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Port/Polish stock iron heads

Bitch'nBronco

Contributor
Loose Cannon
Joined
Dec 1, 2005
Messages
3,348
Loc.
Havre De Grace, MD
Is it worth the effort to port/polish the stock iron 302 heads? I've wanted to try it for a while (going to buy a set of junk yard heads to practice) and have been researching techniques and tools required. I'm not looking to get crazy with it, just gasket match the ports and polish the runners. I'm not opposed to being talked out of it haha. Thanks in advance
 

Joe473

Sr. Member
Joined
Jul 16, 2012
Messages
950
Just go to the junkyard snd get a set of Gt-40's or E7TE Bolt on and you have hardened seats and will flow as good or better than porting most 70s castings. Just watch your CR ratio. 60 or 64 cc. Early heads were smaller. Gt-40P's have header differences

Sent from my SM-G900V using Tapatalk
 

sykanr0ng

Bronco Guru
Joined
Aug 11, 2014
Messages
5,363
On the intake side port but do not polish, the roughness creates turbulence which helps keep the fuel in suspension in the air.

Port and polish the exhaust, no need to worry about keeping it turbulent.
 

RPM289

Sr. Member
Joined
Jan 4, 2008
Messages
835
Agree with SYK also no need to do anything on bottom of exhaust port other than smooth it up gas runs along top and sides not bottom of ports. also make sure headder opening is bigger than exhaust port.
 

jckkys

Bronco Guru
Joined
Mar 15, 2012
Messages
5,196
To know the effect of swapping on different heads you have to know what heads you have. Your profile says you have a '67. The '67 289 heads have 54.5cc combustion chambers. The E7TE heads have 62cc chambers, GT40s have 65cc chambers and GT40Ps have 60cc chambers.They will all lower you compression ratio to something like 8.7 to 1. This is about as high as any EB V8 got after '67. So it shouldn't be a problem.
 

cs_88

Bronco Guru
Joined
Jul 28, 2005
Messages
1,321
When I installed my E7's I port matched them to the intake similar to this video.

https://www.youtube.com/watch?v=ijlPwA7W29M

I also smoothed out the pushrod pinch in the intake runners, opened up and smoothed out the exhaust runners as well as remove the thermactor humps.
Don't know how much it helps but figured it couldn't hurt.
I didn't do any work in the combustion chambers, figured I'd screw those up for sure.;D
 

John Marinan

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Aug 9, 2009
Messages
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Loc.
Durango CO.
If you change to a later model head there's a good chance it came from a roller engine. If so you will to change the spring pressure.
 
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OP
Bitch'nBronco

Bitch'nBronco

Contributor
Loose Cannon
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Dec 1, 2005
Messages
3,348
Loc.
Havre De Grace, MD
So if I went to a JY to pull some E7E heads, is there any difference between the timing chain/gears to convert my flat tappet to roller? I wouldn't take the old cam because I want something different than the stock profile.
 

sykanr0ng

Bronco Guru
Joined
Aug 11, 2014
Messages
5,363
The factory roller lifters need the taller lifter bores of the factory roller block along with a few other parts.
There are aftermarket roller lifters which can retrofit older blocks but it is cheaper to replace the block IMO.

The 5.0 aka 302 has been roller blocks since the late 1980s, they are fairly easy to find in the JY.
 
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Bitch'nBronco

Bitch'nBronco

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Loose Cannon
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Havre De Grace, MD
Yeah, I just found that. I think I am just going to keep what I've got and at a minimum just polish the heads. Those lifter conversions are pretty spendy
 

Broncobowsher

Total hack
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Jun 4, 2002
Messages
34,833
I have a friend who did some port work once. The walls are only so thick before you are into the water jacket.
 

73azbronco

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Bronco Guru
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Nov 11, 2007
Messages
7,796
I would not port polish stock iron heads. By the time your done, a set of aluminum edelbrocks would look cheap.
 

sykanr0ng

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Aug 11, 2014
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5,363
If you're paying someone else to do it, then yes they would be cheaper.

If you are doing it yourself then the aftermarket might not be cheaper.
Labor is the big cost there.
 

73azbronco

Contributor
Bronco Guru
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Nov 11, 2007
Messages
7,796
Porting really shouldn't be a home benchtop hobby, need some skill to do it right. Not saying dont have the skill, just saying
 

Broncobowsher

Total hack
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Jun 4, 2002
Messages
34,833
It isn't hard to open up the holes.

The hard part is doing the exact same thing 7 more times. If each of the ports flows different you will never get full potential out of the engine. Some holes will run better/worse than other at different times. A home porter doing a little gasket match and debur is fine. But a true port job, that's a different story. Lots of people think they can do a good job, when few can really make it happen correctly. That is when a set of aftermarket heads bolted on out of the box really shines.
 

sykanr0ng

Bronco Guru
Joined
Aug 11, 2014
Messages
5,363
Gasket match and light clean up is what the original poster was talking about.
 
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