Hot Rod Forum : Hotrodders Bulletin Board - Reply to Topic
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine> Carb Recommendations?
User Name
Password
lost password?   |   register now

Thread: Carb Recommendations? Reply to Thread
Title:
  
Message:
Trackback:
Send Trackbacks to (Separate multiple URLs with spaces) :

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Additional Options
Miscellaneous Options

Topic Review (Newest First)
02-04-2007 02:15 PM
71C10
Quote:
Originally Posted by mattson70
VE, is that volumetric efficiency? So, buying a 750 cfm carb to put on a motor that eats only 600 cfm at 100% VE is probably a waste of money? Thanks for the help.
Like Curtis said, look at the picture of the 388 dyno sheet. The column "Air 1 scfm" is the measured amount of air passing through the carb at each RPM step.
02-04-2007 01:53 PM
curtis73
Quote:
Originally Posted by mattson70
VE, is that volumetric efficiency?
Yep. Its a representation of how much the cylinders actually fill compared to their volume. A 5500 rpm engine probably is around 85% VE.

A Qjet would be a great choice. They are rated at 750 or 800, but they have secondary air doors that only open as much as the engine needs. That's why the same basic carb was installed on everything from V6s up to the Caddy 500. They're a great way of making sure you have enough carb without getting too much.
02-04-2007 11:05 AM
stepside454
Quote:
Originally Posted by 71C10
BG's Road Demon would be better for 5500 RPM and below, unless your cam has 220 or more duration, as per their recommendation.
BG Link.
Yep Agreed
02-04-2007 10:41 AM
71C10
Quote:
Originally Posted by mattson70
There's a 650 cfm speed demon on Ebay for $419. Brand new, manual choke, comes with spring kit and lines. Is that a fair price?
BG's Road Demon would be better for 5500 RPM and below, unless your cam has 220 or more duration, as per their recommendation.
BG Link.
02-04-2007 10:12 AM
mattson70 There's a 650 cfm speed demon on Ebay for $419. Brand new, manual choke, comes with spring kit and lines. Is that a fair price?
02-04-2007 09:25 AM
stepside454 I think Id consider using the 625 Demon.
02-04-2007 06:49 AM
mattson70 VE, is that volumetric efficiency? So, buying a 750 cfm carb to put on a motor that eats only 600 cfm at 100% VE is probably a waste of money? Thanks for the help.
02-04-2007 01:12 AM
curtis73 At 100% VE that 383 ingests 609 cfm at 5500
At 85% VE, it ingests 519.

600 would be more than enough.
02-03-2007 09:16 PM
mattson70 I wish I knew. I bought the truck from the 2nd owner and he had a lot of info but not the cam specs.
02-03-2007 09:10 PM
71C10
Quote:
Originally Posted by mattson70
Hey, thanks for the info everyone. That was an interesting dyno pull. Nice torque numbers.

I'll list what's been done to my 383, maybe this will help in carb selection.

It's a 72 Chevy high nickel block, scat stroker crank, 400 rods, Keith Black pistons. All rotating assemblies balanced. Block was line-bored, windage tray, high-volume low pressure oil pump. Cylinder heads were milled, bowl-cut, ported, polished and flowed. Stainless steel valves and Z28 valve springs. Chrome molly push rods with screw in studs, 1.6 roller rockers, comp cam and cam was degreed. Distributor has been curved to match the cam. Heads and intake match-ported. Edelbrock perfromer dual plane intake, 600cfm holley dual feed carb with 1 inch riser plate. After burner headers 700r 4 trans with B&M shift kit.

I've looked at Holley's website, Edelbrocks, and Barry Grants. All nice stuff, I just need to know what cfm carb to go with. Thanks.
Cam specs?
02-03-2007 09:05 PM
mattson70 Mostly less than 5500 rpm. Looking for torque as opposed to high rpm HP.
02-03-2007 09:03 PM
DeathRattle It also comes down to what RPM are you going to be hanging out at. Plan on being at or above 5500 a lot? Or mostly less?
02-03-2007 08:57 PM
mattson70 Hey, thanks for the info everyone. That was an interesting dyno pull. Nice torque numbers.

I'll list what's been done to my 383, maybe this will help in carb selection.

It's a 72 Chevy high nickel block, scat stroker crank, 400 rods, Keith Black pistons. All rotating assemblies balanced. Block was line-bored, windage tray, high-volume low pressure oil pump. Cylinder heads were milled, bowl-cut, ported, polished and flowed. Stainless steel valves and Z28 valve springs. Chrome molly push rods with screw in studs, 1.6 roller rockers, comp cam and cam was degreed. Distributor has been curved to match the cam. Heads and intake match-ported. Edelbrock perfromer dual plane intake, 600cfm holley dual feed carb with 1 inch riser plate. After burner headers 700r 4 trans with B&M shift kit.

I've looked at Holley's website, Edelbrocks, and Barry Grants. All nice stuff, I just need to know what cfm carb to go with. Thanks.
02-03-2007 08:48 PM
mattson70 So, smaller cfm will mean more torque and bigger cfm will give more HP? I'm looking for torque as it's a around town stoplight-to-stoplight cruiser. It's got a Holley 600cfm on it now but it's a 1997 model and I just think it might be time for an upgrade.
02-03-2007 08:46 PM
71C10 Cam duration, compression, RPM at shift point, etc...
To give you an idea of what is possible, here is my old worn out 388 with tiny cam, good heads, 600 Edelbrock, Used 388 dyno session.
This thread has more than 15 replies. Click here to review the whole thread.

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


All times are GMT -6. The time now is 06:58 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.