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post #31 of 54 (permalink) Old Oct 19th, 18, 1:08 AM
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Re: Small cam/ big head theory

It's kinda hard to compare the 2018 LT1 with what we drive as those cylinder heads support a direct injection cylinder design and the pistons that go with it.I think when you remove the fuel from the airflow it changes the way the air flows.Plus the direct injection is worth a bunch of HP and driveability on just that alone.

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71 El Camino SS
406 SBC M21 3.31 12 bolt
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post #32 of 54 (permalink) Old Oct 19th, 18, 1:26 AM
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Re: Small cam/ big head theory

Quote:
Originally Posted by Aaron View Post
I gotcha. I forgot about the mainly street driving and etc. Its a great combo.
Thanks he is having fun with it.

69 Camaro
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post #33 of 54 (permalink) Old Oct 19th, 18, 5:05 AM
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Re: Small cam/ big head theory

Aaron,
You are missing the point. Sure, you may get some good HP #s with heads with big port heads & small-ish cam, but using heads with smaller ports that better match the rest of the combination can make the same HP, but more low/mid range torque than the big port heads. That is what you miss out on....

There is a guy who runs a heavy LeMans station wagon, over 4000 lbs. Mild HFT cam 234/242 @ 050 in a 455, Rhoads lifters, idles @ 600 rpm, T 400, air cond, factory iron low perf heads, QJ, has run 11.3 @ 117mph. Heads were home ported. Every thing works together....

In David Vizards SBC book, he tests various port size heads & concludes that going too big on port size produces worse results almost everywhere in the rpm range.
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post #34 of 54 (permalink) Old Oct 19th, 18, 8:34 AM
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Re: Small cam/ big head theory

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Originally Posted by Gtogeoff View Post
Aaron,
You are missing the point. Sure, you may get some good HP #s with heads with big port heads & small-ish cam, but using heads with smaller ports that better match the rest of the combination can make the same HP, but more low/mid range torque than the big port heads. That is what you miss out on....

There is a guy who runs a heavy LeMans station wagon, over 4000 lbs. Mild HFT cam 234/242 @ 050 in a 455, Rhoads lifters, idles @ 600 rpm, T 400, air cond, factory iron low perf heads, QJ, has run 11.3 @ 117mph. Heads were home ported. Every thing works together....

In David Vizards SBC book, he tests various port size heads & concludes that going too big on port size produces worse results almost everywhere in the rpm range.
I agree. My ElCo had a .060 over 350 with a 214 @ .050 and .449 lift cam with 289 power pack heads. The low to mid range torque was truly just brutal for a 350. Lotta port velocity. Neck snapping like when you punched it and had traction.

First car was a 1969 El Camino. .....I miss it, great car.

Currently: 1967 Royal Plum Camaro
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post #35 of 54 (permalink) Old Oct 19th, 18, 9:27 AM Thread Starter
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Re: Small cam/ big head theory

Quote:
Originally Posted by Gtogeoff View Post
Aaron,
You are missing the point. Sure, you may get some good HP #s with heads with big port heads & small-ish cam, but using heads with smaller ports that better match the rest of the combination can make the same HP, but more low/mid range torque than the big port heads. That is what you miss out on....

There is a guy who runs a heavy LeMans station wagon, over 4000 lbs. Mild HFT cam 234/242 @ 050 in a 455, Rhoads lifters, idles @ 600 rpm, T 400, air cond, factory iron low perf heads, QJ, has run 11.3 @ 117mph. Heads were home ported. Every thing works together....

In David Vizards SBC book, he tests various port size heads & concludes that going too big on port size produces worse results almost everywhere in the rpm range.
YES, I realize this. Thanks Gtogeoff.

67 chevelle malibu / SS/ custom

Currently undergoing a metal work to remove all rust, if I ever get there.

Cant decide on prostreet or cruiser with a 4 speed.
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post #36 of 54 (permalink) Old Oct 19th, 18, 9:28 AM Thread Starter
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Re: Small cam/ big head theory

Quote:
Originally Posted by Arch Stanton View Post
I agree. My ElCo had a .060 over 350 with a 214 @ .050 and .449 lift cam with 289 power pack heads. The low to mid range torque was truly just brutal for a 350. Lotta port velocity. Neck snapping like when you punched it and had traction.
John, the original zz4 was like this with the L98 head on the zz4.

67 chevelle malibu / SS/ custom

Currently undergoing a metal work to remove all rust, if I ever get there.

Cant decide on prostreet or cruiser with a 4 speed.
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post #37 of 54 (permalink) Old Oct 19th, 18, 12:46 PM
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Re: Small cam/ big head theory

Quote:
Originally Posted by Aaron View Post
John, the original zz4 was like this with the L98 head on the zz4.
It was a great street cruiser that had just enough to keep entertained from stoplight to stoplight.

First car was a 1969 El Camino. .....I miss it, great car.

Currently: 1967 Royal Plum Camaro
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post #38 of 54 (permalink) Old Oct 19th, 18, 9:24 PM
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Re: Small cam/ big head theory

What's the application.

For a good performing street engine, you would want a very efficient port configuration in conjunction with a Cam that will offer decent driving characteristics. That being, enough vacuum to give a decent idle and vacuum brake operation, while still being able to make power at around 6000 rpm.

More cubic inches don't hurt. Just as with big blocks, where it is just as easy to build a 496 as a 454, it's just as easy to build a 383 as a 350. That is, if you are starting from scratch.

'67 Chevelle Malibu, Catalina Blue, 540 inch Rat, Air Flow Reasearch 290 CNC Heads heads, Custom Hyd Roller, .675 lift, 234, 244 at .050, Lemons Headers, Holley Multiport Fuel Injection, TCI 6X 6Speed Automatic, 12 bolt Posi Eaton TruTrac, 3:31 Richmond Gears, front and rear power disc brakes, Global West Suspension, etc.

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post #39 of 54 (permalink) Old Oct 20th, 18, 12:15 AM
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Re: Small cam/ big head theory

For pulling heavy cars to quick ET I like more cubes.
Or put the car on a diet.
400 cubes should get it done and I do not feel 210cc head as a large head for those cubes.

And comparing an LS head runner volume or BBC runner volume to the gen 1 SBC head is not fair as I know the runner from intake face to the long side of the bowl in longer and this adds to the volume. subtract that extra length and see where you stand.

But shape is much more important than just raw CC numbers.

Lighter car 3300 lbs 357" flat top SBC with bowl ported 1978 305 2 barrel heads with stock 1.72-1.50 valves.
280H comp cam [email protected] .050 .480" lift TH 350, 2200 stall, 457 gears, 12" tall tunnel-ram and 2 600 edelbrocks.

12.51 @ 111 MPH.
Changed to 1985 305 4 barrel heads and 1.94-1.50valves and 292H [email protected] .050 .501" lift everything else the same it went 11.94 @ 115.

Small head small cam lighter car.
The 400" should get it done.. get it dialed in.

I have some very big heads I want to try one day 2.3" tall intake runner but it will get a [email protected] .050 solid flat tappet cam, tunnel-ram, 2 carbs, 456 gear and 4500stall coan.

And I will drive it long distances if my wallet holds out.
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post #40 of 54 (permalink) Old Oct 20th, 18, 8:56 PM Thread Starter
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Re: Small cam/ big head theory

Quote:
Originally Posted by jeff swisher View Post
For pulling heavy cars to quick ET I like more cubes.
Or put the car on a diet.
400 cubes should get it done and I do not feel 210cc head as a large head for those cubes.

And comparing an LS head runner volume or BBC runner volume to the gen 1 SBC head is not fair as I know the runner from intake face to the long side of the bowl in longer and this adds to the volume. subtract that extra length and see where you stand.

But shape is much more important than just raw CC numbers.

Lighter car 3300 lbs 357" flat top SBC with bowl ported 1978 305 2 barrel heads with stock 1.72-1.50 valves.
280H comp cam [email protected] .050 .480" lift TH 350, 2200 stall, 457 gears, 12" tall tunnel-ram and 2 600 edelbrocks.

12.51 @ 111 MPH.
Changed to 1985 305 4 barrel heads and 1.94-1.50valves and 292H [email protected] .050 .501" lift everything else the same it went 11.94 @ 115.

Small head small cam lighter car.
The 400" should get it done.. get it dialed in.

I have some very big heads I want to try one day 2.3" tall intake runner but it will get a [email protected] .050 solid flat tappet cam, tunnel-ram, 2 carbs, 456 gear and 4500stall coan.

And I will drive it long distances if my wallet holds out.
What are the heads your talking about?

67 chevelle malibu / SS/ custom

Currently undergoing a metal work to remove all rust, if I ever get there.

Cant decide on prostreet or cruiser with a 4 speed.
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post #41 of 54 (permalink) Old Oct 21st, 18, 1:24 PM
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Re: Small cam/ big head theory

I have a low compression street/strip 355 with a set of -11RI Brodix sprint car heads cast for Jones Engineering. Steve Kinser was the original customer for the heads, so i'm pretty sure these were state of the art back when 410's still ran 23 degree based heads. Rolled a bit before the head bolt holes were drilled, with a .060" dowel pin shift. 2.125" x 1.60" titanium valves and Jesel shaft rockers. These were recently competitive on a 360, I picked them up when the west coast went to the spec ASCS head.

My combo is currently solid roller .638/.625 251/261 114, flat tops w/ .084" quench.

It pulls pretty clean all the way down to 2000, with a couple small knee points at roughly 3400 and 5000. It's run 5.70's on pump gas w/ spray, and gets 20mpg on the hwy with 28" drag radials, 3.73 gears, manual 4spd w/ no overdrive.

Here's a link to a graph of a 3rd gear NA pull LINK
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post #42 of 54 (permalink) Old Oct 21st, 18, 5:16 PM
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Re: Small cam/ big head theory

How bout, small heads big cam?
Worked well for me.
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73 nova,3515#(all steel)Pump gas!(91octane)406ci N/A, best 1/4,1.45 '60,[email protected],10.6 @ 122.38, short shifting,NO tuning!


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post #43 of 54 (permalink) Old Oct 21st, 18, 5:21 PM Thread Starter
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Re: Small cam/ big head theory

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Originally Posted by WHT/73 View Post
How bout, small heads big cam?
Worked well for me.
Chris

I think all of us have used this before, probably more than small cam and big heads.

67 chevelle malibu / SS/ custom

Currently undergoing a metal work to remove all rust, if I ever get there.

Cant decide on prostreet or cruiser with a 4 speed.
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post #44 of 54 (permalink) Old Oct 21st, 18, 5:22 PM
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Re: Small cam/ big head theory

Quote:
Originally Posted by dirtlips408 View Post
For sure would love some 1 3/4' longtubes. Now the 750 to 850 might pick up a bit on the dyno but for overall street car manners I would take the smaller carb. With the 3.42 gears/lock up converter the car cruises down the freeway in the 2200 rpm range. We dialed the carb in with a wide band and it cruises at 14.5.....WOT is right at 12.8. Quick pic of the car.
IMG_20180408_101757619_HDR by ronfasano, on Flickr
Love this car! The 406 makes it that much better!
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73 nova,3515#(all steel)Pump gas!(91octane)406ci N/A, best 1/4,1.45 '60,[email protected],10.6 @ 122.38, short shifting,NO tuning!


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post #45 of 54 (permalink) Old Oct 21st, 18, 5:25 PM
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Re: Small cam/ big head theory

Quote:
Originally Posted by Aaron View Post
Chris

I think all of us have used this before, probably more than small cam and big heads.
Yeah, I hear ya.
I did it because I ran out of money building the short block.
So back went the old heads with sr springs and steam hole.

73 nova,3515#(all steel)Pump gas!(91octane)406ci N/A, best 1/4,1.45 '60,[email protected],10.6 @ 122.38, short shifting,NO tuning!


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