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Old 04-05-2009, 01:57 PM
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Mild 350 build... need help

alright fellas, im in need of a little help. Im gonna rebuild my Gm 350 and just lookin for a little more power, its a 80-85 crate 350 with about 1000 miles on it that after i put in my rebuilt jeep realized i shoulda added a few more horses before i did the install. Im not lookin to run down the strip and get 600 horses out of it.... Its mainly gonna be low rpm, street cruisin, beach ridin, muscle car sound weekend cruiser that i wanna be able to ROAST some rubber down off my 35's when need be.... ..... but all i was gonna do is change the cam, intake and call it good, but i now decided to change the heads too, and go with aluminum. any suggestions on cc, brand, what ever???? iv done plenty of builds.. but for SB's runnin a constant 5 or 6000 RPM.. never a low rpm motor.. i know alot of guys out there build for torque and low rpm.. and thats the ones im lookin for. so yalls openion of cam and head specs would be greatly appreciated. Thanks

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Old 04-05-2009, 02:13 PM
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Ayuh,...

I'd go with an RV grind Cam,.. Dual plane intake,+ 4bbl. Carb, with Vortec heads....
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Old 04-05-2009, 04:04 PM
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Blazer53 has put together a dandy little torque motor. See this thread....
91 silverado 355,carb.
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Old 04-05-2009, 05:48 PM
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I guess I'm alone on this, but I have a problem w/the knee-jerk prescription of 1-3/4" headers on every SBC build-up, especially a mild build.

I disagree with this, and I suppose I will eventually be either chastised or exonerated for my thoughts on the subject- and so be it, I can live with either.

But to supply that info to the uninitiated without full disclosure of why that is being recommended- because the results are better when the big headers are "run" on a computer simulation program- is misleading, IMHO.

I ask- who uses these 1-3/4" headers on their mild (or not-so-mild) 355's and have empirical data showing they outperform 1-5/8" headers in average power output or power under the curve? Because there are many "traditional" dyno runs (the kind that involve engines, heat, fuel and noise) that contradict this recommendation.

TI, this is not a personal attack by me. And anyone who might think otherwise would be way wrong. I like your writing style, your information with this small exception, as well as your sense of humor (wanna go somewhere sometimes? LOL). But I do feel compelled to call you on this.

Now, is there any data that you may have- other than a Dynosim- that supports 1-3/4" headers making better power under the curve than 1-05/8" headers- on a 355 that would be considered a daily driver?
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Old 04-05-2009, 06:10 PM
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I have no intention of gettin into a pi**ing match with you on this. I've already posted my logic on the subject and will continue to post 1 3/4" headers for 350 builds because I think it is the right thing to do. If you want to come right in behind me on every post and say what you want to about using 1 5/8" headers, that's up to you.

You're not one of those flat earth guys are you?
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Old 04-05-2009, 06:34 PM
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You know what? Don't care no more. Got better things to do w/myself than worry whether someone who I'll never meet buys what the heck ever pipes they want.

Nor do I care what any dyno says, simulated or real.

I know what I believe, and I know why I believe it- and that's good enough for me.

Quote:
You're not one of those flat earth guys are you?
No, I'm on technically sound ground, though. Does that count?

Difference between you and I seems to be I build and race engines in cars, you race software.

Last edited by cobalt327; 04-05-2009 at 09:04 PM.
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Old 04-05-2009, 08:50 PM
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hey guys, thanks for all the useful info. But i just scored a set of edelbrock performer heads with 64cc combustion with 170cc intake and 60cc exhaust with a max valve lift of .575 with a performer RPM intake ALL POLISHED for 600 bucks for a buddy of mine who just moved. so this is what i will be running now. So with that said... what cam should i be looking for?? a nice idle, with good low rpm numbers and somthing to lay down the law from time to time .. thanks guys !
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Old 04-05-2009, 09:00 PM
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Quote:
Originally Posted by cobalt327
You know what? Don't care no more. Got better things to do w/myself than worry whether someone who I'll never meet buys what the heck ever pipes they want.

Nor do I care what any dyno says, simulated or real.

I know what I believe, and I know why I believe it- and that's good enough for me.
COOL.
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Old 04-06-2009, 12:05 AM
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Quote:
Originally Posted by cobalt327
You know what? Don't care no more. Got better things to do w/myself than worry whether someone who I'll never meet buys what the heck ever pipes they want.

Nor do I care what any dyno says, simulated or real.

I know what I believe, and I know why I believe it- and that's good enough for me.



No, I'm on technically sound ground, though. Does that count?

Difference between you and I seems to be I build and race engines in cars, you race software.
Pullleeez....I was drag racing what I built when you were still crappin' green.
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Old 04-06-2009, 12:37 AM
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350cruiser, let's get back to your motor with the Edelbrocks.
These heads flow pretty well, so we'll have to pull back on the static compression ratio and cam to get any torque out of 'em. Otherwise, you would have a high hp motor that probably wouldn't do what I'm hearing you say that you want the motor to do, make torque on the bottom.
KB142 18cc D-cup pistons
http://kb-silvolite.com/performance....tails&P_id=154
Comp 12-205-2 hydraulic flat tappet cam installed retarded 2 degrees and using 1.6 rockers intake and exhaust.
http://www.compcams.com/Cam_Specs/Ca...x?csid=71&sb=0
High-rise, dual-plane intake w/ 750 carb.
9.10:1 static compression ratio.
8.19:1 dynamic compression ratio.
Long-tube, equal-length headers. I don't care what size you use, so in the interest of keeping the peace I'll leave it up to you. Just don't use those cheezy 1 1/2" shorties. You'll be down 40 hp and 29 ft/lbs if you do.
RPM HP TQ
2000 150 395
2500 190 398
3000 242 423
3500 295 442
4000 337 442
4500 369 430
5000 388 407
5500 375 358

Last edited by techinspector1; 04-06-2009 at 12:43 AM.
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Old 04-06-2009, 07:47 AM
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hey tech... thanks for keepin that reply FREE of any exhaust talk.. lol ... but anyways, I wasnt going to change the pistons, i was goin to keep with the stock. but with numbers like that... i think im gonna buy some pistons now, lol. I think i got the winning combo now. ima use my 64 cc heads, with the pistons you picked out, but what about the cam? how much difference would it make if i went a liiiiiiiiiiiiittle bit longer on the duration? just curious, if you dont think it would be any better, ill stick to what you got right there.. i like numbers like that in a jeep
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Old 04-06-2009, 07:57 AM
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Quote:
Originally Posted by techinspector1
Pullleeez....I was drag racing what I built when you were still crappin' green.
yep, you da man! lol
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Old 04-06-2009, 03:48 PM
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Quote:
Originally Posted by 350cruiser
hey tech... thanks for keepin that reply FREE of any exhaust talk.. lol ... but anyways, I wasnt going to change the pistons, i was goin to keep with the stock. but with numbers like that... i think im gonna buy some pistons now, lol. I think i got the winning combo now. ima use my 64 cc heads, with the pistons you picked out, but what about the cam? how much difference would it make if i went a liiiiiiiiiiiiittle bit longer on the duration? just curious, if you dont think it would be any better, ill stick to what you got right there.. i like numbers like that in a jeep
More cam will lower the torque at low r's and lower the dynamic compression ratio because of an extended intake closing point. Tell me what you want the motor to do and I'll put some different parts together from what I used here.
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Old 04-06-2009, 04:19 PM
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I know you're shooting for LOW rpm, but those heads have a lot of power potential. I wouldn't go with anything less than a 262 to get the full bennefit from them. There is the ol' tried and true XE262 cam that would work really well, or the Isky 264MEGA- that cam has better durability but still great street power.

I'm not trying to get in a pissin match with TI but I'd go a small step up.

THAT IS ASSUMING you'd change your pistons or mill the heads to make it about a 9.5:1 compression though. 9:1 is awfully low.
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Old 04-06-2009, 04:23 PM
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Quote:
Originally Posted by ap72
I know you're shooting for LOW rpm, but those heads have a lot of power potential. I wouldn't go with anything less than a 262 to get the full bennefit from them. There is the ol' tried and true XE262 cam that would work really well, or the Isky 264MEGA- that cam has better durability but still great street power.

I'm not trying to get in a pissin match with TI but I'd go a small step up.

THAT IS ASSUMING you'd change your pistons or mill the heads to make it about a 9.5:1 compression though. 9:1 is awfully low.
I agree it is low, but that's what it took with a short cam to get the torque. These heads are too good to be using for a grunt motor. If you use more cam, then you'll need more static compression ratio to keep the dynamic compression ratio in line.

Last edited by techinspector1; 04-06-2009 at 07:17 PM.
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