head/ flow question need answers
11-23-2008, 07:33 PM
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head/ flow question need answers i found a set of nice heads for my build that im workin on its a 383 the heads flow 305 cfm @ .620 lift on the intake and someone told us that was to much for the efi system that id hav to spin the motor to high to acheive that. the cam will be between .610-.620 lift not sure yet. but will this be to much? if so wats a good cfm?
Last edited by z28rob18; 11-23-2008 at 07:41 PM.
11-23-2008, 08:33 PM
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some more info would help us all with the situation.
what brand/porting of heads? runner volume. valve sizes. springs used, etc.
detailed specs on the cam. lift, duration, LSA, etc.
what brand/porting of heads? runner volume. valve sizes. springs used, etc.
detailed specs on the cam. lift, duration, LSA, etc.
11-23-2008, 08:57 PM
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ok the heads were trickflow casting sent to caloway and made for a special project. the intake valve is 13* and is 2.055 and the exhaust is 23* and 1.6 dont no wat springs they r 215cc and hav a 56cc combustion chamber. i dont hav detailed info on the cam yet because it will be custom but lloyd elliot said probably around 234 242 duration with .612/.612 lift thats all the info i know
11-23-2008, 09:30 PM
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ok the heads were trickflow casting sent to caloway and made for a special project. the intake valve is 13* and is 2.055 and the exhaust is 23* and 1.6 dont no wat springs they r 215cc and hav a 56cc combustion chamber. i dont hav detailed info on the cam yet because it will be custom but lloyd elliot said probably around 234 242 duration with .612/.612 lift thats all the info i know
11-23-2008, 09:59 PM
#6
I'm more interested in "the intake valve is 13*"
How does that affect the geometry? Can you use standard roller rocker arms? With the 56cc combustion chamber what compression will that come out to? I don't see a problem with the 215cc runner heads on a 383 for a high perfomance motor unless they have really been hogged out.
How does that affect the geometry? Can you use standard roller rocker arms? With the 56cc combustion chamber what compression will that come out to? I don't see a problem with the 215cc runner heads on a 383 for a high perfomance motor unless they have really been hogged out.
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11-24-2008, 06:27 AM
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it will definitely make most of its power toward the high end, but i think it should be a killer combo. probably up to the 6500+ mark for shift points (guess). it wont leave you with a ton of torque, but the top end will put your *** in the seat and make the loss of torque worth it.
the 13* valve should be interesting though.
the 13* valve should be interesting though.
11-24-2008, 07:46 AM
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it will definitely make most of its power toward the high end, but i think it should be a killer combo. probably up to the 6500+ mark for shift points (guess). it wont leave you with a ton of torque, but the top end will put your *** in the seat and make the loss of torque worth it.
the 13* valve should be interesting though.
the 13* valve should be interesting though.
11-24-2008, 09:12 AM
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mak sure you have pistons made for the special valve angle or you will destroy some parts. Sounds like the old TFS Twised wedge heads. If they have the factory steel guides in the, make sure and budget for new guides and valve job. if they have bronze guides already, they should last.
These heads use a special guide plate and will also need a different PR length for intake and exhaust (measure both for exact length). They did use normal SB Chevy roller rockers though.
They will make som GOOD power when all is done right.
No such thing as flowing too much air but the port could be too big in a few areas fro a certain cubic inch and RPM combination.
if you have a 383 and these are the TFS Twisted wedge heads, they will not be too big. The Calloway CNC portjobs that I have seen are usually in the 275-285 CFM range and still have a lil swirl bump in them. I have seen hand ported ones over 300 CFM but even at 285 cfm, the offset pushrods allows for a larger cross section at PR pinch. This along with the valve angle and dbl quench pads will make more power compared to some standard 23 degree heads. Just do very thing right with PR length and guides.
Lloyd
These heads use a special guide plate and will also need a different PR length for intake and exhaust (measure both for exact length). They did use normal SB Chevy roller rockers though.
They will make som GOOD power when all is done right.
No such thing as flowing too much air but the port could be too big in a few areas fro a certain cubic inch and RPM combination.
if you have a 383 and these are the TFS Twisted wedge heads, they will not be too big. The Calloway CNC portjobs that I have seen are usually in the 275-285 CFM range and still have a lil swirl bump in them. I have seen hand ported ones over 300 CFM but even at 285 cfm, the offset pushrods allows for a larger cross section at PR pinch. This along with the valve angle and dbl quench pads will make more power compared to some standard 23 degree heads. Just do very thing right with PR length and guides.
Lloyd
11-24-2008, 09:26 AM
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mak sure you have pistons made for the special valve angle or you will destroy some parts. Sounds like the old TFS Twised wedge heads. If they have the factory steel guides in the, make sure and budget for new guides and valve job. if they have bronze guides already, they should last.
These heads use a special guide plate and will also need a different PR length for intake and exhaust (measure both for exact length). They did use normal SB Chevy roller rockers though.
They will make som GOOD power when all is done right.
No such thing as flowing too much air but the port could be too big in a few areas fro a certain cubic inch and RPM combination.
if you have a 383 and these are the TFS Twisted wedge heads, they will not be too big. The Calloway CNC portjobs that I have seen are usually in the 275-285 CFM range and still have a lil swirl bump in them. I have seen hand ported ones over 300 CFM but even at 285 cfm, the offset pushrods allows for a larger cross section at PR pinch. This along with the valve angle and dbl quench pads will make more power compared to some standard 23 degree heads. Just do very thing right with PR length and guides.
Lloyd
These heads use a special guide plate and will also need a different PR length for intake and exhaust (measure both for exact length). They did use normal SB Chevy roller rockers though.
They will make som GOOD power when all is done right.
No such thing as flowing too much air but the port could be too big in a few areas fro a certain cubic inch and RPM combination.
if you have a 383 and these are the TFS Twisted wedge heads, they will not be too big. The Calloway CNC portjobs that I have seen are usually in the 275-285 CFM range and still have a lil swirl bump in them. I have seen hand ported ones over 300 CFM but even at 285 cfm, the offset pushrods allows for a larger cross section at PR pinch. This along with the valve angle and dbl quench pads will make more power compared to some standard 23 degree heads. Just do very thing right with PR length and guides.
Lloyd
11-24-2008, 05:55 PM
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thanx for ur reply im between these and a set of bare afr 227cc heads i found for a great price and im leanin toward the afr heads so i can run in the ltx shootout my dad seems real interested in that now and the 13* valve angle would put us out of both classes we would want to run
11-24-2008, 07:51 PM
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They belong to a local guy named Tony I guess.
I have SEEN the heads before but never starpped them on the flow bench. I just disassembled 1 cylinder and looked at the portwork to see what all was done.
I have seen 2 sets of these Calloway CNC heads before and this set looked on par with the other 2 sets I have seen. This set probably flowed around 275-285 cfm like the other 2 sets.
I have got over 300 CFM with a 2.055 valve in these heads with more portwork than these have but this set that he has will not go 300 CFM.
I never spoke with Calloway at all for any reason. I have heard that there were like 50 of these Calloway vettes with these heads but there could be more of them. Straneg that I have seen 3 sets and if there are only 50 sets, those are some pretty amazing odds for me to have seen that many sets, lol.
I do not remember them being a 2.055 valve but it was a lomng time ago when I checked them out for this guy. In my mind, I am remembering them to be a 2.02 but I could be wrong here.
I do not remember if they had steel or bronze guides in them. If they are steel, you will need to install bronze quides and a fresh valve job. If they have bronze guides and have beenm ran on an engine where the PR length was checked, they might still be good. If they were ran on an engine with out checking PR length, they are either already bad or an there way to being bad. That valve angle and offset rocker stud was pretty hard on guides and if the customer doesn't check PR length (intake AND exhaust since you need 2 different lengths), it will destroy the guides . . . . guaranteed.
These heads can make AWESOME power when everythiong is set up right buy you MUST have bronze guides in the heads. You MUST check PR length (int and ex). You MUST hav epistons made for this valve angle.
Get all of these worked out and you can make some GOOD power with these heads.
Lloyd
I have SEEN the heads before but never starpped them on the flow bench. I just disassembled 1 cylinder and looked at the portwork to see what all was done.
I have seen 2 sets of these Calloway CNC heads before and this set looked on par with the other 2 sets I have seen. This set probably flowed around 275-285 cfm like the other 2 sets.
I have got over 300 CFM with a 2.055 valve in these heads with more portwork than these have but this set that he has will not go 300 CFM.
I never spoke with Calloway at all for any reason. I have heard that there were like 50 of these Calloway vettes with these heads but there could be more of them. Straneg that I have seen 3 sets and if there are only 50 sets, those are some pretty amazing odds for me to have seen that many sets, lol.
I do not remember them being a 2.055 valve but it was a lomng time ago when I checked them out for this guy. In my mind, I am remembering them to be a 2.02 but I could be wrong here.
I do not remember if they had steel or bronze guides in them. If they are steel, you will need to install bronze quides and a fresh valve job. If they have bronze guides and have beenm ran on an engine where the PR length was checked, they might still be good. If they were ran on an engine with out checking PR length, they are either already bad or an there way to being bad. That valve angle and offset rocker stud was pretty hard on guides and if the customer doesn't check PR length (intake AND exhaust since you need 2 different lengths), it will destroy the guides . . . . guaranteed.
These heads can make AWESOME power when everythiong is set up right buy you MUST have bronze guides in the heads. You MUST check PR length (int and ex). You MUST hav epistons made for this valve angle.
Get all of these worked out and you can make some GOOD power with these heads.
Lloyd
11-24-2008, 09:58 PM
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They belong to a local guy named Tony I guess.
I have SEEN the heads before but never starpped them on the flow bench. I just disassembled 1 cylinder and looked at the portwork to see what all was done.
I have seen 2 sets of these Calloway CNC heads before and this set looked on par with the other 2 sets I have seen. This set probably flowed around 275-285 cfm like the other 2 sets.
I have got over 300 CFM with a 2.055 valve in these heads with more portwork than these have but this set that he has will not go 300 CFM.
I never spoke with Calloway at all for any reason. I have heard that there were like 50 of these Calloway vettes with these heads but there could be more of them. Straneg that I have seen 3 sets and if there are only 50 sets, those are some pretty amazing odds for me to have seen that many sets, lol.
I do not remember them being a 2.055 valve but it was a lomng time ago when I checked them out for this guy. In my mind, I am remembering them to be a 2.02 but I could be wrong here.
I do not remember if they had steel or bronze guides in them. If they are steel, you will need to install bronze quides and a fresh valve job. If they have bronze guides and have beenm ran on an engine where the PR length was checked, they might still be good. If they were ran on an engine with out checking PR length, they are either already bad or an there way to being bad. That valve angle and offset rocker stud was pretty hard on guides and if the customer doesn't check PR length (intake AND exhaust since you need 2 different lengths), it will destroy the guides . . . . guaranteed.
These heads can make AWESOME power when everythiong is set up right buy you MUST have bronze guides in the heads. You MUST check PR length (int and ex). You MUST hav epistons made for this valve angle.
Get all of these worked out and you can make some GOOD power with these heads.
Lloyd
I have SEEN the heads before but never starpped them on the flow bench. I just disassembled 1 cylinder and looked at the portwork to see what all was done.
I have seen 2 sets of these Calloway CNC heads before and this set looked on par with the other 2 sets I have seen. This set probably flowed around 275-285 cfm like the other 2 sets.
I have got over 300 CFM with a 2.055 valve in these heads with more portwork than these have but this set that he has will not go 300 CFM.
I never spoke with Calloway at all for any reason. I have heard that there were like 50 of these Calloway vettes with these heads but there could be more of them. Straneg that I have seen 3 sets and if there are only 50 sets, those are some pretty amazing odds for me to have seen that many sets, lol.
I do not remember them being a 2.055 valve but it was a lomng time ago when I checked them out for this guy. In my mind, I am remembering them to be a 2.02 but I could be wrong here.
I do not remember if they had steel or bronze guides in them. If they are steel, you will need to install bronze quides and a fresh valve job. If they have bronze guides and have beenm ran on an engine where the PR length was checked, they might still be good. If they were ran on an engine with out checking PR length, they are either already bad or an there way to being bad. That valve angle and offset rocker stud was pretty hard on guides and if the customer doesn't check PR length (intake AND exhaust since you need 2 different lengths), it will destroy the guides . . . . guaranteed.
These heads can make AWESOME power when everythiong is set up right buy you MUST have bronze guides in the heads. You MUST check PR length (int and ex). You MUST hav epistons made for this valve angle.
Get all of these worked out and you can make some GOOD power with these heads.
Lloyd
Lloyd,
If these are the original TW 2.5x1 heads.... not a good idea. Apparently everyone at TFS was absent on Geometry day....
Dennis
11-24-2008, 10:02 PM
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i found a set of nice heads for my build that im workin on its a 383 the heads flow 305 cfm @ .620 lift on the intake and someone told us that was to much for the efi system that id hav to spin the motor to high to acheive that. the cam will be between .610-.620 lift not sure yet. but will this be to much? if so wats a good cfm?
BTW.. forget about CFM... find a good head guy (Ie...Lloyd) and have him make the calls. I have shipped heads that flow as much as 345CFM for factory PCM LTx 383 cars... Never had a problem. The flowbench is a tool...not a JUDGE! Mother Nature is the JUDGE!