Welcome to the THE H.A.M.B. forums.

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

Go Back   THE H.A.M.B. > General Discussion > The Hokey Ass Message Board

Reply
 
Thread Tools Display Modes
Old 04-04-2012, 04:55 PM   #1
Rpmrex
Member
 
Rpmrex's Avatar
 
Join Date: Nov 2007
Location: Indiana
Posts: 671
Default How much pressure does a stock mechanical fuel pump have?

I have a 350 with a stock fuel pump and just bought 2 rodchester carbs set on a vintage speed 4 to 2 adapter. Will I need a regulator or does the stock chevy fuel pump not pump enough to wory about it?

How much does a stock pump, pump?

Whats the best pressure for the rodchester 2G's?


.
offline   Reply With Quote
Old 04-04-2012, 05:03 PM   #2
Stroker McGurk
Grenade Inspector
 
Join Date: Feb 2012
Location: Canada
Posts: 293
Default Re: How much pressure does a stock mechanical fuel pump have?

Stock pump is usually under 6 lbs, which should be fine for those carbs
offline   Reply With Quote
Old 04-04-2012, 06:30 PM   #3
Mat Thrasher
Alliance Member
 
Mat Thrasher's Avatar
 
Join Date: Nov 2007
Location: Middlefield Ohio
Posts: 1,004
Default Re: How much pressure does a stock mechanical fuel pump have?

I don't know about the pressure of a mechanical pump. But I run my 2GC's at 3 PSI. It seems to work good on my set-up.
online   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 04-04-2012, 06:31 PM   #4
1971BB427
Old School HAMBer
 
1971BB427's Avatar
 
Join Date: Mar 2010
Location: Oregon
Posts: 5,161
Default Re: How much pressure does a stock mechanical fuel pump have?

I'd put a pressure gauge inline after the pump. I've seen stock SBC mechanical pumps put out as high as 9 lbs., and when they do they always cause carb problems. Been there, done that.
offline   Reply With Quote
Old 04-04-2012, 06:34 PM   #5
XXL__
Member
 
XXL__'s Avatar
 
Join Date: Dec 2009
Location: CA
Posts: 685
Default Re: How much pressure does a stock mechanical fuel pump have?

3-4# is good for those carbs. Mechanical pumps are all over the place, depending on manufacturer, model, batch, condition, etc. Stick a gauge on it, at least... so you know what's going on, and possibly a regulator so you don't feed the carbs too much.

Edit: What the post before me said.
offline   Reply With Quote
Old 04-04-2012, 06:41 PM   #6
n847
Old School HAMBer
 
n847's Avatar
 
Join Date: Apr 2010
Location: Dayton Ohio
Posts: 2,706
Default Re: How much pressure does a stock mechanical fuel pump have?

I would expect 3-5 lbs if its a bone stocker but we put one on a stroker motor that ran 7-9 and it "looked" like a bone stocker!
online   Reply With Quote
Old 04-04-2012, 07:13 PM   #7
Saxman
Alliance Member
 
Saxman's Avatar
 
Join Date: Nov 2009
Location: Fallbrook, California - Home of Don Montgomery & Dode Martin
Posts: 2,468
Default Re: How much pressure does a stock mechanical fuel pump have?

My stock pump runs about 5-6 lbs. I also run about 3 lbs on my 2gs. You will probably need a regulator but you could try it without first and see how it goes.
offline   Reply With Quote
Old 04-04-2012, 07:25 PM   #8
31Vicky with a hemi
Alliance Member
 
31Vicky with a hemi's Avatar
 
Join Date: Nov 2008
Location: cleveland ohio
Posts: 10,661
Default Re: How much pressure does a stock mechanical fuel pump have?

Just a thought,,,,,

Every pump is going to be a little different, so far on this thread we've heard from 3 to 9 psi.
It's imperative that you know the pressure going into the carb in order to properly tune, diagnose, and troubleshoot any fuel delivery problem.

,,,,, after you get it mounted put a gauge on it. Make your call on a regulator then.

record the pressure someplace as " fuel pressure new psi X " that way in a few months when you want to post a " car acting funny, why ?" Thread, you'll be able to tell what was and is the fuel pressure. That will save you so much tail chasing.
__________________
Thank you, I will be installing a breathalyzer on my keyboard

the hamb relay network
http://www.jalopyjournal.com/forum/g...hp?groupid=214
online   Reply With Quote
Old 04-04-2012, 07:27 PM   #9
putz
Grenade Inspector
 
Join Date: Jan 2007
Location: wisc.
Posts: 283
Default Re: How much pressure does a stock mechanical fuel pump have?

3 pounds...............
offline   Reply With Quote
Old 04-05-2012, 07:50 AM   #10
carbking
Senior Member
 
carbking's Avatar
 
Join Date: Dec 2008
Location: Eldon, Missouri
Posts: 1,737
Default Re: How much pressure does a stock mechanical fuel pump have?

Quote:
Originally Posted by Rpmrex View Post
I have a 350 with a stock fuel pump and just bought 2 rodchester carbs set on a vintage speed 4 to 2 adapter. Will I need a regulator or does the stock chevy fuel pump not pump enough to wory about it?

How much does a stock pump, pump?

Whats the best pressure for the rodchester 2G's?


.
How much does a stock pump pump? Depends on the design and quality control of the pump. Even some name brand pumps produced today (made in a different country) have been measured above 15 psi!!! A fuel pressure gauge is going to be your only definative answer.

What is the best pressure for the Rochester 2G? Depends on fuel valve orifice, float height, and the bouyancy of the float used (several different were used in various 2G series carbs). With a STOCK tripower on a 1964 GTO I ran 5 1/2 to 6 psi with zero issues. Carbs were originals, with original floats, and the correct fuel orifices.

Edit - the phone hasn't started yet, so checked two common 2G fuel valves used by Chevrolet: one was a 0.082 orifice, the other 0.120. I suspect if one checked some other brands (maybe the 2G used on the Pontiac 455 and the 2G used on the Mercury marine small six) the range would be even greater. Now which valve is in that universal kit you buy at the FLAPS that services 792 different carburetors?


Jon.
__________________
Good carburetion is fuelish hot air!

The Carburetor Shop of Missouri 573-392-7378 (9-4 M-Tues CT)

Last edited by carbking; 04-05-2012 at 08:08 AM.
offline   Reply With Quote
Old 04-05-2012, 08:08 AM   #11
Truckedup
Old School HAMBer
 
Truckedup's Avatar
 
Join Date: Jul 2006
Location: Western NY hillbilly
Posts: 3,227
Default Re: How much pressure does a stock mechanical fuel pump have?

Got a large base brass float 2G being fed with an electric pump at 5 psi.No flooding or rich idle problems even after a hot restart.
offline   Reply With Quote
Old 04-05-2012, 10:54 AM   #12
tommy
Old School HAMBer
 
tommy's Avatar
 
Join Date: Mar 2001
Location: Davidsonville, Md.
Posts: 14,406
Default Re: How much pressure does a stock mechanical fuel pump have?

I've never had a problem with the Rochester carbs. I ran a Rochester on my old Chevy with an electric pump and no regulator. The Rochester carbs came stock from the factory on Chevys on a stock mechanical pump and no regulator. It's the 97s and 94s that seem to be more pressure sensitive.

That being said I have 2 97s running on my stock Studebaker mechanical pump with no regulator at all. I bought it that way and the need never came up. I bought a kit and rebuilt the stock pump. I don't look for problems so I just go with the flow if it wants to flood then by all means add a regulator but I don't assume that there will be a problem before it occurs.
Electric pumps with 97s are different animals of course. IMHO.
__________________
Quote...You are hereby Knighted...'Sir Asseth of Hole' Tommy... 3W Larry.
Quote...It's called "HOT RODDING", not paint by numbers....Fab32
offline   Reply With Quote
Old 04-05-2012, 07:01 PM   #13
brokenspoke
Alliance Member
 
brokenspoke's Avatar
 
Join Date: Jul 2005
Location: Anderson Texas
Posts: 2,518
Default Re: How much pressure does a stock mechanical fuel pump have?

GMC Bubba has a great tech on testing fuel pressure W/O a guage
offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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 On

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 07:52 PM.