whole rest of the project!
What a feeling of satisfaction when I got it out
with no damage to the threads in the head!!!!
With the the head installed , valves adjusted to .017
cold (by the book) , I connected all the vent lines
and linkages . I found a couple of them to have bad
flairs and repaced them so as to not have Vacume
leaks.
Now for the exhaust, Ron provided a modified head
tube to match the header and the header design
made for easy bolt up and no clearance
problems.The Mutt needed a new exhaust system
anyway so now was a perfect time to do it. Ron told
me a trick to do with the stock muffler.There is a
baffle in the center of the main tube that looks like a
washer and causes a lot of back pressure,it can be
drilled all around with an 18 inch long drill bit from
the rear of the muffler and knocked out .Not the
easyest job but I managed to get it out and installed
my free flow Mod muffler to go along with the head
and header.
I switched the fan belts to NAPA# 7360 to move the
generator farther away from the header so as to not
have the wiring get too hot , cleaned up and got
ready to fire up the Mut and go for a Test Drive.
cold (by the book) , I connected all the vent lines
and linkages . I found a couple of them to have bad
flairs and repaced them so as to not have Vacume
leaks.
Now for the exhaust, Ron provided a modified head
tube to match the header and the header design
made for easy bolt up and no clearance
problems.The Mutt needed a new exhaust system
anyway so now was a perfect time to do it. Ron told
me a trick to do with the stock muffler.There is a
baffle in the center of the main tube that looks like a
washer and causes a lot of back pressure,it can be
drilled all around with an 18 inch long drill bit from
the rear of the muffler and knocked out .Not the
easyest job but I managed to get it out and installed
my free flow Mod muffler to go along with the head
and header.
I switched the fan belts to NAPA# 7360 to move the
generator farther away from the header so as to not
have the wiring get too hot , cleaned up and got
ready to fire up the Mut and go for a Test Drive.
Happy Mutting ,
otter
otter