420A Head flow numbers

[fun kart kid]

So i searched and couldn't find any flow numbers on the 420A head so i thought i would post this.
I had a chance to flow two different 420A heads a stock one and one that was ported by a reputable shop. Both of the heads were flowed on a superflow Fl-600 flow bench. Test pressure was the standard 28 inches of water. The intake port had clay for a radius the exhaust port was tested with no pipe.
The first head was a 420A head core I got from a junkyard the ports were untouched as cast.
Flow in CFM
Valve lift Intake Exhaust
.100 48.3 55.3
.200 109.5 109.5
.300 194.8 194.8
.400 241 241
.500 252 252
Next is the same head after I ported it I feel the there is more flow left in it but I was running out time.
Flow in CFM
Valve lift Intake Exhaust
.100 84.2 82.5
.200 168.3 157.5
.300 231.4 188.9
.400 250 192.1
.500 263.7 192.3
At this point I had a stock lower intake that put on to see how it would affect the intake flow
Flow in CFM
Valve lift
.100 96.5
.200 174.9
.300 230.3
.400 250.5
.500 246.4
Up next was a “stage 4” I had left over from one of my brothers builds. It had 1MM oversize valves. However the valve to seat contact was not I would considered ideal
Flow in CFM
Valve lift Intake Exhaust
.100 68.4 38
.200 134.1 112.6
.300 194.1 160.3
.400 261.1 168.9
.500 269.5 170.1
Like I did with the stock head I ported on it for bit. I would really like to re cut the valve seats however we didn't have the correct size pilot
Flow in CFM
Valve lift Intake Exhaust
.100 112.1 93.1
.200 192.9 160
.300 249.1 196.6
.400 277 203.6
.500 290.2 203.9
I put the intake on it and was shocked to see the amount the flow drop
Flow in CFM
Valve lift Intake
.100 112
.200 189.2
.300 238.3
.400 259.6
.500 271.5

 

[oldag98]

So what conclusions can we draw from your experiment?

 

[fun kart kid]

Mostly I wanted to the numbers out there. But the head does respond great to porting.

 

[BogusSVO]

What size bore tube did you use?

 

[blindboarder_02]

Interesting. Nice to see someone putting the work in for others to see. I've been looking for info on the 420a flow.
(Now if i could just understand what some of these numbers mean)

 

[fun kart kid]

I'm can not remember the exact size of the tube at this time. I will look some time this week I do know it was a little larger than the 420a bore thinking it was 3.5 or 3.7

 

[all_motor_mike]

Interesting. Nice to see someone putting the work in for others to see. I've been looking for info on the 420a flow.
(Now if i could just understand what some of these numbers mean)

U just gotta look better, I've been putting numbers up for years.


Mike

 

[fun kart kid]

Mike I did search for your numbers a bit I ran across them a few years ago. I was wanting to know how thay compared. Also the bore size was 3.600 when the testing was done.

 

[all_motor_mike]

Mike I did search for your numbers a bit I ran across them a few years ago. I was wanting to know how thay compared. Also the bore size was 3.600 when the testing was done.

depending on the port profile anywhere from 280-320 on the intake side @ .500" and 225-240cfm on the exhaust side @ .500". dont remember all the rest of the rest of the lifts #s.


mike