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<blockquote data-quote="swampratt" data-source="post: 3220929" data-attributes="member: 15054"><p>The 5.5" if vacuum from the 305H cam was due to the terrible designed intake port of the china head I bet it would not flow 230 cfm as it was and velocity through a huge runner just is not there if it does not move any air.</p><p>Those heads had a huge area in the intake runner around the head bolt. terrible design.</p><p></p><p>The deal with a loss of RPM with the 2.02 valve head is not shrouding of the cylinder wall but shrouding of the chamber wall.</p><p></p><p>Even in factory form like the 492 angle plug 2.02 head the chamber wall is very close to the intake valve.</p><p>This will kill power and RPM and you will lose as much as 20 cfm of flow going to a 2.02 valve if you did not port the port correctly and if you left the combustion chamber stock.</p><p></p><p>Look up "flow balls" and their use on valve deshrouding.</p><p></p><p></p><p>Now on the 650 being too much carb for a V8 that is all Hooey.</p><p>An engine pulls in air and it is all about velocity and mixture.</p><p>It is up to the tuner to get the right fuel jet in that carb and the correct power valve setting.</p><p>I have many old AFB carbs and other carbs..I bet I have over 60 carbs here.</p><p></p><p>Anyway I tested many different sizes and styles on my old Van a 6000 lb Ford E150 from 1984 a 302 bored .030 with keith black flat tops and a 260H comp cam. ported small valve heads from 1982 and ported 2V intake and ported exhaust manifolds.</p><p></p><p>Yea I port everything I have.</p><p>Anyway I tried Q jets and 465 600 and 750 AFB carbs and 2 motorcraft 2 V carbs.</p><p>After all were tuned to the last degree there was no difference in power or MPG.</p><p></p><p>I built a little 350 with 268H cam hunting gas MPG and power and believe it or not the 750 Edelbrock gave the best MPG out of all carbs tested. This was with a square bore Edelbrock performer RPM intake.</p><p></p><p>Reason it got best MPG was the primaries are larger than the others and I was in idle circuit until 2400rpm.</p><p>The smaller 600's would come into the mains and fuel would come out of the boosters right off idle.</p><p></p><p>How much MPG difference after it was tuned only 1/2 MPG.</p><p></p><p>Now for the absolute best MPG the Cast iron Q jet intake with a Q jet was the winner.</p><p>But on a wheel dyno it was down 30HP.</p><p>I then ported the cast manifold and picked up 20 HP so it was only behind the RPM intake by 10 HP.</p><p>That was plenum porting only No runner porting.</p><p></p><p>If you have issues with the 650AVS feel free to PM me.</p><p>I have been playing with the AFB and other carbs for over 35 years.</p><p>Probably not near as long as many of you guys.</p><p></p><p>I have tweaked 100's of carbs I like carbs.</p><p></p><p>On a second note I seen a newer SS camaro heading down the highway last night with 818 on the quarter glass.</p><p>Yep he just got back from the race track.</p><p></p><p>I had to see if I could beat him in my 57 chevy.</p><p>We finally got a chance from a slow roll and he out ran me. He had me by 3 lengths in a 1/4 mile stretch.</p><p></p><p>I just could not run him down in my 4 door.</p><p>I got to thinking I need to stick my solid flat tappet in and my tunnel-ram.</p><p></p><p>I just want to run down these new LS and Ford engines so bad with my old school junk.</p></blockquote><p></p>
[QUOTE="swampratt, post: 3220929, member: 15054"] The 5.5" if vacuum from the 305H cam was due to the terrible designed intake port of the china head I bet it would not flow 230 cfm as it was and velocity through a huge runner just is not there if it does not move any air. Those heads had a huge area in the intake runner around the head bolt. terrible design. The deal with a loss of RPM with the 2.02 valve head is not shrouding of the cylinder wall but shrouding of the chamber wall. Even in factory form like the 492 angle plug 2.02 head the chamber wall is very close to the intake valve. This will kill power and RPM and you will lose as much as 20 cfm of flow going to a 2.02 valve if you did not port the port correctly and if you left the combustion chamber stock. Look up "flow balls" and their use on valve deshrouding. Now on the 650 being too much carb for a V8 that is all Hooey. An engine pulls in air and it is all about velocity and mixture. It is up to the tuner to get the right fuel jet in that carb and the correct power valve setting. I have many old AFB carbs and other carbs..I bet I have over 60 carbs here. Anyway I tested many different sizes and styles on my old Van a 6000 lb Ford E150 from 1984 a 302 bored .030 with keith black flat tops and a 260H comp cam. ported small valve heads from 1982 and ported 2V intake and ported exhaust manifolds. Yea I port everything I have. Anyway I tried Q jets and 465 600 and 750 AFB carbs and 2 motorcraft 2 V carbs. After all were tuned to the last degree there was no difference in power or MPG. I built a little 350 with 268H cam hunting gas MPG and power and believe it or not the 750 Edelbrock gave the best MPG out of all carbs tested. This was with a square bore Edelbrock performer RPM intake. Reason it got best MPG was the primaries are larger than the others and I was in idle circuit until 2400rpm. The smaller 600's would come into the mains and fuel would come out of the boosters right off idle. How much MPG difference after it was tuned only 1/2 MPG. Now for the absolute best MPG the Cast iron Q jet intake with a Q jet was the winner. But on a wheel dyno it was down 30HP. I then ported the cast manifold and picked up 20 HP so it was only behind the RPM intake by 10 HP. That was plenum porting only No runner porting. If you have issues with the 650AVS feel free to PM me. I have been playing with the AFB and other carbs for over 35 years. Probably not near as long as many of you guys. I have tweaked 100's of carbs I like carbs. On a second note I seen a newer SS camaro heading down the highway last night with 818 on the quarter glass. Yep he just got back from the race track. I had to see if I could beat him in my 57 chevy. We finally got a chance from a slow roll and he out ran me. He had me by 3 lengths in a 1/4 mile stretch. I just could not run him down in my 4 door. I got to thinking I need to stick my solid flat tappet in and my tunnel-ram. I just want to run down these new LS and Ford engines so bad with my old school junk. [/QUOTE]
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