99 L29 454 build

[Scottm]

After seeing these pics, I think I want to redo the number 1 tube. It's not fully welded yet. I want it to turn up after the steering shaft, then down so it runs parallel to the number 3 tube.

 

[Christian Steffen]

There is a way to get exactly what you want - make it yourself! In this case I used a cheap ebay stainless bbc header for a good head start. I cut each tube off an inch or so from the flange, and cut the tubes off at the collector with staggered lengths to make it easier to reconnect them. I tacked the collector to a plate and clamped it to the crossmember for a fixed target. Here is the modified left side header, tacked up with steel mig wire. Plug access is better and it's more compact than the header was originally. Yes it's ugly! I could have made longer continuous sections with my tubing bender, but I don't have the time or extra material to experiment with. My bender can only make shallow bends in thin material because it wants to kink.

I bought a 6 ft straight piece of 1-3/4 x .049 wall 304 stainless tubing from Mcmaster Carr, and a couple U bends from ebay. It turns out I didn't need the ebay u bends, as the original header bends were enough. I did use most of the straight piece. The tacks were sanded off and the tubes were tig welded with 308l stainless filler and nitrogen back-gassing. Argon is better but a lot more expensive, and nitrogen works fine. The last pic shows my back gas flow meter setup. The next task will be to weld each tube to the collector, which will probably be the hardest part.

Those look like they're coming along well!

As far as injectors go, those should work. Imo ls6 injectors would be better though, then you have factory data for the tune.

 

[Scottm]

Finally got the header (mostly) done. With two of the tubes finished, I could move everything to the engine stand and finish the header on the new engine. I was trying to mate new tubes up to the tube stubs on the original collector, and it wasn't working. So I cut the collector off and cleaned it up for reuse. It's a lot easier to gather the 4 tubes into a bundle, then trim them to be even. I had to make a 'star' with a hole saw and weld it in, then refit the collector. After testing the fit on the truck, I put a slight angle in the collector, then put on a v band clamp with an extra 7 inches of collector with 3" tube. I welded in an O2 bung and took the last pic. Then I realized I still need to weld an egr fitting into the number 7 tube.

 

[Scottm]

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[Piratehunter]

Looking awesome. Great clearance for the spark plug.

 

[Scottm]

Thanks, it fits better than the cheap header did in many ways. Sent you a pm on something else.

 

[Scottm]

Today I worked on the egr connection. I turned the threads off the back of the manifold fitting and welded on a piece of 3/4" stainless tubing. I tacked the tube to the #7 header pipe, but then the header wouldn't go into place in the truck. So I made the egr fitting removable. I welded a stainless 3/8 male pipe nipple to the egr fitting, and welded a stainless half-coupling to the header. It goes in and out of the truck easily now and plug access is still good. While working on the back of the old engine, I found that the old egr flex pipe had actually sawed a hole right through the firewall. I'll post pics of it when I get the old engine out.

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[Supercharged111]

Too bad you weren't closer. I need a friend with a TIG machine.

 

[Scottm]

This weekend started out great when my Comp 01-411-8 cam finally arrived on friday. 212/218 at .050, .510 valve lift, and 110 lobe separation angle. It will run better than the stock cam I had reground at delta, which will be for sale if anyone needs it. I got the cam installed and dialed in at 2 deg advanced. The cam has 4 deg advance ground in, so I set the cam sprocket at 2 deg retarded on the Comp 3149KT to get 2 deg cam advance. They build in the 4 deg advance on all their cams, but not because that's better for power. It's only because they are trying to save us from ourselves when we buy a cam with too much duration.

I went to put on the timing cover and noticed something was holding it up. The crank tone ring was hitting the inside of the cover hard. It turns out the comp crank sprocket is .100" thicker than the stock sprocket, causing the tone ring to hit. The timing set is for a 96-99 gen 6, so I don't know wtf is wrong. I sent comp a contact form, and I will call in the morning. If nothing else, I will mill .100 off the face, though that will wipe out the alignment marks. Dang it something always goes wrong..

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[Scottm]

I am so annoyed with comp cams. The page for the 3149kt timing set says it is not compatible with the factory efi, but doesn't say why. I don't remember seeing that when I bought it back in '21. It also says it comes with a torrington bearing, and that's not true. But it also doesn't make sense for it to work without the efi tone ring. The ring is .200 thick, but the crank sprocket is .100 wider than stock. So running it without the tone ring would need a .100 thick spacer, or the damper would go in too deep. Again, not mentioned. *****!