572-13 head flow-by flow tech 2
#3061746
07/22/22 11:23 PM
07/22/22 11:23 PM
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gregsdart
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Larry Smith of flow tech 2 did these beautiful ports. I know little about all the ins and outs of what makes power, but trust Todd of Marsh Performance to steer me in the right direction. The numbers came back, and look good to me. If you compare them to the 440-1 numbers , looks very promising. I run a . 848 net lift cam for help in comparison. The jesel gear arrived, pistons are supposed to arrive tomorrow.
Last edited by gregsdart; 07/22/22 11:38 PM.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: 572-13 head flow-by flow tech 2
[Re: gregsdart]
#3061818
07/23/22 11:52 AM
07/23/22 11:52 AM
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pittsburghracer
"Little"John
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"Little"John
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It will be interesting to see how they stack up on the other flowbench.
1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.42@138.27
Livin and lovin life one day at a time
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Re: 572-13 head flow-by flow tech 2
[Re: pittsburghracer]
#3061919
07/23/22 07:02 PM
07/23/22 07:02 PM
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gregsdart
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It will be interesting to see how they stack up on the other flowbench. it will for sure. Since you port heads, a little info on valve angles. No back cut on either intake or exhaust. I was told a back cut brought up the flow up to . 100, but a net loss occurred in the midrange. So i was told don't let anyone change that.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: 572-13 head flow-by flow tech 2
[Re: gregsdart]
#3061925
07/23/22 07:18 PM
07/23/22 07:18 PM
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Joined: Feb 2005
Posts: 20,116 PA.
pittsburghracer
"Little"John
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"Little"John
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It will be interesting to see how they stack up on the other flowbench. it will for sure. Since you port heads, a little info on valve angles. No back cut on either intake or exhaust. I was told a back cut brought up the flow up to . 100, but a net loss occurred in the midrange. So i was told don't let anyone change that. I went to a two day theory only class on head porting years ago and Darren Morgan recommended putting a 30 degree back cut on everything and his reasoning was it will never hurt and usually help. Like I said that was years ago so that thinking may have changed. He has some really good videos on YouTube that I have shared and guys really enjoy them. I have never watched them because by now I know how I want to go about it and after 100’s of flow tests Im kinda set in my ways. I prefer to do it at least on the intake valves. The 30-45 minutes that he spent on the exhaust side was worth the 600.00 plus the 300.00 I spent to take my son.
1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.42@138.27
Livin and lovin life one day at a time
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Re: 572-13 head flow-by flow tech 2
[Re: sasquatch]
#3062030
07/24/22 10:19 AM
07/24/22 10:19 AM
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gregsdart
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Greg What you said is exactly what happened here. Larry did a flow test with back cut valves, (ones I had) and found exactly that. Small gain down low but gives it all back in the mid range. NOT saying that would happen with every valve and port combo but on these that is what happened so hence no backcut. Todd He will talk to you about anything you have questions about or I will try to answer them. Thanks Todd. I think about a similar situation where 30 degree seats work well in some situations, like pontiacs. But mopars and others do well with 45 degree seats, and some high rpm high duration combos want steeper seat angles. It all goes to show that there are no tried and true rules, just trends.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: 572-13 head flow-by flow tech 2
[Re: gregsdart]
#3064433
08/01/22 05:41 PM
08/01/22 05:41 PM
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pittsburghracer
"Little"John
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"Little"John
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I guess that shows you a back cut valve is the way to go.
1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.42@138.27
Livin and lovin life one day at a time
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Re: 572-13 head flow-by flow tech 2
[Re: pittsburghracer]
#3064448
08/01/22 06:18 PM
08/01/22 06:18 PM
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Posts: 14,479 So. Burlington, Vt.
fast68plymouth
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Looks to me like pretty substantial gains from the back cut thru .700 lift.
The crossover point is probably around .750” lift.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: 572-13 head flow-by flow tech 2
[Re: fast68plymouth]
#3064515
08/01/22 10:17 PM
08/01/22 10:17 PM
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gregsdart
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Looks to me like pretty substantial gains from the back cut thru .700 lift.
The crossover point is probably around .750” lift. I agree, it LOOKS like the back cut is the way to go, but look at the duration at various lifts with the cam i have. My guess is a cam of .800 net lift like Indy suggests might do well with a back cut? No back cut, 205 and 213 duration at .200 lobe lift, gross lift .868 might fair better Since the port stalls before .700 lift. Only way to tell is run it, swap to back cut valves after getting a baseline. The duration at valve lifts is net, after lash is accounted for.
Last edited by gregsdart; 08/01/22 10:20 PM.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: 572-13 head flow-by flow tech 2
[Re: Cab_Burge]
#3064525
08/01/22 11:11 PM
08/01/22 11:11 PM
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gregsdart
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I wonder how much actual CFM flows through the motor at or below 3/4 max lift that works out to about half the valve event, time wise. Another question to ponder- if a port goes turbulent, does the turbulance continue as the valve starts to close, causing a net loss of potential cylinder fill at lower lifts, end of the induction cycle? Makes me think of a cattle stampede heading for a narrow gate,,,,,,, it may not end well!
Last edited by gregsdart; 08/02/22 12:08 AM.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: 572-13 head flow-by flow tech 2
[Re: gregsdart]
#3064537
08/02/22 12:24 AM
08/02/22 12:24 AM
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EvilB1Dart
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Very nice hardware, Greg! Can’t wait to hear the results when the time slip prints! It’s gonna ride for sure LOL!
"Any fool can know. The point is to understand"
- A. Einstein
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