[73LeMans]

A few folks have asked me to post the progress of my 73''s partial rebuild here on the board. I don't normally engage in all of this, (how else does one keep post count under 700 in 18 years?) but then I thought about everyone's posts on which I lurk, and how they inspired me to get in the garage when I was less than motivated to do so. I can't say this thread will do that for you, but you can give it a shot and let me know.

Its no Boosted Bandit Build thread (that is going to be awesome!) but its a walk-through of a decent street car that will see the strip a few times a year.

Over the next bunch of days, weeks, etc, I'll post the progress shots of the work I've done and discuss the issues encountered along the way. I'm not one to take a ton of pictures, but hopefully there are enough to keep it interesting. At the very least, you might be able to use this a guide of what NOT to do.


Lets get started -

Back in 2014, I learned roller lifters have a life expectancy. Behold the genesis of their untimely demise:

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https://www.youtube.com/watch?v=EZgVmKz5tX4
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Tip #1 don't do that ^^^

That Summer was the last of any seat time for me. Two weeks later, I heard the engine pop, power went down, and while I was happy to make it the 5 miles back home, the car was not.





Yeah, that bearing took some heat, huh?

Wish I had more pics of the wreckage. The cam was ruined - while lifters gave up all their needles to the bottom end, the rollers were left to grind up the cam. The oil pump was blue in some areas and the windage tray had evidence of getting extremely warm in the pump area. Hard to say if it root cause was lack of spring pressure or if the lifters were just in past their prime. Guess it doesn't much matter.


Since the engine was coming out, this would be the best time to make more power. Early 2015, heads and intake went out to increase overall flow, (mainly exhaust), new cam was selected (4/7 swap), and CR was to increase to 12.5:1. Unfortunately, it was 6 months before those pieces made their way back to me. That put me the end of the Summer for that year. More on those later.

Trying to work in parallel, I turned my attention to the block. Cylinder walls weren't as bad as the pistons, and no major pieces were gobbled up by the bottom end. Re-bearing, turn crank and get new pump - right? Yeah, no.



This was documented in a previous post of mine. Number 3 main cap. Its fracture is not a part of the lifter failure, builder error (me) when putting it on. It happened when I was checking clearances on the bearings.

Tip # 2. Dont put main caps on backwards

Funny thing about those clearances too....they were tighter in the middle of the block (mains 2,3) than they were on the rest. My new engine builder (circle track guy) said its common for Pontiacs to slightly cave in on themselves over time. He said I'd be fine since I wasn't spinning a lot of RPM for any great length of time. It was likely this way for some time as well, perhaps the previous build or longer. Me though? I knew I wouldn't be able to put my foot in without second guessing my decision here. So with the cracked cap and tight clearances, I made the decision to go ProGram 4 bolt splayed mains. I'll leave you with the pics from the machine shop for now.