Quadrajet Problem Solving > Dialing in your rebuilt Quadrajet carburetor

Stock 301 jetting

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17058263:
Ok does any one know the stock 301 jetting pontiac. I tried  72 jet with 52p rod had o power went to  43k rod 72 apt now has power will break the tirers loose. Also i do not run a egr or cat. Timeing 15 intial.any help would be great

billy 2:
The carburetor number for a 1978 Pontiac 301 is: 17058272.  Jets and rods for that carb are:
72 jets, 51 rods.  The stock rods and jets  for the 17058263 are: jets 70, rods 39.  That carb is listed for a 1978 Pontiac 400 c.i. engine. Hope this helps  billy 2

17058263:
Im using a , 79 301 carb. number 17059272 with.065 air bleeds. It was lean and mpg did not improve by leaning it out. So i went back to 43k also tried custom 44 rods.  :) it runs good with the richer rods. Also with the 52p rods the throttle responce wasent that great. On line the manual 301 has 72 jet and 44rod. Just want some mpg

Cliff Ruggles:
There is no power difference using "K" or "P" metering rods at heavy and full throttle, as the tip size on either one is .026". 

Used in .072" main jets, the 52P rods would allow .042-.052" of the upper section in the jet at light throttle cruising. 

Using 43K rods you have a range of .039"-.043" in the jets cruising or any other high vacuum situation. 

If using .072" main jets, you will have a broader range of control with the APT with our custom .044" metering rods, as the upper section tapers all the way down to .026", and is .044" at the greatest diameter with the APT fully seated.

Some tips on tuning.  Choose the jet size first, based on heavy throttle power/performance without using the secondaries.  Climb some steep grades at heavy throttle on the primary side only and change jets until you have the best power.

Install a set of tapered metering rods just over .030" difference than the jets size.  For .072" main jets, .044" metering rods would be perfect.

Adjust the APT at apprx 3.5 turns up from seated, or use the "tip-in" method described in our book.

Do some extensive driving at light part throttle, and fine tune the APT screw for best transition off idle, light throttle power, and fuel economy.  This may take several tankfuls of fuel to find the ideal setting(s).

Rarely does going really lean with the APT screw delivery best fuel economy, or power, unless you are driving strictly at freeway speeds on flat roads with very light load.  More often than not, richer settings yield the best fuel overall fuel economy as the throttle angle will be lower for most driving situations.

Don't forget about the vacuum advance, it is equally as important as the carb setting(s) to find the best fuel economy.  Lean mixtures need more lead time (advance timing at light part throttle) to be effective.  You may have to add more timing in conjunction with leaning up the APT screw to see improved results......Cliff

17058263:
Well last year i had the 44custom rods and 72 jet and it faild smog at 23000 rpm co was to high so i went to a 70 jet and it past. And aso got 21mpg at that time. Also what jet would be good for a   49p rod.  And trust me o power with 52p rods and it ran hot plugs wear bone white. But had a tan color on the rim of the plug. Total timing is 38.

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