locobob

I've begun working over my 368's intake in search of a few more ponys. The port work was done by LPE in the late 90's. It looks pretty good overall although I think it may be a bit conservative. The plenum was cut down the middle so the interior region could be ported hence the weld seam on the underside. Looks good in there, not going to mess with that part. The plenum port divider was left completely intact but nicely blended at the top. Plenum ports measure between 1.415 and 1.450 at the gasket surface. Inside the injector housings the secondarys are opened up all the way through but the primarys neck down to 1.370 about halfway down. Injector bosses look pretty good, just need a little cleanup. In this configuration the car consistantly dynos between 450 and 456rwhp.

The plan: First off the four corner bolt holes on the plenum will be drilled and sleeved with aluminum tubing. This tightens up the slop between the plenum and injector housings. Next I'll take out the plenum dividing wall and part of the wall in the injector housings. Then I'll open up the primary ports a bit and cleanup around the injector bosses. Lastly I'll bolt everthing together and do a final port match. When I'm all done it will be dyno time again and well see if I made any difference. Here's some pics of my progress so far, I'll update as I go.

Untouched except for the aluminum sleeve in the bolt hole


Wood template for port matching


Cutting through the wall

locobob

All the way through





One side done


Smoothing things out again

korvetkeith

Cool, let us know how it turns out.

DDSLT5

Looks like fun! Hope you get another 15 at the wheels!

Jeffvette

Jesus Christ!!!!!!!!!!!

Ever hear of resizing your pictures need to revoke your access to the website.

locobob

Sorry Jeffrey I haven't figured out how to resize yet, I'm kind of internetly challenged you know. At least I'm not using dial up anymore.

ZZZZZR1

Looks familiar, Rob!

And I for one like the size of the pictures. Given my advanced age, I need the visuals as big as possible.

DDSLT5

That's not the only challenge you have - still keep the cork on your fork?

locobob

Okay pics have been resized, can I take the cork off now?

95ZR1#418

Robert-

Not sure about the order your doing this but I found I had better precision by opening the primary & secondary ports to the desired value first. It's easy to measure and port symetrically when the bifurcation is still intact, then remove the bifurcation. You have some nice tools for this work from what Nick tells me....
Come to think of it, your ports were probably already at 36mm from the previous job? So basically, all you need to do is remove the bifucation. I then knife edged the bifurcation into the IH's, as I believe Jeffs are.

Can't wait for August, I assume we'll all meet at Jeffs Friday night as in the past?

locobob

The ports are already roughly 36mm at the gasket surface from the previous job.

Here's a couple of my solutions for port symmetry.

95ZR1#418

[QUOTE=locobob]The ports are already roughly 36mm at the gasket surface from the previous job.

Oh, I went back & corrected my post, sure enough I couldn't remember the max dia of 36mm- thats what I did, I just went and checked my website & there it was 36, Alzheimers without a doubt. It has nothing to do with the last 30 years of drug abuse & rehab.

Starting from stock dia though, I used a burr to rough out the port to near 36 or it would taken a lifetime using the flappers. Although, I'm under the impression some well known zr-1 mechanics do little more than run flappers down the ports- as porting.

Maybe that other course looking attachment you have works better than flappers. Either way, whatever, it will be really interesting to see what(if any-as some think) HP you pick-up with essentially just removing the bifurcation(as if that is an insignificant process-"thats one hell-of-a-job").

I guess you have the before dyno, so can't wait to see what it does. It will also make me feel better knowing all that was for something! But, as always, I suppose you can't compare the two port jobs because mine is stock bore yours is a 368. Of course that dosen't matter to me...

locobob

I decided to have a bit more material welded into the crease on the underside of the plenum so while its out I've begun work on the injector housings. Here's some pics of the injector housings pretty much as is from LPE. At this point all I've done is run a flap wheel though the ports to clean up the carbon deposits.






Here's a close up of the bosses. They are still a bit rough for my taste, I'll be doing a good bit of clean up here.


In this pic I've installed a couple of junk injectors so you can see how the injectors sit in relation to the bosses. The dark brown patches in the secondary port are carbon deposits that I missed with the flap wheel sander. The whole secondary port was this color to start with.

SAM/CH ZR-1

Remove the bosses from the primaries. You'll get some extra air flow.

Sam

95ZR1#418

For the record- I knife edged the superior end of the IH bifurcation, not at the head. Damn, I just came off 7 straight days around the clock work- I really don't know what I'm saying here.

Those ports look so nice with a little buffing, don't they? Problem is they never stay that way...Your last pic(with the injectors in place), the right hand side port with injector looks like how I did mine, then just took as much as visually acceptable(contour wise) on the boss below. I did have a razor edge of the boss right up to the bottom surface of the injector-which is how that RT side injector/boss looks to me. I don't think you can do much more than that, especially knowing it's been done before.

I think your right-on just clean it up, and removing the bifurcation is the big job, at this point probably the only place you'll notice any difference in picking up horses, I would think, since everything else is basically maxed out.

So, are you standing up or leaning over doing this job? I can feel my back just looking at your pics......

95ZR1#418

Robert-

I wanted to ask, if you got that knock problem sorted out. Don't bother to go into detail- I followed the post(very interesting)but mostly over my head. It couldn't be as simple as a new knock sensor could it? I remember a post where someone had some sort of a problem there also(ZR-1Net)and their remedy was wrapping teflon tape around the threads of the knock sensor & reinstalling to specs.

locobob

Bob: Still haven't figured out the knock sensor activity but I have a few more ideas to try once this project is done.

As far as the bosses go I plan on taking the primary down quite a bit more. The secondary has to stay pretty much as is because the O-ring seal is right at the bottom of the injector, I'll just clean it up a bit.

One thing I found out tonight is that the injector housing ports are not as big as I had originally thought. I found some spots in the primarys necked down to 1.340 or so and some of the secondarys are tighter in the middle as well. Should be room for some improvement here. Overall the port work is surprisingly inconsistent, I had expected better considering the name involved.

DDSLT5

Jeff get in there with a nail file?

90 Corvette ZR-1

What are you using to clean off the carbon? I have a bit of build up and I would like to get rid of it without removing any of the metal.

RatRacer

Remember that sub-sonic speed air flows over a radiused edge better than a knife edge. A knife edge causes turbulance in sub-sonic speed airflow.