Jump to content
Forums Gone... but not forgotten!
Pontiac of the Month

GTO TEX's 1966 GTO

2020 February
of the Month

  • Welcome!

    Welcome to Forever Pontiac, where we keep the memory of Pontiac alive with great discussion, maintenance tips, restoration/modification progression "blogs" and help from professional & DIY mechanics. Also, wonderful competitions that occur regularly. Please register for an absolutely free account to join in!

Sign in to follow this  
Kurk_Kurk

i need assistance with a New Proform 650 carb i've got

Recommended Posts

Kurk_Kurk

i'm incredibly new to this carb tuning so i'd like to start with the fact that i have no idea what Jetting is and what a 'jet'does. does it regulate air? does it help the mixtures? 

my proform is pouring WAY too much fuel and i cant seem to sort it out. i'm talking 5 gallons of fuel in 20 minutes, idling. i opened it up and i cant get the billets off but i did find some odd numbers on what i think the 'jets' are. primary fuel bellow or barrel, whatever was .36 and the secondaries was .70

i think i just need understanding of these Jets

Share this post


Link to post
Share on other sites
Frosty

While this first link is related to motorcycle engines,  but the terms and theories are sound and accurate.

http://www.3wheelerworld.com/showthread.php/55086-Carb-Jetting-101-Terms-Tips-and-Jetting-Theory

 

How to re-jet a Rochester carb - parts I & II

 

 

Let us know if you have any other questions.

Share this post


Link to post
Share on other sites
Last Indian

Kirk Kirk, .36 & .70 really does not tell what size the jets are. So I can’t comment on how big they are. Different manufacturers use different designations for jets.This I will say this though, if you are truly putting 5 gallons in 20 minutes that engine, and I find that a little hard to conceive, as most nearly all engines would be flooded out. 

I ran a 600 hp. 302 Z/28 that got 6 miles to the gallon, 2 gallons in 15 minutes. I changes oil every 2000 miles because of concern about fuel dilution. So, be very careful! That much gas through that engine you will definitely ave fuel dilution and that can cause to very catastrophic occurrences. One wipe out a bearing because of poor viscosity or even worse a engine explosion! 

So please be careful! 

If you take a number drill set you can actually measure the diameter of the jets. Knowing this will help choose the jet for your application. You may actually have a bad power valve.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.