460 Running to rich!!

Hello all!

I have a 1970 Lincoln Dove block bored .60 over with same heads w/ 2.19 intake and 1.90 exhaust, 4.39 Bore and 3.85 stroke, 10.5 compression Cam lift intake .518 @ 293 duration, Lift exhaust .544 @ 303. duration.

I am running a Holley 850 on a Weiand stealth 8012 intake. The peak Hp is at 508 @6000 RPM with 514 peak ft lbs torque @4500 RPM. I have the 8577 MSD billet distributor with the MSD 6AL ignition and MSD Blaster SS coil using the big wires and even bigger coil wire. I have the mechanical advance set @ 4500 RPM.

I run 110 to 112 Race fuel...ONLY

Runs at around 180 to 190 degrees on a 90 degree day.

My deal is this. When jetting I started with a pair of #75 jets....too rich. Dropped to a pair of #73 jets...too lean settled at a pair of 74 jets...too rich again!

I have the timing at 12 to 13 degrees at 800RPM and 32 to 33 Degrees at 3000 RPM.

Any ideas out there??
Thank you in advance my fellow gearheads!
Chris

what rpm range are you running to rich?

Power valve blown out? One or two jet sizes is not going to make one too rich or too lean if you're even close on correct size. 73-75's in an 850 doesn't sound right. Is it a double pumper or vacuum secondary?

How are you determining if it's too lean or rich?

With only 10.5:1 compression you really don't need 110-112 octane racing fuel. That may be part of your problem.

Big mistake...My 460 is at 11.5 to 1 compression.

850 Double Pumper. Power Valve is good. I smell the fuel in the exhaust plus runny eyes inside ( no, I am not a cry baby!) the car! It runs a bit smokey at idle when under 180 degrees and a bit when gettin on it. Strange but true, #73 jet, plugs show lean #75 show rich. After about 3 hours of toolin around town after puttin in the #74's, plugs show a more normal combustion. Very minimal oil consumption..Black smoke not blue.

Hi-test causes plugs to foul at around 190 to 200 degrees, and that can be a bitch when you are not close to home.

Thanks all!

Almost sounds like you may have too cold of a plug or the power valve is pulsing, you may need to use a different number PV. Double check the float levels. May have a gasket allowing fuel to leak by somewhere. Other than that I really don't know. 1 or 2 numbers in jet should never make that much difference in rich/lean. 110-112 race fuel is still a bit much even for 11.5:1. I use 112 in a 14:1 557.

What plug are you running?

Your initial timing seems low and if you are saying you don't see full mechanical advance until 4500 rpm that seems a bit slow. Are you running power valves? The jetting does not seem excessively rich but if the PVCR's are large you will be rich under WOT. Is this a new carb or used? If used do you now the history of it? I would get the timing squared away first and then disassemble the carb and get a baseline measurement of every orifice, ifr, pvcr, iab, mab, tslot etc...

460fairlane wrote:Big mistake...My 460 is at 11.5 to 1 compression.

850 Double Pumper. Power Valve is good. I smell the fuel in the exhaust plus runny eyes inside ( no, I am not a cry baby!) the car! It runs a bit smokey at idle when under 180 degrees and a bit when gettin on it. Strange but true, #73 jet, plugs show lean #75 show rich. After about 3 hours of toolin around town after puttin in the #74's, plugs show a more normal combustion. Very minimal oil consumption..Black smoke not blue.

Hi-test causes plugs to foul at around 190 to 200 degrees, and that can be a bitch when you are not close to home. Thanks all!

Don't forget that, at idle, the jets are not coming into play at all. You are getting fuel entirely from the idle circuit. In fact, most crusing is on the idle circuit. If you have a vacuum gauge, tune the idle mixture for the highest vacuum, If not, turn in the idle mixture screws until the engine stumbles and back out 1/4 turn. You may have to readjust your idle speed while doing this adjustment.

Thank you all for your in-put! You all have been very helpful. I am going to play with all of your suggestions, after all, owning a hot rod is a big boys toy and meant to be played with!
Reguards,
Chris

Sure sounds like a tslot uncovered to much or power valve fuel circuit not closed.
I have seen 2 different baseplate gaskets that were identical except for the hole thats lets the vac from under the carb pull pv closed.
One had it and one did not.the one that didnt had the vac shut off from pv.
Also make sure to check the rear butterfly opening in relation to the rear tslot.
If t slots are uncovered to much and it want idle when you set the butterflies to cover tslot. And set timing and idle mix .you may need to drill 1/16 hole in the butterflies.

Hope this helps.Clyde