I had a vision in the night. In the course of my fitful sleep, I was visited by an entity. Formless and empty, this absence of being was devoid of tone, feeling, or impression. It was defined by nothing, save the message it had been charged with delivering to me.
I woke with no regard towards how little time I had spent resting through the six hours of sleep, and words fell from my mouth.
"Fuck. I'm gonna have to get Helicoils."
Discovering you need Helicoils for a task is like going to an old man who's spent more time fine-tuning his craft than you've even been a member of the "things residing on Earth" club, asking him his expert opinion on what to do for a given situation, and waiting as he silently leans back in his chair. After his feels-like-hours pause, he dryly opens his mouth. Following the sound of his lips cracking apart you hear,
"Well. . . I've got an answer for ya, but you're not gonna like it. . ."
The base plate that fastens to the adapter plate provided in the Redline Weber kit for the AMC 258 is made of some flavor of cast aluminum. The cast part is okay-ish. Not bad enough to be bad, and useful enough to not totally hate it. The problems with it seem to stem not so much from the casting process as much as the lack of obvious finishing work done once the part is demolded. The biggest pains in the ass I've had from working with it have all been directly related to the threads in the holes for the mounting studs.
While some grades of aluminum can provide threads that can withstand the torque needed to secure a carb to an intake (not to mention the stress of thermal expansion and contraction delivered by engine operation and cool-down periods), the mystery meat used to make these plates doesn't hold such a distinction.
I guess whoever was calling the shots figured "Why bother?" when determining manufacturing and QA processed for these parts, since the quality of the threads themselves are about as up to the task as the material. And to clarify: I've been heckled on more than one occasion for my insistence on taking great care to make sure fasteners are torqued appropriately. Like anyone else, I've stripped, broken, and rounded off my share of hardware, but it's not because I'm a reckless mongo that hamfists every threaded object I come in contact with.
The entirety of yesterday was spent doing the finishing work on a roughout of a phenolic spacer that's needed to give some clearance for linkage components, and to make sure the carb isn't just dumping fuel onto the floor of the intake from being too close. The phenolic is some sort of horrible shit used to make lab workbenches, and can be a serious bastard about being worked in some respects. So as I'm sure you know, I fucked up parts of it that will let it be alright to use with break-in, but doesn't really belong on the road.
The spacer is relevant here because I hadn't (and haven't) reached the point of even trying to install the carb to the intake before three of the threads were stripped. It was the stress of dry fitting the plates to the carb and torquing the bolts only as much as required to confirm things lined up that was too much for the plate to handle.
As I made my way back to the house, I thought I would be fine sticking a bolt in the holes and flowing alumiweld into the gap to recreate the threads. I had been up for 30 hours at that point, so cut me some slack. It was a terrible idea, and it took me having The Ghost of Fuckups Future visiting me in my dreams for me to realize why.
I think alumiweld is kinda neat. Not a bad thing to have around. Kinda limited in its range of use, though, and a little fussy compared to brazing ferrous metal. It's not really up to the task of flowing through passages as narrow and having as long a run as the mangled crap in the bolt holes without ending up as porous as spray foam. It's also not an enchanted glue stick that will magically ensure a bolt will sit and remain centered in the worst of the three points that needed attention.
The idea of having the threads give out for good while on the road was entirely unacceptable, so these threads needed to be fixed for good. That meant threaded inserts. The piss-poor supply of this kind of thing in a storefront here means the threaded inserts were going to be Helicoils.
After looking for a kit that I could buy for less than $30 (and failing), I got my kit and went to the shop. It was at this point that the bad points of the baseplate really got their chance to shine.
Depending on the location, material, drill size needed, and so on, I'll use the original fastener to fully strip the threads out and then turn a drill bit by hand that's equal to the thread diameter to clean up before tapping. The reasoning behind this is that doing this will prevent me from making a bigger mess by drilling a drifting oval hole. If I take my time, pay attention, and use good cutting oil when tapping the hole, the tall should be good with cutting through the extra material. This should result in a clear, straight, threaded hole. After today, I say "should" and not will.
For whatever reason, the godawful threads don't run completely through the bore. There's a gap about 3 threads thick towards the bottom surface of the plate that interrupts the run. It's this gap that gave my tap a chance to get distracted and wander off. The result? Two holes out of four are straight through. The other two were so bad off that I had to get the easy out to extract the Helicoils, and then fill the holes with alumiweld so that I can drill new holes and start over again.
So to be perfectly clear, I went to go install the carb two days ago and am hoping that tomorrow doesn't end before I actually get it on there. Here's hoping for a spirit-free sleep. I don't need any more wise ideas.
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