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> Holley 650 DP Mec Sec or 750 Vac Sec
User Name
Password
lost password?   |   register now

Thread: Holley 650 DP Mec Sec or 750 Vac Sec 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)
12-29-2003 05:25 PM
stepside454 DTL, how much RPM you plan to run this 406 too ?
12-29-2003 12:28 AM
lluciano77 I would run the 750 vac. for now. The 650 DP is too small for your combo. That is a bigger cube motor with a cam that is good sized. I would go with a 750 DP or a 750 vac. sec.. If you want better performance use the DP. If you want better mileage and streetability use the vacuum carb.
12-28-2003 11:37 PM
camaroman7d Ohio Dan is right on the money. I am shocked your engine builder didn't know this (or maybe you mis-understood him).

Judging by your cam, it looks like you are more concerned with performance. Basic rule of thumb, heavy cars work well with a vacuum secondaries, auto cars typically work well with vacuum secondaries, light cars or stick cars work best with mechanical secondaries. This basic rule applies to street only. If you want all out performance and don't care about mileage I say go with a double pumper (mechanical secondary). What size engine are we working with? Why would you compare a 750 VS to a 650 DP? True with vacuum secondaries they are more forgiving if you over carb but, if this is a 406 you are working with you need at least a 750 (maybe more depending on the planned use of the car).
12-28-2003 10:57 PM
poncho62 Something I didn't know, makes sense.
12-28-2003 10:55 PM
Ohio-Dan Manifold vacuum doesn't open the secondaries. Air velocity in the front half of the carb creates the vacuum needed to open the secondaries on a Holley carb.

You can see the hole air passes over, and even use an air hose to check the operation of the secondaries. If you look in the right front bore, from the top, there is a small hole on the back rear corner of the venturi. It's small, so look close.

If you can pass enough air past that port for it to over come the spring pressure in the can, the secondaries will open. Dan
12-28-2003 10:36 PM
DTL504 Cam: Grind: Solid Lunati/ (Recommended by Harold Brookshire)
280/284F10 .525/.530 Lift, 247/251@.050, 159/162 at .200, .560/.565 valve lift(1.6), Pro-Street power with an extra 5* at .200" 2500-7000 RPM Range, Advance Cam 4* Degrees as Per Harold, .026" Valve Lash Hot, Adjustment Range: .018" to .030" Hot. The SB280/284F10 has 62 of overlap. The valve timing is: IVO 33 BTDC IVC 67 ABDC EVO 75 BBDC EVC 29 ATDC. The int CL is 106 ATDC.
12-28-2003 10:35 PM
poncho62 Vacuum depends a lot on your cam specs....what are they?
12-28-2003 10:33 PM
DTL504
Holley 650 DP Mec Sec or 750 Vac Sec

I talk to my engine builder and he thinks I should run a Holley 650 DP Mec Sec rather than my plan to use the 750 Vac Sec. He dont think that I will have enough vacuum to operate the vac sec of the Holley 750. However I think my combo is calling for the 750 Vac Sec. UDHarold said he did not have a problem with this cam running power brakes in a 406.

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 09:18 AM.


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.