[DA GOAT]

Looking for real‑world feedback on Tomahawk vs ’72 H/O aluminum for my street 455

Here’s the combo:

ENGINE

• 455, .030 over

• SD‑ported 6X‑8 heads (264 cfm)

• Cam H1750

• Advertised duration: 280° / 288°

• Duration @ .050: 223° / 231°

• Lift (1.5 rockers): .463” / .485”

• LSA: 110°

• Q‑Jet (800 cfm)

• Doug’s 1‑7/8” headers

DRIVETRAIN

• 200‑4R

• 2400 stall (flashes ~2600–2800)

• 3.23 gear

• 225/60R15 tires

CAR

• 1965 GTO convertible

• Street use: roll‑ons, cruising, some track

QUESTION

Which intake works better with this setup? I plan on staying in low 5000s rpm, so Performer RPM probably not ideal?

[steve25]

If those -8 heads have only had a clean up mill then I would mill those heads .050” to .060” before doing an intake swap.

[Half-Inch Stud]

Dual-Plane.some good choices. Probably in this order:

Factory iron (port matched, means get the grinder out).
Speedmaster ( mild port matching, means get the grinder but not much to do).
Performer RPM. ( probably need grinder to port match ).
72 HO manifold: ( port match, means get the grinder out)

Seems you got to grind for intake runner CSA match.

[PAUL K]

The HO will be faster at the track with a good pass

[Formulas]

Not nearly enough camshaft for a single plane... The Tomahawk excels at a higher RPM than that camshaft will go and the camshaft excels where the single plane intake is lazy... In use you would end up with a truncated power band = narrower than usual

[65 Lamnas]

FWIW, my ported #488945 picked up 56HP over a stocker.

[steve25]

The OP is not going to pick up 56 hp with only 260 cfm heads under either intake manifold!

[sdbob]

Truman Fields told me with stock intake try a thicker carb gasket and tune it. I cant remember if open or closed though.

[Half-Inch Stud]

Assure Full advance gets to 34* at ~2400 rpm ( no vacuum adv ).

Assure Secondaries open fully with gas pedal. Tune the Q-JET for crisp Accel Pump response, and Sec Air damper action. Then try thinner=richer Sec Rods.

Hmmm, the cam seems 10*-15* shy on the Intake side. Compare to my signature cam sizes ( i can't see em until this posts) for what is too much duration ).

So maybe 1.65:1 on the intakes only? Not a daily driver so Lobe Life not too big a worry.

[DA GOAT]

Some really great comments. Thanks guys. AI brought me down a bad g rabbit hole. I have a torker 1 and Holley 750 double pumper on it now. I do want to put a rebuilt quadrajet 800 cfm quadrajet on it. I’m thinking I may want to experiment with the qjet, adapter, and keep the Torker 1 on it and see how that goes for street driving.

[65 Lamnas]

Originally Posted by steve25

The OP is not going to pick up 56 hp with only 260 cfm heads under either intake manifold!

I've not seen where anyone has indicated he would. Good job of reading comprehension.

[DA GOAT]

Originally Posted by DA GOAT

Some really great comments. Thanks guys. AI brought me down a bad g rabbit hole. I have a torker 1 and Holley 750 double pumper on it now. I do want to put a rebuilt quadrajet 800 cfm quadrajet on it. I’m thinking I may want to experiment with the qjet, adapter, and keep the Torker 1 on it and see how that goes for street driving.

Originally Posted by Half-Inch Stud

Dual-Plane.some good choices. Probably in this order:

Factory iron (port matched, means get the grinder out).
Speedmaster ( mild port matching, means get the grinder but not much to do).
Performer RPM. ( probably need grinder to port match ).
72 HO manifold: ( port match, means get the grinder out)

Seems you got to grind for intake runner CSA match.

So you’re saying there’s a chance a grinder may be in my future lol. I’ve done some on my last Buick GS so that’ll be alright. New to pontiacs so not familiar with speed master… is that a modern RPM? Also, in your order are you saying the iron intake is the best fit? Even with my 2400 stall? Thanks!

[Singleton]

If that 455HO intake is a new reproduction, keep in mind that the port alignment is probably WAY off. May require extensive grinding to get them anywhere near close.

[steve25]

And your reply in post number 6 wasn’t put up with the intention of alluding to that?

Give me and others on this string a break.

[Steve C.]

Regarding your SD‑ported 6X‑8 heads (264 cfm).
Depending the a amount of port work done to them some grinding may be necessary on a "Tomahawk" intake as well.

See posts 18 & 19 here:

https://forums.maxperformanceinc.com...omahawk+intake

Other comments within that thread might be of interest as well.



.

[65 Lamnas]

Originally Posted by steve25

And your reply in post number 6 wasn’t put up with the intention of alluding to that?

Give me and others on this string a break.

You already made an assumption and you were incorrect.

I didn’t imply or allude anything, other than I run a ‘72 HO intake, and they have a decent potential.

If you inferred anything else than that, it’s on you.

I’m out.