Cascade Crew

[nonsensekid20]

So I've had this question before, but I haven't really brought it up. So I have a rebuilt chevy 350, 4 bolt main, 2 piece rear seal, holley 670 carb, 221/224 cam, and stock iron heads. What I'm wondering is what can I do to build more than 221 HP/276 TQ? It seems like with the cam and carb I should be running a lot higher than that. Maybe jetting?

[Alphius]

What compression is your motor?
Head casting and valve size?
Need more specs on the cam as well. Max lift, LSA, Adv. duration, etc.
What intake manifold are you using?
What about your exhaust setup?

Given that I used to run a pretty similar carbed setup on pretty low compression, I'd say your numbers are not too far off. Is this through an automatic as well?

[nonsensekid20]

IIRC compression is around 9:1.

Valve lift: .470 intake .470 exhaust
Duration at .007 tappet lift 270in 270ex
Valve timing - Open: 29* BTDCin 69 BBDC Ex. Closed: 61 ABDC ex 21 ATDC ex
Duration at .050 Int: 224, Ex: 224
Lobe Lift: .3130 Int, .3130 Ex.
Rocker Arm ratio: .00
lobe seperation 110.
Grind # CS 270H-10

IIRC heads are 76cc chambers.
Intake manifold I believe is stock replacement. This was just a long block built by Paul at Bowtie.

I've got Hedmen headers w/ 2 1/2" collectors that meets up with a Y-Pipe to lead back 3" exhaust into the Flowmaster 40 series and back out with dual 2 1/2s.

And this is through stock rear end, stock t5.

[Twilightoptics]

Put some 64cc aftermarket heads and enjoy 280-300hp with a decent intake.

Your cam is marginally small, but your heads are crap, your compression is crap, and your intake is crap. You're doing well at 221hp. Your torque number is good and is a direct indication of the small intake/heads.

[nonsensekid20]

Should I go aluminum or stay with iron? And should I go with an air gap intake and take off the carb spacer I put on? Vortec? If I'm changing the heads I can switch to vortec heads and intake.

Found these, don't know if they're good or not. Comments or speculation? http://www.summitracing.com/parts/tfs-30400003-m64/overview/make/chevrolet

[Alphius]

Yeah, I had almost the same build except I had a little bigger split pattern cam and a Qjet on an OEM aluminum intake. I made like 243RWHP IIRC with that combo through a T5 and 3.23 gears.

Switching to fuel injection with a Holley Stealth Ram and a MegaSquirt and a new exhaust and matching the cam to my heads a little better I made 274RWHP. Also switched back to 3.73 which helped acceleration a lot.

Switched to aluminum 64cc heads (10.3:1 CR)and made 310RWHP with a bad tune and lots of room for improvement. Then I broke my engine and put an LS1 in.

Probably a pretty cost effective route is going with a set of worked over iron Vortecs and seeing what that gets you. IMHO if you can get around 300WHP that's pretty solid fun for a street car. It starts getting more and more expensive to build for more power above and beyond that with an SBC.

If you do this, you need to measure your engine specs (deck height, dish volume, head volume) while you have it apart and build for a specific compression ratio and quench area. This will help you make good, reliable power.

[Twilightoptics]

Trick Flow makes good heads. If you're spending that kind of coin, go Brodix or at minimum AFR.

Budget means iron heads. Go with something that has a heartshaped chamber: RHS, Vortecs, etc

IN the middle, rock the GM Fastburn heads. Fastburn heads and the LT4 hot cam (which you can't do unless you go retro roller) makes 300+ easy and it's NICE power.

Air gap is a bad ass street manfiold with easy 300HP yields and good street manors since it's still a dual plane.

Gabe is right, 300RWHP in a thirdgen is a great go fast, streetable combo. Start going beyond that and other things become sacrifices.



You need to know your piston CC, your actual bore, and your deck height.

[Twilightoptics]

Also factor in hardened pushrods, guide plates, and a set of rockers than can handle it all.

[nonsensekid20]

I noticed on my dyno sheet that my power line looked like a tweaker drew it. It was a smooth line besides the shallow up and down movement, some people said it was because my valve springs weren't strong enough and I was beginning on valve float. So with that said, I've heard great things about cost effectiveness and performance out of GM Fast Burn heads, but the highest CC is comes in is 62cc. Probably close enough right? And the more important question, should I get the unassembled set and get my own push rods and rockers? And what do you mean by hardened guide plates, push rods etc?

[DBL_TKE]

You all really think that's what it should be at? that's only 5 more hp and the exact same torque that my stock LB9 puts out at the wheels...

[aaron_sK]

Your engine has better heads, better quench, and higher compression. It is also running a reasonable tune.

IMHO His car being untuned is leaving horses on the table but, as Paul and Gabe have already pointed out, the heads and intake are the limiters for him.

[Alphius]

[izcain]

Do you know what total timing and AFR you were running when putting the readings down. Im not saying you are going to magically pick up a ton but if it is off there is free hp laying there ready to be picked up.

If you want considerably more time to tear into it!

[nonsensekid20]

Alright here are my two dyno sheets. One is a 3rd gear pull, the other a 4th gear pull.

[Alphius]

Looks about right to me except it is too lean. Richer would probably help smooth that graph out. Maybe getting a little predet too? Any idea on total timing?

I wouldn't expect too much more from that engine with those heads and cam. Like izcain said there is probably a little more to be unlocked but not a ton.

[izcain]

[nonsensekid20]

IIRC I have it at 8* when I set it with the line on the harmonic balancer. Since then I've turned my mix screws out 1/4 turn. Couldn't really tell much of a difference. But you think I need to change the cam? I like the rump it gives.

[aaron_sK]

[91RSVert]

I'm still learning carbs, but shouldnt it have more timing, and also isnt out "leaner"?

[Twilightoptics]

Out is richer at idle only. 8 at idle tells us nothing. We need total timing without vacuum.

Depnding on the curve should be closer to 12-14 at idle wihout vacuum advance.