heads and intake for 427 sbc

[gnicholson]

yep new cam and heads from speier

[F-BIRD'88]

Sheet metal would be great for making up a TEMPLATE divider. easy to cut, trim and shape... Then when the shape is right
transfer to a Plate aluminum or plate steel to make the finished divider.
File to final fit.
I'd make it with tabs at the top to slide into receiver slots cut in a carb spacer.
Make it strong and well supported in the plenum.

[NewbVetteGuy]

im freshening a 427 cu sb i put together about 10 years ago for a street driven 69 vette. The engine was an 11 to 1 mechanical roller cam engine.250 260 on 106. dart 210 heads i ported that flowed 290 220 at 600 from memory and a super victor with a 750 hp holley. the engine made 565 hp at 6k and 550 ft lbs. I've talked about this thing on here before. It runs great but the problem is that with the manual 5 speed in overdrive its cammy and rough at about 2 k on the highway. Obviously the cam is the issue and i thought about trying a dual plane but the car is getting brand new aftermarket suspension and he wants more power in the 630 to 650 range.
in the interest of time constraints im going to replace the heads intake and cam. was thinking about dropping the compression a half point and going with around a 230 cc fully ported 23 degree head new taller super victor and a smaller cam around 8 degrees less on 110. looking for advice before i start oredering parts

fwiw- I used Chad's VFactor 2.5 Profiler heads on a 4.155" x 3.875" 420" combo, with a 2925 milled @ 2.75° to fit the 16" filter housing under the hood of a 1977 LeMans GT. 11.1:1 with a 237° @ .050" HR, .670"/.660" lift with 1.7 rocker, QFT 1050AN 4150 carb. It managed 604 observed @ 6400 and 560lb-ft observed @ 5000.

Folks, isn't this starting to move very rapidly towards the OP's Customer's ask? (CPMotor's response above?) -Link to the heads: http://speierracingheads.com/v250pf23ordm-227cc.html

Yes, they're only 227cc intake volume, but they flow 24 CFM @ 0.600" more than the current motor's Ported Dart Pro 1s; @ .670" -probably 29 CFM more. Keeping the acceleration on the valve with the 1.7 rockers seems like a good way to go, too. -The trade-off is on better springs and replacing them more often- totally worth it, IMHO.

Make more HP with slightly less duration and overlap and maybe the D-shaped exhaust ports mildly help the low end for a minor AR boost, too?



Why not some anti-reversion goodness in the headers to help the low-end, too? (One size smaller starting pipes and then do the 1st step using the Hytech anti-reversion chambers?)

This is where cam phasing for SBCs would be SO useful...


Adam

[kimosabi]

The key to that was the Performer RPM dual plane intake with plenum divider.
A superstock Race prepped Qjet makes 650hp when on a 700HP superstock motor.
If you were to take the S/S Qjet off a S/S 350 SBC and replace it with say a 950 Holley
that motor would pick up a ton of top end power around 50hp.

I run a 1/2" spacer so the plenum divider is somewhat negated. I'd like to see a fully sufficient fuel supplied Qjet lose 50 horse over a Holley 950 on a 700hp engine. Why I mention fuel supply is 700hp is very demanding on a Qjet single needle and seat, no secrets there. I run a fuel catch tank with a submerged Walbro pump with a pressure regulator. All this after the mechanical engine mount pump, to make sure I don't drain the bowl at WOT and a bigger needle and seat. It acts as if I had a Holley on. It's not that I don't believe you but 50hp is alot of powerloss and if you have done some dyno time to confirm, would you mind sharing the comparison?

[cpmotors]

fwiw- I used Chad's VFactor 2.5 Profiler heads on a 4.155" x 3.875" 420" combo, with a 2925 milled @ 2.75° to fit the 16" filter housing under the hood of a 1977 LeMans GT. 11.1:1 with a 237° @ .050" HR, .670"/.660" lift with 1.7 rocker, QFT 1050AN 4150 carb. It managed 604 observed @ 6400 and 560lb-ft observed @ 5000.

What did it make corrected?

633.8 HP @ 6300 RPM 585 lbs @ 4900 RPM
This was the combo I made to look like a 305 SBC for the '77 Lemans GT

[gnicholson]

the frame is out of this thing right now and im thinking about going to a good multi port fi unit or tb.being able to tune cold enrichment and fast idle so this guy can jump in and drive without having to feather the throttle during warm ups would be an imprivement over the hp holley plus maybe help the low speed caminess although i think a well tuned carb would work about as well. any recommendations on aftermarket injection systems