This is part 3 of many in Limitless’ engine build. – be sure to check out the rest of the posts there. Doug and Dougie at Competition Automotive are *awesome*. Without them, this build wouldn’t be possible!
Intro / Background
Ok, so we’ve planned our build, and we’ve picked out our parts. Surely it’s time to start putting things together? Not quite! A few things need to be done to fully prep the engine for assembly – almost always to the block, and occasionally to other stuff too. For this, you’ll need a machine shop. This is the one part of the build that I can’t do myself – but it’s important to note that a good machine shop will do far more than just the machine work, and a bad one will be truly awful.
As some people already know, or have heard me alluding too – this is actually engine number 2. What happened to engine number 1? I dropped it off at a shop to have some basic machine work done, and over a year later, they admitted they’d messed up and destroyed the engine. They did the right thing and paid me in full for that engine…but I still lost a year of time. So for machine shop number 2, I really did my research. Starting with a google search (performance shops are a rare breed these days!), I narrowed things down to shops that had both performance and marine experience. Then I sent them an endless number of e-mails asking for quotes and advice and all sorts of crap…effectively trying to be as difficult as possible. Through it all, one of them stood out among the rest, and having now worked with them, I cannot recommend them enough. Huge shout-out to Doug and the team at Competition Automotive!
Why do I need a machine shop anyways?
Well, it depends. In almost every case, you’ll want them to clean up your block, refresh the surfaces, and check all of the tolerances. In my case, I also wanted them to fully balance my rotating assembly so that it was internally balanced, and do a bit of modification to some key dimensions. In no particular order, here’s all the work I had done, and why:
Cleaning
You need your block cleaned. You’ll clean it yourself anyways, but it’s important to get the shop to do it first because it can never be too clean, and they’ve got better tools and chemicals than you.
Bore / Hone
I wanted my cylinders bored 40 over (they were already 30 over and I wanted to save 60 over for down the road), with a torque plate, and then honed to spec for my pistons and rings. Using a torque plate (a big thick plate that you bolt to the block to simulate cylinder heads being bolted down, which can distort the cylinder shapes) is recommended for higher performance builds. If you’re using new rings in a rebuild or new build (and you should), then you have to hone the cylinders. Otherwise the rings won’t seat properly and bad things will happen!
Mains Hone
The previous owner of the block recommended it because they’d spun a bearing. It’s also affordable as heck. And it ensures that my new crank will hit the correct tolerances needed for my application. Plus, as with decking and cylinder honing, you generally want to clean up all of the machined surfaces of a seasoned block.
Decking
Getting the correct quench distance – how far the piston is from the cylinder head at top dead center – is critical for any performance build, and even for non performance builds. There’s a bit of disagreement over it, but generally I’m on the side that the correct quench (as tight as possible without running into clearance issues) is critically important for promoting power and durability. How often can you, effectively for free, maximize both?! So this was key. I went to 10 thou in the whole (as opposed to zero decking or 5 thou) because that will a) get me in the quench range I want, b) leave room to re-deck to 5 thou down the road, similar to the cylinder boring to only 40 over instead of 60 over.
Internal Balancing
A stock 454 is actually externally balanced. But internally balancing your rotating assembly (pistons, rods, crank) is better for a number of reasons – more longevity, smoother operation, more parts selection, etc. And since I was getting a whole new rotating assembly anyways, it just made sense to get one that’s internally balanced. You can buy them balanced off the shelf, or ready to be balanced. I recommend the second, because I trust a good machine shop more than the manufacturer, the price is a tiny bit better since they’re doing all this work anyways, the lead time is better, and since they’re going to set your clearances anyways, it’s not much more work to get things balanced for them.
Setting and checking clearances
I could have done this myself…but I trust the shop more, they have the right tools, and they’re doing the machining work anyways. It makes no sense to me to bring them the block, ask them to do lots of work, take the block back, measure the clearances, send it back to them to change them, take it back, measure, etc etc. Might as well do it all at once. There are three critical clearances that I got them to set – Mains, Rods, and Cylinder. In all cases, because I’m building a marine engine, I need looser clearances than might otherwise be needed. This is because the engine is run under load at high RPM for extended periods of time – heating things up and causing more expansion. But the block is fresh water cooled, meaning it has to run a bit colder than a car, cooling things down and giving less room for that expansion. So, you need a few thou more clearance for everything. I set my mains at 30-32 tenths, my rods at 28-30 tenths, and my piston/cylinder clearance to 55 tenths. These are all a little bigger than “normal”, and right in line with manufacturers recommendations.
Machinists with Benefits
Having a good shop that you can really trust goes way beyond the actual machine work! Doug @ Competition has helped me source a ton of my parts, and all the little things that you forget about or can’t order online (oil galley plugs, woodruff keys, assembly lube, break in oil, etc) are there for me when I need them. He’s also got a full dyno and is going to help me break in and tune the engine – which is way easier when I’ve worked with him to build it. But most importantly, he’s checked through all of the critical stuff and giving everything the once over. I got a call one day from him saying that he’d found one of the tapped holes for a head bolt in the block didn’t look great to him, so he was going to Helicoil it – for free. Nice! He grabbed my cam and fully mocked up the short block to ensure that my stroker kit would clear everything – the block, cam, the works. He noticed a few of my oil galley plugs were pretty worn and the heads were close to stripping…so he replaced them for me free of charge.
When you’re building by far the most complex and expensive project you’ve ever worked on, the peace of mind you get from working with someone who’s done this for decades, and really knows what they’re doing, is invaluable. I’ve probably called Doug 100 times over the past few months to pick his brain, get his advice, check up on progress, etc. He is always happy to talk, and always able to help. Plus, since my engine is relatively unique, he’s been pretty interested in it – and that’s awesome, and very nice to hear that I’m not totally off base with my selections.
Ultimately, I feel like I got all of this machine work done for free – because I’d gladly pay the relatively minor fee I’ve been charged for having literally everything taken care of, worry free, whenever I need. I’m not sure if I would have had the confidence to do this entire build myself without their help, so I cannot stress enough how important it is to find a good machine shop you can really trust, and make as much use of them as you can! The difference between a good shop is literally night and day…or destroyed engine vs. total peace of mind. So it’s worth really taking the time and doing this step right – the whole rest of the build depends on it!
