650 Mechanical vs. 680 Vacuum Secondaries - Team Camaro Tech
Engine General Engine Discussion.

 
LinkBack Thread Tools Display Modes
post #1 of 3 (permalink) Old Jul 10th, 14, 02:10 PM Thread Starter
Tech Team
JPT
 
Join Date: Sep 2013
Location: Connecticut
Posts: 31
650 Mechanical vs. 680 Vacuum Secondaries

Hello all,

This topic may have been beaten to death as far as theory goes, but I have a seat of the pants question.

I have a 383 stroker going in my 1969 Camaro next week. The engine is on the mild side with stock Chevy 1.90/1.60 heads, CompCams hydraulic roller part #12-420-8 (.501 lift, 215 duration @ .050 on both intake and exhaust, 110 LSA) 10.0 to 1 compression ratio, 2.5 in. dual exhausts, full length Hedman Headers, 200-4R overdrive automatic tansmission and 3.73 posi rear end. Power steering, power brakes, and front disks.

The car is street driven only, it is not a daily driver, and I want the best seat of the pants pull that I can get from this combination, especially at low speeds or from a stop light.

I am considering a Quick Fuel 680 cfm vacuum carb vs a 650 mechanical carb. I talked to Quick Fuel today and they did not recommend a 750 cfm carb.

Your thoughts?

John T.
jptonks is offline  
Sponsored Links
Advertisement
 
post #2 of 3 (permalink) Old Jul 10th, 14, 02:58 PM
Gold Lifetime Member
Tom
 
Join Date: Mar 2008
Location: the 02176
Posts: 5,985
Re: 650 Mechanical vs. 680 Vacuum Secondaries

I run both vacuum secondary and mechanical secondary carbs on mine, changing periodically depending on my mood. The mechanical secondary gives me the best off the line responsiveness but the vac secondary gives smoother around town cruising with a stick.

With the gearing you have in the rear and first gear ratio of the 200-4r(2.73 first) you should be smoking plenty of tire with either carb.

'67 rs - ordered new by my Grandfather
327 L30, K-K, Deluxe int, tach & gauges, 12 bolt posi, 4 speed.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
-
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Melrose RS is offline  
post #3 of 3 (permalink) Old Jul 10th, 14, 03:04 PM
Senior Tech
Al
 
Join Date: Nov 2002
Location: Vancouver, USA
Posts: 10,511
Re: 650 Mechanical vs. 680 Vacuum Secondaries

I have the same CID, trans and rear gear as you - I use a 700DP and am quite happy with the low end performance, though I have never tried a vac secondary carburetor on it.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
BPOS is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user 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.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



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
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome