heads and intake for 427 sbc

[gnicholson]

2.05 intake .i dont have the port dimentions right now. the intake flow was 290 at 600. i know the port volume is less than 220

[ptuomov]

This may be totally out of the scope of the project, but it’s my understanding that four Webers in an independent runner configuration and long-tube headers would tame the part-throttle cruise with high overlap cams. Might also look appropriate on a sports car.

[randy331]

2.05 intake .i dont have the port dimentions right now. the intake flow was 290 at 600. i know the port volume is less than 220

The reason I asked about throat size is to see if there was room for a good valve job. Lots of times people grind that area out too big chasing a few CFM, and it's one of those things you can't easily go back on. I guess that area is easy to reach so it gets lots of attention. LOL

If the super victor hasn't been worked on, that's one place for improvement. I've seen one of those take 35 CFM off a 300 CFM port.

It's also likely if you improve the drivability, gain 50 HP with an improved power curve, the customer will be happy without the 75 HP gain.

Randy

[user-29956]

Port saturation will be paramount to achieving your goals. The raw airflow column will need to remain elastic past sonic. Review your choice of camshaft lobe separation,,,,,,,,,Along with your intake valve opening and exhaust valve closing. And try to make a decision of what potential intake contamination may be occurring from possible reversion. A different set of valve events would likely cure the driveability issue. Obtaining more power on top of that will require being more analytical of the intake tract dynamically. ( Camshaft-Intake manifold)

[stealth]

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

106 lobe separation?

That'll be lumpy for sure....

[F-BIRD'88]

Was thinking more along the lines of a underhood centrifugal supercharger.
And the L88 hood is just right. Ditch that intake.. Should have installed a Performer RPM intake and test drive the car first before dissassemble. You'd see the difference right away. Even if it gives up a few poneys up top. * that does not limit you to using a dual plane on it...)
Just not the super vic which is not going to get better ( at 2200 rpm) by porting it.

Does this car have enough rear gear ratio...?

Be nice to get the cam down to a 242-248 deg on a 110-112LSA solid street roller.

Supercharger territory.... Or 18deg heads is another path.

You are really going to have to step on the heads and exhaust system to get this much real power
N/A with a mild cam.

This car should be supercharged. The customer will really enjoy the result in all the ways that matter to him. including a real deal 600+++ Horsepower from a street package.

What does this car run in the 1/4 now? ET and MPH

[cv67]

be curious to see what they pour also
Mine were almost 20cc larger than advertised same era head.

[gnicholson]

it might take a while but i will get all the info on the heads. It would be awesome with a supercharger but the customer doesn't want to go that way. no et info

[gnicholson]

maybe its time to step up to an 18 degree head. it would add a lot of additional work and money but it would make some power

[geraldtson]

Go with the 110 LSA with at least 6 degrees advance and give it lots of ignition advance.

[cjperformance]

MPEFI on IR t-bodies would probably be your single biggest helping hand if he will go for it..
Bigger heads and wider lsa are going to help but even with a great carb and some vac advance etc running at 2Krpm and expecting a smooth ride is in reality asking a lot from a 650+ hp 427ci NA carb engine.

[ptuomov]

MPEFI on IR t-bodies would probably be your single biggest helping hand if he will go for it..
Bigger heads and wider lsa are going to help but even with a great carb and some vac advance etc running at 2Krpm and expecting a smooth ride is in reality asking a lot from a 650+ hp 427ci NA carb engine.

I think it’s the combination of large camshaft overlap, low rpms, and part throttle that is problematic for a plenum intake manifold, whether it’s carbureted or fuel injected. Individual throttle bodies, or even independent runner carbs, that have a very small volume between the intake valve and the throttle blade seem to drive very well at cruise rpm and at part throttle even with significant camshaft overlap. That’s what I believe, who knows if it’s true.

[plovett]

Don't independent runner intakes usually use wider LSA's? I'm not sure. Just asking. But I thought that meant they liked less overlap.

paulie

[F-BIRD'88]

If you had installed a full plenum divider in the intake
the whple nature of the beast will change in the critical low rpm for OD driving. A much larger carb is then used.

Thus my 6 venturi 2 qjet setup. This is yhe car that will like it.
1300 cfm. Small central primaries. 4 big "secondaries"

[F-BIRD'88]

At just 2000-2200 rpm driving in OD you are driving in the off idle transition zpne on the carb.. This area of the carb fuel circuit must be dialed in . It is specific to each car.

It makes a huge difference. This area needs work on that carb. Its not that hard to do.