just got a used 750, need jet size - Hot Rod Forum : Hotrodders Bulletin Board
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
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 06-26-2008, 12:50 PM
Registered User
 
Join Date: Aug 2007
Location: Live Oak Fla.
Posts: 11
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
just got a used 750, need jet size

I just got a good used Holley strip dominator manifold and a 750 dbl pumper
gonna drop it on my 406 and let the tunnel and 2 450s take a break, eat'n me outta house and home.
the eng. is a 13:8:1 406/ 268/278@.50 .630 lift, the 450s finally settled on 64 jets vs. 582's< stock, and left the plate alone ( 134R ) had great plug color, but needed a 3.5 valve only had 10 inches at 1100RPM, I had 6.5 to start with...taking the formular: drop 2.0 off ur idle vac#..ran like a pos...kept playing 5.5/4.5/ 3.5 nice an crisp!
the 750 now has 70F and 79R and a 6.5 pv, now that its a single carb vs 2 450s how do select a PV thats close, drop in a 3.5 again or will the -2.0 of the idle vac rule now apply once more
any of U racers have a eng combo like mine? what jets R U using, I have jet-hot coated headers and I dont want to trash'em on a lean set-up, it dont take long, faster then U can get the plug to color
BTW its in a flat bottom Drag Boat, 1 gear only, but pulls like a train
thanks all, peace, Sunman

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 06-26-2008, 05:27 PM
Registered User
 
Join Date: Nov 2005
Location: Duffield ,Va
Age: 67
Posts: 526
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Block power valve and jet 80 square!

Quote:
Originally Posted by sunman
I just got a good used Holley strip dominator manifold and a 750 dbl pumper
gonna drop it on my 406 and let the tunnel and 2 450s take a break, eat'n me outta house and home.
the eng. is a 13:8:1 406/ 268/278@.50 .630 lift, the 450s finally settled on 64 jets vs. 582's< stock, and left the plate alone ( 134R ) had great plug color, but needed a 3.5 valve only had 10 inches at 1100RPM, I had 6.5 to start with...taking the formular: drop 2.0 off ur idle vac#..ran like a pos...kept playing 5.5/4.5/ 3.5 nice an crisp!
the 750 now has 70F and 79R and a 6.5 pv, now that its a single carb vs 2 450s how do select a PV thats close, drop in a 3.5 again or will the -2.0 of the idle vac rule now apply once more
any of U racers have a eng combo like mine? what jets R U using, I have jet-hot coated headers and I dont want to trash'em on a lean set-up, it dont take long, faster then U can get the plug to color
BTW its in a flat bottom Drag Boat, 1 gear only, but pulls like a train
thanks all, peace, Sunman
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 06-27-2008, 06:27 AM
Registered User
 
Join Date: Aug 2007
Location: Live Oak Fla.
Posts: 11
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I wanna get some more outta my fuel comsumption Tunnel nets 5mpg. w/P.Vs
but thanks anyway...I need a jet set up that will burn the 118 on a 13.8:1 and not lean out the mill, the stock 582's in the 450'2 on the tunnel almost cooked off the Jet-Hot Coating at the 1st bend in the pipe, my bad
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 06-27-2008, 11:42 AM
Registered User
 
Join Date: Nov 2005
Location: Duffield ,Va
Age: 67
Posts: 526
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Just how do you use that boat? You drag or just putt around?
If you get rid of the power valve, you ain't got anything to lean it out at part throttle and such.
Ran a 750 holley DP plugged and jetted 80 square, ran it on a 355 ci chevy roller motor .630 lift, took it off and slapped it on a 447 CI stroker 700+ lift, didn't touch it and it ran fine.
The more things you got in the system that can screw up, the more trouble you got. My motto is "Keep it simple!"



Quote:
Originally Posted by sunman
I wanna get some more outta my fuel comsumption Tunnel nets 5mpg. w/P.Vs
but thanks anyway...I need a jet set up that will burn the 118 on a 13.8:1 and not lean out the mill, the stock 582's in the 450'2 on the tunnel almost cooked off the Jet-Hot Coating at the 1st bend in the pipe, my bad
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 06-27-2008, 12:59 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,210
Wiki Edits: 0

Thanks: 5
Thanked 388 Times in 382 Posts
Normal jetting for a 750DP will range from 69-75 pri and 78 88secondary.
I would start at 75pri 86sec jetting 3.5PV.

its safer to start a little rich and work back lean to best power.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 06-27-2008, 02:55 PM
Registered User
 
Join Date: Aug 2007
Location: Live Oak Fla.
Posts: 11
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I cruse around 30mph, and when the lake lice come out I like to wack it 80-90mph..if the waters there, but like I said the Tunnel and 13.8:1 is killing my wallet, thats why I wanna switch to a 750 and single plane.

I dont know about running 80 square$$$$$$$$
isnt the 4779 like 75F 76R????

F-Byrd I agree on the 3.5, the prop loads the eng. at idle and the vac drops to 5-6in. w/a 4.5 I still had to blip/feather the throttle a little to keep the eng from loading up, the 3.5 give me a little seperation, was fine w/a 9% gear and a 10.75 wheel & 4.5 PV went to a 15% gear same prop and had to go 3.5
where? else can U go 100mph 1/2 naked? DragBoats
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 06-27-2008, 02:57 PM
Registered User
 
Join Date: Aug 2007
Location: Live Oak Fla.
Posts: 11
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
F-Bird
How bout them Red Wings
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 06-28-2008, 12:07 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,210
Wiki Edits: 0

Thanks: 5
Thanked 388 Times in 382 Posts
Quote:
Originally Posted by sunman
F-Bird
How bout them Red Wings
Bet I'm the only Canuck on this board thats not into Hockey.
Good stuff for Detroit thou. If Toronto ever gets their act together agin in our lifetime maybe I start following hockey again.

When cruising at 30MPH, what is the tach rpm? How far open is the throttle ( %)

What is the tach rpm at WOT? flat out? What is the spark timing curve like?
Does your 750 holley have one PV or two?

I think you gave up on the T ram too easy.
Probabily just needs further primary metering block fine tweeking to improve the PT AFR at low speed cruise (30ish MPH) (cruising on the primaries)
PV channel orifice size and idle feed resstriction size.
A tune up using a Wide band to dial in the AFR at cruise would really help.
WIht 13.8:1 cr you need a good bit of cooling fuel (richer WOT) afr to keep the combustion chambers out of priegnition at WOT.
A water water/methanol injection system would allow you to dial back the extra WOT fuel you are using ( wasteing) for internal cooling, combustion heat control. (leaner WOT jetting can be used without burning up the motor)
The cost of a WI system would soon pay for itself the more yu run at WOT.
Really allows you to dial back on the fuel. Not only in terms of WOT jetting but you can $$$reduce the octane requirement$$$ by mixing your race gas with pump gas.
www.snowperformance.net

Last edited by F-BIRD'88; 06-28-2008 at 12:12 PM.
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

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.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
TH400 Speedo size Derkyb Transmission - Rearend 0 08-21-2007 07:27 PM
Starting Holley jet size question/suggestions 70bird Engine 1 06-13-2005 03:38 AM
What Jet size and Vac advance spring ships in a 390 4bbl Holley? rick458 Engine 4 04-10-2005 05:01 PM
Holley 750 on a 454, what jet size? JamesRS Engine 4 02-18-2005 08:34 PM
Crank Pilot size for 429 Ford '67Pony Transmission - Rearend 0 10-01-2003 04:00 PM


All times are GMT -6. The time now is 06:26 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.