Author Topic: Port matching or Gasket matching  (Read 358 times)

Offline 6pack8014

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Port matching or Gasket matching
« on: September 04, 2017 - 08:50:34 am »
HI,
I need some expert advise. I have Edelbrock rpm heads with a full port and polish done by a local shop with a cfm of 295 at 600 lift. I would like to know if port match  is better than gasket matching the cylinder heads and edelbrock 6 pack intake manifold. What amount of gain at 600 lift in cfm can I gain by port matching or gasket matching. Would there be a power gain and is it worthwhile doing it. Here is my setup. This is a Street& Strip setup. 440 engine with 505 stroke, 4.25 stroke. zero deck and 11.1 cr. using pump gas.  I will be using a edelbrock 6pack intake and carbs.  Full port and polished Edelbrock rpm 84 cc heads. Flat tappet solid camshaft not selected yet. My goal is 600+ horsepower that will run in the 10.80 to 10.90 range in a b-body car. I would also like some camshaft recommendation on a solid cam. Your advise would be appreciated.




Offline cudabob496

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Re: Port matching or Gasket matching
« Reply #1 on: September 04, 2017 - 01:22:34 pm »
guess I'm not sure what the diff is between port and gasket matching?
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.
Up to 4000 RPM, Warp Speed, Up to 5000, Rediculous Speed, Up to 6000 RPM, Ludicrous Speed!

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

Offline 70chall440

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Re: Port matching or Gasket matching
« Reply #2 on: September 05, 2017 - 05:09:34 pm »
I "assume" he is referring to making the ports on the intake match the heads.. regardless, you would probably want to match the gaskets as well if you are trying to squeeze every ounce of HP out it. If the ports on the intake are vastly different than the heads (not sure why that would be), then gasket matching probably doesn't give you much; perhaps I am misunderstanding the question... wouldn't be the first time  :bigsmile:
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Offline 6pack8014

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Re: Port matching or Gasket matching
« Reply #3 on: September 05, 2017 - 05:49:33 pm »
I was reading an article.
http://ascot500.com/index.php?topic=106.0
To port match- measure the height and width of the largest intake port on the cylinder head, use these measurements and apply to the intake ports of the intake manifold.
The article thinks that port matching is better than gasket matching.
In my opinion from reading this article, I would still think that by gasket matching you would gain more cfm.

Offline Bullitt-

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Re: Port matching or Gasket matching
« Reply #4 on: September 05, 2017 - 06:36:37 pm »
Wondering myself what's the diff so I went looking & found this...interesting

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Offline cudabob496

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Re: Port matching or Gasket matching
« Reply #5 on: September 05, 2017 - 07:01:31 pm »
as I have read, all this matching might buy you 10 hp at 7000 rpm
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.
Up to 4000 RPM, Warp Speed, Up to 5000, Rediculous Speed, Up to 6000 RPM, Ludicrous Speed!

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

Offline moper

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Re: Port matching or Gasket matching
« Reply #6 on: September 05, 2017 - 09:18:02 pm »
If the heads were indeed "full ported" then you should have matched the intake to them. A step up in size from intake's port to the head's port is not that big a deal but no step is always preferred on the intake side.

Offline Chris Pauluk

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Re: Port matching or Gasket matching
« Reply #7 on: September 07, 2017 - 12:14:04 am »
You've gone this far, might as well jump in there. 

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Offline AussieMark

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Re: Port matching or Gasket matching
« Reply #8 on: September 07, 2017 - 06:27:12 am »
Ports matching the manifolds is ideal the situation you want to avoid is having a larger port in the intake manifold then the head as there will be a step which will interrupt flow and with the exhaust it is the opposite you don't want a larger port in the head then the manifold or the step will interrupt flow.

Offline 734406pk

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Re: Port matching or Gasket matching
« Reply #9 on: September 07, 2017 - 11:50:27 am »
 IMO you should already have the cylinder head intake ports gasket matched since the Eddys  were ported (but check with an intake gasket). Take the same gasket and match the intake manifold ports to it. Now both the heads and intake are gasket matched, but do the ports match when you bolt up the intake to the heads? Maybe but probably not, the block has been zero decked, so the cylinder heads are closer together. This can make the intake manifold sit higher and mismatch the ports. You would have to install the intake with the right gaskets and look down at the intake ports through the carb mounting flanges to see. If this is the case, the intake side of the heads or the intake manifold itself would have to be milled to correct the misalignment. Sometimes a thinner gasket will work if you aren't using the factory valley cover. Good Luck with your build! :thumbsup:
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Offline Mopar Mitch

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Re: Port matching or Gasket matching
« Reply #10 on: September 08, 2017 - 02:12:17 pm »
Whatever you do, on aluminum mflds (six-packs most particularly), there may be offset port alignments (high vs low) of the cast ports (sand-casting irregularity).  I've seen this on the SB six-pack mflds.   So, the gasket matching would then be preferred method.
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