Variable hydraulic lifters for 440 engine
Update:
I've set the initial to 12* and fiddle about with the idle screw and mixture screws.
It took a little adjustment on the idle screw to open the blades a little more and managed to close in the idle mixture screw a 1/4 turn. (just over 3/4 turn)
I had set it at 800 rpm, it pulls 6"Hg vacuum.
While running disconnected the brake booster hose (wants to stall) and plugged the hose end, but no change in rpm or idle quality so the booster can be ruled out for 100%.
I used a piece of hose with a small funnel in the end to listen below the intake manifold but i cannot find any sucking noise coming from there.
Looking below the intake the valley pan seals nicely against the intake, also no leaks of any kind to be found, if there is a vacuum leak i would expect some fuel/soot to drip out maybe when the engine is off?
Anyway, did a test drive and found nothing strange, engine reacts on the throttle quite crisp.
Maybe i feel a very small hesitation when driving slow and increasing the throttle a bit, when stomping it it goes fine.
AFR readings are around 10.5 during cruising over all speeds, it seems to lean out a little to 11.0 if the rpms are higher due to higher cruising speeds.
So after all that i hooked up the PCV hose with the orifice installed, and started up.
Idle rpm went up a little as expected and screwed back the idle adjustment a little.
Now during driving the AFR gauge shows 11.0-11.5, so the additional air obviously leans it out a little.
Again, i am not sure anymore about the AFR meter.
After 15-20 miles on it the spark plugs look as below, all same.
Now to me, this does not seem like 10-11 AFR to me though.
When stomping the throttle the AFR goes around 10.0-10.5.
Now this is with the original (from Holley) jets in place, which are a "72" (hole size approx. .079") on the primary and a "77" (hole size approx. .086") on the secondaries.
These holes sizes are given by the Holley website for guidelines, and actually these sizes do not match the carburator spec sheet (0-80770) on their website as there it says "70" and "75" but i think this is a rough guideline as well and they will install jets depending on the wet flow testing.
Anyhow, i think i can try and lean it out a little with smaller jets to see if the AFR meter shows any difference when coming into, during and after transition from transfer slot to main jets.
Because i think i am earlier at the transition where the main jets start to flow then i think.
I am not looking at the actual AFR reading anymore, but use it more to see if the number goes up or down after changes made.
Update:
I've set the initial to 12* and fiddle about with the idle screw and mixture screws.
It took a little adjustment on the idle screw to open the blades a little more and managed to close in the idle mixture screw a 1/4 turn. (just over 3/4 turn)
I had set it at 800 rpm, it pulls 6"Hg vacuum.
While running disconnected the brake booster hose (wants to stall) and plugged the hose end, but no change in rpm or idle quality so the booster can be ruled out for 100%.
I used a piece of hose with a small funnel in the end to listen below the intake manifold but i cannot find any sucking noise coming from there.
Looking below the intake the valley pan seals nicely against the intake, also no leaks of any kind to be found, if there is a vacuum leak i would expect some fuel/soot to drip out maybe when the engine is off?
Anyway, did a test drive and found nothing strange, engine reacts on the throttle quite crisp.
Maybe i feel a very small hesitation when driving slow and increasing the throttle a bit, when stomping it it goes fine.
AFR readings are around 10.5 during cruising over all speeds, it seems to lean out a little to 11.0 if the rpms are higher due to higher cruising speeds.
So after all that i hooked up the PCV hose with the orifice installed, and started up.
Idle rpm went up a little as expected and screwed back the idle adjustment a little.
Now during driving the AFR gauge shows 11.0-11.5, so the additional air obviously leans it out a little.
Again, i am not sure anymore about the AFR meter.
After 15-20 miles on it the spark plugs look as below, all same.
Now to me, this does not seem like 10-11 AFR to me though.
When stomping the throttle the AFR goes around 10.0-10.5.
Now this is with the original (from Holley) jets in place, which are a "72" (hole size approx. .079") on the primary and a "77" (hole size approx. .086") on the secondaries.
These holes sizes are given by the Holley website for guidelines, and actually these sizes do not match the carburator spec sheet (0-80770) on their website as there it says "70" and "75" but i think this is a rough guideline as well and they will install jets depending on the wet flow testing.
Anyhow, i think i can try and lean it out a little with smaller jets to see if the AFR meter shows any difference when coming into, during and after transition from transfer slot to main jets.
Because i think i am earlier at the transition where the main jets start to flow then i think.
I am not looking at the actual AFR reading anymore, but use it more to see if the number goes up or down after changes made.
