Quadrajet Problem Solving > Dialing in your rebuilt Quadrajet carburetor

Primary jets and rods for AFR?

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lrust:
smooth transition from idle to off idle.  AFR is in band during WOT.

Cliff Ruggles:
If it's smooth and not surging or "flat", down on power, etc at light throttle plus smooth thru transition then it's well within range.

I put an A/F meter on mine once and saw anywhere from mid 13's to high 17 to 1 depending on throttle angle, rpm, engine load etc.  Since it runs flawlessly I didn't touch anything, removed the meter and never messed with it again.  Had a visitor here a few years back and he saw one of the spark plugs from my engine and told me it was "WAY too lean" because the plug was white.  I told him that he must be used to MSD billet distributors w/o vacuum advance and "pig" ars rich Holley carburetors, as black sooty plugs and exhaust are pretty much the norm there!.....LOL

I really don't recommend tuning specifically with an A/F gauge but they are good tool for reference.  Tune for best results in all areas, you can watch the meter to where you are at and where you are going, but I don't shoot for any particular A/F ratio anyplace.

For WOT tuning I run mine a little "fat".  It really doesn't slow it down much at the track and better than putting a piston on the oil pan or burning an exhaust valve, etc.....

lrust:
Cliff, thanks for the response.  Reason I am concerned is that I went through the motor after 1,000 miles at dragweek and the bearings showed signs of detonation.  I since opened up the combustion chambers and am using thicker head gaskets.  CR should be under 10 now but I figured getting the part throttle mixture a litter fatter should give me some more margin for error.  ~Lowell

Cliff Ruggles:
The A/F ratio on the primary side has NOTHING to do with detonation that would damage bearings.

Go after the secondary side and timing for that problem.

Are you using dished pistons with the 670 heads, or flat tops?....

lrust:
15cc dished pistons from Ross

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