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-   1st Generation Specific (1979-1985) (https://www.rx7club.com/1st-generation-specific-1979-1985-18/)
-   -   Porting Fundamentals (https://www.rx7club.com/1st-generation-specific-1979-1985-18/porting-fundamentals-1136474/)

Benjamin4456 06-24-19 01:48 PM

1. Well I haven't touched the opening edge whatsoever so I guess that means I still won't touch it.

2. I'll clean up the sides a bit on the back end. I don't think they'll come all the way out to the sleeve though since I kept the stock 12A width. Is that what you were referring to about the 'funnel'? As in, should the sides of the port be brought at an angle going out the back to meet with sleeve? I had thought that you wanted to keep the step for gas expansion reasons, but perhaps I'm off.

3. When I do the touch up from the rear I'll try to neaten out the closing edge. Based on that thread you linked, I feel like my bevel is probably fine if I just even it up a bit, maybe polish it up a little more too.


Thanks for the remark on the paint, I've always thought the black and aluminum scheme looked pretty sharp. I ended up doing the rotor housings with 'aluminum' color paint, and then everything was clear coated to match the gloss across the different parts. And yes, we are often our biggest critics - your comment just goes to prove that my "you won't see it from the engine bay" mentality will hold up just fine :). Thanks for the assembly pointers too.

Benjamin4456 06-29-19 11:54 AM

Unfortunately life happens sometimes and the engine didn't get put together until Thursday (oh pity, a two day delay ;)) but... a couple long nights later and the car is running almost perfectly. Extremely smooth power - definitely a little lacking on the low end but I haven't done the carb work yet to compensate for the larger ports and honestly, it doesn't bother me much. I'm not going full ham on it yet - all metal seals were reused (they were well within spec and no damage; springs were replaced) so not much to bed in - but from the driving I've done so far I am very happy with the results. There is one sad thing however; I have a dowel pin leak (center iron to rear housing). It's not terrible since it only leaks some after I stop the engine - I'm positive that the o-ring is in there. While running it doesn't do much.

So thanks all for the help in walking me through my first porting endeavor. The results are something that I believe I'll be happy with, until I try and go for more power later down the road of course (which won't start with porting) :). I should mention that the idle is rock solid other than the same slight low rpm misfire issue that my other engine had (I'm working on what's up with it - not engine related). Sometime here I'll get my nikki modding thread going again when it's time for the venturi's.

Here's a before and after shot of the tidied exhaust port from the rear. Unfortunately due to being in a jam, I forgot to take photos from the inside but take my word that it's nice and cleaned up too.

Before (glad I went back and checked because they were much more uneven than I had thought):
https://cimg5.ibsrv.net/gimg/www.rx7...2af487fc26.jpg

After (yes, the photo is tilted slightly):
https://cimg0.ibsrv.net/gimg/www.rx7...2b7504e884.jpg

Of course I'll still reply to comments and the like, but otherwise I think that wraps this up. Thanks again all.


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