heads and intake for 427 sbc

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gnicholson
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heads and intake for 427 sbc

Post by gnicholson » Tue Nov 14, 2017 8:52 pm

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

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Re: heads and intake for 427 sbc

Post by redliner » Tue Nov 14, 2017 10:26 pm

Talk to Chad Speier @ Speier Racing Heads and Mike Jones @ Jones Cams. They both participate here.

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Re: heads and intake for 427 sbc

Post by MadBill » Wed Nov 15, 2017 12:01 am

I'd say 'give it the gears.' Literally, e.g. the 0.82:1 TKO 600 5th rather than the 0.64:1.
Felix, qui potuit rerum cognscere causas.

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Re: heads and intake for 427 sbc

Post by gnicholson » Wed Nov 15, 2017 12:08 am

i need to check but i think its the .82 now

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Re: heads and intake for 427 sbc

Post by mag2555 » Wed Nov 15, 2017 6:30 am

A 850 or so Carb with high gain boosters will turn that ruff Tiger at low rpms into a kitten!

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Re: heads and intake for 427 sbc

Post by F-BIRD'88 » Wed Nov 15, 2017 7:31 am

Don't expect to pick up near 75-100hp while dropping down the cam overlap and the compression ratio too. N/A

But....
You can have it all if you build him a supercharged motor.

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Re: heads and intake for 427 sbc

Post by gnicholson » Wed Nov 15, 2017 7:37 am

i did quite a bit of tuning on it. locked the timing out worked on the idle and transfer circuit. its actually not to bad right now. its really not even noticeable now except in od around 2k. With some better cylinder heads the cam will probably be too tight anyway.should be able to pick up some power and help the low speed issues with a cam and better heads . The car does make a tremendous amount of torque around 3k as it is. the car was about done at 6k. i expect to turn it up closer to 7 in order to meet this goal. even if i dont change the duration much i know i need to spread the lsa out some .the engine has a vacuum pump. when its finished its important that the low speed performance is straightened out but it should go atleast 620 if i get the combination right. Anyway i appreciate the info before i start ordering parts

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Re: heads and intake for 427 sbc

Post by mag2555 » Wed Nov 15, 2017 9:06 am

Your wanting to have your Cake and eat it too there!
If your willing to go thru the expense of different heads and Intake then why the Hell not put a Centrifugal supercharger on it and only dial in 5 to 6 PSI of boost and if need be add a supplement Akly injection!

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Re: heads and intake for 427 sbc

Post by RevTheory » Wed Nov 15, 2017 9:12 am

I'm guessing the customer won't be too keen on hacking a hole in the hood of a 'Vette.

But yeah, cleaning the snot out of a cruise in O/D while adding 75 hp up top is going to be problematic.

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Re: heads and intake for 427 sbc

Post by MadBill » Wed Nov 15, 2017 9:21 am

Most of an engine's low RPM cruise characteristics are of course a result of cam specs, but as discussed carb tuning is also very significant. One often overlooked factor though is spark advance. I have several times cured low speed surge via 12° or more vacuum advance. The last was a 2 x 4 800 HP 572" Hemi with a 260°/272° roller. The owner had been going richer and richer trying to tame the cruise surge and we eliminated 90% of it by going leaner and adding spark.
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Re: heads and intake for 427 sbc

Post by gnicholson » Wed Nov 15, 2017 9:30 am

ok its my fault for how i posed the question. the guy asked me to freshen the engine and address the cruise issue if i could. adding a really good set of 23 degree heads that flow 230 plus and the right cam and intake should increase the power a fair amount but im also looking to improve the overall engine drivability . i realize everything is a trade off but i feel i can improve both areas. hood clearance isnt an issue with the l88 hood and carb base. it has a super victor and 1 inch spacer now. looking for recommendations on the best head intake for this application. 230 afr spier etc. the current engine is a very strong especially in the mid range and im sure i could solve the issue without redoing the engine but he wants to upgrade it so thats what im doing

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Re: heads and intake for 427 sbc

Post by randy331 » Wed Nov 15, 2017 10:14 am

gnicholson wrote:
Wed Nov 15, 2017 9:30 am
ok its my fault for how i posed the question. the guy asked me to freshen the engine and address the cruise issue if i could. adding a really good set of 23 degree heads that flow 230 plus and the right cam and intake should increase the power a fair amount but im also looking to improve the overall engine drivability . i realize everything is a trade off but i feel i can improve both areas. hood clearance isnt an issue with the l88 hood and carb base. it has a super victor and 1 inch spacer now. looking for recommendations on the best head intake for this application. 230 afr spier etc. the current engine is a very strong especially in the mid range and im sure i could solve the issue without redoing the engine but he wants to upgrade it so thats what im doing
Why not work on the heads you have, if they are good castings ? It could be more cost effective.

Steeper seats will help that drivability at low RPM quite a bit, and probably help the power curve.

Wider LSA cam, port the intake....

Randy

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Re: heads and intake for 427 sbc

Post by gnicholson » Wed Nov 15, 2017 10:17 am

they are pre platinum 210 darts that i ported

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Re: heads and intake for 427 sbc

Post by randy331 » Wed Nov 15, 2017 10:19 am

RevTheory wrote:
Wed Nov 15, 2017 9:12 am

But yeah, cleaning the snot out of a cruise in O/D while adding 75 hp up top is going to be problematic.
Why ?

Randy

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Re: heads and intake for 427 sbc

Post by randy331 » Wed Nov 15, 2017 10:20 am

gnicholson wrote:
Wed Nov 15, 2017 10:17 am
they are pre platinum 210 darts that i ported
Good enough castings for what your wanting to do.

Valve sizes/throat sizes ? Current CC after porting ?

Randy

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