not running like expected at the drag strip

[crash]

So I am trying to track down a problem with my car, or at least what I believe to be a problem.

Last year I ran the Cutlass at the strip and ran a best of 13.77 @ 99 MPH with a 2.0 60 ft. That was with a flex fan and an Edelbrock 600 CFM carb. This past weekend I took it out again but swapped on a Holley 750 CFM carb (dual feed, vacuum secondary) and I am now running an electric fan instead of the flex fan. I still only managed a best run of 13.77 but hit 100 MPH and nailed a 1.9 60 ft.

I was racing against a couple friends and their G8 GTs with tune, intake, and headers. I can rape them off the line but they reel me in quick and blow me away at the bottom half of the track pulling 13.2 - 13.3 @ 106 MPH and 2.1 60 ft.

It just seems like my engine falls on its face after 4,000 RPM and I can't figure out why. My car is lighter and has a lower rear end gear ratio then the Gas, yet they pull hard in the upper RPM and my car just basically does not...

This is my setup - 350 .030" over (355) SBC, 14" K&N filter (brand new), Holley 750, Edelbrock Performer intake, Trick Flow Kenny Duttweiller CNC aluminum heads (195cc intake runners, 2.02 intake 1.60 exhaust valves, 64cc chambers), Comp Cams 280H (.480" lift, 230 @ .050" duration) Trick Flow 1.5 ratio roller rockers, Hooker comp long tube headers, 3" duals with flowmasters and turn downs right before the axle. 200-4R trans with TransGo shift kit and stock converter, 7.5" rear with 3.73 gears, 255/45/17 tires.


Is it just me or should I be running better then this with this setup?

 

[khan0165]

ok... first few details... Were the track/wind/weather conditions same or very similar to last time?
also, is there anything else that has changed in your setup? Tires, Fuel, Timing, Weight, etc...?

I assume you are running down with the fans OFF, so let's eliminate electrical bogg...

let's focus on your carb. Can you provide more info... stock jetting? stock accelerator pump settings? stock squirters? idle mixture? float level?

... Looks like your bottom end has improved, so we can ignore things like idle mixture and squirters/accel pumps for now. And by doing that, something tells me your "Vacuum" secondaries aren't doing what they're supposed to.

do you feel the secondaries coming on at all? I am guessing, your motor does not have the sufficient vacuum to open them fully... thus starving your engine at the top end.
What type of idle vacuum are you pulling? And then at wide open throttle?

let's start with this,

 

[RITTER]

Its the LS power band in the G8 GT that pulls so hard.

A higher stall speed converter would help you, tremendously :idea:

 

[khan0165]

also should mention... Drag ET is all about bottom end, and 60ft. A big improvement in top end won't necessarily show on the ET, but it will show on MPH.

this explains your generally same overall ET... but seeing your improved 60ft tells me your bottom has improved also.

Your top end still needs work though, your motor should be eating alot more than it is with a 750carb.

 

[chevy2480]

What compresson ratio?
How much timing?
And as previously stated by another member a highe stall converter will help alot.
Not a fan of the 480 cam but combo should go low 13's.

 

[JBreu]

Its the LS power band in the G8 GT that pulls so hard.

A higher stall speed converter would help you, tremendously :idea:

X2 8)

 

[pontiacgp]

what kind of oil are you running in the engine, transmission and rear?

 

[GhettoRacingKid]

in addition to what everyone said in the above...

thats a dual plane intake right?

try finding a single plane or something like a air gap. it has better runners which will help your top end.

 

[GhettoRacingKid]

ohh something cheap and easy to do at the track.

try adding some spacers for the carb. youll have more air volume which will help the top end.

 

[crash]

Timing is 31 degrees all in, running minimum 91 octane, 9.5.1 compression, Valvoline VR1 20W50 (was told to run 20/50 by the engine builder) Trans fluid is just basic valvoline dex/merc, rear gear lube is synthetic 75/90, all fluids are fresh too.

The performer intake is a dual plane, as is the performer RPM intake that will be on it soon. I know a stall converter would help, and that will come hopefully over the winter...