This will be the thread for flow data on AMC Cylinder Heads. All data is at 28" H2O unless otherwise noted.
This first group of info was posted by Ken Parkman:
More testing on the flow bench today
AMC 2.02 valve heads:
Intake:
291 090 502
.100 71 74 70
.200 127 156 143
.300 179 201 192
.400 209 219 213
.500 217 226 220
.600 222 232 228
.700 228 238 236
Exhaust:
.100 55 56 59
.200 107 112 113
.300 135 141 146
.400 142 145 150
.500 145 149 152
.600 145 150 153
.700 145 151 153
The 291's are 3196291, 1970 51 cc chamber heads, the 090's are 1973 58 cc heads, and the 502's are 3220502 1974 60 cc heads, I have tested an example of all 3 combustion chamber sizes. The 291 and 090 heads have a multi angle valve seat, the 502's are utterly stock. There is no porting on any of these. They were all tested as identical as I could make it - same port, valves, inlet radius plate, flow bench, day, operator, and bench temperature. The correction factor for the bench temperature is a reduction of 1.6%, I couldn't be bothered adding it in.
The shrouding on the 291 heads really hurts the flow, it really surprised me. The later 60 cc chamber heads probably flow the best, I figure a valve job would make up the little difference with the 090 heads.
Interesting stuff, I'm not answering the phone in case they want the flowbench back. Figure I can stall them a few more days.
Can't add anything on the X heads Jeff. Have a small valve set with an X on them, but can see no differences. Have a single 993 head here, it has no X.
Did some valve job work on the 050 casting, performing the conventional hi-performance multi-angle seat on the test port. This seat is extremely similar to that on the 291 head tested. This was cut with stones because my buddy didn't have a cutter for a 30 degree seat. We then cut the next port with his trickest 45 degree seat radius edge custom cutter, makes a magnificent looking seat with no edges between the multi angles. This is the seat in some books as the trickest and best to use. Here are some results:
Test 1 2 3 4 5
.100 70.3 69.1 67.8 61.5 61.5
.200 143.0 138.5 138.5 126.2 125.1
.300 192.1 193.2 194.4 186.5 185.4
.400 212.6 222.4 224.4 220.5 220.5
.500 220.5 224.4 226.4 226.4 228.3
.600 228.3 230.3 234.3 228.3 232.3
.700 236.2 236.2 238.2 236.2 236.2
Test 1: Utterly Stock, as above with an extra digit
Test 2: Multi angle valve job
Test 3: As test 2 except edges of angles lightly radiused
Test 4: 45 degree seat, trick radius cutter, 'tulip' valve
Test 5: Same seat, performance valve, reduced stem, backcut
Both 4 and 5 were on a different port, and I don't have a baseline for this port.
Conclusions:
A 45 degree seat is a real good way to hurt flow below .500 lift. A multi angle valve seat will help flow at mid lifts but hurts a bit at low lift. The trick performance valve did help a bit at high lift, but it hurt at low lift. The valve and seat have almost nothing to do with flow at very high lift.
Big conclusion - a stock setup works friggin good.
A couple of other bits of info - had a big dollar AFR small block Chev, 2.08 valve, ported by an "expert", that came with an almost to good to be true flowsheet. It was too good to be true, I didn't get anything like the same flow. Buyer beware. Had an almost stock TFS 2.02 valve small block Ford on the machine, and it gave shockingly good numbers, nearly the same as the AFR. The 2.08 valve in the AFR did give better low and mid lift flow. Man I love this machine, am I ever learning a lot.
Here is the next set of test data. I went to a 2.05 valve to try to get some low lift flow back with the 45 degree seat. Then I did very minor pocket porting in the 3 different valve/seat combo's to see what that shows. This is all on the 502 head.
Test 1: 2.05" valve with 30 degree backcut, 45 degree seat, nothing else touched
Test 2: Same with minor pocket porting
Test 3: As test 5 yesterday (2.02 valve, 45 seat) with minor pocket porting
Test 4: As test 3 yesterday (2.02 valve, 30 seat) with minor pocket porting
1 2 3 4
.100 68 68 62 77
.200 137 137 127 150
.300 191 197 190 202
.400 221 234 228 232
.500 224 232 232 232
.600 228 236 238 238
.700 232 240 240 242
Conclusions: with a 45 degree seat even a 2.05 valve does not get back the low lift flow of a stock valve when both have good valve jobs. With minor pocket porting a stock valve still works better. With the rest of the port stock max lift flow changes with all of this are almost insignificant. A little pocket porting gives nice gains in the mid lift range.
Big conclusion: AMC must have known something when they designed this port - it works real well!
I've also had a sbc double hump head and a sbd 'J' head up on the machine, neither can touch an AMC - by a bunch!
Here are some comparison numbers for sbc and sbd
Lift / AMC 502 / Chev 370 / Dodge 'J'
Intake
.100 70 60 55
.200 143 122 112
.300 192 167 161
.400 213 190 198
.500 220 199 210
.600 228 203 205
.700 236 203
Exhaust
.100 59 40 49
.200 113 80 106
.300 146 114 125
.400 150 128 132
.500 152 135 134
.600 153 143 136
.700 153
Testing tonight has been dissapointing. I've machined the throats, narrowed the guide bosses, and machined the chamber to unshroud the valves, testing each time. For the most part I've gotten nothing in flow increases, and some loss in low lift flow with the 2.02 valves, but the 2.05 valve did show a little gain, and it liked the unshrouding, showing slight low lift improvement, almost up to a stock valve. It also now shows the best flow by a smitch, at 248.
Conclusion: Air doesn't know it should flow more with "obvious" port improvements, so it doesn't. The 502 head with a 2.02 valve doesn't need any unshrouding. A stock valve is still pretty hard to beat.
I have seen as much gains in the bowl as I am going to. Now to go looking elsewhere. Maybe some of tonight’s mods may have helped if the rest of the port flowed better.
Here's tonight's flow numbers. I'm sticking to one port now because I am running out of time. Tonight I smoothed the cast port surface, up til now it's been completely untouched. This is not polishing, just smoothing the surface. Then I opened the pushrod pinch a bit, sizing the cross sectional area for a 6000 rpm 401, maximizing velocity. I did not enlarge the port, because I am shooting for a certain velocity.
Test 1 2 3 4
.100 68 69 69 68
.200 136 142 142 140
.300 198 200 201 201
.400 236 238 246 246
.500 242 240 252 256
.600 242 246 256 258
.700 248 250 260 264
Test 1: Throat machined and valve guide boss narrowed
Test 2: Combustion chamber unshrouded with a 2.4" cutter
Test 3: Cast wall surface smoothed
Test 4: Pushrod pinch sized
Conclusion - the numbers are coming around nicely. This is not radical race porting, this is for a street 401. Once again the AMC is proving to be an excellent design.
Now to go for the details that make or break a port.
For a 45 degree seat I bore the throat .200 smaller than the valve diameter. On a 30 degree seat I make the throat .020 or .030 smaller than that.
Intensive testing session tonight, I'm losing the flowbench in the morning. Here is the end result, compared to stock. the head is a 502 large chamber head that started with a 60 cc chamber, and now has a 2.05 1.68 valve combination.
Lift, Intake Stock and Ported, Exhaust Stock and Ported
.100 70 69 59 56
.200 143 141 113 111
.300 192 201 146 172
.400 213 248 150 178
.500 220 260 152 185
.600 228 266 153 190
.700 236 272 153 193
I'm real happy with this port, because I did not raise it or make it big. This is sized for max velocity in a 6000 rpm 401 so it should make a great torque curve. This should be an awesome street head.
The exhaust was flowed without the bellmouthed pipe on the exhaust that is recommended, so the exhaust flow might be a little low, but these are the numbers I've got. It was wild how incredibly small tweaks could HUGE effects at mid lift on the exhaust. Here unshrouding made a big improvement.
Here is my stupidly ported intake and exhaust, I would not run this, this was just an exercise in how far I could push it. If you need flow like this by an Aluminum head.
Lift Intake Exhaust
.100 74 50
.200 146 104
.300 210 154
.400 258 188
.500 289 211
.600 297 226
.700 305 229
This was with a 2.10 1.65 valve combination.
Yep, I flowed the intakes on a head Steve, and on a stock 291 that is exactly what I found, 2-3%. On a max ported head a stock torker hurt the flow to the tune of about 8%, but working on the torker brought it back to about 3%. The air gap on a mild ported head took nearly 14% off the flow, where a R4B was 8% and a stock cast iron was 9.5%. Most of this (except the air gap, and I did baseline a R4B to double check) was a while ago, and was all on the same upper port to try to be consistant. With what I have recently learned I would like to do it again, checking both the upper and lower halves of the dual plane's. We did that to a BBC intake, and found never make any assumptions because the lower half flowed WAY better than the upper half.
4/15/2004
Somehow I've ended up with 2 sets of 291 heads here that I am porting for board members. It wasn't my plan to do much porting, because it is too much work for not enough money, but due to a couple of situations here I am. So I thought I would post some flow data during the process if you guys are not tired of it. The first set is for a 360, so I will not be making them that big to keep the velocity good. Here is the completely stock flow test: Lift Intake Exhaust Exhaust with stub .100 69.1 53.7 53.5 .200 142.6 95.1 101.3 .300 192.5 130.8 143.4 .400 218.4 143.4 161.1 .500 221.3 144.6 167.1 .600 224.6 145.9 169.1 These heads had extremely badly pitted seats, and for the exhaust I was using a 1.68 valve. Both of those things will not make a big difference for flow. The intake shows the slightly poorer flow compared to the later heads, but is typical. Notice how much difference the exhaust stub makes. The dog leg really comes to life with the stub, and of course that is the way it is on the engine with headers. I have now learned most of the exhaust flow numbers are done incorrectly (including my own from earlier testing). This is much more representative, and the AMC dog leg really is good. Next test with 11/32 valve guides, hardened exhaust seats cut for a 1.65 valve, and the intakes cut for 2.055 valves. I do have a good Ferrea 2.055 intake, but not the correct exhaust, so I am using a 1.600 Ferrea chev valve. This will have an effect on the exhaust numbers, but it should not be huge. Lift Intake Exhaust with stub .100 65.7 47.4 .200 127.7 94.0 .300 181.0 134.7 .400 212.8 158.6 .500 221.5 170.0 .600 229.1 175.6 .700 235.6 178.5 This is with a top notch valve jub, but nothing else. Notice how just a bigger intake with a 45 degree seat is a pretty good way to kill low and mid lift flow. There was not much effect on the exhaust, a little worse low lift and a little better high lift. I'm not bothering with no stub because it is misleading.
Next test with the basic work on the mill. I sized the throats correctly for the new valves, did the most minor unshrouding, but that got rid of the machined lip in the combustion chamber a 291 has. Also used the mill to square the port opening and size the pushrod pinch. Just a little bigger, trying to target velocity for about a 6500 rpm max 360. Then I did basic blending of this machine work. On the exhaust I did basic hand porting of the throat. Here are the results: Lift Intake Exhaust with stub .100 67.5 49.7 .200 137.8 107.9 .300 192.7 153.1 .400 236.5 177.9 .500 256.8 220.0 .600 248.0 227.5 .700 257.2 229.8 Now we're getting somewhere! I got most of the low lift intake flow back, and the upper lift flow is taking off. The drop above .500 lift tells me I have some more work to do yet, but the improvement are huge. The exhaust is amazing. That was not much work, and fantastic results. The dog leg really is that good, and way ahead of the ported rectangular SS heads with a 1.74 valve. Awesomely good design that dog leg!
Ken_Parkman on Mar 29th, 2004, 12:06am wrote: Ran across an original set of the SS/AMX heads, casting 3188558. Or at least they are supposed to be original, they were supposed to have come off a car that started a conversion to a comp style car, but never got finished. It is supposed to be in a garage somewhere a few hours from here, sometime I will have to go hunting. They look right, but who knows for sure. Seeing as I am a kid with a new toy I put one on the flowbench - my buddy says I would flow the kitchen toaster if I thought I could learn something. If anyone is curious here are the numbers:
Lift/Intake/Exhaust/Exhaust with stub
.100 69.6 57.2 58.2 .200 153.8 100.3 106.9 .300 206.5 129.3 142.2 .400 242.1 146.0 161.4 .500 239.5 151.8 172.0 .600 246.0 159.5 180.9 .700 248.2 167.2 190.5
I have discovered flowing an exhaust without a stub is a mistake, especially on an AMC. The shape of the port without a pipe makes the flow direction wrong and entrains air. The dogleg ports really pick up with a correct stub, much more than this rectangular. Even though the raw data does not show the dogleg to be that much better, add a stub and the dogleg really shines. AMC knew what they were doing with that.
Been doing some more testing on the flow bench with different headers, thought I would post some data. First thing to remember this is a flow test only, it cannot judge cylinder scavenging or how the header works on an engine. There is a lot more to headers than just flow. And if you want a good torque curve use a full length header. First set of tests was using a VERY well ported (if I do say so myself) exhaust on a 291 head with a 1.65" valve. All of these tests are on cylinder #1. Lift w/stub #1 #2 #3 #4 #5 .100 50.8 50.5 49.8 50.3 49.5 52.5 .200 111.9 108.5 105.4 107.1 99.9 102.1 .300 166.9 153.7 142.2 147.1 126.4 131.4 .400 206.4 180.2 159.0 167.7 138.5 143.1 .500 232.7 194.4 167.3 178.0 143.9 148.8 .600 247.8 202.9 171.8 184.5 146.7 151.4 .700 255.2 209.0 175.6 189.9 148.6 153.3 This set of tests is on a more mildly ported exhaust, still well better than stock, but not as effective as the above head. Lift w/stub #1 #2 #3 #4 #5 .100 45.8 46.2 45.7 46.0 45.4 45.5 .200 100.8 97.5 94.5 96.5 91.3 98.8 .300 143.6 135.7 128.4 132.8 120.8 123.7 .400 175.8 161.7 150.5 156.3 136.5 140.0 .500 189.8 171.0 158.0 164.8 143.1 147.8 .600 198.4 176.7 161.8 170.3 146.9 150.6 .700 203.2 179.5 164.3 173.1 147.7 152.4 Just to really OD on numbers I did the same set of tests on a unported, but with a very effective valve job, small valve rectangular exhaust port 290 head. This is with a 1.406" valve Lift w/stub #1 #2 #3 #4 #5 .100 48.7 48.2 45.8 48.3 45.8 46.6 .200 101.1 98.3 94.8 97.7 92.2 92.8 .300 131.2 126.0 120.7 123.9 115.1 116.2 .400 141.3 134.7 128.6 132.6 122.3 123.3 .500 144.0 138.0 131.7 136.3 125.2 125.6 .600 145.8 139.9 133.1 138.2 126.7 127.7 Header #1: 1 7/8 dog leg race header, made from a tube chassis weld up kit, Hedman components. Header #2: 1 3/4 dog leg dyno header, actually a Hedman Jeep fenderwell header with the port modified to properly fit the dog leg. Header #3: 1 3/4 dog leg Hooker pn 7105. It fits the port reasonably well. Header #4: 1 5/8 dog leg Hedman pn 98310. It fits the port absolutely terrible, way smaller than the port exit. Header #5: 1 5/8 rectangular Hooker pn 7104. It fits a rectangular port very well, but of course does not match the dog leg head. Interesting data, but it is sort of hard to make many conclusions. Here are mine: The better flowing the head the more important the headers are. If you are using a crappy header there is almost no use in porting the exhaust. If you have a small valve head the header really has very little influence on the flow. At the same size the Hookers flow better than the Hedmans, probably because of the nicer looking collector. The non-dog leg 1 5/8 Hooker actually flows better than the badly fitting dog leg 1 5/8 Hedman. The Hedman's are still a great deal at 1/3 the price of the Hookers
Edelbrock head flow
Date: Friday, March 12, 2004 10:04 AM From: mailto:amx69@swbell.net?subject=Edelbrock%20head%20flow - Randy Guynn <amx69@swbell.net> The published air flow on the new Edelbrock heads is now available. From my understanding it will be May before any heads are released. At any rate, here are the flow figures. .100 lift, intake 65 cfm, exhaust 52 cfm .200 lift, intake 130 cfm, exhaust 96 cfm .300 lift, intake 192 cfm, exhaust 127cfm .400 lift, intake 235 cfm, exhaust 163 cfm .500 lift, intake 258 cfm, exhaust 182 cfm .600 lift, intake 260 cfm, exhaust 190 cfm
|