Heads

fredybear · Post by **fredybear** » Thu Jul 18, 2002 5:57 pm

porting and polishing...Does it make a difference and how much??? and after 5000 miles???

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Fredy-
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James2 · Post by **James2** » Thu Jul 18, 2002 9:46 pm

alot of difference on a modified motor, less on a stock motor.

They way to build a HI PO engine, is figure out your budget , buy the best heads you can afford, then build the rest of the motor around the heads.

Post by **Marc** » Fri Jul 19, 2002 3:51 am

So long as porting's not taken to extreme it won't weaken the head or cause any longevity problems. Improving the airflow capability of the heads at high RPM will cause a loss of responsiveness at low engine speeds as a rule; head selection needs to be balanced with the rest of the combination to get the results you're after.
Polishing is overrated but it looks cool and people will be happier paying for ported heads if they're shiny. (Polishing of the exhaust port does help with heat rejection, but it's of questionable benefit on the intakes).

waltermitty · Post by **waltermitty** » Fri Jul 19, 2002 3:59 am

also depends on what the fuel system exhoust system and the which heads they are to start with, if they are 311 heads then there is a lot of potential for porting and gasket matching 040s there is less, the exhaust for example is similar to an 044 , if they are 044 or street eliminator there are noo real gains in porting alone. Its an rewarding task thow and with a sensible approach and paitence the outlay is really ony labour so have a go

type IV mainframe · Post by **type IV mainframe** » Fri Jul 19, 2002 4:50 am

porting the heads can make a substantial difference. Just be warned there is such a thing as over porting(when building a smaller motor). But then again it all depends on other aspects of the motor.

James2 · Post by **James2** » Fri Jul 19, 2002 7:09 am

Damn it, guess I got ripped off for 1300 bucks,

044s can show a huge increase in flow with the proper porting.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by waltermitty:
, if they are 044 or street eliminator there are noo real gains in porting alone. <HR></BLOCKQUOTE>

fredybear · Post by **fredybear** » Fri Jul 19, 2002 3:34 pm

So i have my eepco 40x35 heads that r 311...they have been blasted clean and checked... so that means id have to take them back apart to port them some to make em pretty ....is it worth it on these heads???78x90.5--44s-- 1 1/2 merged and building....

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Fredy-
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Post by **Marc** » Fri Jul 19, 2002 3:38 pm

EEPCOs tend to have pretty small ports - even if all you did was open them up to the ID of a stock gasket and blend them in, and port-match the intakes to your manifolds, it would be worth the effort. EEPCOs are harder to port than OEM heads (denser casting) so it's worth the investment in a good cutter bit too.

James2 · Post by **James2** » Fri Jul 19, 2002 3:46 pm

On that engine with those carbs, the right cam and heads could make a 40 hp plus increase. More with larger exhaust.

fredybear · Post by **fredybear** » Mon Jul 22, 2002 8:24 am

The intake ports r 1 1/4 and the exaust ports r 1 5/16 and the exaust system has and inside diameter of 1 1/2....should the exaust ports on these heads b opened up alittle and whats the max on 40x35 heads??

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Fredy-
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danimal · Post by **danimal** » Mon Jul 22, 2002 10:39 am

you might consider getting 'em flow-tested before doing any grinding... you'll need the intake manifolds... they might already have the optimal ratio of exhaust/intake flow.

flow ratios are what makes h.p., not hogged-out ports.

dan
oceanstreetvideo.com

fredybear · Post by **fredybear** » Mon Jul 22, 2002 4:09 pm

I was gonna do that...ill post more after im done...

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Fredy-
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ray greenwood · Post by **ray greenwood** » Fri Jul 26, 2002 10:23 am

Porting makes a difference on any engine. Unless you talk to someone who does nothing but porting on high performance equipment, and has been doing it SUCCESSFULLY for a long time, there will be answers you won't hear. Porting is not just removing material to make the port bigger. Porting for performance is individual to evry single motor. It is a combination of improvements to both velocity and volume. In some heads, material may actually be added in to change shape to affect how the charge contacts the valve head, swirls in the combustion chamber or how turbulence is produced for positive or negative effect, and how it is controlled. A flow bench and experience with the heads in question as well as the application in question...is required. Thats not to say that a skilled amateur, carefully removing material could not do benefit by matching manifold to valve pocket, or overall increasing flow by removing obvious unneeded material on an obviously restricted head. Most people do over-port. If you remove too much material...and velocity drops...you flow less anyway. If you remove too much or in the wrong place....you may flow more...but have poor fuel atomization, excessive turbulence or poor swirl characteristics...and lose HP instead of making it. It can even run hotter because of these things. But bottom line, go to someone skilled and porting...done correctly..benefeits every engine. Polishing can be taken too far. In general, in valve pocket area, fuel injected engines will benefit from high polish more than carbed cars. In FI, velocity is everything, since the fuel is mixed in at the valve pocket. In carbs, the extra roughness may help to keep the fuel mix homogenized. Ray

Post by **Marc** » Fri Jul 26, 2002 10:29 am

Like Ray said.
On the intake you can't get in too much trouble if you stay with a "mini-D" and don't go nuts.