Thursday, June 29, 2023

Exhaust Really IS Exhausting...

Yes, I'm slow... Yes, I'm detail-oriented (nitpicky)... but this exhaust job still took me three days to complete--even with the bed off. Well, to be honest I smoke a lot of weed too, so things get analyzed and measured lots of times for the sake of accuracy.

The easiest part of the job was taking the old headers off. I don't know what they were originally designed for, but they didn't appear to be for a GM pickup. The tubes snaked fairly closely to correct, but the collectors were way too low. I guess they were something the previous owner had laying around or something. I don't like headers. Unless I'm racing, the last thing I want to do is make more under-hood noise, and deal with spark plug access (or lack thereof). The exhaust on this truck took such a wild turn downward to mate up with the header collectors that I had to saw both of them off before I could pull the rest of the exhaust system out. Once I could get it all off the truck I scavenged a few choice straight sections in case they might be needed.


With no headers in the way, I was finally able to remove an old temperature sensor from the driver's side head. It had been broken and mangled at some time in the past but left in. Maybe cheaper than buying a brass fitting to plug it? Apparently so. I couldn't remove it before because the hex on the outer casing was hitting the header flange (barely visible in the picture below) and wouldn't allow it to turn. This time it got a nice, new brass plug.



It was also the perfect time to replace the oil dipstick and tube. The previous owner used what he had around I guess, but they were both wrong. I believe they come from a early 90's Camaro or similar. It was the perfect time to install (with a tad bit of custom bending) the new one I had just gotten from Summit. Now the tube bracket aligns with the bolt hole so it could be bolted in like it should have been.

Here's where the job took a 2-day detour: Motor mounts.

With the exhaust out of the way I would have been a fool not to replace them--they looked original. After taking the spark plugs all out the whole area was nicely exposed. Getting the mounts out was easy enough, but it's not for everyone unless you've got a decent assortment of tools to get those lower mount bolts out. Once I got the tools needed all figured out it was just a matter of taking my time. These are jobs that can get frustrating real easy if you're in a hurry. Anyway, it took the rest of that day and most of the next before I figured out the optimum way of getting all the bolts lined up. The initial struggle was with the final long thru-bolts. I just couldn't get the mounts to line up well enough to get them to go through. The secret ended up being to put only the lowest two of the 3 lower mount bolts in, (leaving the the mount to flop), and putting the long thru-bolts in. At that point, the mounts are lined up nicely, but tipped up off the frame. The bolts drew them down perfectly.

Back to the exhaust.

My original plan was to use standard GM exhaust manifolds. I bought myself a used set, knowing they needed flange bolts drilled and re-tapped. I started in on the process one day and said to myself, "You dumbass--what are you doing this for? You've got money--buy the ones you really want!"


My updated plan: Hooker exhaust manifolds, continuing 2.5" through an H-pipe, into 2.5" Magnaflow 18" (the longer, quieter ones) straight-through mufflers, reducing down to the 2.25" OEM tailpipes already on the truck.

I had bought the Hooker exhaust manifolds a month or so earlier, and so had plenty of time to ponder them. I was a little concerned with them having unique, 2-bolt flanges, and I wasn't sure exactly how to tie things together. To ensure fit I decided to buy a pair of Hooker head pipes designed to bolt to their manifolds. Well, I didn't do my homework very well, because they definitely didn't fit. Come to find out they were designed for an LS engine conversion into a squarebody truck. At first I was pissed at myself because I'd have to return them and find something else, but then I thought, "Hell, even if Hooker made just plain flanges with a short length of straight pipe they'd probably almost the same price" so out came the saw. I only ended up using the sections of straight tubing attached to the flanges, but I'll keep the rest anyway of course. It's a nice O2 bung on each one of nothing else.



Being the worrywart I am, I had to keep thinking about fit as I went, as well as being able to remove the crossmember afterwards. The H-pipe came from Summit as a kit, and went together nicely. It came with a straight section and a V-section to give more fit options. I went with the V-section to help go around the driveline. I had to browse the local O-Reilly's and Autozone (luckily right next to each other) for exhaust pieces to complete my jigsaw puzzle. I did several mock-ups as I was spot-welding the joints, finally removing the whole front section to weld it up:



Because of the crossmember design, I had to go with one side under and one side over, so I was very concerned with clearances. I did lots of bracing, jacking, prying, etc. When all was said and done, I think I got it tucked up fairly well:


Because I'm kind of a "one-man band" I didn't have a helper to hold the muffler as I went, so I cut a few rings and tacked them inside one end of the muffler, giving me a "insert" to assist holding it onto the pipe while I fussed at the other end. It worked out well. I can't imagine doing exhaust work without the bed removed. That really made the difference. Here's everything finished. I sure do love the new sound. 



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