350 SBC needs more power?

[Grumpy]

Gday fellas. I've been running a 350 sbc for a few years now but only put about 2-3 thous. miles on the clock. Although it has good power, I'd like to try and improve it. The combo I currently have and running gear is as follows:

Quickfuel 750 dp carb,
Weiand stealth airstrike dual plane manifold,
1 3/4" headers,
Edelbrock performer rpm 64cc heads 7/16 studs,
Crane 1.5 roller tip rockers,
Compcams xs274s solid cam,
3500 stall converter,
TH350 trans,
3.73 10 bolt,
26 inch wheel dia.
Vehicle weight= 3200 lbs.
A recent dyno made 465 nm @ 3600 rpm and
300 hp @ 5200 rpm although redline was not reached.
Any recommendations on what changes I need to do to gain more hp. and to get those tires to smoke up of the mark?! :evil:

you should rather easily exceed that power level with those current parts,IF EVERYTHING'S PROPERLY ADJUSTED
I have a strong feeling that one or more factor's in this engine are in need of adjustment, or improperly installed!
whats your fuel/air ratio, at each 1000 rpm step,

http://garage.grumpysperformance.com/index.php?threads/fuel-air-ratio-meter.577/

and whats the ignition advance curve

http://garage.grumpysperformance.com/index.php?threads/verifying-your-real-advance-curve.4683/

and whats the plenum vacuum read at each 1000 rpm?
whats the exhaust system BACK PRESSURE read at every 1000 rpm

http://garage.grumpysperformance.com/index.php?threads/is-backpressure-hurting-your-combo.495/

whats your fuel pressure at the carb inlet port ?
at idle? at 4500rpm?
whats each cylinder read on compression test?
what is the cam indexed at/ IE dot-to-dot 4 degrees advanced etc.?
have you verified the cams not got a worn lobe or two?
what are the cab jets? are the carb float levels set at?
are the valves correctly adjusted?
any vacuum leaks?
can you post clear pictures of each spark plug and labeled as to its cylinder location
before we start contemplating spending cash on new parts lets find out whats NOT correctly functioning now

http://garage.grumpysperformance.co...rt-throwing-parts-at-a-problem.808/#post-2957

http://garage.grumpysperformance.com/index.php?threads/fuel-pressure-regulators.635/#post-849

http://garage.grumpysperformance.com/index.php?threads/carb-tuning-info-and-links.109/#post-6685

http://www.secondchancegarage.com/public/186.cfm

http://garage.grumpysperformance.co...ouble-shooting-rebuilding-hei-ignitions.2798/

http://garage.grumpysperformance.com/index.php?threads/setting-up-your-fuel-system.211/#post-6904

http://garage.grumpysperformance.co...elay-switch-locations-and-info.728/#post-1025

the most valuable tool you can acquire is as broad a selection of valid information, on exactly how and why things work in your car,s engine, drive train , and suspension , as a reference base to work from, and acquiring a good set of testing and measuring tools to verify and test with
you really should get these books and read them before going any further, it will help a good deal


http://www.amazon.com/exec/obidos/A...5079777/sr=2-1/ref=sr_2_1/102-1234339-0571324

http://www.amazon.com/exec/obidos/t...gy_img_2/102-1234339-0571324?v=glance&s=books

http://www.amazon.com/exec/obidos/t...gy_img_2/102-1234339-0571324?v=glance&s=books

http://www.amazon.com/exec/obidos/t..._books_1/102-1234339-0571324?v=glance&s=books

http://www.amazon.com/exec/obidos/t..._books_3/102-1234339-0571324?v=glance&s=books

http://www.amazon.com/exec/obidos/t...f=sr_1_2/102-1234339-0571324?v=glance&s=books

INVESTING THE TIME AND EFFORT IN PURCHASING AND READING A FEW BOOKS WILL BE VERY COST EFFECTIVE

http://www.dragzine.com/tech-stories/en ... ine-block/
"

SMALL BLOCK REFERENCE BOOKS YOULL WANT
start by buying these books and watching the video

http://www.themotorbookstore.com/resmchstvi.html

http://www.amazon.com/David-Vizards...8&qid=1456194032&sr=8-5&keywords=DAVID+VIZARD
HOW TO BUILD MAX PERFORMANCE CHEVY SMALL BLOCKS ON A BUDGET by DAVID VIZARD
.

JOHN LINGENFELTER on modifying small-block chevy engines
http://www.amazon.com/Lingenfelter-...=1456193940&sr=8-1&keywords=JOHN+LINGENFELTER

http://www.amazon.com/Smokey-Yunick...2&sr=8-1&keywords=smokey+yunick+power+secrets

heres two well thought through engine builds, and several related links
they will take a while to read through the links and sub-links
[color:red]but[/color]
if you take the time and effort to read all the LINKS and SUB LINKS YOULL LEARN A GOOD DEAL

BUILD THREADS

http://garage.grumpysperformance.com/index.php?threads/tbucket-engine-project-dart-shp.3814/

http://garage.grumpysperformance.com/index.php?threads/renegade-intake-for-cross-fires.2796/


USEFUL RELATED LINKED INFO

http://garage.grumpysperformance.com/index.php?threads/what-to-look-for-in-a-good-engine-combo.9930/

http://garage.grumpysperformance.co...le-that-don-t-use-resources.12125/#post-58374

http://garage.grumpysperformance.com/index.php?threads/383-information-overload.11137/

http://garage.grumpysperformance.com/index.php?threads/bjautos-383-build-pictures.9483/

http://garage.grumpysperformance.com/index.php?threads/tips-on-building-a-383-sbc-stroker.428/

http://garage.grumpysperformance.com/index.php?threads/stroker-tips-by-len-emanuelson.1249/

http://garage.grumpysperformance.co...ty-thats-key-in-building-a-good-engine.11682/

 

[Grumpy]

Going by the dyno sheet, do you guys think that this combo is producing about what would be expected or should I be getting more horse power out of it? If so where in the RPM range and by how much is the power and torque lacking?

http://garage.grumpysperformance.com/index.php?threads/should-you-buy-bare-or-assembled-heads.534/

http://www.compcams.com/v002/Pages/389/XE274H-10.aspx

Dyno Results

Camshaft Part # 12-246-3 Designation XE274H-10
Duration @ 0.006": 274° / 286° Duration @ 0.050": 230° / 236°
Max Lift w/ 1.5RR: .487" / .490" Lobe Separation: 110°
Lobe ID#'s: 5445 / 5208 Intake Centerline: 106°
Engine Type: Chevrolet 350 Small Block
Bore: 4.040" Stroke: 3.480"
Displacement: 356ci Compression: 9.25:1
Heads: Dart S/R Intake: Edelbrock Performer
Carburetor: Holley #3310 Vac. Sec. Exhaust: 1 5/8" Headers
Max Torque: 410 ft*lbs @ 3900 RPM Max Power: 369 HP @ 5900 RPM
Manifold Vacuum: 11" Hg @ 800 RPM & 14" Hg @ 1000 RPM w/ no load.

heres a link to comp cams website and a similar flat tappet HYDRAULIC cam in a SIMILAR 350 , you can easily see your engine SHOULD produce better power.
I wish you had the dyno in (the at least for us more common ft lbs of torque and horse power configuration)

roller TIP rockers like this are basically a total waste of time, money and effort, the tips of the valves on the rocker provide MINIMAL friction its the fulcrum the rocker pivots on at the rocker stud, that needs a roller bearing and thats where you gain most of the power gain, in reduced friction, the increase in valve lift is a small help but not nearly what the reduced friction in the valve train provides

your FAR BETTER OFF WITH TRUE ROLLER ROCKER DESIGNS
https://www.summitracing.com/parts/sum-g6991/overview/make/chevrolet

heres what you listed

Quickfuel 750 dp carb,
Weiand stealth airstrike dual plane manifold,
1 3/4" headers,
Edelbrock performer rpm 64cc heads 7/16 studs,
Crane 1.5 roller tip rockers,
Compcams xs274s solid cam,
3500 stall converter,
TH350 trans,
3.73 10 bolt,
26 inch wheel dia.
Vehicle weight= 3200 lbs.
A recent dyno made 465 nm @ 3600 rpm and
300 hp @ 5200 rpm although redline was not reached.


your using BETTER HEADS,roller rockers and a bit more cam, plus solid lifters that allow more rpm
CC XS274S(12-677-4) 236/242@.50 .501/.510 lift

the next larger flat tappet hydraulic cam dyno they list is actually closer to what you should be seeing

Camshaft Part # 12-250-3 Grind # XE284H-10
Duration @ 0.006": 284° / 296° Duration @ 0.050": 240° / 246°
Max Lift w/ 1.5RR: .507" / .510" Lobe Separation: 110°
Lobe ID#'s: 5447 / 5209 Intake Centerline: 106°
Engine Type: Chevrolet 350 Small Block
Bore: 4.040" Stroke: 3.480"
Displacement: 356ci Compression: 9.25:1
Heads: Dart Sportsman II Intake: Edelbrock Victor Jr.
Carburetor: Holley 750 dbl. pmp. Exhaust: 1 3/4" Headers
Max Torque: 377 ft*lbs @ 3900 RPM Max Power: 390 HP @ 5800 RPM
Manifold Vacuum: 9.5" Hg @ 1000 RPM & 11.5" Hg @ 1200 RPM w/ no load.

there is an almost direct relationship between getting the fuel/air ratio and volumetric efficiency correct, and YOUR torque starting to fall after 3800 rpm seems to indicate some restrictive factor such as a restrictive exhaust or fuel pressure and volume supply issues, not enough valve spring pressure,or ignition advance curve problems again TESTING WOULD RATHER QUICKLY ISOLATE THE CAUSE!
READING THE POSTED LINKS AND SUB-LINKS WILL HELP!
[color:red]GUESSING IS A WASTE OF TIME[/color]
http://www.chevrolet.com/performance/crate-engines.html

http://www.hotrod.com/articles/hrdp-0503-chevy-383-engine/

http://www.superchevy.com/how-to/en...-build-a-383-small-block-engine-sledgehammer/

http://www.superchevy.com/how-to/project-cars/sucp-0706-small-block-chevy-stroker-kit/

http://www.chevyhardcore.com/tech-stories/engine/building-the-little-383-small-block-that-could/

http://www.hotrod.com/articles/ccrp-0808-383-stroker-small-block-chevy/

 

[Loves302Chevy]

GUESSING IS A WASTE OF TIME

What a disappointment. It looked like he had a pretty good combination of parts.
He didn't say what his compression ratio was. It looks like he probably used every top end bolt
on part he could order and put them on a stock engine, expecting to end up with a race engine.
Probably had single exhaust with manifolds too.

 

[87vette81big]

I was scrolling down Mike.....
I seen Big Block Chevy Books Galore.
I had to Laugh.
Grumpy Loves the BBC.
I respect it too.