Which cam, intake, carb and headers for a 350?

[leftcoast66]

I know this subject has been beat into the ground but I just wanted to get some of you all's input on a motor I've got laying around. The background is built it in highschool 7 years ago, its got about 10,000 miles on it. I daily drove it at the time in my C10 but now I'm done with college and going through the truck to make a fun track toy and all around fun truck to screw around with.
It has a set of 041 big valve heads that have had some light port work, and LT1 valve springs on them. The truck has 9.7:1 compression and is all forged.

We built it originally with the idea of nitrous but I'm leaning against that now as I'd like to make it all around quick.

What cam and intake would you all suggest, as well as header tube sizes and carburator?
I'd like to build as much power as possible, and its not important to be streetable. I'll be doing some drag racing as well as some pro touring stuff, and generally just screwing around on weekends.

[Marv D]

First let me Say it's always refreshing to have someone who KNOWS their compression, not say "it's about 10:1" or a guess based on some chart on a piston box. How the hell does any piston manufacturer know what deck height gasket thickness and diameter your going to build the motor with. That said.....

We have 9.7:1 and want usable POWER not a 'sound' or some other irrelevant criteria(whew, thank you!!!) There's not enough info here to make informed, intelligent choices but we can do some very general build up thoughts.Because you don't have headers, converter, gears, etc to match,, let's talk building power and will discuss matching the vehicle to the motor later LOL

FUEL:
The fuel you choose dictates the cylinder pressure you should have. (inversely, the cylinder pressure dictate the fuel)
A wise old engine builder once gave me this table for compression
Based on a 350 SBC...
For 9:1 compression use a cam with no more than 240° @ 0.050"
10:1 no more than 250° @ 0.050"
11:1 no more than 260° @ 0.050"
12:1 no more than 270° .... etc and was 'generally' based on cams with a 106 centerline

Interpolating between the lines his table would put you at no more than 245° @ 0.050"

His table is the MAXIMUM duration the compression will support. It's not an exact science no,, but it will get you in the ball park for building cylinder pressure to support combustion of the fuel associated with the compression. I mean obviously your not building a race only motor, but the table still applies for the most part. Do NOT choose a cam with 245° @ 0.050 unless your going to be running at WOT a LOT trying to make best power.

So at least we have a MAXIMUM to start from. With some street driving I'd HIGHLY suggest you drop back at least 10° from there,,, and if you want power brakes nothing over 230° @ 0.050". But that's just a guess.

Next thing is I'm going to suggest you do some reading. Here's a page that engine builder and I put together that is pieces of cam discussion gathered from various sources. After you come back thouroughly confused,, (and you will) at least you will be armed with some insite of why the custon cam designers get $300 for one of their cams. There really is a lot of rocket science that goes into designing a cam for a particular combination.

I mean it would be really easy here to say,,, based on what I believe you are looking for,,, I think a HR270 hydraulic roller, a RPM airgap intake with a Prosystems 780 carb, and a set of 1-5/8" long tube headers, with a 2400-2800 stall convertor is going to be what your looking for. That's a pretty common build with the GM heads that makes decent use of a motor just under 10:1

But then,, everyone has an opinion

[leftcoast66]

Thanks Marv!

It looks like you didn't attach the page on cams that you and engine builder put together, I'd love to read up and learn to make more educated decisions.

Sadly I don't know the duration on the current cam(duct tape got put over that end of the box and tore up the specs), I do know that the powerband the builder set it for was 2500-6500rpm's, and at the drag strip when I was younger it seemed to agree. I never had slicks or a rear axle to support it so it never made any good passes. It would drop off about 6300rpm and that was with a 660cfm Edelbrock we tuned for daily driving.

The truck:
- Muncie M21
- Currently procuring a Currie 9"
- More than likely will go with 4:11 gears but I'm flexible on that spec as I don't have any slicks yet, so height can change
- I have a set of Hooker Super Comp's that I ran, but with the truck as low as it is those aren't going to be put back on, I'll be doing a build your own kit and see where that leads me

As you can see, I'm early on in my rebuild of this motor as well as the truck so I'm very flexible on everything. Any reading you can point me to I'm glad to see, I'm always open to learning more.


Before posting here this is what I was thinking about running:

Torker 2 Intake
Comp Cam: CL12-673-4
Holley 4150 HP 750cfm

I'm hoping to do some road course lap days as well as drag racing, so that's the reason for the higher powerband.

[Marv D]

I have only seen the torquer II intake work on ONE motor,, a 355 with a set of Vic Jr heads. I'd highly suggest you consider a RPM air gap. Or if you 'really' want a single plane,, I've got one of these for sale LOL




Here's the cam talk pages,, Simply forgot the link. Thats what I get for being an .. or it could be the HEAT,,damn Arizona my brain is boiling!!!

http://www.small-block-chevy.com/cb_1.htm

[leftcoast66]

Originally Posted by Marv D

I have only seen the torquer II intake work on ONE motor,, a 355 with a set of Vic Jr heads. I'd highly suggest you consider a RPM air gap. Or if you 'really' want a single plane,, I've got one of these for sale LOL




Here's the cam talk pages,, Simply forgot the link. Thats what I get for being an .. or it could be the HEAT,,damn Arizona my brain is boiling!!!

http://www.small-block-chevy.com/cb_1.htm

Thanks Marv, that gives me a little extra learning to do. NO worries on not attaching it, you're doing me a favor by sending it so I don't mind having to wait.

I trust your judgment and experience a lot more than my lack of experience, so if the Air Gap is what looks to be best I'll go that route. I just thought the single's were better for a higher powerband. What do you think about powerbands? Would it be worth it to have a higher one to fit the racing oriented application? I'm not questioning your judgment, just asking questions to learn. Now I'm off to read that article.

[BigDan3131]

Hey Marv is it about 120 -122 degrees down there or has it cooled off to 110? My uncle lived in Yuma year round and hot is hot even if it is "Dry Heat". I noticed you said to drop back ten degrees on duration but if he goes real roller he can actually go ten degrees higher in duration. I know hydro rollers are all the rage but true roller cams have come a long ways in the last few years especially the roller lifters. Since he built it right, I would go with a solid roller cam[low lash type] either the Performer RPM Air Gap or the Weiand Stealth both are good to 6800 rpm, the 750-780 sized Holley and a magnetic pickup distributor/Crane HI6 combo and skip the HEI.

[leftcoast66]

Originally Posted by BigDan3131

Since he built it right, I would go with a solid roller cam[low lash type] either the Performer RPM Air Gap or the Weiand Stealth both are good to 6800 rpm, the 750-780 sized Holley and a magnetic pickup distributor/Crane HI6 combo and skip the HEI.

Thanks Dan, I appreciate the help. I'm planning on a Digital 6 with the crank trigger on the front so I can use a low profile billet distributor from MSD. It sounds like the concensus is RPM Air Gap, sounds good to me. Thanks guys for the help, I really appreciate the guidance, I wasn't sure where to start.

I see you're local, Auburn Auto Machine did the machining and collecting the parts and I did the final assembly of the motor.