Porting IH and would like tips

[Torchred96]

I decided that I just couldn't leave the HP on the table, so I went to ebay and purchased a grinder, burrs, flapper wheels and a few other odds and ends along with the 1/8 plugs for the coolant bypass to put in the IH and to plug the plenum vacuum for the spt blades that I removed.

Now, Since I have time to study while I wait for the arrival of all the goodies, I have some questions:

1: The primary IH is much smaller than the secondary...Should I make both the same size now?

2: How do you stay centered on the IH and consistently take off the same amount 360 degrees. I was thinking that I would spray paint the inside of each hole, grind a few thousandths until all the spray paint is gone, spray again, grind and continue this process until the desired diameter is reached. Any suggestions would help.

3: At the top of the IH (looking down into it) where the dividing wall is, should I knife edge this, take it down a few mm and then knife edge it or take it out completely? I saw a few posts on this but I couldn't make out how far down to go.

4: Plenum: Would you take out the dividing wall (from the inside of the plenum to where they mate with the IH...siamesing?) or leave them in for stock displacement? Remember my Spt blades and shafts are removed.


Thanks for the help.

[LGAFF]

I decided that I just couldn't leave the HP on the table, so I went to ebay and purchased a grinder, burrs, flapper wheels and a few other odds and ends along with the 1/8 plugs for the coolant bypass to put in the IH and to plug the plenum vacuum for the spt blades that I removed.

Now, Since I have time to study while I wait for the arrival of all the goodies, I have some questions:

1: The primary IH is much smaller than the secondary...Should I make both the same size now? yes

2: How do you stay centered on the IH and consistently take off the same amount 360 degrees. I was thinking that I would spray paint the inside of each hole, grind a few thousandths until all the spray paint is gone, spray again, grind and continue this process until the desired diameter is reached. Any suggestions would help.

To some extent keeping the carbide moving in a circualr patter helps...use a bore gauge or a fooseball(35mm) to drop in....that helps..

3: At the top of the IH (looking down into it) where the dividing wall is, should I knife edge this, take it down a few mm and then knife edge it or take it out completely? I saw a few posts on this but I couldn't make out how far down to go.

I would leave it be

4: Plenum: Would you take out the dividing wall (from the inside of the plenum to where they mate with the IH...siamesing?) or leave them in for stock displacement? Remember my Spt blades and shafts are removed.

Leave it be .......keep an eye on the areas of the plenum were it squares off, material is thinner.....it is easy to fix. Also don't worry about nicking the fuel Inj O-Rings normal

[Torchred96]

Thanks Lgaff. I'm looking forward to doing this, but I'm kind of glad I don't have all the tools at my disposal yet...I tend to jump in and ask questions later.

[LGAFF]

You need a grinder: Harbor Freight $39.00
Carbide Bit, no more that 4" if using HF die grinder
Speed controler....if you run the bits at wide open they whip and bend
3/4" to 1.5" flap wheels 60 grit
WD-40 or lube
Rubber gloves
Something to hold IH in place, I use a fireplace hearth with bungee cords, work well and lets shavings drop down
Fooseball with string attached to it
Good vacuum as its messy, very messy
An even better Divorce Attorney when she gets sick of the noise and mess.

[Torchred96]

Thanks again Lee for all the information. I bought an ebay set, Neiko 8 piece double fluted usa standard set of burrs, flap wheels 1x1x1/4 80 grit qty 20 and a grinder that looks very similar to the makita ge0600 but is not labeled as such..again from ebay. All together about 100 bucks added to my paypal :(

I plan to practice on a honda h23a intake manifold until I get the hang of it. If I butcher that, I will just call it a day and put my lt5 back together as is. Taking it off at a later time should prove to be pretty easy after the mods I am doing (coolant/spt) to send it out to have someone do it for me.

[LGAFF]

Its not rocket science, you can't really butcher it.....just don't start it up at 25K RPM...... have some kind of speed control

http://www.harborfreight.com/router-speed-control-43060.html

[HAWAIIZR-1]

I would consider farming this out to one of the pros builder/tuners if you want to ensure it is done right. I ported my own IHs and plenum and found it was not worth it, but just me. I ended up gettig everything full ported in the end by Greg Van DeVenter who has done more of these than we can count. There are very capable folks here that have done their own and who knows the exact difference better the work of everyone. I was on a budget and trying to save bucks and in the end, did not but that was just me thinking I could do the work to satisfaction.

Here is a sample of some prices few years ago for thought and keep in mind that if you open up something, you will need or want to open up something else for the full benefit hence why I went all the way:

Port and polish Left hand cyinder head.
Dis-assembly, cleaning and re-assembly of cylinder head assembly including,
Secondary port inlet valve system cleaning and adjustment.
Polishing and back cut on intake and exhaust valves. $600.00


Port and polish Right hand cylinder head.
Dis-assembly, cleaning and re-assembly of cylinder head assembly including,
Secondary port inlet valve system cleaning and adjustment.
Polishing and back cut on intake and exhaust valves $600.00

Port and polish L.H. Injector housing ports $ 300.00

Port and polish R H. Injector housing ports $ 300.00

Port and polish, plus open throttle body bores to 63.5mm $400.00

Bore Throttle Body secondary inlet valves to 63.5mm
and replace blades w/ 63.5mm Brass blades .062” thick $300.00

Machine 1990 exhaust guides and install your new seals. $100.00
.
Open up secondary bores to 63.5mm plus contour and polish inlets $50.00

Mill Cylinder head decks (set) $100.00

Polish cylinder head combustion Chambers (set) $100.00

All Prices includes return shipment in continental U.S.

[mike100]

I did mine in 3 or 4 days and I didn't even go very big with it. You can basically use the hole center on both ends as a guide and if you only go about 34-35 mm you won't be getting into the thin spots.

--I left the secondary outlets the stock size- just massaged the radius leading to them.
--Like Paul W's pics, I did port into the 8 primary head opening about an inch and a half down into the port because the new bottom hole size on the inj housing was 34-35 mm.

--I just opened up the plenum ports to match and took off material all around to make the inside radius shorter and to alleviate the constriction there- not really scientific- just duplicating what has been shown on this website by others.
--My hands were real sore after each session. I used an air grinder- a $150 rubber coated Snap-on one I bought years ago- very decent valve that allowed good speed control.

I scribed the new circles I wanted using the new gaskets and machinists blue to see where to grind to. I didn't go too crazy with trying to get the full 36 mm in the middle, but you if you compare the old ports to new after the work, there is a much straighter shot and more volume afterwords.

I wish I could legally run headers where i live because i know that with the porting and chip I have, it would lend to better than average gains, but even with stock manifolds, there will be more pull over 5000 rpm ported.
I spent about $100 on supplies including the bottle of machinists blue (still have tons left) and longer carbide bits. Your regular length grinding bits will be only good for the very outside areas near the mating surfaces.

[mike100]

stock:
http://i29.photobucket.com/albums/c265/mschrameck/Cars/secondariesclean-1.jpg

ported final finish (not crazy, just bigger):
http://i29.photobucket.com/albums/c265/mschrameck/Cars/IH_small_1.jpg

Matching the primary head port (intake valve closed w wd-40 soaked towels stuffed under work):
http://i29.photobucket.com/albums/c265/mschrameck/Cars/makingamess.jpg

done:
http://i29.photobucket.com/albums/c265/mschrameck/Cars/port_match_1.jpg

fitting injector housings to clean up + final port matching/finish work:
http://i29.photobucket.com/albums/c265/mschrameck/Cars/test_fit_IH.jpg

After internal pressure washing, this is how I got the rest of the chips and oil out of the plenum (not married):
http://i29.photobucket.com/albums/c265/mschrameck/Cars/plenum_wash_sm.jpg

I'm not sure I'd do this job again unless I gave myself 3-4 weeks to do it. I did this job in about 4-1/2 days total. I did injectors at the same time.

[rhipsher]

Hahaha! That fits in the dish washer perfectly.

[sammy]

hey rick why don't ya share the pic of what your bathroom looked like when you were porting yours .(just having a little fun with ya )

[rhipsher]

hey rick why don't ya share the pic of what your bathroom looked like when you were porting yours .(just having a little fun with ya ) Oh yea! I almost forgot about that. My wife was f@#%ing pissed. She got over it though after a dozen roses and a Swarovski charm bracelet. That did the trick. Lol!
http://i301.photobucket.com/albums/nn63/keeno1970/18.jpg
http://i301.photobucket.com/albums/nn63/keeno1970/17.jpg

[Paul Workman]

The cutting/sanding itself is not too difficult. But, as flyin ryan says, you have to follow a specific, well thought out and proven design/plan less you become a "carbide cowboy" and venture into uncharted territory. :confused:

Lots of ways to skin a cat: some work better than others, and those that work real well are held close by those that paid the price getting there...and the LT5 is a pricy "mule" to experiment on.

A few pix o portin!

Plastic shower curtain over the engine bay to do (the head) port matching in place. (Using a 4% taper, it came out to a 3-1/2" cone to transition properly from 36mm (at the time) to stock (~33.5mm) at the guide.) The secondary (stock) side on my 90 had an abrupt transition just below the SPT plate from 36 to 33ish over maybe 1/2". SO! both got "the treatment", only it was 1/2 the work doing the secondary side. I used Pete's balls - one being 35mm and the other being 36mm - as gauges.

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/IH7Large.jpg

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/ZR-1008.jpg

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/IH3Large.jpg

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/porting10-22-11025Large.jpg

I used WD-40 as a lube to keep the burs from loading up and to speed the cutting. It worked quite well, in that regard. The problem with that stuff came to light when running into trouble a year later - when porting the heads.

I had to have a leak welded and re-ground. Aluminum is very porous and the WD' contaminated the aluminum, making a minor repair into a major chore! I switched to some lime green stuff recommended by my tool supply dealer (forget the name of it just now) specifically recommended when working aluminum.

[Torchred96]

Lee, I ordered all the goodies now, except for the fireplace hearth.. In south florida, those are as rare as an LT5. :) Might be able to find a cinder block though. Thanks again. Been following your LT5 build lots of interest. good luck with getting the hickups worked out.

Hawaii, Glad you posted those prices in this thread. If I am going to farm it out to someone,I'll be putting the whole thing back together and waiting till funds become available.

Paul, Rhisper et al, Excellent information. Thank you all for your input. I havent been able to read through the whole thing yet but I am going to start looking this morning.

Keep the pictures coming too with captions. Sometimes a pic says a lot but it says so much more when you know the story behind it.
Glad to see some of you have matched the heads in place. I was thinking that with a little creativity, it could be done safely...I see I was right on the creativity part. :)

Thanks again.

[Pete]

If you can find a 35mm ball bearing works best for me.
Rick, needs to make some of these 35mm,36mm balls.

I use a drop light on the oppisite side of the IH to see where the ball is touching to know where to port.

Take your time go slow.

Pete

[lbszr]

I don't remember where these pics came from, but this was the style I followed and ended up with 395 rwh as compared to a stock ron fellows c6 zo6 on the same dyno getting 435rwh, so I was pretty happy.

I found it easier to remove the divider with constant results from runner to runner, the bors were also enlarged, but I never reached 36mm. I quit at 50 hours of grinding, (not counting blending the heads to match the IH) with more left to do. The die grinder bit I used was specifically for aluminum, had 7 spiral flutes, did not use a lube and it was still cutting good after 50 hours with no clogging.

http://i188.photobucket.com/albums/z41/myphotos123456/Nicks120036resz.jpg

http://i188.photobucket.com/albums/z41/myphotos123456/DSC00007.jpg

[mike100]

I did mine at work after hours and over the weekend because it was easy to sweep up the shavings, plus we have a corner area used for drilling and cutting with a vac, air, and a vise etc. It also helped a lot to have an outside air compressor that won't make you go deaf.

I still managed to track aluminum shavings into my car and home, but like I said, I would be hesitant to do this job at home unless it was in an area where you could close off and maybe change shoes before you walked back into your residence. Only gear oil fragrance stuck to your clothing and in the house is worse than this job.

[Torchred96]

This is great, informative and exciting too.

Ibszr, is your engine stock displacement? What is the purpose of dropping the bifurcation on the injector housing down and then knife edging it? I mean, does it make a difference if it is left flush with the gasket surface? How far down is it from the gasket surface, hard to tell from the pic because it's straight on.

Paul, when you talk about taper, does that mean 4% per inch using 36mm as the starting number? I'm not too quick on the uptake, sorry.

[rhipsher]

If you can find a 35mm ball bearing works best for me.
Rick, needs to make some of these 35mm,36mm balls.

I use a drop light on the oppisite side of the IH to see where the ball is touching to know where to port.

Take your time go slow.

Pete I should have made 10 of each size at that time 35 36 & 37mm ball gages. It would have been so easy at that time. Corey also needs me to make him 10 sets of aluminum plenum spacers for the drop forged plenums. Im going to schedual it all in so all of this stuff will be available for everybody at a reasonable price.
http://i301.photobucket.com/albums/nn63/keeno1970/imageCAP39JGW.jpg
http://i301.photobucket.com/albums/nn63/keeno1970/imageCAH2QHZK.jpg
http://i301.photobucket.com/albums/nn63/keeno1970/Picture054.jpg
http://i301.photobucket.com/albums/nn63/keeno1970/5.jpg

[mike100]

^^^ sick! I need to become friends with a machinist. I had to go to a 'Billiards and Barstools' store and buy a 35mm foosball. I threaded a long 1/4-20 bolt into the end of it.

[rhipsher]

^^^ sick! I need to become friends with a machinist. Now you are.:mrgreen:

[Paul Workman]

This is great, informative and exciting too.

Ibszr, is your engine stock displacement? What is the purpose of dropping the bifurcation on the injector housing down and then knife edging it? I mean, does it make a difference if it is left flush with the gasket surface? How far down is it from the gasket surface, hard to tell from the pic because it's straight on.

Paul, when you talk about taper, does that mean 4% per inch using 36mm as the starting number? I'm not too quick on the uptake, sorry.

Taper length = (Larger-Smaller)/4%

Taper length = (36mm-33.5mm)/.04 = 2.461" (min)

It was about 3.5" to the guide, and so I ran the taper a little longer - to the guide boss.

The results were stunning, even with the stock exhaust on it. It transformed the characteristics considerably! Just doing the top end was very well worth it, IMO.

P.

[lbszr]

This is great, informative and exciting too.

Ibszr, is your engine stock displacement? What is the purpose of dropping the bifurcation on the injector housing down and then knife edging it? I mean, does it make a difference if it is left flush with the gasket surface? How far down is it from the gasket surface, hard to tell from the pic because it's straight on.

Paul, when you talk about taper, does that mean 4% per inch using 36mm as the starting number? I'm not too quick on the uptake, sorry.

It's stock, stock cams are degreed to 93-95 specs, but at the most from what I've read that is only good for 10hp, but it will carry the power band higher, and headers. It had 360 before the port with a Marc Haibeck tune on the dyno. It has not been tuned with the port, just fuel added.

The IH are blended down .5 inch from the gasket at the farthest point. I don't really know why to blend it down, but it seems from a aerodynamic point, part of the edge is a downslope for the air to slide down, as compared to a straight edge that the air needs to cross all at once, instead of gradual.

I always wanted to see what would happen from removing the rest of the divider in the IH and taper the head like the IH are after seeing what was planned on the lt5 for 1996. It was suppose to only have 8 fuel injectors. I've seen pics of them totally removed, but only on the bigger cubes.....except for this one.

http://i188.photobucket.com/albums/z41/myphotos123456/IMG_0822.jpg
http://i188.photobucket.com/albums/z41/myphotos123456/IMG_0816.jpg
http://i188.photobucket.com/albums/z41/myphotos123456/IMG_0817-1.jpg
http://i188.photobucket.com/albums/z41/myphotos123456/IMG_0825.jpg
http://i188.photobucket.com/albums/z41/myphotos123456/IMG_0821.jpg

http://i188.photobucket.com/albums/z41/myphotos123456/IMG_0827.jpg

[Torchred96]

very interesting Ibszr, so you say there are some examples of larger cube lt5's running around with 8 injectors instead of 16.

Hmm.. this begs for the search button and possibly another thread... thanks

[lbszr]

very interesting Ibszr, so you say there are some examples of larger cube lt5's running around with 8 injectors instead of 16.

Hmm.. this begs for the search button and possibly another thread... thanks

I haven't seen one with 8 injectors, just thought that was an interesting part of the 96 model.

Removing the dividers all the way down to the heads is what I don't recall seeing done on a 350ci, but have seen posts on the bigger cubes. I don't know if it could make lower rpm suffer on the 350. Removing the plenum divider didn't seem to affect the lower torque range on mine, but gas mileage went down, or that could be from the secondaries missing.

Maybe somebody remembers.....but I think the 96 version was going to have varable valve timing also.

[Paul Workman]

Yeah, it just slays me to think of what the LT5 development may have led to, had the program been allowed to continue. :cry: Big inches, VVT, direct injection, supercharging, 8000+ rpm range, 1200+ hp... Naaah. [-X THAT would never sell.:rolleyes:

Can you imagine what the 1997 C5/LS1 sales would be up against with 475 hp DOHC predecessors lurking around? Mr "134" (for one) shines a bit of light on what might have been. Pete's car too, and all of the "500"s on stock cams that idle as tho completely stock, for that matter, are shining examples of the potential left untapped when moving to the throw-back (LSx) platform.

Sorry for the rant...It's one of my pet peeves.

P.

[Pete]

Rick,why can you make more ball's? Did you loose the recipe.

Make 35mm and 36mm
37mm is not for most DIY'rs

Pete

[Torchred96]

I'm about 90% done with porting the plenum and IH. For you guys who do this on the side, my hat is off to you. This is a LOT of work! My hands are DONE!

I broke up my grinding into mostly 2 hour blocks. It also helps in that it keeps the eyes fresh. Used mostly a 5/8 burr that Paul mentioned in one of his posts. When I first started, I was using a cylindrical burr, flat at the top and it really was the wrong choice so I had a lot of cleaning up to do in the curves of the plenum. But it came out okay.

I still have the sanding to do and the heads are going to get the first inch or so matching the IH, (heads on the car).
Lastly, My work doesn't look anywhere near as nice as what others have posted here, but I think it will get the job done. It's amazing how much a couple mm's make in diameter!
I'll post the ball size I used for reference later. I don't recall it's size off hand, it was what I had on hand.

Thanks for all the tips!! I hope it works now :)

[LGAFF]

Flap wheels make the difference, remember smooth is not important..too smooth build a dead zone near the runner wall and actually hurts flow....

[mike100]

To be fair, I posted my prettier bores, but yeah-I'm not going to be competing with Lee or anybody else- probably 30-40 hours of work including putting it back together and my hands hurt after a few hours.

surprisingly the head port match went very quickly, especially once you have developed a technique with the burr and grinder. It took about as long to rotate the engine 90 degrees 8 times to close the valves before getting to work on that cylinder as it did to cut it.

Now if I could just get headers and realize the potential of the work.

[Torchred96]

Thanks Lee. On the first couple ports on the IH, I did what I thought was right and made a complete mess. I was actually considering boxing it up and sending it to one of you guys to fix for me....then, I took a flap wheel and smoothed it out. To my surprise that one botch job came out pretty good considering it was my first, and it gave me confidence to go on knowing I could do better on the next one.

:) Mike, you won't be seeing any picture of my "rough" work. My finish work mght compare to some of the rough pics I've seen. This is definitely a learning process and I've gotten better. I'm getting impatient though, so I had to stop for tonight.

Tomorrow, I'm gonna go over all the holes, plenum and Ih with the big burr, smooth it out as much as possible. Then scrutinize more and finally check the gasket one last time to make sure I matched okay. At some point I guess I'll have to say "good enough" and put it back together.

I'm wondering if I should paint it now or get it running first, then disassemble and paint or PC since it might have to come apart again. Thanks all.

[Torchred96]

Hey Mike, in regard to rotating 8 times. I was thinking that there might be more than one cylinder with the valves closed, eg, when one cylinder is on the power stroke, maybe another would be on compression???

If I can find out for sure, it might make it less tedious.

[mike100]

you can look up the valve adjusting procedure for a sbc and work alternate pairs of cylinders, but the reason i did it 8 times is because
1) it is not really that hard to spin the engine over once you get the right wrench and socket on the crank bolt (you can pull the plugs if you really want to).
2) The way I masked off the engine top with towels and paper, tape and whatever to catch the grindings was such that i had to finish one side before redoing it all over to work the other side...so a clever use of the firing order was kind of out the window.

[Paul Workman]

I've used both the 'lectric and the pneumatic grinder, both straight and with a 90 degree head.

My favorite (by far) turned out to be the straight, Snap-On pneumatic due to the light weight, power at low speed, AND instant speed control.

A trick I learned from Marc was to drape the air hose over my shoulder, and grab the tool with one hand gripping above the other - like holding a baseball bat. While locking my elbows, I rotate my hips in a circle, rather than my arms or wrists. As result, the amount of material removed with each rotation is uniform around the circumference and maintaining "the line".

After some practice, it was easy to get into a combination of speed, and pressure that made for smooth, efficient, and accurate cutting.

Because the snout on my particular grinder is long and narrow, I was able to use the bit with the shorter shank - the 5/8 single fluted "football" with the 2-1/2" shank - for like 90% of the work. The long snout allowed me to reach down inside the runners - affording good control while maintaining higher working speed.

Marc uses those big aluminum carbides that have something like 6-8 flutes. Man, you should see the chips fly when he's doing some porting! I have a couple, and tried one a little. maybe for a man that does it for a living, and had as much practice as Marc has, one can get away with using those bits. But, for us mortals, the old warning "don't try this at home!" is good advise, methinks!;)

One burr I would have liked to have had was a 1" ball like the one locobob uses. I can see how it would very useful, especially in doing the large radius bends.

I enjoyed the project, and really like the results!!! But! I'm glad to leave that one behind me. If one is conservative, a pretty good lift in performance can be had w/o getting into trouble. But, if you're a "no guts, no glory" kind of guy, very few have gotten away without having to have a bit o' welding done to fix an "oops" or two. As Marc told me once, "If you don't break through at least once, :censored: you aren't trying very hard!";) Just be sure to arrange to have a skilled welder guy handy.

P.

[Torchred96]

Thanks for all the information guys...


So much for my plans for the other day. Things just aren't going as planned.

At that point, i had only the bottoms of the IH's to finish up. Thinking that this part would go quickly, i didnt even mention it above. Getting back to work, I turned the ih's over and placed the new gasket over the top and lined up the bolt holes to see how far i'd have to port match the bottoms (head mating surfaces). I thought this part was going to be a quick 5 minutes per hole job. To my surprise, the primaries were way off. I mean, not just smaller which i already knew, but if one point of the gasket was tangent (gasket bolted down) to the port on one side, the opposite was off approximately 1/4 inch. The secondsaries were all pretty close though. So, then i thought it might be the gasket. Got the other gasket from the box Jerry sent me and...same thing.

How could they be cast so far off? I saw a post that Jerry used the original drawings for the gaskets and i think even he was surprised how far the castings were off...but, the question i have for you guys is how does this happen in a motor that's touted as precision built this, machined to microtolerances that, and hand assessmbled etc etc.

or am i just plain doing something wrong....a more plausible explanation.

[Paul Workman]

Thanks for all the information guys...


So much for my plans for the other day. Things just aren't going as planned.

At that point, i had only the bottoms of the IH's to finish up. Thinking that this part would go quickly, i didnt even mention it above. Getting back to work, I turned the ih's over and placed the new gasket over the top and lined up the bolt holes to see how far i'd have to port match the bottoms (head mating surfaces). I thought this part was going to be a quick 5 minutes per hole job. To my surprise, the primaries were way off. I mean, not just smaller which i already knew, but if one point of the gasket was tangent (gasket bolted down) to the port on one side, the opposite was off approximately 1/4 inch. The secondsaries were all pretty close though. So, then i thought it might be the gasket. Got the other gasket from the box Jerry sent me and...same thing.

How could they be cast so far off? I saw a post that Jerry used the original drawings for the gaskets and i think even he was surprised how far the castings were off...but, the question i have for you guys is how does this happen in a motor that's touted as precision built this, machined to microtolerances that, and hand assessmbled etc etc.

or am i just plain doing something wrong....a more plausible explanation.

Even with some "core shift" between castings, assuming the port on the primary side is approx 33mm ± .5mm (.020"), 36mm-33mm is only .118", NOT .25"!

I suggest you cut back on the rum in that eggnog and measure that again. ;) Far as the skew goes, you can reduce it slightly by taking a little off of the tangent side.

Not a good photo, but you can see the web between the runners is a bit thinner than stock - resulting from skimming a bit off of the tangent side of the primary to reduce the overall skew, just a tad. As result, the gasket may require a little trimming when you're done.

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/IH4Large.jpg

The outlet side of the IHs is no 5 minute job. The large radius needs to be blended to reduce the otherwise angular transition to the head. And, the transition from the relatively straight runner above the injector, around the injector, and into the curve and exit below the injector is going to take as much time to do as it took to do the entire length of the runner above the injector...or at least it did me.

This photo is an example of what you don't want to see at the IH/head transition. It's hard to see in this photo, but the IH/head junction has an angle transition - which is not a good thing. Locobob had some pretty good pictures showing where he pins the IH to the head to radius the junction - blending the head with the IHs. Hell, you could barely see the joint, up until the gasket was installed. (I've since gone back in and reworked that area. It B much mo bettah now!:thumbsup:)

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/ZR-1007.jpg

If you have some pix, it would help us understand exactly what you are talking about.

:cheers:

P.

[Torchred96]

Shift key is acting up so pls forgive the typos.

phew, im glad to hear it's not supposed to take five minutes...because I spent at leat 20 minutes per port...and i'm not close to being done. yes, i did notice that the large radius needed to be straightened out. i am glad you mentioned it because i was wondering if maybe I was going too far by doing so.

:) Well, no paul, power tools and eggnog don't mix, but i will admit to exaggerating the distance a bit. i would have expected it to be off from the gasket, but just eyeballing it, it does look like more than you would expect a factory tolerance would allow given the pedigree...no?

i had thought about taking a bit off the opposite side, but i was afraid that the gasket was where it was suppose to be and if i cut the opposite side, i would be doing that cowboy thing you spoke about earlier. i did find it necessary to do a little bit because otherwise it wouldn't have been round.

Thanks paul. i do appreciate your comments and thoughts. youve been very helpful.

[mike100]

I kept the secondary side the same size and mine matched up fine, but there was a little core shift on the primary and you could see the bevel factory port-match was sort of less than perfectly centered. I scribed the ports with the gaskets Jerry sells and cut the bottom of the I/H to that size. The head inlets then needed to be massaged to blend to that, but the material removed was all on one side more than if it was concentric.

[Torchred96]

Yes, mike, that's a better description than what i said, but essentially, that's what i had. The secondary matched almost perfectly, the primary biased to one side (outlet end).

i have one more hole to do, then, I am going to sand. Hopefully, I will be proud enough to show my results. Right now, i'm not so sure.

At least I haven't broken through so all the damage is on the inside ;)

Thanks for the support guys

[Pete]

Nice.
That is awesome to see you guys porting your Z's. :thumbsup:
After all done you will be proud of her and yourself cause you did the work.

I think all Z's should get the top end porting,best upgrade for the LT5.

Pete