Hot starting issues
LOL, no worries.
as to this;
It’s when I let off the gas and it starts coming back to idle that it sputters and dies.
>Depending on the exact circumstances surrounding this event, I would give a different answer;
but; if this occurs at closed throttle, then I would say that the throttle is too far closed, and the transfers are switching from flowing fuel, to bypassing air.
This sometimes happens when you try to run too much timing and still maintain a slow idle speed. The T-slot exposure under the throttles HAS to be a minimum of square. and the mixture screws have to be in the center of their adjustment range. The Idle-timing can be whatever. I can make that cam run dandy fine with just 5* of ignition advance.
Try this; using the speed screw, increase the idle-rpm by 200rpm. This will increase the transfer-slot fuel. Let's see if it goes away.
If it does then you are on the right track.
from the 200up rpm, decrease the idle-rpm by 100rpm, and if the idle-rpm is still too fast, drop timing until it gets back to 550/600 in gear. Then retest. If it still does it, increase the rpm again 100, and reduce timing if the rpm is too high. then retest.
>The idle-rpm is NOT too high until the transmission bangs when shifting from N/P to Manual-Low.
The Idle-rpm is too low if/when you get a tip-in sag when starting off gently. Or if the oil-pressure falls below 10psi; and especially if you have a heavy foot,lol
A good target Idle-rpm for that cam is 550/600 in gear, and up to 150 rpm higher in N/P; 100 is better. I would not purposely idle it higher than 750 in N/P
>As for your altitude; OOps, I have no experience for tuning at 3000ft. Mine stops at 1100.
At 3000ft, due to the thinner air, this will make a difference to your jetting. It will be rich. Compared to sealevel, you will need to drop all the MJs at least one size, two if running an oxygenated fuel. But, I think we can get the transfers to work OK.
> remember; at idle, you can switch back and forth between T-slot fuel and mixture-screw fuel to get the carb to behave. Just maintain the minimum square T-slot exposure.
> And don't forget about the fuel-level. A wrong WET level will wreak havoc with your low-speed tuning. If it is high, then your idle circuits will be rich, which at 3000ft is bad. If the Wet level is low, then your idle circuits will be lean; usually this is bad. In your case, a lil lean might be OK. At WOT, you can easily compensate for low fuel level with jet sizing.
If you haven't guessed it by now, for a street car, your low-speed circuits are by far the most important to have tuned right. This is where you spend your time. Take your time.
Part-2
But as to this;
It’s when I let off the gas and it starts coming back to idle that it sputters and dies.
>Depending on the exact circumstances surrounding this event, I would give a different answer;
if this begins happening right away as soon as you lift, then very likely the engine has gone over-rich. Try this; as soon as it sputters, gently open the throttle a few degrees and hold it there.
If the engine picks up a lil, and the car then surges ahead, like being pulled by a rubber band; then it is recovering from a lean condition.
But if it burbles, farts or coughs before it picks up, then it was likely flooding. You will have to pull your PV out and test it.
>The plugs should tell the story.
>If the nose dropped just before this began, the fuel might be sloshing around in your bowls and you will need some slosh control. or
the fuel-level could simply be too high. or
the engine temp is too low, and fuel is puddling in the plenum.or
the too-big MJs have flooded it and you slammed the throttle shut at a bad moment, lol.
I run my 367 at 207*F, because the cooling system is dead-nuts reliable. Keep in mind; the thermostat sets the MINIMUM coolant temperature, and NOT the maximum, which is governed by the efficiency of the system. To that end I run a thermostatically-controlled clutch on my 7-blade hi-attack-angle, all metal fan. The temp runs just about exactly 207* no matter what goes on around it.