is all this talk going on the assumption that all the
comparisons of vehicles are using the same rear end ratio? that will make a
difference in off the line snap.
mo jo
-----Original Message----- From:
John Sadowski <jsadowski@xxxxxxx> To: mailing-list@xxxxxxxxxxxxxxxx
<mailing-list@xxxxxxxxxxxxxxxx> Date:
Friday, July 12, 2002 1:24 AM Subject: Re: IML: Off line
response, was: 413 vs 440!
To very briefly sum it up, I think the 413 just plain runs
better then the 440. You can make all the improvements you want, but if it
doesn't run as good, its all for nothing.
----- Original Message -----
Sent: Thursday, July 11, 2002 7:12
AM
Subject: IML: Off line response, was:
413 vs 440!
At 10:12 PM 7/10/2002 -0700, you wrote: >I think we've
had a failure to communicate here. It's the exhaust valve >sizes
that I quoted as smaller. If there is a difference in intake ports,
I >have not noticed it.
Actually, I thought that these two
conversions went together (ie, when the intake ports were enlarged, the
exhaust valves were also changed at the same time). However, you
and Mike both say that your 67 heads are measured similar to the
66. What might be happening here is that Chrysler came up with the
new head design in the 67 model year (explaining the automotive press
reports), but there were several old 915 heads left over. Also,
(based on 67 road test of a GTX) it appears that the HP engines got
priority to the new head design, and the regular 440s got all the old
heads till they ran out of 915's. This is just a speculation on my
part, but I think it explains the conflict of information.
As for
off-line response, here is an interesting note. Both my 68's have
cam upgrades. The LeBaron seems to have an equivalent to an HP cam
(strong low end, but it peaks a bit higher than standard at about
3300-3500 rpm) but the sedan has an even bigger cam and a CH4B Ederblock
manifold (peaks about 4000-4200 rpm). My 68 Sedan has a lot less
torque than the LeBaron in the 2000-3500 range, but it also has quite a
bit better off-line response than the LeBaron! Confusing?
When wet for example, I can get both tires loose with the sedan (has
limited slip) but with the LeBaron, you can barely get one tire loose
(regular differential). This is done without revving the engine
with brakes on, just hit the gas. My guess is that the LeBaron
would soon catch up due to its better torque, and then the Sedan might
pull away again due to its considerably stronger upper end!
I think
the explanation may be in the carburetors, but it gets confusing there
too. Both have spread bores. The LeBaron has an unusual
Rochester (with fairly small primaries) and the sedan has a "standard"
(a bit bigger primaries) Carter. It is likely that the accelerator
pump on the LeBaron is not properly set, and causes the lag. Also,
there is a spacer to et the Rochester to fit, and may be the spacer
kills the low end. Also, the two cars have different torque
converters. The LeBaron has a lock up converter from the late
seventies, which seems to be slipping a bit more. So, the LeBaron
should have had the edge during the initial take off, but it
doesn't!
The difference in displacement between the 413 and the 440
is due entirely >to a bore change, they are both 3.75" stroke engines,
thus the low speed >torque is probably not much affected by the
displacement change as it would >be if it were due to a longer stroke
in the larger engine. Dick, very often people claim that a longer stroke
will give you more off line torque. I am not sure if this is
directly true. A longer stroke engine will usually have smaller
intake ports and valves than a short stroke engine of similar
displacement, and that might give you good low end response, but its not
the longer stroke that provides directly this "advantage". So, a
66 440 with the same intake manifold and ports as the 413 should have a
stronger off line response almost proportional to the displacement
difference... D^2
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