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>Thank you all for your great input. Daniel - WOW!.
You're welcome :-)
>Since I want to increase the engine output for as little cost as possible,
>this is a prioritized list of changes I came up with based on everyone's
>input, keeping the cost in mind.
Okay.
>1. Install the exhaust side port plates on my current open chamber 4V heads.
Yes.
>2. Tune the carb.
Yes. The new DIY wide band O2 kits make this much easier.
>3. Install a new, more aggressive cam; 230-232 duration @ .050, .545-.550
>lift (possibly ~530 if I want to be somewhat conservative), 108-110 lobe
>centers (non roller), replacing the 220/.505/114.
Yes. Go for the higher lift. My 220 deg @ 0.050 is 0.530". 230 deg should
be more like 0.545"-0.550". If you want it milder, go for 110 lobe centers.
>But this may give less than optimal results and driveability with the current
>open chamber heads.
Yes.
>4. Install closed chamber 4V heads to get the compression up and really make
>use of the new cam. Retain the restrictor plates on both intake and exhaust.
Dump the intake port plates. Consider Roush-type port stuffers. If you
use the port stuffers, have the intake manifold ports welded up to match
(raise the port floors).
>5. Install a new Holley Strip Dominator single plane intake, replacing the
>Edelbrock Performer dual plane.
Holley Strip Dominator single plane or Blue Thunder dual plane. If cold
weather operation or quick warm up is important, consider the Blue Thunder
as it has carb heat (the Holley Strip Dominator does not). Do not block
off the dual plane's carb heat port.
You may want to do this at the same time as the cam swap since you'll
already have the intake off. If not, 351C intake manifold swaps are dead
simple since no water flows through them and the distributor can stay in
place.
>6. Install new header downtubes with a diameter smaller than 1 7/8.
You may not be able to find a 1 3/4" off-the-shelf header with a 4V
flange. 1 7/8" should be available though. Not a problem if building
your own.
>7. Install a trick IR EFI intake system.
Big dollars but allows a much larger cam to run while retaining street
manners. The Pantera Performance Center in Colorado sells a low
profile kit for Panteras that would fit under a Cobra hood. Price is
around $5000 though. Cheaper systems are under development...
>While most all of the changes will probably increase torque along with
>big HP gains, it sounds like the Aussie heads would NOT be the best
>choice of heads for use in a Cobra due to their torque bias.
Unported Aussie heads will limit peak horsepower but be very responsive.
Properly ported, they'd do just fine across the board but will cost
more than 4V's.
>Also, considering the Aussie's need porting work whereas the 4V's are
>bolt on and the restrictor plates will help somewhat on the port size
>and velocity issue, the 4V would be much more cost effective - true?
True. I'm not a fan of the MPG intake side port tongues but I do like
the Roush port stuffers (Marino Perna at Panteras East also sells a
similar port stuffer), provided you weld up the intake manifold ports to
match. You must make the decision to do this before you install the
heads as there is some machining involved (drilled for a set screw and
faced). If you go this way, I'd tend towards the Strip Dominator as the
slope on one plane of the Blue Thunder ports may not match well.
>Well, how's that look?
Remember the timing reqirements of open and closed chamber heads are
different. Closed chamber heads require less total timing.
Dan Jones
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