How much torque and hp will it make?
 

466 .020 over 73 455 block, 6X -8 well ported heads (285 cfm int), 2.11/1.77, milled .060", 9.3:1 compression, flat top piston, solid flat tappet 250/260 duration @ .050", 110 lobe sep, 1.65 roller rockers, 4.250" stroke, 6.800" rod, cleaned up Perf RPM intake, 1" plastic open spacer, out of the box 950 HP Ultra carb, 2" pri GTO headers 3.5" flat collectors, 18" extensions.
How much muscle?
Will it have obnoxious idle characteristics at 1000 rpm? Subjective I know, but thought I would get opinions.

680 hp
625 tq

I ran a single pattern [email protected] 110 lsa 106 icl solid in a 400 and idle was right at about 850-900 rpm.... About 10" vacuum in gear with an 8" convertor. With your longer stroke I'd expect your cam to behave at least as nice.

Power... The dual plane intake is probably going to hold peak power down some... I'm thinking @575 hp 600 ft lbs.
Personally I'd try a T2 or Victor or at least the equivalent of a well ported HSD.

570 HP

I had a similar setup once butt the heads flowed 250's and about 1.5 higher compression than yours. Made like low to mid 500 hp range on the dyno if I remember right. That cam and rockers should make for a noticeable idle....even more so if you added some more compression. I used the T2 intake,,,,liked it very much,,,very responsive for a single plane.

My numbers say 595 HP mostly because of the HP Holley Ultra Carb and the 285 cfm head flow.

Tom V.

550hp, 572 tq.

Choppy good sounding idle...

520 @ 5900

Jim , I put together a very similar combo for my son to drive in my car a few years back . Used a bunch of stuff laying around the garage . Used torker 2 with dominator adapter , solid flat tappet cam , shift at 5500 . Ran some 10.70s @123 weighing 3750 . Dusting it off and putting it in the T37 for this year . I figured it had to be 575 at least .

Not positive about the HP, but 285cfm out of cavernous 6X-8 D ports. That is not easy, good job my man.

582 HP, will be a beast in a street car.

585 HP.My 455 with 290 KREs at 10.25 CR,245-252@50 on a 110 600 lift with a factory dual plain and a 750AFB,2in headers made 550.More CI,more cam,bigger carb and better intake has to be worth at lease 35HP.Tom

603hp 558trq

Hey Jim

I’ll put in a WAG. With what you know with head porting, it’ll be a torque beast.
627 tq
581 hp

Brian

Outtada box 950 carb may not idle unless there a hellava idle bleed air circuit.

My 9.0:1 will idle on modified Q-JET & 1050 2-circuit carb, but would not even fire with a Stock 68 Q-JET rebuild.

You may want to try a known-capable low-compr low-vacuum carb on break-in.

Once itsa idlng and all, 468 HP.

580 HP @ 5600
630 TQ @ 4400

Copy cat. Lol

Brian

Wow, just realized you had almost the same numbers. I wasn't paying attention, and thought yours were reversed with higher HP and lower TQ.

594 hp
621 tq
This guy knows his way around an engine.

It’s all good. Just givin ya sh!t. :)

Brian

This very streetable 466 made peak tq of 621 lb-ft at 4700 and a peak of 616.5 hp at 5800. Mike McCarty must have been there hiding in the corner. :-) We took extra care with the mods to the heads and intake to extend the RPM a few hundred over previous similar combinations. Idled very nicely at 1050 at a steady 10" vacuum. Going in a restored 77 Can Am...That looks like all the other Can Ams. If you run across a Can Am with Texas plates be careful picking on this one. He plans to autocross, drag and street drive it. Giddy up.

Great build! Impressive.

Nice Jim. Glad it's more torque/hp than I estimated. Thanks for sharing.

Jim, you can port some heads. Those are VERY good numbers for what it is. Numbers like "pump gas 600HP E heads" get only with bigger cams.
I have a iron headed TRW 455 that does good. Same 9.3 CR but with round port HOs. About 570HP by weight/ET/MPH. But with bigger solid roller that is not very streetable.
People can seem to give away those 6 X-8s. Just gave them a reason to think about builds with them. I have a set given to me.
Again, nice job.

So I was off in 4 ft lbs of torque

Hell that was EZ for Jim,he got 292 on my friends 127 heads with a 2.02 intake!Tom

Looks like a tie to me with my good friend Mike McCarty. He hit the torque number on the nose.

His hp was 594. My HP number was 598 hp.
I did not post a torque number.

Last Time I looked 598 HP is closer to your Dyno HP number vs 594 Hp but Mike did give you both numbers.

Ton V.

tom s I thought only bad news traveled fast...Dang! I told the customer about his 127 heads yesterday. Those 127s have some roof height that is missing from the 6X and they responded nicely. Thread for another day.

68azbird I wish it made 680Hp.:-)

Jim,so few people have actually worked on those heads that are still around.A head that was born around 1960,I know Nunzi had got over 300 on a set of 980s years ago.He told me he would never do a set that high again.He said the 290s was about as far as he liked.The 980s had a lot better exhaust.Tom

127 exh went 242 cfm. These will make a great set of heads. There is more than one reason Smokey was successful with the Pontiacs of the early 60s.

A few tweaks and an intake manifold change and it would be there.

Hi Jim, great numbers, hope I'm next. Going to have to step back on cam a bit for my combo with stock rods short block.
Sean

Hello Sean. Lots of cool projects taking shape here including yours. Your heads are smaller and thus will peak at a lower rpm.

On the subject of intake manifolds...We did believe there were some good info to be gained by testing other components with this engine combination. So, we tested 6 different intake manifolds on this engine along with another set of ported 6X heads with the same manifolds. In addition to Performer RPM we tested a ported Nash designed intake (aka Warrior & SK), stock Torker II, Offenhauser 360, Ported OEM (1972) iron intake and Performer Pontiac. The results were eye opening. We try to accomplish R&D regularly but it is hard to fit it all in with the cool projects already on the to-do list. Has anyone run an Offy 360 intake? Our dyno test may be one of the very few ever recorded. How much did we loose with the Performer Pontiac? Is an OEM iron intake worth any more than scrap metal prices?

Manifold test info would be interesting. Offy h-rise has me curious. Seems like it's all plenum.

Would love to see those test results!

Outstanding numbers Jim!! At a relatively low compression ratio to boot. I'm impressed to say the least.

Would love to see an intake manifold summary of your testing if you care to share.

Me too!

Please, do tell on manifold testing.

Great job Jim! Outstanding as expected. :)

Brian

subscribed! Nice job!!

Looking forward to hearing more. Lots of good Pontiac data gained it sounds like.

Jim, what did the other 6Xs flow? Smaller ports? what number did they make?

thanks

how many cc did you get out of the runners?

This thread just convinced me to retain the 6x on my current setup (250cfm) knowing there is the potential to get another 20-30cfm out of them from the right porter of course.

Is the cam off the shelf or custom grind?

Did you or will you try out a tapered 4-hole 1" spacer? It may help get the idle down under 1000rpm and not hurt the overall power numbers you got.

No real surprise but the SK made the most power followed very closely by the RPM. Performer Pontiac was a distant last/worst. Did I mention we swapped the 2" headers for a set of Ram Air Restorations RA III manifolds? Will post some numbers in a few...

Hurry up, I keep hitting refresh! :D

A little more clarification:
I originally ported the heads described in the first post in 2005. Those intake ports are "large" for a 6X. Because this short block was my close friend's, he allowed me to use it for this special manifold shootout. So I ported another set of 6X -8 heads for this effort and installed same part number valves, springs, retainers, locks, and set up dimensions. These flowed 292 cfm and are "smaller" in cross section areas than the 285 cfm. I knew the port cross section would increase velocity and the additional flow was a bonus but could we find the point where more flow did not result in more HP. Was there a sweet spot in our old iron that resulted in better TQ and HP? We went to great lengths and expense (time and money) to minimize variables. The results below are with the 292 cfm heads.

Peaks
Performer RPM - TQ 609.4 and HP 587.9
SK - TQ 611.1 and HP 598.7
Offy 360 - TQ 586.9 and HP 586.4
Stock Torker II (port match to vintage 503 only) - TQ 602.2 and HP 592.4
Ported OEM iron with Hamburger adapter to 4150 - TQ 593.1 and HP 583.1

I want to send a special thanks to my team of dyno junkies for your can-do attitude, for your abilities to move quickly through the wrenching chores and for the comradery as we whipped on these old pieces of Detroit wonder metal.

Don't trade your ole D-ports off just yet...

Iron D-ports still rock!

Thanks for the results. Years ago I did some back to back "poor mans" drag strip testing with stockish 96s. Warrior was best then RPM, T2 then T1.
I have a 4150 P4B, has large runners so it looks interesting. Anyone want to try it let me know.
I have a Tomahawk with a little work done and it runs very close to the Warrior. Have a Northwind on the way, should be interesting too. Dan Whittmore always said the Warrior was very good dispute what some said.

Jim- do you know how two fours on a Nash tunnel-ram would compare with those [impressive!] single-four numbers? Or would the rest of the combo not be optimum for two fours?

I kick myself for not buying one of those Warrior 2x4 intakes when I bought mine. They were only like 480 $
Kick myself for not buying a Thompson .45 cal too when you could get them.