moondoggy1302

HEy guys im in a bit of a predicament here I bought this SBC for a smokin deal off craigslist a little while back heres the specs. Gm forged crank, KB forged flat top pistons, Trick flow 8 inch push rods. 1.6 mag roller rockers, vortec iron head port/polished, comp cam 290 int/304 exh, lift .540/.534, RPM air gap intake, and a holley 850. MY engine should easily rev to 7k. it starts pullin hard about 5200 but starts bouncing at redline at about 6200 just when it feels like its startin to pull. So my main question what else can i do to up that red line?

9000th01ss

iTrader: (10)

Check the valve springs and upgrade the fuel system. Dial in the carb, check the timing.

Gotta love those 'make it sound good' lines, trick flow 8 inch push rods?

Truckracer

Check the valve springs to make sure they are correct for the cam. Put a fuel pressure gauge in the system, you need 5 psi minimum at high RPM. What's the jetting like in the carb?
If all that is ok I'd look at the lifters (if they are hydraulic).

1 FMF

iTrader: (1)

rpm air gap intake (dual plane? ) to 7k rpms?

- how's the ignition system, electronic I hope. What kind of coil are you running?
- how's your air intake setup, are you running a velocity stack type air filter over the carb?
- fuel pressure, what kind of fuel pump you running?
- valve springs especially,

kenSS

iTrader: (1)

i agree with1 FMF. even a ported air gap might struggle to reach 7K. try a victor jr. is it hydraulic or solid. like said above, check the valve springs. and 8" pushrods seem about .100" too long.

ZONES89RS

iTrader: (25)

**** fellas, i have never seen a damn set of Vortec heads hit over 6300 RPM, they just dont flow to 7k, especially if the heads he has arent ported and polished professionally.

FU_I_AM_UltraZ

iTrader: (20)

wrong valve lash?

ZONES89RS

iTrader: (25)

Should be zero lash if it is hydrolic.

1997bird

iTrader: (2)

The air gap will let you rev to 7200 rpm non-ported, however I'm not saying that you will make any power past that point. I would say that the 8.00" pushrods are a your #1 problem and that you should also look at the valve springs as your #2 problem. Also what kind of ignition system are you running? How is your plug color looking after useing that 850 cfm carb?

moondoggy1302

my bad its not a air gap its a http://store.summitracing.com/partde...9&autoview=sku Im running 8" cuz there was 8.050 in it with 1.6 rockers and the rockers kept coming loose so me and a buddy came to the conclusion the rods were hitting the valves so now we put the 1.5's in with 8" and everythings fine, was thinkin about going back to the 1.6's though. So should i get a shorter rod? if so what length. And IM running a mallory ignition which im going to lockout here next week. And the 850 has 80 jets in it was gonna go down to 76's though. And this is the cam http://store.summitracing.com/partde...7&autoview=sku and i havent checked the plugs yet. And the vortecs are professionalls port and polished(2grand worth of work) dunno the flow #'s though :/ thanks guys

kenSS

iTrader: (1)

i wonder why they don't give the valve lash for that cam. i have close to the same came in my 383 and i have 7.900" pushrods. perfect valvetrain geometry. mine revs to 7200 no problem.

moondoggy1302

What does your "perfect valvetrain geometry" consist of please? What size rockers? What springs?

ZONES89RS

iTrader: (25)

You have to get the ajustable pushrods for measuring the right size.

kenSS

iTrader: (1)

i have comp pro magnum rockers, 1.6 on intake and 1.5 on exhaust. 929 comp dual springs with 10 degree titianium retainers with spring cups. manley 7.900 swedged end prushrods. not the greatest rockers but they work well. my roller tip rides in the center of the valve tip. right where you want it. the rockers are close to hitting the retainer though but they don't. i have a bullet solid flat tapper cam with a .265/.260 duration at .050 and .577/565 lift lift on a 106 lobe sep.

1 FMF

iTrader: (1)

http://www.compcams.com/information/Products/Pushrods/

hope that helps.

kenSS

iTrader: (1)

1 FMF got it. alot easier then me trying to explain it. good job.

LS1 Coupe

I'll go with the Zone man, Vortec heads are good only for street motors, they have excellant low and midrange but top end and they fall off big time, the last I heard that after 4500 flow starts dropping fast. I also go with FMF on the Duel plane intake, if your looking to go 7K duel planes shouldnt even be a consideration, most duel plane manufactures say 6500 rpm range but most will start falling off well before that. Also check your ignition, I had a smular issue where I was bouncing all over the place with a brand new supposedly blue printed HiPo HEI setup, switched to an MSD setup and problem went away.

Chevy406

iTrader: (12)

ouch!!! I would hate to have been the one who spent $2k on a set of Vortec heads. There are way to many excellent flowing aftermarket heads on the market for less money that that.

moondoggy1302

I picked the motor up for 2500.00 so its no biggie to me how much he spent on the heads, so keeping my wallet in mind what would you guys say is a pair of heads i could use that would easily make power and flow to 7k+?

ZONES89RS

iTrader: (25)

Brodix IK200s are a good head for the money, a tiny bit of bowl blending takes them further also.