Technical Jetting 600 Holley.

Hi all looking for some advice, running a 305 SBC with a 600 Holley and an after market inlet other wise its stock it running really rich and after suggestions on jetting the carb.

Be gentle I'm new to the big motors.

thank in advance.

 

Rich at idle? Part throttle? WOT? does it stumble or just smell? an 1850 holley should be pretty close out of the box - what model do you have?

 

First I would use a vacuum gage to adjust the idle air screws in the side of the metering block obtaining the highest reading

Then drop two jet sizes until you get a stumble at cruise speed.

I assume timing is correct.

 

Be sure to check the float level and fuel pressure before you get to involved with making changes to the carb. Start with the basics.

 

Try to find a pair of "close limit" jets that are numbered 623...
The "3" in that number means those jets flow within 3% of each other..

 

FIRST...
As was noted, first things first...
Where...is it running rich. Idle, slow speed rpm, high speed rpm, hard accelerating ???
Please provide all information for the best answer returned.

Fuel pressure should be about 5-1/2 to 6 PSI. Adjust as required.
Verify the float level is correct. Adjust as required.

Stock, both Holleys and Edelbrock carburetors come out of the box fairly close to right. That is not too rich, black smoke !, or too lean.

Mike

 

And don't forget to check the power valve ....

 

Jackpot! Holley carb, SBC, one backfire and BOOM! one new power valve please