950 HP jet size for street - Chevelle Tech

Performance Our High Performance area

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
post #1 of 17 (permalink) Old Aug 3rd, 09, 9:28 PM Thread Starter
Tech Team
 
Join Date: Feb 2006
Location: Wildwood, MO
Posts: 388
950 HP jet size for street

What are you guys running for jets in your 950 hp for street strip? I have 80's in the front and 89's in the rear with factory power valves front and rear. I am killing plugs and it is pig rich.

I have run my best ever et with these, but it is not worth l
killing the plugs. I am running NGK R5671-7's on the street and spray a 200 shot with NGK R5671-8 on the bottle.

Dart Pro 1 325's on a pumnp gas 462 if it matters.

Thanks!

1972 SS Chevelle sold
1955 Chevy 454/T-ram
1970 GTO 455 rag top
1965 Biscayne 598
adeeos is offline  
Sponsored Links
Advertisement
 
post #2 of 17 (permalink) Old Aug 3rd, 09, 9:40 PM
Tech Team
John
 
Join Date: Oct 2004
Location: Vancouver BC
Posts: 484
Re: 950 HP jet size for street

Way too rich in the rear with a power valve.
Block the power valve in the rear or change the jets to 82.

69SS396 Chevelle
90454SS Truck
69shovel&90454SS is offline  
post #3 of 17 (permalink) Old Aug 3rd, 09, 9:46 PM
Tech Team
mike
 
Join Date: Jan 2008
Location: michigan
Posts: 497
Re: 950 HP jet size for street

i dont know what cam your running but that might be why your fouling plugs if the power valves are open while your cruising. i run 77 primary jets with a 3.5 power valve. and 86 secondary with no power valve and my plugs are last years. i think you'll need to be around 76 to 77 jets to run clean. and if you have very much cam the power valve is the big problem stock ones are 6.5 .hope this helps
yenkomike is offline  
post #4 of 17 (permalink) Old Aug 3rd, 09, 9:53 PM Thread Starter
Tech Team
 
Join Date: Feb 2006
Location: Wildwood, MO
Posts: 388
Re: 950 HP jet size for street

Here are cam specs: Crane mechanical flat tappit,

638/659 lift
242/272 duration.

1972 SS Chevelle sold
1955 Chevy 454/T-ram
1970 GTO 455 rag top
1965 Biscayne 598
adeeos is offline  
post #5 of 17 (permalink) Old Aug 3rd, 09, 11:41 PM
Senior Tech Team
Ron
 
Join Date: Jul 2005
Location: stockton,ca
Posts: 3,711
Re: 950 HP jet size for street

I was running 76/86 in mine with a blocked rear p/v.

69 Camaro
491/AFR 315/Straub hyd roller
TH400/GV OD/9" 3.50
dirtlips408 is offline  
post #6 of 17 (permalink) Old Aug 3rd, 09, 11:51 PM
Tech Team
Wade
 
Join Date: May 2008
Location: Savannah G.A.
Posts: 337
Re: 950 HP jet size for street

If you have a power valve in the front and the rear. The jets should be about the same size. The jetting you have should be right for just a power valve in the front and the back one blocked off.

71 chevelle, 505 dart heads. 6.62 at 105 with 87 in the tank all motor.
wade w is offline  
post #7 of 17 (permalink) Old Aug 4th, 09, 5:57 AM
Tech Team
 
Join Date: Oct 2000
Location: torrington ct.
Posts: 654
Re: 950 HP jet size for street

in summer air and especially street driving i can't see why the stock 78 square jetting wouldnt work for you

btw,your power valve size should be 50% of the vacuum at idle reading.

the way it's jetted now for racing doesn't seem right even though you've have your best times with it

could be a weak fuel system for you to have to use that much jet,kind of just a band-aid

69 camaro ex-NHRA superstocker,548" 93 octane,g-force 4speed,9" w/ 4.86's and a lenco billet locker,NEVER to be trailered.9.63 at 141.80,1.38 60',126 mile round trip[3000rpm's at 60mph]
ericrickster is offline  
post #8 of 17 (permalink) Old Aug 4th, 09, 6:45 AM
Lifetime Premium Member
Green Weenie
 
Join Date: Sep 1999
Location: s.w. Mo.
Posts: 13,689
Send a message via Yahoo to Bob West
Re: 950 HP jet size for street

You're a long way from 78 sq. jetting. I dont know how it runs. I think I ran 78-80/86-88's with no rear power valve.
Bob West is offline  
post #9 of 17 (permalink) Old Aug 4th, 09, 6:50 AM Thread Starter
Tech Team
 
Join Date: Feb 2006
Location: Wildwood, MO
Posts: 388
Re: 950 HP jet size for street

Thanks for the replys guys. I will check the size the the P/V's tonight and likely plug the rear as suggested and reduce the jet sizes. As far as fuel is concerned, I run a Manga Fuel 500 pump and filter
-10 line to the reg and two -6's to the carb.

I'd like to run True Street near here at Z-Max on Saturday and I do not want to fowl plugs on the cruise.

1972 SS Chevelle sold
1955 Chevy 454/T-ram
1970 GTO 455 rag top
1965 Biscayne 598
adeeos is offline  
post #10 of 17 (permalink) Old Aug 4th, 09, 7:00 AM
Senior Tech Team
BILL
 
Join Date: Oct 2007
Location: HENDERSONVILLE NC
Posts: 1,028
Re: 950 HP jet size for street

80/84-86 is fine
SPARK69 is offline  
post #11 of 17 (permalink) Old Aug 4th, 09, 7:02 AM
Senior Tech Team
Vinny Vince
 
Join Date: Jun 2003
Location: Thornton, Pa
Posts: 12,950
Re: 950 HP jet size for street

I had 2 Holley 950HP's, both ran phenomenal, but very rich at cruise. They ran something like 10.8 AFR. I tried everything in the world to lean it out, and all it did was screw-up the throttle response. Ended up with a Prosystems 950HP that ran like the Holley but gave a cleaner cruise.

Is yours newer or older?

*69 CHEVELLE SS EFI 502/T56 Mag/3.90
*06 C6 LS2/T56
*96 Stang LQ9 6.0 turbo - everybody should have one!
69-CHVL is offline  
post #12 of 17 (permalink) Old Aug 4th, 09, 7:38 AM
Lifetime Premium Member
Robb
 
Join Date: Feb 2007
Location: Va.
Posts: 2,798
Re: 950 HP jet size for street

Quote:
Originally Posted by Bob West View Post
You're a long way from 78 sq. jetting. I dont know how it runs. I think I ran 78-80/86-88's with no rear power valve.

Bob's advice is prob a great start.
Just for reference - I run 85/90 with rear pv blocked , this is where it flowed best @ the carb shop on a bench .It seems a little rich still. I think Bobs #'s are real cose to where I will end up.

WARNING!!!
Big Blocks Are ADDICTIVE
creeper72 is offline  
post #13 of 17 (permalink) Old Aug 4th, 09, 8:55 AM
Senior Tech Team
 
Join Date: Feb 2001
Location: MO
Posts: 2,262
Re: 950 HP jet size for street

The richest I ever ran with the HP 950 was 80/88 with the rear PV plugged in less than 1000' DA.
40Coupe is offline  
post #14 of 17 (permalink) Old Aug 4th, 09, 10:07 AM
Team Member
Joe
 
Join Date: Nov 2003
Location: Thornton, Pa
Posts: 12,778
Re: 950 HP jet size for street

JMHO, the Dart Pro One heads have terrible low RPM response. Flow great at higher RPM / higher CFM demands, but poor at cruise. Went through the same thing. You run 325's on a 462" motor, I run 310's on a 469" motor. Kept jetting up to get it to cruise, them went fat at WOT. Switched to a BG 800 annular. Completely different motor with the annular. Not advocating it, just stating a personal experience. Only carb that I had that was close was the 750HP street which is really the 950HP with the smaller baseplate and street jetting. I would try a smaller carb w/ down legs or an annular booster carb.
GRN69CHV is offline  
post #15 of 17 (permalink) Old Aug 4th, 09, 8:39 PM
Senior Tech Team
 
Join Date: Nov 1999
Location: Oregon
Posts: 3,463
Re: 950 HP jet size for street

Quote:
Originally Posted by adeeos View Post
What are you guys running for jets in your 950 hp for street strip? I have 80's in the front and 89's in the rear with factory power valves front and rear. I am killing plugs and it is pig rich.

I have run my best ever et with these, but it is not worth l
killing the plugs. I am running NGK R5671-7's on the street and spray a 200 shot with NGK R5671-8 on the bottle.

Dart Pro 1 325's on a pumnp gas 462 if it matters.

Thanks!
I had 82 front/87 rear's in mine, with PV plugs. And that is with a car that was running a 10.57@125 mph at the time. I can assure you, you are pig rich.

78 Malibu, 540, PG.
Under construction, 25.5B.
SS_Sean is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Chevelle 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, you will be sent a confirmation request to this address.

Email Address:
OR

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.



Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
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