GM Engine Sizes (was Chevy engines)

[Greg Hermann]

>On Fri, 6 Nov 1998, Tom Sharpe wrote:
>
>>
>> > All this talk about GM engines leads me to postulate a theory about GM
>> > engine size and ask if anyone really knows...
>> >
>> 421,425, 426, 427, 428 engines from Ford, GM and Chrysler were all <= 7
>>Liters,
>> the FIA limit, same as the 5 liter (302) limit. The 428 Ford is actually
>>at 426,
>> but that name was already taken. The marketing name often did not match the
>> actual displacement, ie 396 and 402s called 396 and 400.
>>
>True. The marketing size and the actual size are often different. We are
>dealing with a trivial size difference of course. This reminds me of the
>urban legends surrounding trivial axle ratio differences in 4X4s.

Not sure what you are calling trivial here--

For example, if you are going to run a 4.09 (45:11) and a 4.10 (41:10)
gearsets; or 4.10 and a 4.11 (37:9) gearsets, you are way better off to
have the 4.09 or 4.10 gearset (respectively) in the front pumpkin--as
turning the front wheels a fuzz faster when in 4 wheel drive, locked up,
makes a fair bit of difference in terms of vehicle stability. (The second
sets of numbers in parentheses are actual ring and pinion tooth counts
which correspond to each stated ratio, demonstrating that the seemingly
trivial differences in ratio numbers DO have a basis in the physical facts
of the situation. Another SIGNIFICANT fact, for 4-wheelers, drag racers,
and street racers alike, is that, for a given size (diameter) of ring gear,
a gear set with a higher number of teeth on the pinion is significantly
stronger than one with less teeth (in rough proportion to the number of
pinion teeth)! Then you get into the question of whether you are driving a
gearset on the drive or the coast side of the teeth, particularly in a
front drive axle--this is what "reverse rotation" (high pinion) gearsets
are all about--and the fact that driving on the drive side of the teeth
gives about 20% more gear strength for  the same gears. Also, driving on
the drive side of the teeth tends to push the pinion OUT of mesh, and so
puts the thrust onto the inner pinion bearing (larger), driving on the
coast side does the reverse, and puts the thrust on the smaller outer
bearing (and on the crush sleeve, if you are silly enough not to change one
of those %^&*$  things out to a non-yielding spacer sleeve and solid
shims!!

Sorry--non-efi! :-)

Regards, Greg