My BBC 468 is slow.... - Chevy Nova Forum
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Old 9th-May-2008, 11:34 PM   #1
johnh
 
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My BBC 468 is slow....

I unintentionally high jacked this thread: SORRY.

http://www.stevesnovasite.com/forums...ad.php?t=94468

So I started a new one.....
Why is my car so slow?

Based on the information in above thread and this....

Year: 73

Model: Nova

Body/Exterior: GM Bright Blue Metallic. All steel except fiberglass hood and bumpers. Mini Tubbed.

Front End: Moroso Trick springs, Lakewood 90/10’s, SSBC Dual Piston Disk Brakes Rotors, Low Friction Ball Joints and bushings.

Engine: Chevy Big Block on CAM2 110 Octane
468 Cubic Inches 13-1 Forged Domed Pistons Speed PRo
Solid Cam Shaft.....Comp cam 680/605..256/266 3500-6500
GM Iron Heads Gm12T F9/78 336 781
Large Oval ports 2.06 intake and 1.72 exhaust????
1.7 Aluminum Roller Rockers
Aluminum Valve Covers
Crankcase Evacuation System
Edelbrock RPM Air Gap Dual Plane Manifold
Holley Double Pumper Carb 770 (????)
K&N 5 7/8 x 14 Air Filter and Extreme Lid
Holley Blue Electric Fuel Pump w/ Regulator


Transmission: TH350 / 3600 Conv.

Rear End: Narrowed 9 inch, 35 Spline, Detroit Locker, 433’s, Rancho RS9000 shocks, Caltracs and Split leaf Monos on Sliders, CEE Frame Conn.

Exhaust: Headers with Flow master 44 Series, 3 inch

Wheels/Tires: M&H Race Masters street slicks, 28x12.5x15 on 10inch Weld Rim

Interior: Still have the back set and front buckets custom Blue Diamond tuck, stock dash and gauges. 8 Point Cage.

Electrical: ALL MSD: Dist. Coil, 6al, start retard and High RPM retard, 2 step

Accessories/Options: Single Stage Plate Kit 150-300 HP
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Old 10th-May-2008, 01:03 AM   #2
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How slow is it?
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Old 10th-May-2008, 01:10 AM   #3
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Quote:
Originally Posted by bowtie0069 View Post
How slow is it?
Aug 2007
first time out with the car...6 runs...brand new caltracs splt monos and ranchos....new to me 100% ...top hole, too much preload, shocks at 6
1.825 11.69 @ 117.07
1.684 11.56 @ 115.06
1.71 11.038 MPH unknown (150 shot) Slip shows 79.16MPH
1.73 11.572 @113.48
1.65 11.550 @ 115.27
1.70 11.58 @ 112.98

Last week 3 runs, over the winter i rebuilt the front end, moroso trick springs, lakewood 90/10, Low friction ball joints and bushings
caltracs set in lower hole, no pre load, launch from idle
1.62 11.71 @ 112
1.73 11.77 @ 114
1.64 11.70 @ 113

I expected alot more out of all the work and money i have put into this car.
I need alot more track time to tune it i guess.
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Last edited by johnh; 11th-May-2008 at 06:50 PM.
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Old 10th-May-2008, 01:11 AM   #4
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Quote:
Originally Posted by NOVACA1N
John, I don't want you to take this the wrong way but...You have a 13:1 468 and you're only running 11s. Something is seriously wrong. Your 60 foots are dead slow, and I seen your car and suspension wise it is good. Just our of curiosity, what converter is in your car?

I dont know the brand or size, but the trans and convertor was redone this fall... the trans guy sent the conv. back to manufacture for rebuild....
3600 stall


My thought exactly ***...or what i have i got wrong......thats why i posted about the timing queastion...


I just looked at some old time slips from the previos owner....

before any work that was done after i purchased........
it had the oldest front end known to man kind......still had the front sway bar.
slapper bars with multi leafs and worn out shackles, lowering blocks...you get the idea

best eighth
1.54
6.97 @ 98.71 MPH

What did i do wrong?
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Old 10th-May-2008, 01:17 AM   #5
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Aug of 2007. Right after installing the rear suspension...4 motor passes and one Nitrous 150 shot......




This year after all the front suspension work.
All motor, Disregard the leaning suspension, i had a spring out of the pocket. ALL FIXED NOW......

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Old 10th-May-2008, 01:22 AM   #6
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Your claimed HP, how was that recorded? Rear wheel?
I take it you DIDN'T build the engine/drivetrain?

Have you validated:
-the engine, as in comp. ratio/heads/cam.
-gear ratio.
-compression check, verify all mechanicals.
-are the valves set correctly?

What elevation are we talking about?

Your MPH relates to hp, so I'm taking a guess and thinking 400RWHP???? 117MPH just doesn't compute.

Does the car "pull hard all the way", or does it seem to "lay down" in some RPM range?

Are you running an alternator and running 14+ volts to ign. system?

Did you or someone you know build the trans?

The reason I'm asking is something that I ran across lately. At work we have a 90 GMC 1 ton with 350/th400. We bought it 6 years ago, the last owner said the truck got gutless with time. He bought a GM crate motor and there was little to no difference. We bought the truck and drove in on and off for six years. The thing was GUTLESS. Fast forward to three months ago, the trans blew up. I just rebuilt it and one of the forward clutch pack spring retainers broke, causing the clutch to drag all the time. It finally wore through, disinigrated, and all the springs went everywhere. It was like we went from a six cylinder to an eight cylinder.

My guess is somewhere in the mid 10's, with that much HP. I know you're missing something because my Malibu with a 400hp 355 ran low 12's 110mph.

Keep the info coming and someone will point you in the right direction.
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Old 10th-May-2008, 01:31 AM   #7
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What size cam? What size carb? Which heads and what work has been done to them? You 60ft's are in line with a 11.50 car, and your spped (which indicates HP) matches up with your ET pretty well as well. Too many varibales left unanswered, but I'd say it's a slightly mis matched combo. You probably have a big cam, but stock unported heads? A dual plane intake isn't what a drag engine wants, maybe switch to a Victor. You're running an 850 or 950 carb? Your convertor could stall a little higher for better launch.Also Flowmasters suck for performance, you need better flowing mufflers like Dynomax UltraFlo's.
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Old 10th-May-2008, 01:32 AM   #8
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If the car really ran 98 in the 1/8 before, your down about 80 hp. What does it run now in the 1/8 ?
I would do a compression test, a leak down, run the valves ( I hope you have the correct cam card and have the correct lash setting) , check for broken valve springs.
How do the plugs look? Are you running the same heat range the previous owner was? How old are the wires? Is the distributor locked out? maybe a stuck mechanical advance mechanism.
Pull the carb apart and look for junk in a fuel jet, a bad needle and seat, power valve loose, base plate loose. Change the fuel filter, check the vent tube to the fuel tank. How old is the fuel? Some fuel goes bad over time.
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Old 10th-May-2008, 09:16 AM   #9
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Wow your making no power for some reason. How does it seem to run? I wouldn't worry at all about the 60' times till you get it running right. You don't want to hurt the motor. Are you shure the timing is right? May have the wrong pointer/balancer combo on it? Fuel pressure?
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Old 10th-May-2008, 09:20 AM   #10
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"double pumper" ??? 650,750,850?? jets???? timing??? with NOS and without NOS???

GM performance heads?? what casting? what valves?? any work?
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Old 10th-May-2008, 09:33 AM   #11
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I think you still need to confirm that the engine is a 13.5:1 468 BBC if you have any doubts.

You're close to where you were before your changes, maybe a little better 60' but your MPH will tell you any HP changes.

Like others have said. I'd verify the timing is right first and go from there. Make sure the #1 piston is at TDC and the balancer mark is correct, then put a light on it and see what you got.
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Old 10th-May-2008, 09:33 AM   #12
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WOW..........lots of questions to answer. .......

I did not build the motor........it came with the car...

Lets just pull the motor out and start from scratch and make it a 496 stroker or something. that way next time i can answer all those questions.......................
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Old 10th-May-2008, 09:43 AM   #13
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Years ago my car ran those numbers with a 396 in it. Are you sure it is in fact a 468? Nobody will be able to offer you any real info without knowing alot more about the motor. Cam info and type heads would answer alot right after being sure it is a 468 incher. RM
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Old 10th-May-2008, 10:16 AM   #14
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Quote:
Originally Posted by Real McCoy View Post
Years ago my car ran those numbers with a 396 in it. Are you sure it is in fact a 468? Nobody will be able to offer you any real info without knowing alot more about the motor. Cam info and type heads would answer alot right after being sure it is a 468 incher. RM
Well when i blew a head gasket last fall, the mechanic pulled the heads and verified pistons were as advertised... he also measured the bore and said its a standard 454 bore by his standards...... so unless a 454 can go to a 468 with a crank and not honed.....not sure.....

heads were verified by these numbers
GM Iron Heads Gm12T F9/78 336 781
Large Oval ports 2.06 intake and 1.72 exhaust????
Definatly not stock........


Here are the ad 's from which i bought the car...off of racing junk

this is a chevy nova that i've put alot of time and money in it.the car has a narrowed ford 9 inch rearend,with 433 gears,35 spline moser axles,nodular iron center section with a detroir locking differential.13 inch wide street slicks mounted on weld draglite xp wheels.also have a brand new set of drag slicks that go with car.the car is painted a blue/purple pearl.it has fiberglass bumpers front/back,a 6 inch bolt on cowl hood.a new 468 cubic inch big block chevy has been installed.it has 13 to 1 forged pistons,solid cam shaft& high performance gm heads.it has had porting and polishing work done.a nitrous plate system has been installed but never sprayed through engine yet.its adjustible from 50hp to 300hp.the transmission has been upgraded to a stage 3 trans.a hardned input shaft,doubled up the clutches,the bell housing has been cut and a blow proof bell housing has been installed.the stall converter has been matched to the car.it stalls about 3600 rpm on motor and should stall about 4500 rpm on nitrous.estimated horse power on motor is 600hp,and on nitrous is up to you.this car is street legal and a must see




new 468cu big block chevy with 600hp.nitrous plate system/never used yet.msd ignition,timing computer.mini tubbed with ford nine inch rear,35 spline axels,433 gears,detroit locker posi unit,fuel cell,8pt roll cage,frame has been tied in,disk brakes,blue diamond tuck interior,fiberglass bumpers,6 inch bolt on cowl hood.350 turbo trans with hardned input shaft & blow proof bell housing.car has been raced several times and ran a 690 on motor in 1/8 mile.car could run high 5's with right driver.
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Old 10th-May-2008, 10:20 AM   #15
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Quote:
Originally Posted by Ironman View Post
I think you still need to confirm that the engine is a 13.5:1 468 BBC if you have any doubts.

You're close to where you were before your changes, maybe a little better 60' but your MPH will tell you any HP changes.

Like others have said. I'd verify the timing is right first and go from there. Make sure the #1 piston is at TDC and the balancer mark is correct, then put a light on it and see what you got.


Timing has been verified @ 36......all in at 3000 locked dist....
Purrrrrrrrrrrrrs like a kitten........
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