dudeboy

The idea is to maximize the time the valve is at 'max flow'...
It isn't rocket science, but don't underthink it portmaster.

LIfting the valve a little beyond 'max flow' allows you to take better advantage of max flow.


look to maximize the area under the flow curve... not just hitting the peak flow number....

w8less

i would get a trick flow track heat or holley systemax intake. ive had both and they are good intakes

Portmaster

This is why I told him to back out of using the 1.72 rockers. To let the cam do the work without overstressing the valve springs. With a lift of .498 (IIRC) on the E cam it puts him just past max flow of the heads. The object is to hold the valve open longer not farther. Lifting the valve off the seat .538 will get the head out of maximum flow. I didn't underthink it but I didn't want to try to go over the OP's head either.

Joel5.0

..... go get a hooker?..... ... why?

Of course I know flow drops past a specific lift point, that's the inherent definition of "peak flow".... if flow peaks at .500" lift, it should drop at .550" lift, and be less at .450" lift. Now..... do you know what flow area means? You could have a set of heads "peak" at .500" and another at .450", but the flow area of the latter be bigger than the higher lift case..... so why limit it?

Let's explain it the "logical way" then....... if a set of heads peak at .450" lift, and a custom dwell cam at .450" lift will kill the valve train, doesn't it make sense (flow/breathing wise that is) to keep it above .450" lift? ..... even if it "breaths" less at .550" lift? ....... hey... it's going through the peak flow lift area twice during the intake cycle instead of once.... . Better yet.... take your A/F velocity theory...... Velocity = scalar x time... simple physics.... if you can't modify the scalar (quantity)...... increase the time (aka crankshaft degrees above .xxx" lift)..... wouldn't that = an increase in velocity? ...... Or would a barometric/thermometer type of illustration help understanding it?

Better yet!... allow me to describe it. Within the same duration figure......

0 - .2 --.3---.4---.5---.55--.60 (lift)
0 - 40 - 60 - 80 - 100 - 80 - 60 (flow %)
------------------> (open)
==============< (close)
--------------------------> (open)
====================< (close)

Which one allows more A/F in the cylinder?

Baddog

Yikes! I'm going for popcorn. Can't wait to see how this unfolds...

Joel5.0

It is not peak flow that matters...... since a custom cam peaking at .498" valve lift for 35° is out of the question (to pick a number), you need to approach the flow limitations differently.... and those would be?...... keeping A/F flow below the cylinder heads flow peak numbers based on valve lift?....... SBF's are not as forgiving as a BBC (or a BBF) for flow error setups. You do not have the CID's to compensate for setup screw ups.

The cam will do the work regardless of rocker ratio, since he is limited due to his selection of parts, he might as as well try to compensate for their limitations. Going over the OP's head?...... if he's doing something you know by experience doesn't work, is not going over his head....... it's a experienced based freebie.

Portmaster

Yeah OK, lol