434 sbc ??

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Monza355
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434 sbc ??

Post by Monza355 » Tue Feb 06, 2018 3:59 pm

I’m in the beginning stage of building my self a 434 Chev. I’we set my mark at 600+ hp with decent torque as well.

4.165”x4” bore and stroke 12:1 compression. Flat top pistons. Solid roller camshaft. 263/278 @ 50” 292/308 adv. 704/667 lift with 1.6/1.5 rocker arms. 112 lsa.

Old pro topline 235cc heads that have been bowl blended and cleaned up. 2.08”/1.6” valves. Pac 1943 valve springs.
Plenum modified and ported Edelbrock Super Victor intake 2925 with old Holley 950 cfm hp carburetor. 1.3/4” headers.

The plan was to build a street engine that will make peak power under 6500 rpm. Would my goals be doable and is there something you guys would do differently at first glance ?

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Re: 434 sbc ??

Post by lefty o » Tue Feb 06, 2018 4:19 pm

i dont think you need 12:1 to make 600hp off of 434 inches. id really sit down and evaluate what you want, then plan backwards.

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Re: 434 sbc ??

Post by 6.50camaro » Tue Feb 06, 2018 4:46 pm

I think your looking at an easy 650 hp , depending on what the head flow is. Go 1-7/8" minimum on the headers . 1-7/8" x2 " stepped headers would be better yet . Nobody would use 1-3/4" headers on a built 427 bbc why doing we think they will work on a sbc of the same size . The we in that sentence means I tried it.Dan

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Re: 434 sbc ??

Post by Newold1 » Tue Feb 06, 2018 8:13 pm

MY thought is why add a lot of special parts and push the bore size to the extreme. Keep the bore size at or near 4.125" with a nice 11.0 to 1 compression and it will do a lot more things for you.
1. You can easily make 650HP out of the resulting 427 cubic inches with good heads and great camshaft.
2. The shelf stock pistons will be cheaper.
3. The block cylinder walls will be stronger.
4. You will have future overbore available for repairs, rebuilds or freshenings.
5. The 11.0 to 1 compression will be safer on things with pump gas and street driving.

If you were trying to get above 650Hp by a sizeable amount I would not be saying this.

As for header size you might get a small tweak in power with a stepped header going from 1-3/4" to 1-7/8" etc. but again the much higher cost of the headers does not make it a good "bang for the buck" proposition. Just a good 1-3/4 header with correct lengths, collector size and type will do just fine.

All this is just my opinions and you will get quite a few others here!

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Re: 434 sbc ??

Post by 67RS502 » Wed Feb 07, 2018 1:44 pm

My 420 were 1.5mph faster with a 1 7/8" Hooker SC compared to a 1 3/4" Hooker SC,
with a 3 1/2" system, and straight thru muffs.
With 4" stroke I would go 1 7/8".
67 camaro
girly rollers on pumpgas:
420 - 641hp BretBauerCam, 1.39, 9.79 @ 137.5
383 - 490hp 224/224, 1.56, 10.77 @ 124.6
502 - 626hp 252/263, 049s 1.44, 10.08 @ 132.7
62 Nova cruiser
383/200-4R/12-bolt w 373s
224/224 HR cam
1.57 10.97 @ 121.2

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Re: 434 sbc ??

Post by 67RS502 » Wed Feb 07, 2018 1:47 pm

Also Pipemax called for a 1 7/8" for my little 420, so you would need at least that.
67 camaro
girly rollers on pumpgas:
420 - 641hp BretBauerCam, 1.39, 9.79 @ 137.5
383 - 490hp 224/224, 1.56, 10.77 @ 124.6
502 - 626hp 252/263, 049s 1.44, 10.08 @ 132.7
62 Nova cruiser
383/200-4R/12-bolt w 373s
224/224 HR cam
1.57 10.97 @ 121.2

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Re: 434 sbc ??

Post by Frankshaft » Sat Feb 10, 2018 11:21 am

6.50camaro wrote:
Tue Feb 06, 2018 4:46 pm
I think your looking at an easy 650 hp , depending on what the head flow is. Go 1-7/8" minimum on the headers . 1-7/8" x2 " stepped headers would be better yet . Nobody would use 1-3/4" headers on a built 427 bbc why doing we think they will work on a sbc of the same size . The we in that sentence means I tried it.Dan
Good point on the bbc and 1 3/4 headers. headers are a function more of total power and the rpm where that happens, more so than cubic inch. Meaning, even a 355 needs a bigger header if it makes 650hp at 7800. You don't say, well, its a 355, so we just need a 1 3/4. Yes, but to make that 650hp at 7800, it needs the big header. Sorta like stroke and tq. Its more a function of total cubic inch, not so much the stroke.

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Re: 434 sbc ??

Post by Newold1 » Sat Feb 10, 2018 5:14 pm

As a point here I don't think 355 -358 cubic inch conventional SBC engines are limited to under 650HP by 1-3/4" headers! Tell that to all the good old boys in Nascar that ran 355-358 SBC's with good 1-3/4" primary full length headers making well over 700HP back in the 80's! Guess they never got the word! :shock:

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Re: 434 sbc ??

Post by steve316 » Sat Feb 10, 2018 6:18 pm

For street build 10.5 compression; and a lot smaller cam. A 436 in engine like this with .ooo deck height, 65 cc heads and .039 gasket will still have 11to1 comp. with a 16 cc dish piston. More than enough for the street.

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Re: 434 sbc ??

Post by F-BIRD'88 » Sun Feb 11, 2018 11:21 pm

Newold1 wrote:
Sat Feb 10, 2018 5:14 pm
As a point here I don't think 355 -358 cubic inch conventional SBC engines are limited to under 650HP by 1-3/4" headers! Tell that to all the good old boys in Nascar that ran 355-358 SBC's with good 1-3/4" primary full length headers making well over 700HP back in the 80's! Guess they never got the word! :shock:
This is not a 355 CID engine.

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Re: 434 sbc ??

Post by F-BIRD'88 » Sun Feb 11, 2018 11:23 pm

The fun of running a 12:1cr on a street car is going to get old real fast.

Build it with a true 10.50:1 cr. For 92 octane local street pump gas.

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Re: 434 sbc ??

Post by Newold1 » Mon Feb 12, 2018 9:06 am

Somehow the OP's name and its number got stuck in my head when I did my post. (monza355).

You are right this is a 434 not a 355 so I totally agree that 1-3/4" headers are to small and 1-7/8" would be a minimum!

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Re: 434 sbc ??

Post by steve316 » Mon Feb 12, 2018 9:17 am

The OP listed the bore as 4.165 & stroke as 4.00 = 436 cu. in.

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Re: 434 sbc ??

Post by user-9274568 » Mon Feb 12, 2018 9:39 am

Cobb just did a dyno test with a 10.5-1 pump gas 220cc AFR head 421. Tried 6-7 ported manifolds and the new as-cast Pro-Filer/Wilson.

Cam is about the same, might be a good read for you.

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Re: 434 sbc ??

Post by Monza355 » Mon Feb 12, 2018 12:49 pm

I did see that test * and found it very interesting for sure. Great numbers for a pump gas small block ! And the profiler manifold does fantastic against the ported ones ! Definitely an intake to consider

I have been thinking about going with some kind of dish piston for this engine. If i do so i would like to use 91 octane fuel. I have found pistons that give 10.5:1 and another set at 9.9:1
Which compression ratio would you choose for 91 octane gas ?

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