Are you sure the afr reading is accurate?
If it’s really that rich, it should be blowing black smoke out of the exhaust.
Plugs would be very sooty too........ very.
This is one of those situations where the “known good” carb comes in handy.
The brother of one my friends recently bought an engine dyno.
He’s been getting acclimated to how everything works, and what are the things to look for before the damage is done.
He bought a couple of nice looking, but used, Holley HP carbs to use as dyno mules.
The problem is....... he has no history with them(yet).
They had a semi-hot Street 455 Pontiac on the dyno, which was showing really lean....... and jetting didn’t seem to help much.
Tried the other one....... similar results.
So, the problem is...... the motor seems to be down on power.
Is it the carbs...... or something else?
Put the owners old “870” street Avenger on it.
Makes even less power...... fuel curve is all over the map.
After pulling the bowls it seems like the jets are awfully small in it.
I get him to tell me the list number.
Not an 870....... it’s a 670...... and it’s dirty and needs new gaskets.
Take another carb off another 455 my friend owns, Proform 850.
This carb shows really rich.
Similar power between the 4 carbs.
I keep several carbs on hand that I like to use at the start of the dyno session.
They aren’t necessarily the best power makers...... but they run well and the fuel curves are normal.
Good for the baseline.
