Logo
FULL SITE MENU

rochester carb 4bbl

V

vice

Member
i have a rochester 4bbl carb and i really want to know how much cfm is has? the serial number is 17082515 (0693). can i use it on chrysler v8 (318 ci) marine engine.
 
Not sure of the cfm but that particular carb was used onlarger six cylinder engines (3.8’s, 4.3’s, etc.) so my guess is that it’s smaller than 600 cfm (standard size for the 318 Carters, Edelbrock 1409’s,etc.). The issue isn’t whether less cfm's will work on the 318, it’s whether it can handle less cfm’s from a four barrel. Once you go below 550-600 cfm’s, you’re really crossing into two barrel territory…….because the primaries on a small four barrel probably won’t feed the V8 what it needs on the low end.
 
The smallest Q-jet is 750CFM. The q-jet is a spread bore style carb and will need a new intake or at least an adapter.
 
bogdenz said:
Not sure of the cfm but that particular carb was used onlarger six cylinder engines (3.8’s, 4.3’s, etc.) so my guess is that it’s smaller than 600 cfm (standard size for the 318 Carters, Edelbrock 1409’s,etc.). The issue isn’t whether less cfm's will work on the 318, it’s whether it can handle less cfm’s from a four barrel. Once you go below 550-600 cfm’s, you’re really crossing into two barrel territory…….because the primaries on a small four barrel probably won’t feed the V8 what it needs on the low end.
Click to expand...
I run a 500cfm 4bbl Demon on a 318 with out any issues. Small venturi carbs are more efficient do to higher velocity, plus they give you a crisp throttle response.

A stock 318 will only pull 382CFM at WOT 5000rpms
 

Attachments

  • 318VE.jpg
    318VE.jpg
    62.6 KB · Views: 67
Last edited:
To answer your second question, Chrysler did in fact use them from the mid 70's right
up until the end.

Jack
 
Tahoerover said:
On what? I have a 73 and a 74 440 and both came with a AFB.
Click to expand...

I talking small blocks.... I would assume the 440's used the AFB's until they were discontinued
and Chrysler started buying Ford 460's which would have been around the time they would've switched to the Q-jet on all their engines, marine and automotive.....maybe 77-ish. They apparently never used the AVS on the marine engines and could you imagine the Thermo Quad
passing Coast Guard regs even back then.
 
Back
Top