<VV> Prefered motor for 65 Monza 4speed? (John Gull)
d66dewald at gmail.com
Sun Oct 15 14:30:55 EDT 2017
On 10/12/2017 12:00, John Gull wrote:
>> Now to consider a standard140 or a PG140 with Standard shift bell housing for my 4 speed car! I have both motors and they both will need rebuilding before using in my 4 speed Monza. Which would you all prefer to use and why one over the other? Thanks in advance for your reccomendations John in NC pondering this age old question!
I think the decision on which motor to rebuild [which really boils down
to what cam to install] depends on how you will be using your car and
what differential ratio and transmission you have [or want to build].
Please first determine what differential you have. If the car was
originally optioned with a 140 engine then it most likely will have a
3.55:1 R&P ratio. If it had a 110, then it will likely have a 3.27:1
ratio. These often get changed during the 50+ year life of the car so
it is necessary to count teeth or measure turns to find out what is in
there. If you plan to also rebuild the differential and/or the
transmission then there is the option to install a 3.08:1 [OTTO parts]
For s street car with a 3.55:1 differential you will want to rebuild the
standard 140 with the factory 891 or 304 cam or Isky 270, OTTO OT-20, or
similar mild performance cam. There might be some newer cams to
consider. In this case you will want to use the the stock '65
transmission [3.20:1 first gear].
For a street car with the 3.27:1 differential and stock '65 transmission
there is more to consider. You might want to build in a little more low
end torque with the 140 engine by using one of the mild performance cams
(OT-20, 270, etc) with a modest 2 degree advance. This can be done with
an offset key on the cam gear. Talk to your engine builder about this,
especially if he can do some computer modeling.
If you build a 3.08:1 differential to make a highway cruising car then
you will also want to build a custom '65 4-speed using the gearset from
the 64-65 FC with a 3.65:1 first gear. Then you will want to build a
140PG type engine using a low performance engine cam; GM 889, OT-10,
Isky 260, etc (consider also a special torque cam sold by Ken Hand)
installed in the engine with a 4 degree retard. Your 140PG engine will
have the correct retarded gear already installed on the crankshaft. Use
this crank with the cam of your choice.
FWIW, my wife's '65 Monza has a '65 FC transmission and 3.08:1
differential installed behind a rebuilt +0.060 over 110 engine. This is
a very nice combination for a road car. The added torque from the bored
engine makes this combination work. Some improvements to the stock
heads would likely yield even greater performance with the comfortable
cruising RPM's of the 3.08. I have yet to go on a really long trip with
this car to find out what MPG it is able to get.
For more specific information you may email me directly.
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