360 six pack jetting
 

I have a 51 Dodge truck with a 360, non magnum, six pack motor. I have not had it on the dyno and have been using the jetting that came with the new 340 six pack carbs. It has always run a little rich and jetting is in its' immediate future. Everything I read on 360 six pack motors suggests #63/64 center carb jets and both front and rear, #86 drivers side and #73 diaphragm side. Can anyone explain to me why such a difference front one side to the other? PS I eliminated the diaphragms and have mechanical secondaries. Does that change anything? Thanks, and glad to be aboard. HWR

First off it would probably run better with the vacuum diaphragms hooked up. dumping 1000 cfm with mechanical linkage is too much carb for a semi stock motor

you will have to wait for Chryco Psycho to answer you he seems to have more than enough knowledge on the holly setups i'm sure he can get you down the right path on jetting :)

The factory had a lot of this figured out & the fuel atomization would change between the low & hig plenums / left & right side which could allow for staggered jetting although that is a lot .
The big issue is by removing the vacuum pots & forcing the secondaries open you have no accerator pumps adding fuel as the out boards open & if you add enough fuel through the center carb squirter to cover the opening of the out boards it will bog with too much fuel at part throttle . Holley did offer a system with all mechanical carbs that had side hung bowls , accerator pumps & jets in all 3 carbs . It sounds like you may actually may have this system in place but I am not sure ?
If you have the proper mechanical secondary carbs I would not stagger he jetting that much , tuning on a dyno or with a A/F meter & watch plug color side to side should get you close , if you do not have a lot of vacuum at idle you may need to restrict the idle bleeds somewhat to get the idle sorted as well

no 1 i am NOT a 6 pack expert. IMHO if the cam is close to the 1970 T/A 340 cam, i think jetting your set up close the T/A set up would be good. as a start. my dad allways said when in dought "do it like the FACTORY did it." just look at the T/A cam , it is NOT a big cam , but it cranks out a lot of power.

there you go

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