[DeTomaso] 2V Heads?

[Daniel C Jones]

> I am getting ready to replace my 4V closed chamber cast iron heads with
> a set of 2V aluminum units.  My current intake is an Edelbrock Performer.
> I'm assuming that I need to replace my 4V Performer with a 2V Performer.
> It makes sense but I thought I would ask.

You do want to switch to an intake with 2V size and shape intake ports,
though I would suggest a better intake than the 2V Performer.

> If you don't care about the engine screen, you can fit the new Edelbrock
> Performer RPM intake, which is nominally designed to work with the
> Edelbrock heads: It's too tall to allow you to run the engine screen.

Yes.  Notice the RPM is an air gap manifold.  If you live and drive in
a cold climate, cold start will take an annoyingly long time.  Another
option in tall air gap inakes would be a Parker Funnelweb 2V single plane.

> Weiand X-Celerator 351V-2V (7516)
> - low rise single plane with Holley carb bolt pattern
> - ports are larger than head ports. It's essentially pre-ported and
> requires the heads be match ported to the intake.

Be aware there were two versions of the 7516 Weiand.  On has larger
ports than the other other.

> I think that's what he recommended to Charlie McCall, who's 351C is now
> sporting iron Aussie heads and this intake.

Correct.

> Given that Dan is running this intake on his own engine, I'd have to say
> it's a pretty safe guess!

Correction, I used to run that intake.  It's a good choice for a 2V intake
that needs to fit under a stock engine screen.

> One thing I KNOW for sure, Charlie's motor is very, very strong!

A straightforward build with well-matched components.  The cam works
in the same RPM range as the intake and heads.

> He said the ports matched quite well with only a minor port-matching
> required.

I'd suggest not doing this because it alters your cylinder heads,
making the port match less than desirable on other 2V intakes, many
of which work better than the Performer in the first place.

> This is because the Edelbrock 2V intake has LARGER ports than the stock
> 2V Cleveland head,

Not true.  The Edelbrock 2V intake has ports that are the same size as
the 351C-2V heads.  The only commonly available 2V intake woth smaller
ports was the Holley Street Dominator.

> AND the Performer 4V intake has SMALLER ports/runners that the stock 4V
> Cleveland intake.

True.  The Performer 4V has smaller ports than a 351C-4V head but
they are also shaped differently than 351C-2V head ports.  You'd
need to port match but I don't know why you would do that.  If you
want a low rise dual plane, get the Performer 2V.  If you want a
higher performance intake, there are several to choose from.

> The area of the runner should increase all the way to the plenum.

Goran is correct.  Ideally you want a wet flow intake manifold to
taper between 1.5 and 3 degrees from larger to smaller from the
plenum entry to the cylinder head.  This keeps the flow speed up
and lessens the chance of fuel falling out of suspension.  Simply
port matching an intake is often counter-productive because of
this fact.

> I am considering the aluminum 2V Cleveland heads from Trick Flow.
> I saw a pre-production set at this year's SEMA show and liked the
> stated flow characteristics better than the Edelbrocks.

Then you should definately be looking at a better intake than
the Edelbrock Performer.  It does you little good to have a
cylinder head that flows 300+ CFM when your intake only flows
230 CFM.  We saw this repeatedly when flow bench testing dual
plane 4V intakes.  Our iron 4V heads flowed 322 CFM but when
the dual plane intakes were bolted up, half the runners flowed
in the 250 CFM range.  With some flow bench work on the dual
plane intakes, we got much of that flow back (better than
some single plane intakes but not as good as the best single
plane intakes).  On our engine, the difference in intake
manifolding was on the order of 50 HP.

If you do go with the TFS heads, consider shipping them to
me first and we'll flow bench test them with and without
intake manifolds in place.  We can also dyno test the heads
with your choice of intakes.  I'll even work you up a custom
cam, if you'd like.  I have nearly all of the 2V intakes on
hand, including ported versions, so we can do a thorough
evaluation.

I'm not sure if I mentioned it but the dyno mule engine is
ready to fire and should be running on the dyno this week
for break-in.

Dan Jones