Trick flow Double Hump alloy heads

[steve cowan]

Received one of these from Summit today.
Took some measurements today hopefully flow test over the weekend,these heads are going on my weekend cruiser so not going overboard.
450 hp 383 sbc,turbo 350 with 4200 9" converter 3.7:1 rear gear.
Just wanted to share some information.
The couple of things I have found so far-
Guides are tight
Pinch is very small 1.68 " CSA includes radius
Would take some work to fit 3/8" pushrods I will run 5/16"
The casting, valve job and chamber seem good,
I blued and back- blued seat and looks good.
With the 60cc chamber the 37deg top cut is very close to the deck,I want change top cut to 40deg and test.
Intake throat is 1.79" - 88% of 2.02" valve
Exhaust throat is 1.38 " - 86% of a 1.6 " valve.
Intake bowl is 1.90" - 94% of 2.02 " valve
Exhaust bowl is 1.53" - 96% of a 1.6" valve
Will put up flow numbers and velocity profile in a couple of days.

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[mag2555]

The Intake throat is 94%!!!

I would without hesitation step up to a 2.05" Intake valve , recut the seats to get the 45 degree Seat OD out to 2.040" and I would make use of that 1 CC or so larger Intake valve to unshroud the chamber if your not fighting for compression.

You only need 240 cfm to attain your 450 hp.

That deck finish looks great!

[skinny z]

383 sbc...
60cc chamber...

A quick question, a little off topic though.
How will you manage your compression ratio? I'm guessing a heavily dished piston?

[steve cowan]

The Intake throat is 94%!!!

I would without hesitation step up to a 2.05" Intake valve , recut the seats to get the 45 degree Seat OD out to 2.040" and I would make use of that 1 CC or so larger Intake valve to unshroud the chamber if your not fighting for compression.

You only need 240 cfm to attain your 450 hp.

That deck finish looks great!

Mag
Throat is 88%
Bowl is 94%

[steve cowan]

383 sbc...
60cc chamber...

A quick question, a little off topic though.
How will you manage your compression ratio? I'm guessing a heavily dished piston?

Kevin
At a guess it will around 11.5:1
I personally don't have a issue with that with our 98 fuel.
My other 010 383 with my dart 182cc cast iron heads with 0.028" piston to head,64 cc chamber pumps 225 psi cranking compression
Pumpgas runs 11.10s at 120mph at 3650 pounds streeter.
Alot of guys take issue with pumpgas and a bit of compression, I dont

[steve cowan]

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Currently a straight 6 cylinder but upgrades coming.
Picking up a new GM 350 block today.
This is a 1975 HJ Holden 4 door sedan.factory colours.

[F-BIRD'88]

Unique cars there.

[HQM383]

Unique cars there.

And since Holden closed its doors in 2017 a car like that is fetching up to AUD$60,000.

Interested to see what these heads do on a 383.

[1980RS]

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Currently a straight 6 cylinder but upgrades coming.
Picking up a new GM 350 block today.
This is a 1975 HJ Holden 4 door sedan.factory colours.

That little car is friggin cool. I will be watching this thread to see how your project turns out. Great work so far.

[Geoff2]

The two door version is also a great looking car. In my opinion, it has a better shape/style than the US GM A bodies of 1968 to ~1972.

[MELWAY]

The two door version is also a great looking car. In my opinion, it has a better shape/style than the US GM A bodies of 1968 to ~1972.

GM Holden engineers designed some awesome cars in their day for sure

[RevTheory]

I have a feeling that head is going to port out quite nicely. Anyone know how those heads compare to AFR's Enforcer?

[MELWAY]

Steve
Be really interested in the capabilities of this casting
Would be cool if it could flow in the 290s and make 600* Hp
And be made to look original

[skinny z]

383 sbc...
60cc chamber...

A quick question, a little off topic though.
How will you manage your compression ratio? I'm guessing a heavily dished piston?

Kevin
At a guess it will around 11.5:1
I personally don't have a issue with that with our 98 fuel.
My other 010 383 with my dart 182cc cast iron heads with 0.028" piston to head,64 cc chamber pumps 225 psi cranking compression
Pumpgas runs 11.10s at 120mph at 3650 pounds streeter.
Alot of guys take issue with pumpgas and a bit of compression, I dont

Thanks for that Steve.
Your "other" 383 appears to be similar to the long (long) awaited project I'm plodding through. (On a historical note, I actually started back working on the car just yesterday so it begins...)
Do you have a thread somewhere as to what went into the other engine? (.028" PTH?)
It seems a 383 and small(ish) iron heads are part of my plan too.
I apologize if I've asked that before. It's been a long time.

[1980RS]

The two door version is also a great looking car. In my opinion, it has a better shape/style than the US GM A bodies of 1968 to ~1972.

GM Holden engineers designed some awesome cars in their day for sure

Agreed