I have a 3.4L Pushrod that has been up on the stand for some time now...I'm just now getting around to peicing it back together and was wanting to port match the lower/middle/upper intake. i've done some searching on the forum and found some really good info. Does anyone know of a thread that shows from start to finish how to do this. I'm just curious what tools are best to use for drilling...also, if anyone has a before/after pics...that would help also...this is my first time doing this so i want to get all the info i can before digging in...thanks
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09:53 AM
PFF
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lou_dias Member
Posts: 5381 From: Warwick, RI Registered: Jun 2000
Port-matching is usually down with gaskets. Then you mark up the material you need to remove that overlaps the gasket opening. It's also called "gasket matching". You can probably look this up on the internet. The Fiero intake can benefit alot from this...as can the heads...
I've done the gasket matching. It was really easy but time consuming. Probably 1-1/2 hours each port. Becareful if you use a dremel style tool because of the heat. The aluminum will blister. A good O hand file with a once sided curved radius so you don't gouge the walls and sand paper. 80-150 grit. In my flickr page you can get an idea of marking the manifolds with the gasket and then just go to town. I ported and polished all. Even the upper to the throttle body. I did my best on the upper as far as I could reach. You can get it done professionally but with a couple hundred. Anyway, check out the site. Don't forget to port the logs too
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[This message has been edited by unboundmo (edited 02-09-2011).]
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12:04 PM
couldahadaV8 Member
Posts: 797 From: Bolton, Ontario, Canada Registered: Feb 2008
Port matching is a good idea. Gasket matching is a bad idea. With gasket matching you get an expansion loss followed by a contraction loss. For those what won't believe this, just ask any performance engine builder about it. None of them will gasket match.
Rick
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12:29 PM
Isolde Member
Posts: 2504 From: North Logan, Utah, USA Registered: May 2008
On a SBC setup, as the typical example, gasket matching is typically no longer done. Any head that looks to need it, doesn't flow well enough to benefit from it. However, you never want the head opening smaller than the exit from the intake manifold. Reversion is bad. Worse than the sudden increase in cross-sectional area. But the first step is choosing the correct gasket. With SBC intake gaskets, it's pretty easy. Not so in your situation. You'd do better to just ship all 3 pieces off to Extrude-Hone. Then you could have more flow, and consistent cross-section. But your off-idle torque would suffer. Also, this would do you the dis-service, if not boosted, of smoothing the short turns. You want some roughness there to help the air turn. Smokey Yunick found the stock 2.8 MPI intake manifolding to be very good, and not worth grinding on. You using it on a 3.1 does mean your HP after peak will drop off more sharply. But the 2.8 wasn't a revver anyway. Hell, ANY 3800-II is a better revver than a 2.8 ever was. Or best yet, leave your intake manifolding alone, and get a high quality Chinese turbo.
honing would be best but taking the imperfect ledges out so the airflow doesn't hit it would be beneficial too in my book. I did have my head ported also but I left the fins in the exhaust section. My 3.4 pulls. I have illegally raced a souped srt neon boosted with a win by a car and have kept on side of a modified Subaru with no problem either. just sayin.. I'm happy with what I have done regardless of the statistics even though others say sOmething else
I'm just curious what tools are best to use for drilling...
I bought a set of multi-fluted grinding burrs to use on my Northstar. There were 12 bits of different shapes and sizes which came in pretty handy. They've got a standard 1/4" shank for use in a high speed die grinder though. They worked really well for me especially after I started lubricating them with an aluminum cutting oil. Here's two pics of the ones I found most useful:
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01:49 PM
Pyrthian Member
Posts: 29569 From: Detroit, MI Registered: Jul 2002
when I did mine, I used the stained areas as my guide. the area covered by the gaskets were nice & clean - the areas not - were black/brown not the most scientific - but - worked out great. especially on the ports between the lower plenum & the intake manifold. that is such a stupid angle.
edit to add:
quote
Originally posted by Bloozberry: ...... They worked really well for me especially after I started lubricating them with an aluminum cutting oil.
yes yes! any oil will do - it keeps the bits from clogging - ESPECIALLY with aluminum. I used plain old motor oil.
[This message has been edited by Pyrthian (edited 02-09-2011).]
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01:49 PM
82-T/A [At Work] Member
Posts: 25225 From: Florida USA Registered: Aug 2002
when I did mine, I used the stained areas as my guide. the area covered by the gaskets were nice & clean - the areas not - were black/brown not the most scientific - but - worked out great. especially on the ports between the lower plenum & the intake manifold. that is such a stupid angle.
EXACTLY... and here's a picture that I took when I did it the first time around to show as an example...
If you know the old time method of gasket making, you can take some construction paper and made a false gasket on the intake side. You then tape it in place on the head side and use it as a guide. If you are really picky about it, you then do the same exercise on the head side and port the intake side to match.
In case somebody reading this doesn't know the method, you tape the construction paper in place over the intake ports. You use a ball peen hammer to gently tap around the edges of the ports to dimple the paper and then use an exacto blade to carefully trim.
