82Waggy's Head Flow #'s

[82Waggy]

Finally got a chance to flow my AMC 090 heads this evening.

As some of you know I've been working on these for quite some time.

To date, I have installed hardened exhaust seats and opened up the throat with a piloted cutter to match the seat ID (about .100" larger diameter throat), but have not blended this plunged cut into the bowls yet. The 3 angle valve job is done with a 2.025d intake valve on a 30deg seat and 1.68d exhaust valve on a 45deg seat.

I have opened up the chambers by unshrouding the valves, used a fly cutter to open the radius of the chamber, blended all the machine cuts in by hand grinding, and also tuliped the intake valves for more CC's - alot of hard work to get this done but all of the chambers now measure 64.5cc's.

I have also gasket matched the intake ports and ground down any casting flash out of all runners.

Here are my Superflow bench results and stock 090 and Edelbrock head numbers for comparison:

Intake (28")
Lift, Edel, S090, My 090's
100, 65, 74, 85
200, 130, 156, 160
300, 192, 201, 210
400, 235, 219, 225
500, 258, 226, 230
600, 260, 232, 238
AVG, 190, 185, 191

My intake numbers are typical for a 30deg valve seat (Edel have a 45deg seat). I attribute the improvement over stock at low lift primarily to unshrouding the valves.

Exhaust (25")
Lift, Edel, S090, My 090's
100, 52, 56, 53
200, 96, 112, 103
300, 127, 141, 142
400, 163, 145, 163
500, 182, 149, 169
600, 190, 150, 175
AVG, 135, 126, 134

As you can see, even with the rough edge that currently exists in my exhaust bowls, opening the throats made a big difference over stock at high lift and even keeps up with the stock Edelbrocks up to .400" lift.

I expect to see better numbers overall once I am through blending in my machining and working on the bowls.

I'll post back final numbers and pics when I am finished.

PS: I'm not sure how many inches of water vacuum were used to test the Edlebrock or stock heads (I used 28int and 25exh) so this may not be a completely accurate comparison.

[jeepsr4ever]

Great project! Are you testing many times on a flowbench while you go? :t:

[82Waggy]

First test of the current level of modifications was tonight. Really was not much point testing prior to now since I already had stock numbers.

The port and bowl work comes next and that will be the acid test. I currently have a real hard edge between the throats and the short turn radius of the port runners that I know is hurting high lift flow and of course the edge where I stopped the plunge cut into the exhaust bowl.

Interesting, but tedious work. We'll see.

BTW, buying the Edelbrock heads is a much quicker and cheaper way to go if you can figure out how to get the compression ratio where you want it with their 54cc chambers.

[82Waggy]

Here are my final numbers after blending the machining in the bowls:

Valve Intake
Lift, Edel, S090, My 090's
.100, 65, 74, 90
.200, 130, 156, 157
.300, 192, 201, 202
.400, 235, 219, 220
.500, 258, 226, 236
.600, 260, 232, 241
AVG, 190, 185, 191

Valve Exhaust
Lift, Edel, S090, My 090's
.100, 52, 56, 53
.200, 96, 112, 110,
.300, 127 , 141, 149
.400, 163, 145, 175
.500, 182 , 149, 192
.600, 190, 150, 192
AVG, 135, 126, 145

You might note the improvement after blending relative to my previous numbers.

Also note that although my numbers are up, the exhaust valve quit improving after .500 lift - as did the stock port.

I lost a little mid lift flow on the intake after blending but this could just as well be setup error as the difference is marginal. Anywho, I beat the stock Edelbrock heads with my cast Iron AMC heads on average, especially when you consider that my valves pass through the higher flow low lift range twice to Edelbrocks peak numbers once! :lo1l:

The heads are done and assembled now. Motor is going together completely tomorrow. I'll post some Pics tomorrow AM.

PS: The cam I chose hit my peak numbers pretty much on the nose, .482 lift int, .502 lift, exh. Say Halleluiah!!! :!:

[1980_Cj7]

Interesting. At lower to mid lift, your numbers actually got worse, and in the case of the exhaust, are lower that the stock heads.

[82Waggy]

Interesting. At lower to mid lift, your numbers actually got worse, and in the case of the exhaust, are lower that the stock heads.

Yup. I'm not sure I read a whole lot into that due to minor setup differences - The stock numbers are also from a different set of 090 castings on another flow bench , so who knows.

I did not really change much on the intake from the previous test other than clean up the bowls. The only difference from stock on my intakes are gasket matched ports, deburred runners, and cleaned up bowls.

The slightly lower than stock exh flow at .100 and .200 is probably due to the larger throat, resulting in a minor loss of some low lift velocity, but it sure jumps up after that and did show considerable gains over the previous test after cleaning up the machining.

Note that stock heads don't gain much after .400 lift (only 4cfm exh from .400 - .500). Mine jump 27cfm.

Anyway, I got what I was after and acheived an 80% exh/int ratio.

[1980_Cj7]

I'm trying to get my head (no pun intended) wrapped around what these numbers mean. When you think about it, the valve doesn't stay at any lift for any length of time, it's always moving, either on its way open or on its way shut.

Seems like the most important number would be the average. The higher the valve lift, the higher the average would get I would think.

[82Waggy]

I'm trying to get my head (no pun intended) wrapped around what these numbers mean. When you think about it, the valve doesn't stay at any lift for any length of time, it's always moving, either on its way open or on its way shut.

Seems like the most important number would be the average. The higher the valve lift, the higher the average would get I would think.


That's basically true. Some would say you want your valves to pass through the high flow area twice.

[82Waggy]

I think it is also interesting to ponder the difference between a 30 and a 45deg intake seat. The Edel heads have a 45 degree seat, yet the averages would suggest no advantage over the stockers 30 deg seat, especially if you are limiting valve lift to .500 or less - in which case my 090 castings average much better than they do.

Of course, MC has been showing that the Edelbrocks have much higher potential flow after some porting than they do out of the box.

[82Waggy]

BTW, I used a bell-mouthed inlet fairing made from a 1" thick polycarbonate plate on the intake port and various sizes of exhaust stub tubes (1.5", 1.75", 2") . None of these matched up exactly to the ports, though the intake was pretty close, so the numbers should only be used for comparison from one test to the next using the same setup, not actual flow when installed with a matched manifolds. The smaller exh stub tubes resulted in better numbers, for what that's worth.

[82Waggy]

Here are some pics for comparison. Unfortunately I put the valves in so no pics of the bowls.

Stock Chamber
http://i142.photobucket.com/albums/r107/82Waggy/401/head003.jpg

Modified Chamber
http://i142.photobucket.com/albums/r107/82Waggy/401/head001.jpg

Stock Intake Port
http://i142.photobucket.com/albums/r107/82Waggy/401/head004.jpg

Gasket Matched Intake Port
http://i142.photobucket.com/albums/r107/82Waggy/401/head002.jpg

Machined Valve Cover Rail And For Guideplates
http://i142.photobucket.com/albums/r107/82Waggy/401/head5.jpg

[AMX69PHATTY]

Might wanna get all those paint stripes off of those valve springs.

Where I lost a cam lobe and lifter after 3 hours time
I found a lot of that valve spring paint in my oil pick up screen.
Motor is apart and used kerosene to remove all paint from valve springs.

Looks very nice.

[1980_Cj7]

Of course, MC has been showing that the Edelbrocks have much higher potential flow after some porting than they do out of the box.

I read too that aluminum heads let you get away with more compression on pump gas without getting into detonation.

[82Waggy]

Depending upon intake duration, perhaps a full point more compression can be used with aluminum heads.

[82Waggy]

Might wanna get all those paint stripes off of those valve springs.

Where I lost a cam lobe and lifter after 3 hours time
I found a lot of that valve spring paint in my oil pick up screen.
Motor is apart and used kerosene to remove all paint from valve springs.

Looks very nice.

Good Call!

I'm now going around with a rag get the paint off.