At 10:03 AM 1/16/00 -0500, you wrote:
>If they both yield about the same HP increase, why would you go with 1.7:1
>rockers? Please explain in simple terms as I'm new to this aspect. ;-)
The 1.7s do give some hp increase over the 1.6s because the end result is
similar to putting in a cam with a tiny bit more lift than the stock cam
(don't know how much though). I have seen a DML posting that said that
the gain in performance was more than if you put in the MP Magnum R/T cam.
I have no idea if this is the case because I've read in a car magazine
that 1.7s were put in place of the 1.6s on a non-mopar engine and the dyno
results showed no or little gains.
Mopar Muscle had an article on putting 1.7s in a 3.9L. Dyno results
showed gains throughout the rpm range but only 1-6hp and 3-8 lb-ft
of torque depending on the rpm.
>Also, if 1.7:1 are the best choice what are all the parts that should be
>replaced to be absolutely sure there will be no failures or breakage.
In all probability, strengthen pushrods and valve springs.
>Lastly, will the 1.7:1's fit under the stock valve covers? TIA
Only if you 'flatten' out the ridge running lengthwise on the underside
of the valve covers. The other alternative is to get the MP Magnum
valve covers as they a little higher and 1.7s will then fit with no
mods to these covers.
IMHO, the added costs of 1.7s over 1.6s would probably better used
elsewhere for the gains that you get. Some even question the
cost of roller rockers over the stock rockers ... again performance
gains are really small. IMHO, it depends on how much faith you
put the argument that roller rockers provide long term durability
(after all, any performance gains are mainly because the rockers are
no longer slap back and forth across the ends of the valve stems
as they're opened and closed). Another common occurence is that
OE stamped rockers are more likely to vary greatly in sized when
produced ... not really a good thing.
The reason that I chose to go with the 1.6 roller rockers was the
durability factor over a long period of time while getting
the engine to high rpms in the shortest time possible (track).
Can I prove it? NOPE.
Hope this helps.
Bob. Southern Ontario, Canada.
'97 Dakota CC Sport, FR, 5.2L, 3.55 SG, auto.
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 11:46:48 EDT