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need info on head and intake porting


dburgessc

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Hello fellow Z-car enthusiasts,

I am in the process of doing numerous performance upgrades to my 240Z. Currently I am getting ready to match port my intake to my head and port and polish all the runners of both the head and intake. The problem I am confronting is that the intake and the head ports as of right now are almost a perfect match. I could simply get away with cleaning away the casting flash and smoothing the bores for better flow. However the intake manifold gasket (Fel-Pro) does not match the ports on the head very well. It is misaligned slightly in opposite directions on each end of the head. If I shift the gasket to the right to better align the ports on the right then the left is aligned even worse and vice-versa. Seems a shame to grind already matching ports on head and intake to align to the gasket. Just wondering if anyone else has run into this problem and to know what you did to resolve it. Also if anyone knows of any really good articles online about match porting or just on porting and polishing in general I would sure like to read them. Thanks for the help! Don.

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Great informational link, Thanks! but also wanted to hear from anyone who has gone through the process so I can learn before I do it the hard way and ruin a head that I have much invested in. Any other engine builders out there?? Also the head I am using is the E-31 with the larger 280Z valves. I have eyebrowed the edges of the cylinders for valve clearance and will test for sufficient clearance using plastiguage but if anyone knows of additional articles, notes, commentary or photos from anyone else who has performed these mods I would love to see them just to make absolutely sure I am not overlooking anything i might regret later. Thanks again, Don. :ermm:

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hey dude, i know your pain in the gasket situation, i tried lining up that felpro for hours wondering if my head was horribly warped or something and i had an even worse prob with the exhaust lining up, after 2 gaskets with no luck, i called motorsport and asked about their $17 gasket, they said its made in japan and you can tell its really high quality, fit perfect, very worth the pretty pennies. by the way, mine was for my p79 on my 82 zx. its worked like a champ for 6 months now, only leak is at the back side where i have a broken exhaust stud, but that'll have to wait till the p79 gets the new cam i got from northern for $50 plus shipping, now i just need rocker arms and a valve job! at that point i'll be porting a little bit on the intake , probably use a small ball hone with a drill on the runners and a larger one on the openning ( furthering what i started when i port matched the 240sx throttle body).

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  • 3 weeks later...

Just a little followup with this post... I just found a shop where I live now that is a Z-car specialist shop. ROFLROFLROFL The guy I spoke to there told me that Fel-Pro gaskets while good for domestic vehicles are absolute junk for imports with nothing ever lining up very well. He showed me a intake gasket that he had there from an import manufacturer (Sorry but I forgot the brand name) and it was like a night and day difference from the Fel-Pro gasket. Complete different construction and very high quality! Needless to say this will be the gasket set that I will purchase to do my engine and the gasket that I will use to match port my intake to my cylinder head. When I get the brand name I will make another post and pass this info along to all. Thanks again for the responses to my post. Don.

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Went down to that Z specialty shop again to see about buying the gasket kit I was talking about. The name of the shop is "Z Sport" in Everett, WA. 1-800-633-3308. The brand name of the gasket kit is "Ishino". They wanted $160 for it but I found the same kit at "Autopartswarehouse.com" online for about $80 and bought it there. No charge on shipping orders over $50. Much higher quality gaskets that fit right and will allow me to finish match porting my engine. On another note when I was talking to the owner of the shop and telling him what I was doing to my car with the porting and polishing he surprised me by saying I was wasting my time doing this as there was not much to be gained by trying to improve the flow of air through my engine. I was fairly flabbergasted to hear this from someone who claimed to have much experience racing Z cars. He didn't even believe in a 3-angle valve job. I have always believed that improving flow as well as larger valves, better cam, better ignition, better exhaust flow, better carburetion are the only ways to truly coax horsepower out of any type of engine. Many reputable books as well as a lot of posts from other members here seem to confirm this to me as well. Call me "old school" but I will always take this approach when building engines. Too many people these days will just buy a stock car put a new muffler on to get a fast sound, stick a bunch of plastic trim on it and maybe put nitrous on it to get push button power that will probably melt down an engine that was never designed to withstand these stresses in the first place. Anyway I would love to hear the opinions of others at this club about this, especially those who have real hands on experience building engines. Till next time, Don.

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you need a little turbulence in the intake. i don't know why, i'll ask my dad... ;)

The turbulant (sp) air suspends the gas molicules better. On an intake runner with smooth surfaces the air/fuel mixture will "pool" on the runner walls especially durring decelaration. Then when you accelerate those pools will be sucked into the chamber causing a rich mixture.

Like prevously mentioned, clean the area where the runner makes the transition to the seat there is usually a lip there. You can also clean some material away from the valve guide.

Here is a picture of my exhaust. Before and after.

1052before_afterE.JPG

And here is the intake. Also before and after.

1052befor_afterI.JPG

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