Re: Ported heads, How to tell?
[Re: 74RR]
#1056859
08/19/11 07:25 PM
08/19/11 07:25 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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First of all, just because a head has been "ported" doesn't mean it'll flow any better than stock.
The best way would be to have the head on a bench and remove the valves. There are plenty of pictures on this site and others that show you what a porting job looks like, although they won't tell you if the porting job you're looking at is any good.
If the head is on the engine and the intake manifold is on, you won't be able to see anything of value.
Keep in mind that the most basic of porting jobs start with the bowl area under the valve. The last thing to be touched would be the port face. I have seen quite a few "ported" heads on which the porting was only cleaning up the gasket surface and that isn't worth anything as it is the least restrictive part of the entire port.
Also, the 906 is an easy head to mess up if the porter wasn't a pro with a flowbench.
If it sounds like I'm sour on the subject, I am. 906 heads are not magic, they came on almost every big block in 1968, including the 2-barrel 383s in pickups. The few that didn't get them got 250s which are the same head with a different casting number. So if you're lucky the heads will be better than stock. And if you're not, they could be worthless.
A $1000 set of Stealth aluminum heads would be a much surer bet.
R.
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Re: Ported heads, How to tell?
[Re: dogdays]
#1056860
08/19/11 08:34 PM
08/19/11 08:34 PM
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Joined: Feb 2005
Posts: 4,318
Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,318
Prospect, PA
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Quote:
First of all, just because a head has been "ported" doesn't mean it'll flow any better than stock.
The best way would be to have the head on a bench and remove the valves. There are plenty of pictures on this site and others that show you what a porting job looks like, although they won't tell you if the porting job you're looking at is any good.
If the head is on the engine and the intake manifold is on, you won't be able to see anything of value.
Keep in mind that the most basic of porting jobs start with the bowl area under the valve. The last thing to be touched would be the port face. I have seen quite a few "ported" heads on which the porting was only cleaning up the gasket surface and that isn't worth anything as it is the least restrictive part of the entire port.
Also, the 906 is an easy head to mess up if the porter wasn't a pro with a flowbench.
If it sounds like I'm sour on the subject, I am. 906 heads are not magic, they came on almost every big block in 1968, including the 2-barrel 383s in pickups. The few that didn't get them got 250s which are the same head with a different casting number. So if you're lucky the heads will be better than stock. And if you're not, they could be worthless.
A $1000 set of Stealth aluminum heads would be a much surer bet.
R.
Yeah....sounding a little sour....but I do agree.
There are very few people around willing to pay to do what it takes to make a set of iron heads truly good. If they are inexpensive, be skeptical.
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Re: Ported heads, How to tell?
[Re: 74RR]
#1056861
08/19/11 11:14 PM
08/19/11 11:14 PM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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smoothed surfaces/identical port openings w no chipped edges
live every 24 hour block of time like it's your last day on earth
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Re: Ported heads, How to tell?
[Re: RapidRobert]
#1056863
08/20/11 01:27 AM
08/20/11 01:27 AM
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Joined: Jan 2003
Posts: 75,060
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,060
U.S.S.A.
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Quote:
smoothed surfaces/identical port openings w no chipped edges
But as said that doesn't mean they are any better than stock.
The shop I used to do did their COMPETITION valve job to a set of 906's I had them rebuild , I had them flowed on a trusted bench and they flowed worse than stock at the low lifts . Oh well that was only $275 more  ...
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Re: Ported heads, How to tell?
[Re: JohnRR]
#1056864
08/20/11 01:36 AM
08/20/11 01:36 AM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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30 yrs ago noted Mopar (SS iirc) racer Bill Bagshaw built a 440 w 906's he ported w the MP templates cut out wider to match the 2.14/1.81's he installed & iirc he made 511 HP (9-1/750 holley 4779DP/street dom) so I'm going to try a set but use 452's after reading Dulcich's Mopar Muscle porting articles (said 915/906's are far more difficult 2 get right)
live every 24 hour block of time like it's your last day on earth
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Re: Ported heads, How to tell?
[Re: RapidRobert]
#1056865
08/20/11 04:53 PM
08/20/11 04:53 PM
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Joined: Jan 2003
Posts: 8,941
Holly/MI
Dean_Kuzluzski
master
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master
Joined: Jan 2003
Posts: 8,941
Holly/MI
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I ported a set of the "boat anchor" 516's, upgraded to the 1.74 exh. valve, and saw VERY positive results. Gained 2-3 mph through the traps. I used the templates too.
The ticket is to not get too crazy. Port match, clean up the bowls, remove casting flash, transition the area around the guides and be very conservative on the short turn radius.
It's all good experience for when you do get an aftermarket set of heads.
R.I.P.- Gary "Coop" Davis 02/09/68-05/13/04
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