Carb advice
Thread Starter
Drifting
Joined: May 2004
Posts: 1,258
Likes: 0
From: Huntsville Alabama
Carb advice
I need some advice on a carb. Currently i have a 600cfm holley 4160 but I do not think it is enough to get the job done. Comp cams says to ues a big carb for my cam. here is my specs on the cam.
Part Number 12-512-5
Engine 1955-1998 Chevrolet
262ci-400ci
8cyl.
Grind Number CS280TLS-6
Description
--------------------------------------------------------------------------------
Intake Exhaust
Valve Adjustment 0.018 0.018
Gross Valve Lift 0.53 0.55
Duration At 0.02 Tappet Lift 280 288
--------------------------------------------------------------------------------
Valve Timing At 0.05
Open Close
Intake 19 51
Exhaust 56 23
--------------------------------------------------------------------------------
These Specs Are For The Cam Installed At 106 Intake CL
Intake Exhaust
Duration At 0.05 250 259
Lobe Lift 0.3534 0.3667
Lobe Separation 106
--------------------------------------------------------------------------------
Recommended Valve Springs 986-16
This is what the guys used when they built my motor it was purchased as a kit so the question is what cfm carb do I need and what is a good one to go with.
Part Number 12-512-5
Engine 1955-1998 Chevrolet
262ci-400ci
8cyl.
Grind Number CS280TLS-6
Description
--------------------------------------------------------------------------------
Intake Exhaust
Valve Adjustment 0.018 0.018
Gross Valve Lift 0.53 0.55
Duration At 0.02 Tappet Lift 280 288
--------------------------------------------------------------------------------
Valve Timing At 0.05
Open Close
Intake 19 51
Exhaust 56 23
--------------------------------------------------------------------------------
These Specs Are For The Cam Installed At 106 Intake CL
Intake Exhaust
Duration At 0.05 250 259
Lobe Lift 0.3534 0.3667
Lobe Separation 106
--------------------------------------------------------------------------------
Recommended Valve Springs 986-16
This is what the guys used when they built my motor it was purchased as a kit so the question is what cfm carb do I need and what is a good one to go with.
Thread Starter
Drifting
Joined: May 2004
Posts: 1,258
Likes: 0
From: Huntsville Alabama
Comp cams description says SOLID-Good for 350-400 on big 3/8 to 1/2 mile tracks with high sustained RPM. Best with big carburetor and good intake.
So what is a good intake. I currently have an edelbrock Preformer. Also what would be a good tourqe converter?
So what is a good intake. I currently have an edelbrock Preformer. Also what would be a good tourqe converter?
Tech Contributor
Joined: Aug 1999
Posts: 14,370
Likes: 6,364
From: At my Bar drinking and wrenching in Lafayette Colorado
You can even run a Victor Junior intake with that cam and rpm range, if hood clearance is not an issue. I'd run an even higher stall - get the stall up into the 3200-3500 rpm range if you want to get it into the torque curve for launch.
Last edited by lars; Sep 1, 2005 at 04:23 PM.
Thread Starter
Drifting
Joined: May 2004
Posts: 1,258
Likes: 0
From: Huntsville Alabama
I have 10.5:1 compression. The guy that built it supposedly put a 3000 stall in the car but it is a dog I can not even spin the tires if i punch from a dead stop. Also I am running the ecklers l88 style long hood. Also I am not using this as a drag car I am going to drive it about everyother day so I want the lowest stall I can get.
Thread Starter
Drifting
Joined: May 2004
Posts: 1,258
Likes: 0
From: Huntsville Alabama
most of the 750dps if find are mechanical seconday. Is that a problem also so I have a new stock gm hei would that have to be replaced. I had a accel supercoil but got janked when the guy built the motor.
Team Owner
Joined: Jun 2004
Posts: 20,216
Likes: 4
From: Smile, it's just the internet.
Originally Posted by Silver00V6Camaro
I have 10.5:1 compression. The guy that built it supposedly put a 3000 stall in the car but it is a dog I can not even spin the tires if i punch from a dead stop. Also I am running the ecklers l88 style long hood. Also I am not using this as a drag car I am going to drive it about everyother day so I want the lowest stall I can get.
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Tech Contributor
Joined: Aug 1999
Posts: 14,370
Likes: 6,364
From: At my Bar drinking and wrenching in Lafayette Colorado
It's a dawg in every test I've ever seen on it...
Mechanical secondary is what you want - all DP carbs are mech sec.
If you don't want a drag car, you need to re-think your cam and comp ratio... you have a hi-rpm drag car that will not perform well below 3500 rpm.
Mechanical secondary is what you want - all DP carbs are mech sec.
If you don't want a drag car, you need to re-think your cam and comp ratio... you have a hi-rpm drag car that will not perform well below 3500 rpm.
Last edited by lars; Sep 1, 2005 at 05:07 PM.
Thread Starter
Drifting
Joined: May 2004
Posts: 1,258
Likes: 0
From: Huntsville Alabama
Originally Posted by CGGorman
Your builder needs to put a smaller cam in. You've got the OPPOSITE of a daily-driver cam...
Melting Slicks
Joined: Nov 2001
Posts: 2,659
Likes: 7
From: Katy (Houston) TX
CI 7-8 Veteran
I have an extremely similar cam in mine. Mine's a 383 w/10.8:1 compression. .543int/.561ex, total dur 288int/298ex, dur @ .050 249int/259ex and 106 centerline.
I'm still breaking in the motor but it is very healthy and can easily break loose my 275/60/15 Nitto drag radials. I'm running a Holley BG 750 double pumper and Vic Jr intake with 1 inch spacer. I haven't taken it above 4800 rpms yet and it's just barely starting to really wake up at that point.
I'm no expert but I'd say you've got some fairly big bottlenecks somewhere in your setup. Don't forget, a cam that wants to breath needs to inhale AND exhale. Don't forget about your exhaust system as well as intake and carb.
Mine is very streetable with the vic jr and you've got plenty of room under that L-88 hood. An RPM might net you a little more tq but it's going to cost you hp. Totally up to you depending on how you plan to use it.
I'm still breaking in the motor but it is very healthy and can easily break loose my 275/60/15 Nitto drag radials. I'm running a Holley BG 750 double pumper and Vic Jr intake with 1 inch spacer. I haven't taken it above 4800 rpms yet and it's just barely starting to really wake up at that point.
I'm no expert but I'd say you've got some fairly big bottlenecks somewhere in your setup. Don't forget, a cam that wants to breath needs to inhale AND exhale. Don't forget about your exhaust system as well as intake and carb.
Mine is very streetable with the vic jr and you've got plenty of room under that L-88 hood. An RPM might net you a little more tq but it's going to cost you hp. Totally up to you depending on how you plan to use it.
Le Mans Master
Joined: Jul 2005
Posts: 5,752
Likes: 4
From: Austin Texas
Bummer about the cam selection for a street vette, but perhaps you can play with the cam timing (advance) to shift the rpm peak down a little, and stay with a dual-plane intake. On the street, I would still stay with no more than a 2,300 stall on the street. I think a 750 dp will fix your low power problems, as long as you maximize the ignition timing. 
Thread Starter
Drifting
Joined: May 2004
Posts: 1,258
Likes: 0
From: Huntsville Alabama
Originally Posted by tshort
I wonder if your heads are too small?? Lars?
Thread Starter
Drifting
Joined: May 2004
Posts: 1,258
Likes: 0
From: Huntsville Alabama
Originally Posted by big_G
Bummer about the cam selection for a street vette, but perhaps you can play with the cam timing (advance) to shift the rpm peak down a little, and stay with a dual-plane intake. On the street, I would still stay with no more than a 2,300 stall on the street. I think a 750 dp will fix your low power problems, as long as you maximize the ignition timing.
Racer
Joined: Aug 2005
Posts: 308
Likes: 0
From: Salem MA
and thats why modified cars arent worth alot of money.
you dont know what you got.
dont know what the last guy did or why.
and dont know how to fix it except starting from "stock" again.
ive found that you gotta start with something stock and/or semi mass produced and be very scientific with your modifications.
or you end up spending a **** load of money.
best of luck making it "right"
edit: i didnt read your last post... but i think what i said still makes sense.
you dont know what you got.
dont know what the last guy did or why.
and dont know how to fix it except starting from "stock" again.
ive found that you gotta start with something stock and/or semi mass produced and be very scientific with your modifications.
or you end up spending a **** load of money.
best of luck making it "right"
edit: i didnt read your last post... but i think what i said still makes sense.
Thread Starter
Drifting
Joined: May 2004
Posts: 1,258
Likes: 0
From: Huntsville Alabama
by the way so everybody knows the car I am talking about looked like this when i got
BEFORE
AFTER
Sorry for not having updated pics The car is complete and all put together.
BEFORE
AFTER
Sorry for not having updated pics The car is complete and all put together.
Burning Brakes
Joined: Aug 2002
Posts: 1,146
Likes: 10
From: Scottsboro Alabama
If you are going to be tooling around town mostly I believe I would sh*t can that cam. It doesn't match your other engine components. You have spent alot of time and money on the rest of your car, why not install a high torque street engine. These guys here can give you suggestions on what to do. BTW, don't listen to dem rednecks anymore! 