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Old 07-04-2022, 02:28 PM
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Default Additional head porting

I had my #64 heads cnc ported by SD performance years ago to 255cfm intake I believe. How much more could I go without getting into epoxy and that stuff. Probably would have to be hand ported now. If it was the 270 cfm area How much hp would that gain? Running port matched iron intake and ra manifolds. Would I see the gain in cfm with the restrictions?

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72 lemans,455 e-head, UD 255/263 solid flat,3.73 gears,,,10" 4400 converter,, 6.68 at 101.8 mph,,1.44 60 ft.2007
(cam 271/278 roller)9"CC.4.11gear 6.41 at 106.32 mph 1.42 60 ft.(2009) SOLD,SOLD
1970 GTO 455 4 speed #matching,, 3.31 posi.Stock manifolds. # 64 heads.A factory mint tuquoise ,69' judge stripe car. 8.64 @ 87.3 mph on slippery street tires.Bad 2.25 60ft.Owned since 86'
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Old 07-04-2022, 02:47 PM
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The only pre 1967 heads that can go into the 270 cfm realm is the SD 980 casting which starts off far larger then your year casting does.

I have never flow tested a early non SD iron intake, on my bench, but what I can tell you with pretty darn good certainty is that the 255 cfm your heads flow now can not be matched by a stock 1964 single AFB intake like your running, so increasing the air flow of the heads even more will only serve to narrow up on the motors power band more then what is taking place even now!

Looking at what your asking about is a waste of time especially since your pumping out thru log type exh manifolds.

If you want maybe 10 to 15 more hp then get a set of the repro Ram air D port exh manifolds on the car..

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Old 07-04-2022, 02:52 PM
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Probably close to hitting the wall already being at 255 cfm. Going to 270 if it’s even possible or practical (chances of breaking through) will likely not be there.

Not from experience but from what I’ve read the short turn on the intake port isn’t ideal for getting flow much higher than you’re already at. The 1970 455 #64 heads being the first of the deeper combustion chambers when the factory just started going to low compression are the cause, they didn’t adjust the intake ports to match the new chamber. It wasn’t until the 1975 5C and 1976 6X did they relocate the short turn in the port to rectify this issue on the heads with deeper combustion chambers.

I’d be happy with the heads being at 255, unless you’re willing to step up to a set of headers from the current RA manifolds any gains will be minimal or nonexistent with better flowing heads.

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Old 07-04-2022, 02:53 PM
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Quote:
Originally Posted by scott70 View Post
I had my #64 heads cnc ported by SD performance years ago to 255cfm intake I believe. How much more could I go without getting into epoxy and that stuff. Probably would have to be hand ported now. If it was the 270 cfm area How much hp would that gain? Running port matched iron intake and ra manifolds. Would I see the gain in cfm with the restrictions?
i am not the guy to answer this but from what i gather seems to see results one improvement leads to another to get a noticeable gain. in order to know how much can you port the head without breaking through it would have to be sonic checked. i hope this was helpful. maybe this will at least get you some attention from a more experienced person.

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Old 07-04-2022, 03:15 PM
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1970 #64 heads. So it sounds like this particular head is pretty well maxed out as far as just removing more material for a cfm / hp gain. On the dyno I did see a 18hp gain using hooker 1.75 headers over my ra manifolds with mandrel 2.5 pipe. So in other words a set of 290cfm Kaufman heads wouldn't do much for power with the manifolds I'm using.

I agree a sonic test would probably be the order if more porting was attempted.

Currently. Setup is 530 lift.
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72 lemans,455 e-head, UD 255/263 solid flat,3.73 gears,,,10" 4400 converter,, 6.68 at 101.8 mph,,1.44 60 ft.2007
(cam 271/278 roller)9"CC.4.11gear 6.41 at 106.32 mph 1.42 60 ft.(2009) SOLD,SOLD
1970 GTO 455 4 speed #matching,, 3.31 posi.Stock manifolds. # 64 heads.A factory mint tuquoise ,69' judge stripe car. 8.64 @ 87.3 mph on slippery street tires.Bad 2.25 60ft.Owned since 86'

Last edited by scott70; 07-04-2022 at 03:29 PM.
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Old 07-04-2022, 03:26 PM
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I wouldn't even chance it with the use of a sonic checker. When Dave set up his CNC programs, it was through a lot of trial and error to get the best #'s, taking the least risk in the cutting process. There may be a smidgen left to gain, BUT you could possibly take away some flow by a slight change here or there. (I'm not implying you don't know how to do this...I have ground on a LOT of heads, also...).
THe CNC process makes good heads better. The ability to nearly EXACTLY duplicate each port's shape is part of the key to the huge success that CNC porting is about. A huge THANKS to Dave B. for boing a Pontiac enthusiast!!!

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Old 07-04-2022, 03:30 PM
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Quote:
Originally Posted by b-man View Post
Probably close to hitting the wall already being at 255 cfm. Going to 270 if it’s even possible or practical (chances of breaking through) will likely not be there.

Not from experience but from what I’ve read the short turn on the intake port isn’t ideal for getting flow much higher than you’re already at. The 1970 455 #64 heads being the first of the deeper combustion chambers when the factory just started going to low compression are the cause, they didn’t adjust the intake ports to match the new chamber. It wasn’t until the 1975 5C and 1976 6X did they relocate the short turn in the port to rectify this issue on the heads with deeper combustion chambers.

I’d be happy with the heads being at 255, unless you’re willing to step up to a set of headers from the current RA manifolds any gains will be minimal or nonexistent with better flowing heads.
I've heard Jim Hand talk about having to do a lot of work on the 64's he used to run. Specifically the short turn radius. I was glad when he went to the 6X's, mostly because they are so common and are what came on my TA.

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Old 07-04-2022, 03:31 PM
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I wouldn't attempt the additional porting on these myself...it would of been butler or somebody else that knows what they're doing.

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72 lemans,455 e-head, UD 255/263 solid flat,3.73 gears,,,10" 4400 converter,, 6.68 at 101.8 mph,,1.44 60 ft.2007
(cam 271/278 roller)9"CC.4.11gear 6.41 at 106.32 mph 1.42 60 ft.(2009) SOLD,SOLD
1970 GTO 455 4 speed #matching,, 3.31 posi.Stock manifolds. # 64 heads.A factory mint tuquoise ,69' judge stripe car. 8.64 @ 87.3 mph on slippery street tires.Bad 2.25 60ft.Owned since 86'
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Old 07-04-2022, 03:50 PM
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That’s a Horse of a different color if there 1970 #64 castings!

Sorry I misread your post at first .

Yes, they can likely go to 275 @ 28” with sonic checking and hand porting even with the slightly deeper chambers and lesser short turns that those castings have.
Peak flow will be coming in up at .650” lift as in what I got out of the set of 1971 96 castings as in these old flow test before I had my own flow bench.

You should step up to higher ratio rockers also if your not there already.

If you go for numbers in the 270 range you should have 2.14” valves made up and switch over to 45 degree seats with a 30 degree back cut on it.
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Old 07-04-2022, 03:56 PM
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It would pretty much be a wash between buying better aluminum heads and having yours taken to the next level once you factor in the cost of 2-way shipping and the professional porting work along with whatever else they find needing additional work during the process.

Sell those #64 heads and buy 290 cfm aluminum and I think you’ll be ahead of the game, that is unless you really need those particular heads to retain the original look under the hood of a 1970 455 HO car.

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Old 07-04-2022, 04:12 PM
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I'm using crower Enduro SS 1.60 rockers. The 64 heads are the original heads to my car so wouldn't sell them. I do like the stock look under the hood. I would consider 290 Kaufman D ports but if the ra manifolds are going to hold way back the additional cfm for making more HP then I guess it would be a waste of time and money.

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72 lemans,455 e-head, UD 255/263 solid flat,3.73 gears,,,10" 4400 converter,, 6.68 at 101.8 mph,,1.44 60 ft.2007
(cam 271/278 roller)9"CC.4.11gear 6.41 at 106.32 mph 1.42 60 ft.(2009) SOLD,SOLD
1970 GTO 455 4 speed #matching,, 3.31 posi.Stock manifolds. # 64 heads.A factory mint tuquoise ,69' judge stripe car. 8.64 @ 87.3 mph on slippery street tires.Bad 2.25 60ft.Owned since 86'
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Old 07-04-2022, 04:18 PM
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Quote:
Originally Posted by scott70 View Post
1970 #64 heads. So it sounds like this particular head is pretty well maxed out as far as just removing more material for a cfm / hp gain. On the dyno I did see a 18hp gain using hooker 1.75 headers over my ra manifolds with mandrel 2.5 pipe. So in other words a set of 290cfm Kaufman heads wouldn't do much for power with the manifolds I'm using.

I agree a sonic test would probably be the order if more porting was attempted.

Currently. Setup is 530 lift.
Your flow sheet only shows the intake flow to .550" lift, but it was still climbing. Unless it has a problem above .550" I would do what Steve said and try a higher ratio rocker arm of the intake.

Stan

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Old 07-04-2022, 04:20 PM
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I'm using crower Enduro SS 1.60 rockers. The 64 heads are the original heads to my car so wouldn't sell them. I do like the stock look under the hood. I would consider 290 Kaufman D ports but if the ra manifolds are going to hold way back the additional cfm for making more HP then I guess it would be a waste of time and money.
I may have missed it. What are you cam specs?

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Old 07-04-2022, 04:58 PM
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I may have missed it. What are you cam specs?

Stan
yes, wouldn't a cam change give the power instead of head flow?but if you don't change the exhaust to compliment the changes it would not make a difference correct? just trying to learn.

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Old 07-04-2022, 05:05 PM
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Iron heads got no new flow problem above .50" lift. Seems the challenge is ti tune the timing and fuel for best results.M

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Old 07-04-2022, 05:10 PM
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Unless I missed it you have not posted up what your running for a intake manifold, but if it’s the stock or even a well port matched Q-jet iron one there is no sense in shelling out money for a higher level of intake flow.
Even where your intake flow numbers are now you could make good use of a Performer RPM or such duel plane intake.

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Old 07-04-2022, 06:40 PM
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You don’t see max ported 64 heads often because they start out with the smallest port volumes of all the big valve d ports, IRC they often start out in the mid to upper 140s, versus mid 150s on the later heads. Generally need to keep that in mind porting those compared to a head like a 96, 4x, or 6x. Rocky Rotella has one of the 64 heads that Jim Hand had on his wagon. I think Stan has them on his list of head flows, mid 250s as I recall. The reason why they got pulled is because one head started leaking coolant. He let me look that head over a few years ago and it was not very extensive porting to have a coolant leak, I think Hands heads were in the low 160s for port volumes. I have ported later big chamber heads out to 190 cc without hitting coolant passages, pretty sure 64’s would not do that unless you spent a lot of time checking were it was ok to grind.

What I mainly see on the SD CNC head flow chart that could be easily improved is the flows at .3” and below are not great. I think that could be addressed with no risk to finding a coolant passage. My guess is the lower flows at .3” and below are coming from the small port volume on the 64s. I don’t think the SD performance CNC program does much to correct that. On 64s from what I recall it would be mainly porting on the ceiling down to the guide boss, and some off the short side radius to open the port window up a little more. It would pick up 10-15 cfm flow at the low lifts through .3”, then carry that extra flow to max lifts. I think that would get the flow into the 270s range. Not sure what you would gain from that, but it would likely not be worth it unless you had the heads off anyway. I would not do bigger valves or 45* seats in 64 heads because there is enough thickness in the bowl to be opened enough to real utilize the bigger bowl very well. The thickness there would at least need to be checked before hand.

IRC…that same CNC program on a later heads flows in the mid 260s.


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Old 07-04-2022, 07:59 PM
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Cam card. Iron intake that's port matched to ra4 port and the carb inlet has been massaged to look like cliff/ sd performance. I have no idea what power could be gained going from 255 to 270's. Didn't realize the 64's had their short comings when it comes to porting them to 275 area. So by the flow sheet if someone knew what they were doing they could improve the flow of these particular #64 heads?What kind of HP gains would there be going from 250's to 270's? I guess the intake and ra exhaust manifolds are not helping anything. It would have to be a decent gain to go to the trouble of removing heads and cost of shipping and actual labor of the porting itself
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72 lemans,455 e-head, UD 255/263 solid flat,3.73 gears,,,10" 4400 converter,, 6.68 at 101.8 mph,,1.44 60 ft.2007
(cam 271/278 roller)9"CC.4.11gear 6.41 at 106.32 mph 1.42 60 ft.(2009) SOLD,SOLD
1970 GTO 455 4 speed #matching,, 3.31 posi.Stock manifolds. # 64 heads.A factory mint tuquoise ,69' judge stripe car. 8.64 @ 87.3 mph on slippery street tires.Bad 2.25 60ft.Owned since 86'
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Old 07-04-2022, 08:47 PM
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I’m curious how it would change it. It might change more than what you would expect if the low lift numbers pick up and the high lifts gain also. Have to plug in some numbers on a dyno program and get an rough estimate, I think I can find your dyno and flow numbers on here for a baseline.

I don’t think the intake with those mods is going to be holding it back much at all. The RA manifolds will be though.

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Old 07-04-2022, 09:16 PM
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If it was a worthwhile thing to do,,,who would you recommend to do the work?

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72 lemans,455 e-head, UD 255/263 solid flat,3.73 gears,,,10" 4400 converter,, 6.68 at 101.8 mph,,1.44 60 ft.2007
(cam 271/278 roller)9"CC.4.11gear 6.41 at 106.32 mph 1.42 60 ft.(2009) SOLD,SOLD
1970 GTO 455 4 speed #matching,, 3.31 posi.Stock manifolds. # 64 heads.A factory mint tuquoise ,69' judge stripe car. 8.64 @ 87.3 mph on slippery street tires.Bad 2.25 60ft.Owned since 86'
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