My 347 uses 5.400" rods....is the coolest running Tiger that I am aware
of..Mostly on the thermostat at 160 degrees...and somehow it makes 410 ft.
lbs torque at 44oo rpm....and make a tad over 300 at 3000 rpms...Believe the
R/S ratio to be 1.6.
What ought to be focused upon is the piston and ring pkg and how some of
those problems were solved..
Ken Mattice
----- Original Message -----
From: Ronak, TP (Timothy) <Timothy.P.Ronak@akzo-nobel.com>
To: <jpmorrison@erols.com>
Cc: 'Tiger News Group List' <tigers@autox.team.net>
Sent: Wednesday, March 29, 2000 8:26 AM
Subject: Strocker Motor
> Jim and Listers,
> I too am interested in building the 347 motor. A couple of considerations
> that you need to noodle are Wear, Heat and Rod angle. In talking with a
"Old
> Ford Racer" guy named Jim. (He is the guy locally building the killer
> "Alger" 302 powered) He indicated that the 347 suffers from severe piston
> skirt wear and friction (read HEAT) due to the extremely short connecting
> rod in comparison to the larger stroke (Rod / Stroke Ratio).
>
> Example:
> In a small Block Chevy going from the stock 5.65" rod in a 400 to a 6" rod
> improved the Rod / Stroke ratio from 1.5 to 1.6 ...the equivalent of a
stock
> 350 cu. In. motor. (Key point is that stock 400 Chevy's were notorious for
> overheating and piston wear, the low rod/stroke ratio was a contributor).
> The result was about a 15% INCREASE in Torque across the RPM range due to
> the effect of increasing the Piston Dwell at TDC. This also did not result
> in any extra wear on the engine components and the engine was very
> insensitive to timing and jetting.
> Compare to the stock 260 - 289 Rod/stroke ratio of 1.79 which is excellent
> for wear, RPM and loading of the engine and contributes to the high amount
> of low RPM torque. The 302 has a rod/stroke ratio of 1.69 and the 351 W
has
> a ratio of 1.702 which maintains the rod angle similar to the 302. The 347
> however if I am not mistaken uses the 351 stroke of 3.5" with the 302 rod
> length of 5.090" yielding a rod / stroke ratio of 1.45 which is lower than
> the 400 in. Chevy.
>
> Also, Jim indicated the motors are very touchy when it comes to ignition
> timing due to the amount of Dwell the piston sits at TDC. This decreased
> Dwell may in fact result in incomplete combustion and may not be as
> efficient an engine as a 302 with a longer Dwell at TDC (better Rod/stroke
> ratio). This means that you may not be able to "fill" the cylinder with
fuel
> as completely as the 302 motor with all other variables constant. While I
am
> still interested in putting the extra cubes into my Tiger I am concerned
> about the extra friction that side loading the pistons will create and the
> loss of piston Dwell. The longer stroke may also tend to lower the optimal
> (read peak) RPM of the motor. The extra friction (heat) may be the
> proverbial straw that breaks the taxed Tiger cooling system. I am curious
if
> other guys out there running the 347 have had cooling, wear or tuning
> issues. I am still very interested in building the 347 but may be leaning
to
> a .060 over 302 with some compression and excellent heads for more
reliable
> HP with less heat at higher RPM.
> On the other hand every Race motor I have worked with the underlying rule
> that I have abided by is:
> "There is no REPLACEMENT for DISPLACEMENT!!"
> Any one else have comments??
>
> Way to go Jim we are back talking performance stuff !!
>
> Regards,
> Tim Ronak
> B382000680
>
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